@article{BelasriTopalHeydenreichetal.2020,
  author    = {Belasri, Khadija and Topal, Leila and Heydenreich, Matthias and Koch, Andreas and Kleinpeter, Erich and Fulop, Ferenc and Szatmari, Istvan},
  title     = {Synthesis and conformational analysis of naphthoxazine-fused phenanthrene derivatives},
  series = {Molecules},
  volume    = {25},
  journal   = {Molecules},
  number    = {11},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules25112524},
  pages     = {15},
  year      = {2020},
  abstract  = {The synthesis of new phenanthr[9,10-e][1,3]oxazines was achieved by the direct coupling of 9-phenanthrol with cyclic imines in the modified aza-Friedel-Crafts reaction followed by the ring closure of the resulting bifunctional aminophenanthrols with formaldehyde. Aminophenanthrol-type Mannich bases were synthesised and transformed to phenanthr[9,10-e][1,3]oxazines via [4 + 2] cycloaddition. Detailed NMR structural analyses of the new polyheterocycles as well as conformational studies including Density Functional Theory (DFT) modelling were performed. The relative stability of ortho-quinone methides (o-QMs) was calculated, the geometries obtained were compared with the experimentally determined NMR structures, and thereby, the regioselectivity of the reactions has been assigned.},
  language  = {en}
}
@article{KochStamboliyskaMikhovaetal.2019,
  author    = {Koch, Andreas and Stamboliyska, Bistra and Mikhova, Bozhana and Breznica-Selmani, Pranvera and Mladenovska, Kristina and Popovski, Emil},
  title     = {Calculations of C-13 NMR chemical shifts and F-C coupling constants of ciprofloxacin},
  series = {Magnetic resonance in chemistry},
  volume    = {57},
  journal   = {Magnetic resonance in chemistry},
  number    = {4},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.4827},
  pages     = {75 -- 84},
  year      = {2019},
  abstract  = {Ciprofloxacin is a widely used fluoroquinolone antibiotic. In this work, a comprehensive evaluation of MP2 and DFT with different functionals and basis sets was carried out to select the most suitable level of theory for the study of the NMR properties of ciprofloxacin. Their relative predictive capabilities were evaluated comparing the theoretically predicted and experimental spectral data. Our computational results indicated that in contrast to the solid state, the molecule of ciprofloxacin does not exist as a zwitterion in gaseous state. The results of the calculations of the chemical shifts most close to the experimental were obtained with B3LYP/aug-cc-pVDZ. The F-C coupling constants were calculated systematically with different DFT methods and several basis sets. In general, the calculations of the coupling constants with the BHandH computational method including the applied in this work 6-311++G**, EPRII, and EPRIII basis sets showed a good reproducibility of the experimental values of the coupling constants.},
  language  = {en}
}
@article{FudickarLinker2019,
  author    = {Fudickar, Werner and Linker, Torsten},
  title     = {Theoretical insights into the effect of solvents on the [4+2] cycloaddition of singlet oxygen to substituted anthracenes},
  series = {Journal of physical organic chemistry},
  volume    = {32},
  journal   = {Journal of physical organic chemistry},
  number    = {7},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0894-3230},
  doi       = {10.1002/poc.3951},
  pages     = {9},
  year      = {2019},
  abstract  = {The [4 + 2] cycloadditions of singlet oxygen to 9,10-diphenylanthracene (1) and the meta and para isomers of 9,10-dipyridylanthracene (2m/p) and 9,10-methoxyphenylanthracene (3m/p) have been studied by density functional calculations in the gas phase at the UB3LYP/6-31G* level and for the first time in solvents at the conductor-like polarizable continuum model (CPCM) UM062X/6-31G* level. The differences in calculated transition state (TS) energies derived from this method are in line with experimentally observed reactivity orders in solution. For the gas-phase reaction, the first TS of the stepwise pathway (TS1) has biradical character, and its energy lies below the energy of the TS of the concerted path (TSconc). In contrast, in the solvent acetonitrile, TS1 resembles a zwitterion and lies significantly higher than the TSconc. Thus, a concerted mechanism applies in solvents, and the energy gap between the TS of the two processes decreases with decreasing polarity. A change from a pyridyl