@article{KleinpeterKoch2012,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Are lithium and sodium salts of N-(2-hydroxyphenyl)-salicylaldimine aromatic metalla-hetero[10]annulenes? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS)},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {14},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  number    = {24},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c2cp40501f},
  pages     = {8742 -- 8746},
  year      = {2012},
  abstract  = {The spatial magnetic properties (through space NMR shieldings-TSNMRS) of the enol tautomer of N-(2-hydroxyphenyl)-salicylaldimine, the lithium and sodium salts in comparison with cyclodecapentaene and pyrano[2,3-b] pyrrole were studied to answer this question.},
  language  = {en}
}
@misc{PihlajaKleinpeter2012,
  author    = {Pihlaja, Kalevi and Kleinpeter, Erich},
  title     = {Professor Ferenc Fulop a tribute},
  series = {Arkivoc : free online journal of organic chemistry},
  journal   = {Arkivoc : free online journal of organic chemistry},
  publisher = {ARKAT},
  address   = {Gainesville},
  issn      = {1551-7004},
  pages     = {1 -- 5},
  year      = {2012},
  language  = {en}
}
@article{CsuetoertoekiSzatmariKochetal.2011,
  author    = {Csuetoertoeki, Renata and Szatmari, Istvan and Koch, Andreas and Heydenreich, Matthias and Kleinpeter, Erich and Fueloep, Ferenc},
  title     = {Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives},
  series = {Tetrahedron},
  volume    = {67},
  journal   = {Tetrahedron},
  number    = {44},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2011.08.074},
  pages     = {8564 -- 8571},
  year      = {2011},
  abstract  = {A new highly functionalized aminonaphthol derivative, 1-(amino(2-aminophenyl)methyl)-2-naphthol (4), was synthesized by the reaction of 2-naphthol, 2-nitrobenzaldehyde and tert-butyl carbamate or benzyl carbamate, followed by reduction and/or removal of the protecting group. The aminonaphthol derivative thus obtained was converted in ring-closure reactions with formaldehyde. benzaldehyde and/or phosgene to the corresponding naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives. The conformational analysis of some derivatives by NMR spectroscopy and accompanying molecular modelling are also reported.},
  language  = {en}
}
@article{KramerKleinpeter2011,
  author    = {Kramer, Markus and Kleinpeter, Erich},
  title     = {A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings},
  series = {Journal of magnetic resonance},
  volume    = {212},
  journal   = {Journal of magnetic resonance},
  number    = {1},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {1090-7807},
  doi       = {10.1016/j.jmr.2011.06.029},
  pages     = {174 -- 185},
  year      = {2011},
  abstract  = {The conformational analyses of six non-rigid N-acetyl glucosamine (NAG) derivatives employing residual dipolar couplings (RDCs) and NOEs together with molecular dynamics (MD) simulations are presented. Due to internal dynamics we had to consider different conformer ratios existing in solution. The good quality of the correlation between theoretically and experimentally obtained RDCs show the correctness of the calculated conformers even if the ratios derived from the MD simulations do not exactly meet the experimental data. If possible, the results were compared to former published data and commented.},
  language  = {en}
}
@misc{KramerKleinpeter2011,
  author    = {Kramer, Markus and Kleinpeter, Erich},
  title     = {A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings (vol 212, pg 174, 2011)},
  series = {Journal of magnetic resonance},
  volume    = {213},
  journal   = {Journal of magnetic resonance},
  number    = {1},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {1090-7807},
  doi       = {10.1016/j.jmr.2011.09.017},
  pages     = {210 -- 211},
  year      = {2011},
  language  = {en}
}
@article{MarsatHeydenreichKleinpeteretal.2011,
  author    = {Marsat, Jean-Noel and Heydenreich, Matthias and Kleinpeter, Erich and Berlepsch, Hans V. and Boettcher, Christoph and Laschewsky, Andr{\´e}},
  title     = {Self-Assembly into multicompartment micelles and selective solubilization by Hydrophilic-Lipophilic-Fluorophilic block copolymers},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {44},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/ma200032j},
  pages     = {2092 -- 2105},
  year      = {2011},
  abstract  = {Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated.},
  language  = {en}
}
@article{PihlajaSinkkonenStajeretal.2011,
  author    = {Pihlaja, Kalevi and Sinkkonen, Jari and Stajer, Geza and Koch, Andreas and Kleinpeter, Erich},
  title     = {1-Oxo-1,3-dithiolanes - synthesis and stereochemistry},
  series = {Magnetic resonance in chemistry},
  volume    = {49},
  journal   = {Magnetic resonance in chemistry},
  number    = {7},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.2764},
  pages     = {443 -- 449},
  year      = {2011},
  abstract  = {1-Oxo-1,3-dithiolane (4) and its cis- and trans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO(4) in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with (1)H and (13)C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=O(ax) envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=O(ax) (30 and 27\%) as well as S=O(eq) (21 and 22\%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of (1)H-(1)H coupling constants and (1)H and (13)C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data.},
  language  = {en}
}
@article{KleinpeterKoch2011,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes},
  series = {Tetrahedron},
  volume    = {67},
  journal   = {Tetrahedron},
  number    = {32},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2011.06.005},
  pages     = {5740 -- 5743},
  year      = {2011},
  abstract  = {Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl substituents are consequently positioned either above the fluorene moiety or in-plane with it; thus, the methyl protons are either shielded or deshielded, respectively, due to the ring current effect of the fluorene moiety. This anisotropic effect on the H-1 chemical shifts of the methyl protons has been quantified on the basis of through-space NMR shieldings (TSNMRS) and subsequently Delta delta(calcd) compared with the experimentally observed chemical shift differences, Delta delta(exp). In this context, the experimental anisotropic effects of functional groups in the H-1 NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between Delta delta(calcd) and Delta delta(exp) were, for the first time, also quantified as arising from steric compression.},
  language  = {en}
}
@article{ShainyanSuslovaKleinpeter2011,
  author    = {Shainyan, Bagrat A. and Suslova, Elena N. and Kleinpeter, Erich},
  title     = {Conformational analysis of N-phenyl- and N-trifyl-4,4-dimethyl-4-silathiane 1-sulfimides},
  series = {Journal of physical organic chemistry},
  volume    = {24},
  journal   = {Journal of physical organic chemistry},
  number    = {8},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {0894-3230},
  doi       = {10.1002/poc.1811},
  pages     = {698 -- 704},
  year      = {2011},
  abstract  = {N-Substituted 4,4-dimethyl-4-silathiane 1-sulfimides Me2Si(sic)S=NSO2R [R- Ph (1), CF3 (2)] were studied experimentally by variable temperature dynamic NMR spectroscopy. Low temperature 13 C NMR spectra of the two compounds revealed the frozen ring inversion process and approximately equal content of the axial and equatorial conformers. Calculations of the 4-silathiane derivatives 1, 2 and the model compound [R Me (3)] as well as their carbon analogs, the similarly N-substituted (sic)S=NSO2R thiane 1-sulfimides [R = Ph (4), CF3 (5), Me (6)] at the DFT/B3LYP/6-311G(d, p) level in the gas phase and in chloroform solution using the PCM model at the same level of theory showed a strong dependence of the relative stability of the conformer on the solvent. The electronegative trifluoromethyl group increases the relative stability of the axial conformer.},
  language  = {en}
}
@article{KleinpeterLaemmermannKuehn2011,
  author    = {Kleinpeter, Erich and Laemmermann, Anica and K{\"u}hn, Heiner},
  title     = {Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions},
  series = {Tetrahedron},
  volume    = {67},
  journal   = {Tetrahedron},
  number    = {14},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2011.02.012},
  pages     = {2596 -- 2604},
  year      = {2011},
  abstract  = {The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions.},
  language  = {en}
}
@article{NeuvonenNeuvonenKochetal.2011,
  author    = {Neuvonen, Kari and Neuvonen, Helmi and Koch, Andreas and Kleinpeter, Erich},
  title     = {NBO analysis of polar and steric effect using the axial-equatorial equilibrium of cyclohexyl acetates as a probe},
  series = {Computational and theoretical chemistry},
  volume    = {964},
  journal   = {Computational and theoretical chemistry},
  number    = {1-3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2210-271X},
  doi       = {10.1016/j.comptc.2010.12.033},
  pages     = {234 -- 242},
  year      = {2011},
  abstract  = {The proportion of the axial conformer increases in the ax reversible arrow eq equilibrium of cyclohexyl acetates (RCOOC(6)H(11), R reversible arrow Me, Et, iPr, tBu, CH(2)Cl, CHCl(2), CO(3). CH(2)Br, CHBr(2), CBr(3)) with the increasing size of the acyloxy substitution. The nature of this unexpected steric substituent effect, which is opposite to general stereochemical concepts, was studied by means of ab kiln MO method, accompanied by NBO and isodesmic calculations. NBO parameters seem to be good descriptors for quantitative prediction of the experimental Delta G degrees value of the title conformational equilibrium. The origin and propagation of the substituent effect of the polar substitutions (CH(2)Cl, CHCl(2), CCl(3), CH(2)Br, CHBr(2), CBr(3)) differ, however, from those of the pure alkyl (Me, Et, iPr, tBu) substitutions. The Delta G degrees value of the polar derivatives depends on the qC8 charges, on the occupation of the sigma(center dot)(C1-07) orbital and on the hyperconjugative pi(center dot)(c=O) -> sigma(center dot)(C10-X) and sigma(center dot)(C10-X) -> pi(center dot)(c=O) interactions. The substituent sensitivity of these NBC parameters for the two conformers differ to the effect that the ax reversible arrow eq equilibrium is shifted to the left side with increasing electron withdrawing character of the acyloxy group. The Delta G degrees values of the alkyl derivatives are interpreted in terms of the calculated dipole moments. The destabilization in the non-polar medium (the experimental Delta G degrees values used were measured in CD(2)Cl(2)) due to the enhanced dipolar character is more prominent in the case of the equatorial alkyl conformers. As the consequence, the ax reversible arrow eq equilibrium is shifted to the left despite the increasing size of the R group when going from Me to tBu substitution.},
  language  = {en}
}
@article{KleinpeterKoch2011,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS)},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {13},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  number    = {46},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c1cp21942a},
  pages     = {20593 -- 20601},
  year      = {2011},
  abstract  = {The spatial magnetic properties (through space NMR shieldings-TSNMRS) of metal complexes (with ligands such as acetylacetone, 3-hydroxy-pyran(4) one) and "metallobenzenes" have been calculated by the GIAO perturbation method and visualized as Iso-Chemical-Shielding Surfaces (ICSS) of various sizes and directions. The TSNMRS values, thus obtained, can be successfully employed to quantify and visualize partial aromaticity of the metallocyclic ring by comparison with the spatial magnetic properties of the corresponding non-complexed ligands in comparable structural and electronic situations, and benzene, respectively. Because anisotropy/ring current effects in H-1 NMR spectra proved to be the molecular response property of TSNMRS, the results obtained concerning partial "chelatoaromaticity" are experimentally ensured.},
  language  = {en}
}
@article{ShainyanMoskalikHeydenreichetal.2014,
  author    = {Shainyan, Bagrat A. and Moskalik, Mikhail Yu and Heydenreich, Matthias and Kleinpeter, Erich},
  title     = {Conformational equilibrium and dynamic behavior of bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane},
  series = {Magnetic resonance in chemistry},
  volume    = {52},
  journal   = {Magnetic resonance in chemistry},
  number    = {8},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.4086},
  pages     = {448 -- 452},
  year      = {2014},
  abstract  = {Restricted rotation about the N-S partial double bonds in a bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane derivative 1 has been frozen at low temperature (Delta G* = 11.6 kcal mol(-1)), and the existence of all four rotamers about the two N-S bonds, 3-in, 8-in, 3-in, 8-out, 3-out, 8-in, and 3-out, 8-out, respectively, proved experimentally by NMR spectroscopy and theoretically by DFT and MP2 calculations. Copyright (C) 2014 John Wiley \& Sons, Ltd.},
  language  = {en}
}
@article{ShainyanKleinpeter2014,
  author    = {Shainyan, Bagrat A. and Kleinpeter, Erich},
  title     = {Conformational flexibility of 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline and its monoheterocyclic analogs},
  series = {Russian journal of general chemistry},
  volume    = {84},
  journal   = {Russian journal of general chemistry},
  number    = {7},
  publisher = {Pleiades Publ.},
  address   = {New York},
  issn      = {1070-3632},
  doi       = {10.1134/S1070363214070135},
  pages     = {1325 -- 1329},
  year      = {2014},
  abstract  = {Conformational behavior of the first cyclic organosilicon vinylsulfide, 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline as well as its monoheterocyclic analogs, 3,4-dihydro-2H-pyran, 3,4-dihydro-2H-thiopyran, and 1,1-dimethyl-1,2,3,4-tetrahydrosiline is studied in comparison with the carbocyclic analog, cyclohexene, using the methods of low-temperature NMR spectroscopy and theoretical calculations at the DFT and MP2 levels of theory. The barrier to the ring inversion with respect to that in cycloxene is increased in 3,4-dihydro-2H-pyran and 1,1-dimethyl-1,2,3,4-tetrahydrosiline, but, in contrast to the suggestions made in the literature, is decreased in 3,4-dihydro-2H-thiopyran. In 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline the barrier is intermediate between those in the corresponding monoheterocycles, 1,1-dimethyl-1,2,3,4-tetrahydrosiline and 3,4-dihydro-2H-thiopyran. The observed variations are rationalized from the viewpoint of the interaction of the pi-electrons of the C=C double bond with the orbitals of heteroatoms in the ring. The structure of the transition state for the ring inversion is discussed.},
  language  = {en}
}
@article{MovahedifarModarresiAlamKleinpeteretal.2017,
  author    = {Movahedifar, Fahimeh and Modarresi-Alam, Ali Reza and Kleinpeter, Erich and Schilde, Uwe},
  title     = {Dynamic H-1-NMR study of unusually high barrier to rotation about the partial C-N double bond in N,N-dimethyl carbamoyl 5-aryloxytetrazoles},
  series = {Journal of molecular structure},
  volume    = {1133},
  journal   = {Journal of molecular structure},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0022-2860},
  doi       = {10.1016/j.molstruc.2016.12.010},
  pages     = {244 -- 252},
  year      = {2017},
  abstract  = {The synthesis of new N,N-dimethyl carbamoyl 5-aryloxytetrazoles have been reported. Their dynamic H-1-NMR via rotation about C-N bonds in moiety of urea group [a; CO-NMe2 and b; (2-tetrazolyl)N-CO rotations] in the solvents CDCl3 (223-333 K) and DMSO (298-363 K) is studied. Accordingly, the free energies of activation, obtained 16.5 and 16.9 kcal mol(-1) respectively, attributed to the conformational isomerization about the Me2N-C=O bond (a rotation). Moreover, a and b barrier to rotations in 5-((4-methylphenoxy)-N,N-dimethyl-2H-tetrazole-2-carboxamide (P) also were computed at level of B3LYP using 6-311++G** basis set. The optimized geometry parameters are in good agreement with X-ray structure data. The computation of energy barrier for a and b was determined 16.9 and 2.5 kcal mol(-1), respectively. The former is completely in agreement with the result obtained via dynamic NMR. X-ray structure analysis data demonstrate that just 2-acylated tetrazole was formed in the case of 5-(p-tolyloxy)-N,N-dimethyl-2H-tetrazole-2-carboxamide. X-ray data also revealed a planar trigonal orientation of the Me2N group which is coplanar to carbonyl group with the partial double-bond C-N character. It also demonstrates the synperiplanar position of C=O group with tetrazolyl ring. On average, in solution the plane containing carbonyl bond is almost perpendicular to the plane of the tetrazolyl ring (because of steric effects as confirmed by B3LY12/6-311++G**) while the plane containing Me2N group is coplanar with carbonyl bond which is in contrast with similar urea derivatives and it demonstrates the unusually high rotational energy barrier of these compounds. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{HansenKochKleinpeter2018,
  author    = {Hansen, Poul Erik and Koch, Andreas and Kleinpeter, Erich},
  title     = {Ring current and anisotropy effects on OH chemical shifts in resonance-assisted intramolecular H-bonds},
  series = {Tetrahedron letters},
  volume    = {59},
  journal   = {Tetrahedron letters},
  number    = {23},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4039},
  doi       = {10.1016/j.tetlet.2018.05.006},
  pages     = {2288 -- 2292},
  year      = {2018},
  abstract  = {Ring current effects on resonance-assisted and intramolecularly bridged hydrogen bond protons for 10-hydroxybenzo[h]quinoline 1 and a number of related compounds were calculated and the through-space NMR shieldings (TSNMRS) obtained hereby visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. These calculations revealed that this through-space effect is comparably large (up to 2 ppm) dependent on the position of the intramolecularly bridged OH proton, and therefore, contribute considerably to the chemical shift of the latter making it questionable to use delta(OH)/ppm in the estimation of intramolecular hydrogen bond strength without taking this into account. Furthermore, the anisotropy effects of additional groups on the aromatic moiety (e.g. the carbonyl group in salicylaldehyde or in o-hydroxyacetophenone of ca. 0.6 ppm deshielding) should also be considered. These through-space effects need to be taken into account when using OH chemical shifts to estimate hydrogen bond strength.},
  language  = {en}
}
@article{BuyinzaDereseNdakalaetal.2021,
  author    = {Buyinza, Daniel and Derese, Solomon and Ndakala, Albert and Heydenreich, Matthias and Yenesew, Abiy and Koch, Andreas and Oriko, Richard},
  title     = {A coumestan and a coumaronochromone from Millettia lasiantha},
  series = {Biochemical systematics and ecology},
  volume    = {97},
  journal   = {Biochemical systematics and ecology},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0305-1978},
  doi       = {10.1016/j.bse.2021.104277},
  pages     = {5},
  year      = {2021},
  abstract  = {The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and las-coumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.},
  language  = {en}
}
@phdthesis{Heinz2024,
  author    = {Heinz, Markus},
  title     = {Synthese von Monomeren auf der Basis nachwachsender Rohstoffe und ihre Polymerisation},
  doi       = {10.25932/publishup-63794},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-637943},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XVII, 267},
  year      = {2024},
  abstract  = {Die vorliegende Arbeit thematisiert die Synthese und die Polymerisation von Monomeren auf der Basis nachwachsender Rohstoffe wie zum Beispiel in Gew{\"u}rzen und ätherischen Ölen enthaltenen kommerziell verf{\"u}gbaren Phenylpropanoiden (Eugenol, Isoeugenol, Zimtalkohol, Anethol und Estragol) und des Terpenoids Myrtenol sowie ausgehend von der Rinde einer Birke (Betula pendula) und der Korkeiche (Quercus suber). Ausgew{\"a}hlte Phenylpropanoide (Eugenol, Isoeugenol und Zimtalkohol) und das Terpenoid Myrtenol wurden zun{\"a}chst in den jeweiligen Laurylester {\"u}berf{\"u}hrt und anschließend das olefinische Strukturelement epoxidiert, wobei 4 neue (2-Methoxy-4-(oxiran-2-ylmethyl)phenyldodecanoat, 2-Methoxy-4-(3-methyl-oxiran-2-yl)phenyldodecanoat, (3-Phenyloxiran-2-yl)methyldodecanoat, (7,7-Dimethyl-3-oxatricyclo[4.1.1.02,4]octan-2-yl)methyldodecanoat) und 2 bereits bekannte monofunktionelle Epoxide (2-(4-Methoxybenzyl)oxiran und 2-(4-Methoxyphenyl)-3-methyloxiran) erhalten wurden, die mittels 1H-NMR-, 13C-NMR- und FT-IR-Spektroskopie sowie mit DSC untersucht wurden. Die Photo-DSC Untersuchung der Epoxidmonomere in einer kationischen Photopolymerisation bei 40 °C ergab die maximale Polymerisationsgeschwindigkeit (Rpmax: 0,005 s-1 bis 0,038 s-1) sowie die Zeit (tmax: 13 s bis 26 s) bis zum Erreichen des Rpmax-Wertes und f{\"u}hrte zu fl{\"u}ssigen Oligomeren, deren zahlenmittlerer Polymerisationsgrad mit 3 bis 6 mittels GPC bestimmt wurde. Die Umsetzung von 2-Methoxy-4-(oxiran-2-ylmethyl)phenyldodecanoat mit Methacrylsäure ergab ein Isomerengemisch (2-Methoxy-4-(2-hydroxy-3-(methacryloyloxy)propyl)phenyldodecanoat und 2-Methoxy-4-(2-(methacryl-oyloxy)-3-hydroxypropyl)phenyldodecanoat), das mittels Photo-DSC in einer freien radikalischen Photopolymerisation untersucht wurde (Rpmax: 0,105 s-1 und tmax: 5 s), die zu festen in Chloroform unlöslichen Polymeren f{\"u}hrte. Aus Korkpulver und gemahlener Birkenrinde wurden selektiv 2 kristalline ω-Hydroxyfettsäuren (9,10-Epoxy-18-hydroxyoctadecansäure und 22-Hydroxydocosansäure) isoliert. Die kationische Photopolymerisation der 9,10-Epoxy-18-hydroxyoctadecansäure ergab einen nahezu farblosen transparenten und bei Raumtemperatur elastischen Film, welcher ein Anwendungspotential f{\"u}r Oberflächenbeschichtungen hat. Aus der Reaktion von 9,10-Epoxy-18-hydroxyoctadecansäure mit Methacrylsäure wurde ein bei Raumtemperatur fl{\"u}ssiges Gemisch aus zwei Konstitutionsisomeren (9,18-Dihydroxy-10-(methacryloyloxy)octadecansäure und 9-(Methacryloyloxy)-10,18-dihydroxyoctadecansäure) erhalten (Tg: -60 °C). Die radikalische Photopolymerisation dieser Konstitutionsisomere wurde ebenfalls mittels Photo-DSC untersucht (Rpmax: 0,098 s-1 und tmax: 3,8 s). Die Reaktion von 22-Hydroxydocosansäure mit Methacryloylchlorid ergab die kristalline 22-(Methacryloyloxy)docosansäure, welche ebenfalls in einer radikalischen Photopolymerisation mittels Photo-DSC untersucht wurde (Rpmax: 0,023 s-1 und tmax: 9,6 s). Die mittels AIBN in Dimethylsulfoxid initiierte Homopolymerisation der 22-(Methacryloyloxy)docosansäure und der Isomerengemische bestehend aus 2-Methoxy-4-(2-hydroxy-3-(methacryloyloxy)propyl)phenyldodecanoat und 2-Methoxy-4-(2-(methacryl-oyloxy)-3-hydroxypropyl)phenyldodecanoat sowie aus 9,18-Dihydroxy-10-(methacryloy-loxy)octadecansäure und 9-(Methacryloyloxy)-10,18-dihydroxyoctadecansäure ergab feste lösliche Polymere, die mittels 1H-NMR- und FT-IR-Spektroskopie, GPC (Poly(2-methoxy-4-(2-hydroxy-3-(methacryloyloxy)propyl)phenyldodecanoat / 2-methoxy-4-(2-(methacryloyloxy)-3-hydroxypropyl)phenyldodecanoat): Pn = 94) und DSC (Poly(2-methoxy-4-(2-hydroxy-3-(methacryloyloxy)propyl)phenyldodecanoat / 2-methoxy-4-(2-(methacryloyloxy)-3-hydroxypropyl)phenyldodecanoat): Tg: 52 °C; Poly(9,18-dihydroxy-10-(methacryloyloxy)-octadecansäure / 9-(methacryloyloxy)-10,18-dihydroxyoctadecansäure): Tg: 10 °C; Poly(22-(methacryloyloxy)docosansäure): Tm: 74,1 °C, wobei der Schmelzpunkt mit dem des Photopolymers (Tm = 76,8 °C) vergleichbar ist) charakterisiert wurden. Das bereits bekannte Monomer 4-(4-Methacryloyloxyphenyl)butan-2-on wurde ausgehend von 4-(4-Hydroxyphenyl)butan-2-on hergestellt, welches aus Birkenrinde gewonnen werden kann, und unter identischen Bedingungen f{\"u}r einen Vergleich mit den neuen Monomeren polymerisiert. Die freie radikalische Polymerisation f{\"u}hrte zu Poly(4-(4-methacryloyloxyphenyl)butan-2-on) (Pn: 214 und Tg: 83 °C). Neben der Homopolymerisation wurde eine statistische Copolymerisation des Isomerengemisches 2-Methoxy-4-(2-hydroxy-3-(methacryl-oyloxy)propyl)phenyldodecanoat / 2-Methoxy-4-(2-(methacryloyloxy)-3-hydroxypropyl)-phenyldodecanoat mit 4-(4-Methacryloyloxyphenyl)butan-2-on untersucht, wobei ein äquimolarer Einsatz der Ausgangsmonomere zu einem Anstieg der Ausbeute, der Molmassenverteilung und der Dispersität des Copolymers (Tg: 44 °C) f{\"u}hrte. Die unter Verwendung von Diethylcarbonat als „gr{\"u}nes" Lösungsmittel mittels AIBN initiierten freien radikalischen Homopolymerisationen von 4-(4-Methacryloyloxyphenyl)butan-2-on und von Laurylmethacrylat ergaben vergleichbare Polymerisationsgrade der Homopolymere (Pn: 150), welche jedoch aufgrund ihrer Strukturunterschiede deutlich unterschiedliche Glas{\"u}bergangstemperaturen hatten (Poly(4-(4-methacryloyloxyphenyl)butan-2-on): Tg: 70 °C, Poly(laurylmethacrylat) Tg: -49 °C. Eine statistische Copolymerisation äquimolarer Stoffmengen der beiden Monomere in Diethylcarbonat f{\"u}hrte bei einer Polymerisationszeit von 60 Minuten zu einem leicht bevorzugten Einbau des 4-(4-Methacryloyloxyphenyl)butan-2-on in das Copolymer (Tg: 17 °C). Copolymerisationsdiagramme f{\"u}r die freien radikalischen Copolymerisationen von 4-(4-Methacryloyloxyphenyl)butan-2-on mit n-Butylmethacrylat beziehungsweise 2-(Dimethylamino)ethylmethacrylat (t: 20 min bis 60 min; Molenbr{\"u}che (X) f{\"u}r 4-(4-Methacryloyloxyphenyl)butan-2-on: 0,2; 0,4; 0,6 und 0,8) zeigten ein nahezu ideales azeotropes Copolymerisationsverhalten, obwohl ein leicht bevorzugter Einbau von 4-(4-Methacryloyloxyphenyl)butan-2-on in das jeweilige Copolymer beobachtet wurde. Dabei korreliert ein Anstieg der Ausbeute und der Glas{\"u}bergangstemperatur der erhaltenen Copolymere mit einem zunehmenden Gehalt an 4-(4-Methacryloyloxyphenyl)butan-2-on im Reaktionsgemisch. Die unter Einsatz der modifizierten Gibbs-DiMarzio-Gleichung berechneten Glas{\"u}bergangstemperaturen der Copolymere stimmten mit den gemessenen Werten gut {\"u}berein. Das ist eine gute Ausgangsbasis f{\"u}r die Bestimmung der Glas{\"u}bergangstemperatur eines Copolymers mit einer beliebigen Zusammensetzung.},
  language  = {de}
}
@article{XuNieWangetal.2021,
  author    = {Xu, Xun and Nie, Yan and Wang, Weiwei and Ma, Nan and Lendlein, Andreas},
  title     = {Periodic thermomechanical modulation of toll-like receptor expression and distribution in mesenchymal stromal cells},
  series = {MRS communications / a publication of the Materials Research Society},
  volume    = {11},
  journal   = {MRS communications / a publication of the Materials Research Society},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2159-6867},
  doi       = {10.1557/s43579-021-00049-5},
  pages     = {425 -- 431},
  year      = {2021},
  abstract  = {Toll-like receptor (TLR) can trigger an immune response against virus including SARS-CoV-2. TLR expression/distribution is varying in mesenchymal stromal cells (MSCs) depending on their culture environments. Here, to explore the effect of periodic thermomechanical cues on TLRs, thermally controlled shape-memory polymer sheets with programmable actuation capacity were created. The proportion of MSCs expressing SARS-CoV-2-associated TLRs was increased upon stimulation. The TLR4/7 colocalization was promoted and retained in the endoplasmic reticula. The TLR redistribution was driven by myosin-mediated F-actin assembly. These results highlight the potential of boosting the immunity for combating COVID-19 via thermomechanical preconditioning of MSCs.},
  language  = {en}
}
@article{ZudeHashimHassetal.2019,
  author    = {Zude, Manuela and Hashim, Norhashila and Hass, Roland and Polley, Nabarun and Regen, Christian},
  title     = {Validation study for measuring absorption and reduced scattering coefficients by means of laser-induced backscattering imaging},
  series = {Postharvest Biology and Technology},
  volume    = {153},
  journal   = {Postharvest Biology and Technology},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-5214},
  doi       = {10.1016/j.postharvbio.2019.04.002},
  pages     = {161 -- 168},
  year      = {2019},
  abstract  = {Decoupling of optical properties appears challenging, but vital to get better insight of the relationship between light and fruit attributes. In this study, nine solid phantoms capturing the ranges of absorption (μa) and reduced scattering (μs') coefficients in fruit were analysed non-destructively using laser-induced backscattering imaging (LLBI) at 1060 nm. Data analysis of LLBI was carried out on the diffuse reflectance, attenuation profile obtained by means of Farrell's diffusion theory either calculating μa [cm-1] and μs' [cm-1] in one fitting step or fitting only one optical variable and providing the other one from a destructive analysis. The nondestructive approach was approved when calculating one unknown coefficient non-destructively, while no ability of the method was found to analysis both, μa and μs', non-destructively. Setting μs' according to destructive photon density wave (PDW) spectroscopy and fitting μa resulted in root mean square error (rmse) of 18.7\% in comparison to fitting μs' resulting in rmse of 2.6\%, pointing to decreased measuring uncertainty, when the highly variable μa was known. The approach was tested on European pear, utilizing destructive PDW spectroscopy for setting one variable, while LLBI was applied for calculating the remaining coefficient. Results indicated that the optical properties of pear obtained from PDW spectroscopy as well as LLBI changed concurrently in correspondence to water content mainly. A destructive batch-wise analysis of μs' and online analysis of μa may be considered in future developments for improved fruit sorting results, when considering fruit with high variability of μs'.},
  language  = {en}
}
@article{AdebayoHashimHassetal.2017,
  author    = {Adebayo, Segun Emmanuel and Hashim, Norhashila and Hass, Roland and Reich, Oliver and Regen, Christian and M{\"u}nzberg, Marvin and Abdan, Khalina and Hanafi, Marsyita and Zude, Manuela},
  title     = {Using absorption and reduced scattering coefficients for non-destructive analyses of fruit flesh firmness and soluble solids content in pear},
  series = {Postharvest Biology and Technology},
  volume    = {130},
  journal   = {Postharvest Biology and Technology},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-5214},
  doi       = {10.1016/j.postharvbio.2017.04.004},
  pages     = {56 -- 63},
  year      = {2017},
  abstract  = {Quality attributes of fruit determine its acceptability by the retailer and consumer. The objective of this work was to investigate the potential of absorption (μa) and reduced scattering (μs') coefficients of European pear to analyze its fruit flesh firmness and soluble solids content (SSC). The absolute reference values, μa* (cm-1) and μs'* (cm-1), of pear were invasively measured, employing multi-spectral photon density wave (PDW) spectroscopy at preselected wavelengths of 515, 690, and 940 nm considering two batches of unripe and overripe fruit. On eight measuring dates during fruit development, μa and μs' were analyzed non-destructively by means of laser light backscattering imaging (LLBI) at similar wavelengths of 532, 660, and 830 nm by means of fitting according to Farrell's diffusion theory, using fix reference values of either μa* or μs'*. Both, the μa* and the μa as well as μs'* and μs' showed similar trends. Considering the non-destructively measured data during fruit development, μa at 660 nm decreased 91 till 141 days after full bloom (dafb) from 1.49 cm-1 to 0.74 cm-1 due to chlorophyll degradation. At 830 nm, μa only slightly decreased from 0.41 cm-1 to 0.35 cm-1. The μs' at all wavelengths revealed a decreasing trend as the fruit developed. The difference measured at 532 nm was most pronounced decreasing from 24 cm-1 to 10 cm-1, while at 660 nm and 830 nm values decreased from 15 cm-1 to 13 cm-1 and from 10 cm-1 to 8 cm-1, respectively. When building calibration models with partial least-squares regression analysis on the optical properties for non-destructive analysis of the fruit SSC, μa at 532 nm and 830 nm resulted in a correlation coefficient of R = 0.66, however, showing high measuring uncertainty. The combination of all three wavelengths gave an enhanced, encouraging R = 0.89 for firmness analysis using μs' in the freshly picked fruit.},
  language  = {en}
}
@phdthesis{Erler2020,
  author    = {Erler, Alexander},
  title     = {Entwicklung von online-Detektionsverfahren f{\"u}r landwirtschaftlich relevante Analyten},
  doi       = {10.25932/publishup-47340},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-473406},
  school      = {Universit{\"a}t Potsdam},
  pages     = {viii, 123},
  year      = {2020},
  abstract  = {Die Entwicklung nachhaltiger Bewirtschaftungs- und Produktionsmethoden ist eine der zentralen Fragestellungen der modernen Agrarwirtschaft. Die vorliegende Arbeit besch{\"a}ftigt sich mit zwei Forschungsthemen, die das Konzept Nachhaltigkeit beinhalten. In beiden F{\"a}llen werden analytische Grundlagen f{\"u}r die Entwicklung entsprechender landwirtschaftlicher Arbeitsmethoden gelegt. Das erste Thema ist an den sogenannten Pr{\"a}zisionsackerbau angelehnt. Bei diesem wird die Bearbeitung von Agrarfl{\"a}chen ortsabh{\"a}ngig ausgef{\"u}hrt. Das heißt, die Ausbringung von Saatgut, D{\"u}nger, Bew{\"a}sserung usw. richtet sich nach den Eigenschaften des jeweiligen Standortes und wird nicht pauschal gleichm{\"a}ßig {\"u}ber ein ganzes Feld verteilt. Voraussetzung hierf{\"u}r ist eine genaue Kenntnis der Bodeneigenschaften. In der vorliegenden Arbeit sollten diese Parameter mittels der analytischen Technik der Laser-induzierten Breakdown Spektroskopie (LIBS), die eine Form der Elementaranalyse darstellt, bestimmt werden. Bei den hier gesuchten Bodeneigenschaften handelte es sich um die Gehalte von N{\"a}hrstoffen sowie einige sekund{\"a}re Parameter wie den Humusanteil, den pH-Wert und den pflanzenverf{\"u}gbaren Anteil einzelner N{\"a}hrstoffe. Diese Eigenschaften wurden durch etablierte Referenzanalysen bestimmt. Darauf aufbauend wurden die Messergebnissen der LIBS-Untersuchungen durch verschiedene Methoden der sogenannten multivariaten Datenanalyse (MVA) ausgewertet. Daraus sollten Modelle zur Vorhersage der Bodenparameter in zuk{\"u}nftigen LIBS-Messungen erarbeitet werden. Die Ergebnisse dieser Arbeit zeigten, dass mit der Kombination von LIBS und MVA s{\"a}mtliche Bodenparameter erfolgreich vorhergesagt werden konnten. Dies beinhaltete sowohl die tats{\"a}chlich messbaren Elemente als auch die sekund{\"a}ren Eigenschaften, welche durch die MVA mit den Elementgehalten in Zusammenhang gebracht wurden. Das zweite Thema besch{\"a}ftigt sich mit der Vermeidung von Verlusten durch Sch{\"a}dlingsbefall bei der Getreidelagerung. Hier sollten mittels der Ionenmobilit{\"a}tsspektrometrie (IMS) Schimmelpilzkontaminationen detektiert werden. Dabei wurde nach den fl{\"u}chtigen Stoffwechselprodukten der Pilze gesucht. Die durch Referenzmessungen mit Massenspektrometern identifizierten Substanzen konnten durch IMS im Gasvolumen {\"u}ber den Proben, dem sogenannten Headspace, nachgewiesen werden. Dabei wurde nicht nur die Anwesenheit einer Kontamination festgestellt, sondern diese auch charakterisiert. Die freigesetzten Substanzen bildeten spezifische Muster, anhand derer die Pilze identifiziert werden konnten. Hier wurden sowohl verschiedene Gattungen als auch einzelne Arten unterschieden. Die Messungen fanden auf verschiedenen N{\"a}hrb{\"o}den statt um den Einfluss dieser auf die Stoffwechselprodukte zu beobachten. Auch die sekund{\"a}ren Stoffwechselprodukte der Schimmelpilze, die Mykotoxine, konnten durch IMS detektiert werden. Beide in dieser Arbeit vorgestellten Forschungsthemen konnten erfolgreich abgeschlossen werden. Sowohl LIBS als auch IMS erwiesen sich f{\"u}r den Nachweis der jeweiligen Analyten als geeignet, und der Einsatz moderner computergest{\"u}tzter Auswertemethoden erm{\"o}glichte die genaue Charakterisierung der gesuchten Parameter. Beide Techniken k{\"o}nnen in Form von mobilen Ger{\"a}ten verwendet werden und zeichnen sich durch eine schnelle und sichere Analyse aus. In Kombination mit entsprechenden Modellen der MVA sind damit alle Voraussetzungen f{\"u}r Vor-Ort-Untersuchungen und damit f{\"u}r den Einsatz in der Landwirtschaft erf{\"u}llt.},
  language  = {de}
}
@article{ErlerRiebeBeitzetal.2018,
  author    = {Erler, Alexander and Riebe, Daniel and Beitz, Toralf and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Grothusheitkamp, Daniela and Kunz, T. and Methner, Frank-J{\"u}rgen},
  title     = {Detection of volatile organic compounds in the headspace above mold fungi by GC-soft X-radiation-based APCI-MS},
  series = {Journal of mass spectrometr},
  volume    = {53},
  journal   = {Journal of mass spectrometr},
  number    = {10},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1076-5174},
  doi       = {10.1002/jms.4210},
  pages     = {911 -- 920},
  year      = {2018},
  abstract  = {Mold fungi on malting barley grains cause major economic loss in malting and brewery facilities. Possible proxies for their detection are volatile and semivolatile metabolites. Among those substances, characteristic marker compounds have to be identified for a confident detection of mold fungi in varying surroundings. The analytical determination is usually performed through passive sampling with solid phase microextraction, gas chromatographic separation, and detection by electron ionization mass spectrometry (EI-MS), which often does not allow a confident determination due to the absence of molecular ions. An alternative is GC-APCI-MS, generally, allowing the determination of protonated molecular ions. Commercial atmospheric pressure chemical ionization (APCI) sources are based on corona discharges, which are often unspecific due to the occurrence of several side reactions and produce complex product ion spectra. To overcome this issue, an APCI source based on soft X-radiation is used here. This source facilitates a more specific ionization by proton transfer reactions only. In the first part, the APCI source is characterized with representative volatile fungus metabolites. Depending on the proton affinity of the metabolites, the limits of detection are up to 2 orders of magnitude below those of EI-MS. In the second part, the volatile metabolites of the mold fungus species Aspergillus, Alternaria, Fusarium, and Penicillium are investigated. In total, 86 compounds were found with GC-EI/APCI-MS. The metabolites identified belong to the substance classes of alcohols, aldehydes, ketones, carboxylic acids, esters, substituted aromatic compounds, terpenes, and sesquiterpenes. In addition to substances unspecific for the individual fungus species, characteristic patterns of metabolites, allowing their confident discrimination, were found for each of the 4 fungus species. Sixty-seven of the 86 metabolites are detected by X-ray-based APCI-MS alone. The discrimination of the fungus species based on these metabolites alone was possible. Therefore, APCI-MS in combination with collision induced dissociation alone could be used as a supervision method for the detection of mold fungi.},
  language  = {en}
}
@article{RiebeErlerBrinkmannetal.2019,
  author    = {Riebe, Daniel and Erler, Alexander and Brinkmann, Pia and Beitz, Toralf and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Gebbers, Robin},
  title     = {Comparison of Calibration Approaches in Laser-Induced Breakdown Spectroscopy for Proximal Soil Sensing in Precision Agriculture},
  series = {Sensors},
  volume    = {19},
  journal   = {Sensors},
  number    = {23},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1424-8220},
  doi       = {10.3390/s19235244},
  pages     = {16},
  year      = {2019},
  abstract  = {The lack of soil data, which are relevant, reliable, affordable, immediately available, and sufficiently detailed, is still a significant challenge in precision agriculture. A promising technology for the spatial assessment of the distribution of chemical elements within fields, without sample preparation is laser-induced breakdown spectroscopy (LIBS). Its advantages are contrasted by a strong matrix dependence of the LIBS signal which necessitates careful data evaluation. In this work, different calibration approaches for soil LIBS data are presented. The data were obtained from 139 soil samples collected on two neighboring agricultural fields in a quaternary landscape of northeast Germany with very variable soils. Reference analysis was carried out by inductively coupled plasma optical emission spectroscopy after wet digestion. The major nutrients Ca and Mg and the minor nutrient Fe were investigated. Three calibration strategies were compared. The first method was based on univariate calibration by standard addition using just one soil sample and applying the derived calibration model to the LIBS data of both fields. The second univariate model derived the calibration from the reference analytics of all samples from one field. The prediction is validated by LIBS data of the second field. The third method is a multivariate calibration approach based on partial least squares regression (PLSR). The LIBS spectra of the first field are used for training. Validation was carried out by 20-fold cross-validation using the LIBS data of the first field and independently on the second field data. The second univariate method yielded better calibration and prediction results compared to the first method, since matrix effects were better accounted for. PLSR did not strongly improve the prediction in comparison to the second univariate method.},
  language  = {en}
}
@misc{WolffCanilRehermannetal.2020,
  author    = {Wolff, Christian Michael and Canil, Laura and Rehermann, Carolin and Nguyen, Ngoc Linh and Zu, Fengshuo and Ralaiarisoa, Maryline and Caprioglio, Pietro and Fiedler, Lukas and Stolterfoht, Martin and Kogikoski, Junior, Sergio and Bald, Ilko and Koch, Norbert and Unger, Eva L. and Dittrich, Thomas and Abate, Antonio and Neher, Dieter},
  title     = {Correction to 'Perfluorinated self-assembled monolayers enhance the stability and efficiency of inverted perovskite solar cells' (2020, 14 (2), 1445-1456)},
  series = {ACS nano},
  volume    = {14},
  journal   = {ACS nano},
  number    = {11},
  publisher = {American Chemical Society},
  address   = {Washington, DC},
  issn      = {1936-0851},
  doi       = {10.1021/acsnano.0c08081},
  pages     = {16156 -- 16156},
  year      = {2020},
  language  = {en}
}
@misc{WolffCaprioglioStolterfohtetal.2019,
  author    = {Wolff, Christian Michael and Caprioglio, Pietro and Stolterfoht, Martin and Neher, Dieter},
  title     = {Nonradiative Recombination in Perovskite Solar Cells},
  series = {Advanced materials},
  volume    = {31},
  journal   = {Advanced materials},
  number    = {52},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0935-9648},
  doi       = {10.1002/adma.201902762},
  pages     = {20},
  year      = {2019},
  abstract  = {Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their V-OC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the V-OC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome-paving the way to the thermodynamic efficiency limit.},
  language  = {en}
}
@article{SalibaCorreaBaenaWolffetal.2018,
  author    = {Saliba, Michael and Correa-Baena, Juan-Pablo and Wolff, Christian Michael and Stolterfoht, Martin and Phung, Thi Thuy Nga and Albrecht, Steve and Neher, Dieter and Abate, Antonio},
  title     = {How to Make over 20\% Efficient Perovskite Solar Cells in Regular (n-i-p) and Inverted (p-i-n) Architectures},
  series = {Chemistry of materials : a publication of the American Chemical Society},
  volume    = {30},
  journal   = {Chemistry of materials : a publication of the American Chemical Society},
  number    = {13},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0897-4756},
  doi       = {10.1021/acs.chemmater.8b00136},
  pages     = {4193 -- 4201},
  year      = {2018},
  abstract  = {Perovskite solar cells (PSCs) are currently one of the most promising photovoltaic technologies for highly efficient and cost-effective solar energy production. In only a few years, an unprecedented progression of preparation procedures and material compositions delivered lab-scale devices that have now reached record power conversion efficiencies (PCEs) higher than 20\%, competing with most established solar cell materials such as silicon, CIGS, and CdTe. However, despite a large number of researchers currently involved in this topic, only a few groups in the world can reproduce >20\% efficiencies on a regular n-i-p architecture. In this work, we present detailed protocols for preparing PSCs in regular (n-i-p) and inverted (p-i-n) architectures with >= 20\% PCE. We aim to provide a comprehensive, reproducible description of our device fabrication , protocols. We encourage the practice of reporting detailed and transparent protocols that can be more easily reproduced by other laboratories. A better reporting standard may, in turn, accelerate the development of perovskite solar cells and related research fields.},
  language  = {en}
}
@article{KleinpeterKoch2022,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Cyclazines-structure and aromaticity or antiaromaticity on the magnetic criterion},
  series = {European journal of organic chemistry},
  volume    = {2022},
  journal   = {European journal of organic chemistry},
  number    = {8},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1434-193X},
  doi       = {10.1002/ejoc.202101362},
  pages     = {12},
  year      = {2022},
  abstract  = {Structure and spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of all ten cycl[2.2.2]azine to cycl[4.4.4]azine, hetero-analogues and the corresponding hydrocarbons have been calculated at the B3LYP/6-311G(d,p) theory level using the GIAO perturbation method and employing the nucleus independent chemical shift (NICS) concept. The TSNMRS values (actually, the ring current effect as measurable in H-1 NMR spectroscopy) are visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction, and employed to readily qualify and quantify the degree of (anti)aromaticity. Results are confirmed by NMR [delta(H-1)/ppm, delta(N-15)/ppm] and geometry (planar, twisted, bow-shaped) data. The cyclazines N[2.2.2](-) up to N[2.4.4](-) are planar or at most slightly bowl-shaped and, due to coherent peripheral ring currents (except in N[2.3.3](-), N[2.3.4], N[3.3.4](+) and N[2.4.4](+)), develop aromaticity or anti-aromaticity of the whole molecules dependent on the number of peripheral conjugated pi electrons. The cyclazines N[2.3.3](-), N[2.3.4], N[3.3.4](+) and N[2.4.4](+) develop two ring currents of different direction within the same molecule, in which the dominating ring current proves to be paratropic (in N[3.3.4](+) diatropic) including the nodal N p(z) lone pair into the conjugation. The residual cyclazines N[3.4.4], N[4.4.4](-) and N[4.4.4](+) are heavily twisted and, therefore, are not developing peripheral or diverse ring currents. The TSNMRS information about cyclazines and the parent tricyclic annulene analogues is congruent subject to structure and number of peripheral or internal conjugated pi electrons, the corresponding (anti)aromaticity is in unequivocal accordance with Huckel's rule.},
  language  = {en}
}
@article{ShainyanKirpichenkoChipaninaetal.2015,
  author    = {Shainyan, Bagrat A. and Kirpichenko, Svetlana V. and Chipanina, Nina N. and Oznobikhina, Larisa P. and Kleinpeter, Erich and Shlykov, Sergey A. and Osadchiy, Dmitriy Yu.},
  title     = {Synthesis and Conformational Analysis of 3-Methyl-3-silatetrahydropyran by GED, FTIR, NMR, and Theoretical Calculations: Comparative Analysis of 1-Hetero-3-methyl-3-silacyclohexanes},
  series = {The journal of organic chemistry},
  volume    = {80},
  journal   = {The journal of organic chemistry},
  number    = {24},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0022-3263},
  doi       = {10.1021/acs.joc.5b02355},
  pages     = {12492 -- 12500},
  year      = {2015},
  abstract  = {3-Methyl-3-silatetrahydropyran 1 was synthesized and its molecular structure and conformational behavior was studied by gas-phase electron diffraction (GED), FTIR, low temperature H-1 and C-13 NMR spectroscopy, and by theoretical calculations (DFT, MP2). Two conformers; 1-ax and 1-eq; were located on the potential energy Surface. In the gas phase; a slight predominance of the axial conformer was determined, with the ratio 1-ax:1-eq = 54(9):46(9) (from GED) or 53:47 or 61;39 (from IR). In solution, LT NMR spectroscopy at 103 K gives the ratio 1-ax:1-eq = 35:65 (-Delta G(103)degrees = 0.13 kcal/mol). Simulation of solvent effects using the PCM continuum model or by calculation of the corresponding solvent-solute complexes allowed us to rationalize the experimentally observed opposite conformational predominance of the conformers of 3-methyl-3-silatettahydropyran in the gas phase and in solution. Comparative analysis of the effect of heteroatom in 1-hetero-3-methyl-3-silacyclohexanes on the structure, stereoelectronic interactions, and relative energies of the conformers is done.},
  language  = {en}
}
@article{BalciAkkayaAkyuzetal.2016,
  author    = {Balci, K. and Akkaya, Y. and Akyuz, S. and Collier, W. B. and Stricker, M. C. and Stover, D. D. and Ritzhaupt, G. and Koch, Andreas and Kleinpeter, Erich},
  title     = {The effects of conformation and zwitterionic tautomerism on the structural and vibrational spectral data of anserine},
  series = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy},
  volume    = {86},
  journal   = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0924-2031},
  doi       = {10.1016/j.vibspec.2016.08.003},
  pages     = {277 -- 289},
  year      = {2016},
  abstract  = {In this study, the stable conformers of neutral anserine were searched by molecular dynamics simulations and energy minimization calculations using the MM2 force field. Thermochemical calculations at B3LYP/6-31G(d) level of theory followed these preliminary calculations. The results confirmed that neutral anserine has quite a flexible structure and many stable gauche and trans conformers at room temperature. Nevertheless, two are considerably more favourable in energy than the others and expected to dominate the gas-phase and matrix IR spectra of the molecule. The corresponding structural and vibrational spectral data for these two conformers of neutral anserine, whose relative stabilities were also examined by high-accuracy energy calculations carried out using G3MP2B3 method, and for the most stable conformer of anserine in zwitterion form were calculated at B3LYP/6-311++G(d,p) level of theory. The calculated harmonic force constants were refined using the Scaled Quantum Mechanical Force Field (SQM-FF) method and then used to produce the refined wavenumbers, potential energy distributions (PEDs) and IR and Raman intensities. These refined data together with the scaled harmonic wavenumbers obtained using another method, Dual Scale factors (DS), enabled us to correctly analyse the observed IR and Raman spectra of anserine and revealed the effects of conformation and zwitterionic tautomerism on its structural and vibrational spectral data. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{WentrupKochKleinpeter2016,
  author    = {Wentrup, Curt and Koch, Rainer and Kleinpeter, Erich},
  title     = {Twisted C=C Double Bonds with Very Low Rotational Barriers in Dioxanediones and Isoxazolones Determined by Low-Temperature Dynamic NMR Spectroscopy and Computational Chemistry},
  series = {European journal of organic chemistry},
  journal   = {European journal of organic chemistry},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1434-193X},
  doi       = {10.1002/ejoc.201600931},
  pages     = {4985 -- 4990},
  year      = {2016},
  language  = {en}
}
@article{KleinpeterKoch2019,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {The 13 C chemical shift and the anisotropy effect of the carbene electron-deficient centre},
  series = {Magnetic resonance in chemistry},
  volume    = {58},
  journal   = {Magnetic resonance in chemistry},
  number    = {3},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.4979},
  pages     = {280 -- 292},
  year      = {2019},
  abstract  = {Both the C-13 chemical shift and the calculated anisotropy effect (spatial magnetic properties) of the electron-deficient centre of stable, crystalline, and structurally characterized carbenes have been employed to unequivocally characterize potential resonance contributors to the present mesomerism (carbene, ylide, betaine, and zwitter ion) and to determine quantitatively the electron deficiency of the corresponding carbene carbon atom. Prior to that, both structures and C-13 chemical shifts were calculated and compared with the experimental delta(C-13)/ppm values and geometry parameters (as a quality criterion for obtained structures).},
  language  = {en}
}
@article{KolocourisKochKleinpeteretal.2015,
  author    = {Kolocouris, Antonios and Koch, Andreas and Kleinpeter, Erich and Stylianakis, Ioannis},
  title     = {2-Substituted and 2,2-disubstituted adamantane derivatives as models for studying substituent chemical shifts and C-H-ax center dot center dot center dot Y-ax cyclohexane contacts-results from experimental and theoretical NMR spectroscopic chemical shifts and DFT structures},
  series = {Tetrahedron},
  volume    = {71},
  journal   = {Tetrahedron},
  number    = {16},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2015.01.044},
  pages     = {2463 -- 2481},
  year      = {2015},
  abstract  = {The complete H-1 and C-13 NMR chemical shifts assignment for various 2-substituted and 2,2-disubstituted adamantane derivatives 1-38 in CDCl3 solution was realized on the basis of NMR experiments combined with chemical structure information and DFT-GIAO (B3LYP/6-31+G(d,p)-GIAO) calculations of chemical shifts in solution. Substituent-induced C-13 NMR chemical shifts (SCS) are discussed. C-H-ax center dot center dot center dot Y-ax contacts are a textbook prototype of steric hindrance in organic chemistry. The nature of these contacts will be further investigated in this work on basis of new adamantane derivatives, which are substituted at C-2 to provide models for 1,4-C-H-ax center dot center dot center dot Y-ax and 1,5-C-H-ax center dot center dot center dot Y-ax contacts. The B3LYP/6-31+G(d,p) calculations predicted the presence of NBO hyperconjugative attractive interactions between C-H-ax and Y-ax groups along C-H-ax center dot center dot center dot Y-ax contacts. The H-1 NMR signal separation, Delta delta(gamma-CH2), reflects the strength of the H-bonded C-H-ax center dot center dot center dot Y-ax contact. (C) 2015 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@misc{Kleinpeter2014,
  author    = {Kleinpeter, Erich},
  title     = {Quantification and visualization of the anisotropy effect in NMR spectroscopy by through-space NMR shieldings},
  series = {Annual reports on NMR spectroscopy},
  volume    = {82},
  journal   = {Annual reports on NMR spectroscopy},
  editor    = {Webb, GA},
  publisher = {Elsevier},
  address   = {San Diego},
  isbn      = {978-0-12-800184-4},
  issn      = {0066-4103},
  doi       = {10.1016/B978-0-12-800184-4.00003-5},
  pages     = {115 -- 166},
  year      = {2014},
  abstract  = {The anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena as are pseudo-, spherical, captodative, homo-and chelatoaromaticity, to characterize the pi-electronic structure of, for example, fulvenes, fulvalenes, annulenes or fullerenes and to differentiate aromatic and quinonoid structures.},
  language  = {en}
}
@article{KleinpeterKoch2021,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Dative or coordinative carbon-boron bond in boron trapped N-heterocyclic carbenes (NHCs)?},
  series = {Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry},
  volume    = {80},
  journal   = {Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2020.131787},
  pages     = {8},
  year      = {2021},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of isolated as well as B-C bond length varied model compounds (BR3 trapped NHCs) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the present dative vs. coordinative bond character of the boron-carbon bond in the trapped NHCs. Results are confirmed by bond lengths and B-11/C-13 chemical shift variations in the BR3 trapped NHCs.},
  language  = {en}
}
@article{KleinpeterKoch2017,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Identification of mesomeric substructures by through-space NMR shieldings (TSNMRS). Trimethine cyanine/merocyanine-like or aromatic pi-electron delocalization?},
  series = {Tetrahedron},
  volume    = {73},
  journal   = {Tetrahedron},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2017.05.062},
  pages     = {4265 -- 4274},
  year      = {2017},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of amino-substituted heteraromatic six-membered ring systems such as pyrylium/thiopyrylium analogues have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to quantify and visualize the existing aromaticity of the studied compounds. Due to strong conjugation of six-membered ring pi-electrons and lone pairs of the exo-cyclic amino substituents (restricted rotation about partial C,N double bonds) the interplay of still aromatic and already dominating trimethine cyanine/merocyanine-like substructures can be estimated. (C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{BauerHartmannKleinpeteretal.2015,
  author    = {Bauer, Monika and Hartmann, Lutz and Kleinpeter, Erich and Kuschel, Frank and Pithart, Cornelia and Weissflog, Wolfgang},
  title     = {Chiral Dopants Derived from Ephedrine/Pseudoephedrine: Structure and Medium Effects on the Helical Twisting Power},
  series = {Molecular crystals and liquid crystals},
  volume    = {608},
  journal   = {Molecular crystals and liquid crystals},
  number    = {1},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {1542-1406},
  doi       = {10.1080/15421406.2014.949592},
  pages     = {14 -- 24},
  year      = {2015},
  abstract  = {Chiral dopants were obtained by acylation of enantiomerically pure ephedrine and pseudoephedrine with promesogenic carbonyl reagents. The products have been investigated with respect to their chiral transfer ability on nematic host matrices characterized by extreme differences of the dielectric anisotropy. It has been found that the medium dependence of the helicity induction nearly disappears at reduced temperatures. Based on variable temperature H-1 NMR studies on monoacylated homologues, the estimated coalescence temperatures and free activation enthalpies for the hindered rotation around C-N bonds could be correlated with the helical twisting power. Measurements by dielectric spectroscopy reveal the correlation between the molar mass of substituents linked to the chiral building block and the dynamic glass transition of corresponding chiral dopants. Furthermore, the effect of intramolecular and intermolecular hydrogen bonds has been studied by ATR-FTIR spectroscopy.},
  language  = {en}
}
@article{KleinpeterKoch2019,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Benzyne - an acetylene- or cumulene-like electronic structure?},
  series = {Tetrahedron},
  volume    = {75},
  journal   = {Tetrahedron},
  number    = {33},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2019.07.011},
  pages     = {4663 -- 4668},
  year      = {2019},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzyne 1 and analogues (benzene 2, 1,2,3-cyclohexatriene 3, cyclohexen-3-yne 4, cyclohexen-4-yne 5, cyclohexyne 6) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values could be employed to compare the diatropic ring current effects of benzene and benzyne, and, when compared with the spatial magnetic properties of the analogues, to answer the question whether the benzyne electronic structure is more acetylene- or cumulene-like, supported by structural data and delta(C-13)/ppm values. (C) 2019 Published by Elsevier Ltd.},
  language  = {en}
}
@article{KleinpeterKriigerKoch2015,
  author    = {Kleinpeter, Erich and Kriiger, Stefanie and Koch, Andreas},
  title     = {Anisotropy Effect of Three-Membered Rings in H-1 NMR Spectra: Quantification by TSNMRS and Assignment of the Stereochemistry},
  series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  volume    = {119},
  journal   = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  number    = {18},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1089-5639},
  doi       = {10.1021/acs.jpca.5b03078},
  pages     = {4268 -- 4276},
  year      = {2015},
  abstract  = {The spatial magnetic properties (through Space NAIR shieldings, TSNMRSs) of cyclopropane; of the heteroanalogous oxirane, thiirane, and aziridine; and of various substituted dis-, and tris-cyclic analogues have been computed by the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSSs) of various size and direction. The TSNMRS values, thus obtained, can be employed to visualize the anisotropy (ring current) effect of I the cyclopropane ring moiety. This approach has been employed to qualify and quantify substituent influences and contributions of appropriate ring heteroatoms O, NH, and S on the anisotropy (ring current) effect of three-mernbered ring moieties, and to assign the stereochemistry of mono-, bis-, and tris cyclic structures containing cyclopropane as a structural element. Characteristic examples are included.},
  language  = {en}
}
@article{ZborowskiKochKleinpeteretal.2014,
  author    = {Zborowski, Krzysztof Kazimierz and Koch, Andreas and Kleinpeter, Erich and Proniewicz, Leonard Marian},
  title     = {Searching for aromatic celate rings. Oxygen versus Thio and Seleno Ligands},
  series = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics},
  volume    = {228},
  journal   = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics},
  number    = {8},
  publisher = {De Gruyter},
  address   = {Berlin},
  issn      = {0942-9352},
  doi       = {10.1515/zpch-2014-0528},
  pages     = {869 -- 878},
  year      = {2014},
  abstract  = {As a part of searching for fully aromatic chelate compounds, copper complexes of malondialdehyde as well as its sulfur and selenium derivatives were investigated using the DFT quantum chemical methods. Chelate complexes of both Cu(I) and Cu(II) ions wereconsidered. Aromaticity of the metal complexes studied were analyzed using NICS(0), NICS(1), PDI, I-ring, MCI, ICMCI and I-B aromaticity indices, and by TSNMRS visualizations of the spatial magnetic properties. It seems that partial aromaticityof studied chelates increases when oxygen atoms in malondialdehyde are replaced by sulfur and selenium.},
  language  = {en}
}
@article{KleinpeterMichaelisKoch2015,
  author    = {Kleinpeter, Erich and Michaelis, Marcus and Koch, Andreas},
  title     = {Are para-nitro-pyridine N-oxides quinonoid or benzenoid? An answer given by spatial NICS (TSNMRS)},
  series = {Tetrahedron},
  volume    = {71},
  journal   = {Tetrahedron},
  number    = {15},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2015.02.043},
  pages     = {2273 -- 2279},
  year      = {2015},
  abstract  = {The spatial magnetic properties (Through-Space NMR Shieldings-TSNMRS) of a number of substituted para-nitro-pyridine N-oxides have been computed, visualized as Iso-Chemical-Shielding-Surfaces (ICSS) of various size and direction, and were examined subject to the present quinonoid or benzenoid pi-relectron distribution of the six-membered ring. (C) 2015 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{BartaSzatmariFueloepetal.2016,
  author    = {Barta, Petra and Szatmari, Istvan and Fueloep, Ferenc and Heydenreich, Matthias and Koch, Andreas and Kleinpeter, Erich},
  title     = {Synthesis and stereochemistry of new naphth[1,3]oxazino[3,2-a] benzazepine and naphth[1,3]oxazino[3,2-e]thienopyridine derivatives},
  series = {Tetrahedron},
  volume    = {72},
  journal   = {Tetrahedron},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2016.03.058},
  pages     = {2402 -- 2410},
  year      = {2016},
  abstract  = {Through the reactions of 1- or 2-naphthol and 4,5-dihydro-3H-benz[c]azepine or 6,7-dihydrothieno[3,2-c]pyridine, new aminonaphthol derivatives were prepared. The syntheses were extended by using N-containing naphthol analogues such as 5-hydroxyisoquinoline and 6-hydroxyquinoline. The ring closures of the novel bifunctional compounds were also achieved, resulting in new naphth[2,1-e][1,3]oxazines, naphth[1,2-e][1,3]oxazines, isoquinolino[5,6-e][1,3]oxazines and quinolino[5,6-e][1,3]oxazines. H-1 NMR spectra of the target heterocycles 16, 20 and 21 were sufficiently resolved to indentify the present stereochemistry; therefore, beside computed structures, spatial experimental (dipolar coupling-NOE) and computed (ring current effect of the naphthyl moiety-TSNMRS) NMR studies were employed. The studied heterocycles exist exclusively as S(14b),R(N), R(14b),S(N), and S(16b)S(N) isomers, respectively. The flexible moieties of the studied compounds prefer. (C) 2016 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{RasovicBlagojevicBaranacStojanovicetal.2016,
  author    = {Rasovic, Aleksandar and Blagojevic, Vladimir and Baranac-Stojanovic, Marija and Kleinpeter, Erich and Markovic, Rade and Minic, Dragica M.},
  title     = {Quantification of the push-pull effect in 2-alkylidene-4-oxothiazolidines by using NMR spectral data and barriers to rotation around the C=C bond},
  series = {New journal of chemistry},
  volume    = {40},
  journal   = {New journal of chemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1144-0546},
  doi       = {10.1039/c6nj00901h},
  pages     = {6364 -- 6373},
  year      = {2016},
  abstract  = {Information about the strength of donor-acceptor interactions in push-pull alkenes is valuable, as this so-called "push-pull effect' influences their chemical reactivity and dynamic behaviour. In this paper, we discuss the applicability of NMR spectral data and barriers to rotation around the CQC double bond to quantify the push-pull effect in biologically important 2-alkylidene-4-oxothiazolidines. While olefinic proton chemical shifts and differences in C-13 NMR chemical shifts of the two carbons constituting the CQC double bond fail to give the correct trend in the electron withdrawing ability of the substituents attached to the exocyclic carbon of the double bond, barriers to rotation prove to be a reliable quantity in providing information about the extent of donor-acceptor interactions in the push-pull systems studied. In particular all relevant kinetic data, that is the Arrhenius parameters ( apparent activation energy Ea and frequency factor A) and activation parameters ( Delta S-double dagger, Delta H-double dagger and Delta G(double dagger)), were determined from the data of the experimentally studied configurational isomerization of ( E)-9a. These results were compared to previously published related data for other two compounds, ( Z)-1b and ( 2E, 5Z)-7, showing that experimentally determined Delta G(double dagger) values are a good indicator of the strength of push-pull character. Theoretical calculations of the rotational barriers of eight selected derivatives excellently correlate with the calculated CQC bond lengths and corroborate the applicability of Delta G(double dagger) for estimation of the strength of the push-pull effect in these and related systems.},
  language  = {en}
}
@article{ShainyanKirpichenkoKleinpeter2017,
  author    = {Shainyan, Bagrat A. and Kirpichenko, Svetlana V. and Kleinpeter, Erich},
  title     = {Conformational Preferences of the Phenyl Group in 1-Phenyl-1-X-1-silacyclo-hexanes (X = MeO, HO) and 3-Phenyl-3-X-3-silatetrahydropyrans (X = HO, H) by Low Temperature C-13 NMR Spectroscopy and Theoretical Calculations},
  series = {The journal of organic chemistry},
  volume    = {82},
  journal   = {The journal of organic chemistry},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0022-3263},
  doi       = {10.1021/acs.joc.7b02505},
  pages     = {13414 -- 13422},
  year      = {2017},
  abstract  = {New Si-phenyl-substituted silacyclohexanes and 3-silatetrahydropyrans have been synthesized and studied with respect to the conformational equilibria of the heterosix-membered ring by low temperature C-13 NMR spectroscopy and quantum chemical calculations. For 1-methoxy-1-phenylsilacyclohexane 1 and 3-phenyl-3-silatetrahydropyran 4 the conformational equilibria could be frozen and assigned. The Ph-ax reversible arrow Ph-eq equilibrium constants at 103 K are 2.21 for 1 and 4.59 for 4. In complete agreement with former studies of similar silicon compounds, molecules 1 and 4 prefer to adopt the Pheq conformation. The conformational equilibria of 1-hydroxy-1-phenylsilacydohexane 2 and 3-hydroxy-3-phenyl-3-silatetrahydropyran 3 could not be frozen at 100 K and proved to be heavily one-sided (if not anancomeric). Obviously, there is a general trend of predominance of Phax conformer in the gas phase and of Pheq in solution. For the isolated molecules of silanols 2 and 3, calculations allowed to explain the axial predominance of the phenyl group by a larger polarization of the Si-Ph than of the Si-O bond in the Phax conformer and additional destabilization of 3-Ph-eq conformer by repulsion of unidirectional dipoles of the endocyclic oxygen lone pair and of the highly polar axial Si-O bond.},
  language  = {en}
}
@article{KleinpeterWernerLinker2017,
  author    = {Kleinpeter, Erich and Werner, Peter and Linker, Torsten},
  title     = {Synthesis and NMR spectroscopic conformational analysis of benzoic acid esters of mono- and 1,4-dihydroxycyclohexane, 4-hydroxycyclohexanone and the -ene analogue - The more polar the molecule the more stable the axial conformer},
  series = {Tetrahedron},
  volume    = {73},
  journal   = {Tetrahedron},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2017.04.029},
  pages     = {3801 -- 3809},
  year      = {2017},
  abstract  = {para-Substituted benzoic acid esters of cyclohexanol, 1,4-dihydroxycyclohexane, 4-hydroxy-cyclohexanone and of the corresponding exo-methylene derivative were synthesized and the conformational equilibria of the cyclohexane skeleton studied by low temperature H-1 and C-13 NMR spectroscopy. The geometry optimized structures of the axial/equatorial chair conformers were computed at the DFT level of theory. Only one preferred conformation of the ester group was obtained for both the axial and the equatorial conformer, respectively. The content of the axial conformer increases with growing polarity of the 6-membered ring moiety; hereby, in addition, the effect of sp(2) hybridization/polarity of C(4)= O/C(4)= CH2 on the present conformational equilibria is critically evaluated. Another dynamic process could be studied, for the first time in this kind of compounds. (C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{KleinpeterHeydenreichKochetal.2017,
  author    = {Kleinpeter, Erich and Heydenreich, Matthias and Koch, Andreas and Krtitschka, Angela and Kr{\"u}ger, Tobias and Linker, Torsten},
  title     = {NMR spectroscopic conformational analysis of 4-methylene-cyclohexyl pivalateThe effect of sp(2) hybridization},
  series = {Magnetic resonance in chemistry},
  volume    = {55},
  journal   = {Magnetic resonance in chemistry},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.4630},
  pages     = {1073 -- 1078},
  year      = {2017},
  abstract  = {The conformational equilibrium of the axial/equatorial conformers of 4-methylene-cyclohexyl pivalate is studied by dynamic NMR spectroscopy in a methylene chloride/freon mixture. At 153K, the ring interconversion gets slow on the nuclear magnetic resonance timescale, the conformational equilibrium (-G degrees) can be examined, and the barrier to ring interconversion (G(\#)) can be determined. The structural influence of sp(2) hybridization on both G degrees and G(\#) of the cyclohexyl moiety can be quantified.},
  language  = {en}
}
@article{SzatmariBelasriHeydenreichetal.2019,
  author    = {Szatmari, Istvan and Belasri, Khadija and Heydenreich, Matthias and Koch, Andreas and Kleinpeter, Erich and Fulop, Ferenc},
  title     = {Ortho-Quinone methide driven synthesis of new O,N- or N,N-Heterocycles},
  series = {ChemistryOpen : including thesis treasury},
  volume    = {8},
  journal   = {ChemistryOpen : including thesis treasury},
  number    = {7},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2191-1363},
  doi       = {10.1002/open.201900150},
  pages     = {961 -- 971},
  year      = {2019},
  abstract  = {To synthesize functionalized Mannich bases that can serve two different types of ortho-quinone methide (o-QM) intermediates, 2-naphthol and 6-hydroxyquinoline were reacted with salicylic aldehyde in the presence of morpholine. The Mannich bases that can form o-QM and aza-o-QM were also synthesized by mixing 2-naphthol, 2-nitrobenzaldehyde, and morpholine followed by reduction of the nitro group. The highly functionalized aminonaphthol derivatives were then tested in [4+2] cycloaddition with different cyclic imines. The reaction proved to be both regio- and diastereoselective. In all cases, only one reaction product was obtained. Detailed structural analyses of the new polyheterocycles as well as conformational studies including DFT modelling were performed. The relative stability of o-QMs/aza-o-QM were also calculated, and the regioselectivity of the reactions could be explained only when the cycloaddition started from aminodiol 4. It was summarized that starting from diaminonaphthol 25, the regioselectivity of the reaction is driven by the higher nucleophilicity of the amino group compared with the hydroxy group. 12H-benzo[a]xanthen-12-one (11), formed via o-QM formation, was isolated as a side product. The proton NMR spectrum of 11 proved to be very unique from NMR point of view. The reason for the extreme low-field position of proton H-1 could be accounted for by theoretical calculation of structure and spatial magnetic properties of the compound in combination of ring current effects of the aromatic moieties and steric compression within the heavily hindered H(1)-C(1)-C(12b)-C(12a)-C(12)=O structural fragment.},
  language  = {en}
}
@article{ShainyanSuslovaTranDinhPhienetal.2019,
  author    = {Shainyan, Bagrat A. and Suslova, Elena N. and Tran Dinh Phien, and Shlykov, Sergey A. and Heydenreich, Matthias and Kleinpeter, Erich},
  title     = {1-Methylthio-1-phenyl-1-silacyclohexane: Synthesis, conformational preferences in gas and solution by GED, NMR and theoretical calculations},
  series = {Tetrahedron},
  volume    = {75},
  journal   = {Tetrahedron},
  number    = {46},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2019.130677},
  pages     = {9},
  year      = {2019},
  abstract  = {1-Methylthio-1-phenyl-1-silacyclohexane 1, the first silacyclohexane with the sulfur atom at silicon, was synthesized and its molecular structure and conformational preferences studied by gas-phase electron diffraction (GED) and low temperature C-13 and Si-29 NMR spectroscopy (LT NMR). Quantum-chemical calculations were carried out both for the isolated species and solvate complexes in gas and in polar medium. The predominance of the 1-MeSaxPheq conformer in gas phase (1-Ph-eq :1-Ph-ax = 55:45, Delta G degrees = 0.13 kcal/mol) determined from GED is consistent with that measured in the freon solution by LT NMR (1-Ph-eq:1-Ph-ax = 65:35, Delta G degrees = 0.12 kcal/mol), the experimentally measured ratios being close to that estimated by quantum chemical calculations at both the DFT and MP2 levels of theory. (C) 2019 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{ShainyanKleinpeterSuslova2019,
  author    = {Shainyan, Bagrat A. and Kleinpeter, Erich and Suslova, E. N.},
  title     = {Conformational Analysis of (1,1′-Phenyl-1,1′-silacyclohex-1-yl)disiloxane},
  series = {Russian journal of general chemistry},
  volume    = {89},
  journal   = {Russian journal of general chemistry},
  number    = {4},
  publisher = {Pleiades Publ.},
  address   = {New York},
  issn      = {1070-3632},
  doi       = {10.1134/S1070363219040121},
  pages     = {713 -- 716},
  year      = {2019},
  abstract  = {The DFT and MP2 theoretical conformational analysis of the recently synthesized (1,1-phenyl-1,1-silacyclohex-1-yl)disiloxane has revealed the energetic preference of the Ph-ax,Ph-ax conformer. The Ph-ax,Ph-ax: Ph-ax,Ph-eq: Ph-eq,Ph-eq conformers ratio has been estimated as of 46.6: 33.1: 20.3 from the M062X/6-311G(d,p) free energy simulation, suggesting the possibility of detecting individual conformers experimentally, e.g., by low-temperature H-1 and C-13 NMR spectroscopy. However, only the presence of several conformers has been detected by means of H-1 NMR spectroscopy at 113 K; determination of the (Hz) and G(\#) (kcal/mol) parameters for the 6-membered ring interconversion has been impossible due to the signals broadening at low temperature, signal temperature shifts, and extremely low barrier of ring inversion at T-c < 113 K.},
  language  = {en}
}
@article{KleinpeterKoch2019,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Benzenium Ion},
  series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  volume    = {123},
  journal   = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  number    = {20},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1089-5639},
  doi       = {10.1021/acs.jpca.9b03121},
  pages     = {4443 -- 4451},
  year      = {2019},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of the benzenium cation (C6H7+) 1 and of +/- I/M-substituted analogues C6H6X+ 3-8 [X = -Me, -CF3, -NH2, -NO2, -NO, -SiH3] have been calculated using the gauge-independent atomic orbital perturbation method employing the nucleus-independent chemical shift concept, and iso-chemical-shielding surfaces of various sizes and directions have been observed. The TSNMRS values were employed to compare the spatial magnetic properties (TSNMRS) of benzene and the benzenium ion 1 and then further compared with analogues 3-8, to answer the question whether the electronic structures of 1 and 3-8 are still similar to those of aromatic species or somewhat similar to the antiaromatic cyclopentadienyl cation 2, supported by structural data and delta(C-13)/ppm values.},
  language  = {en}
}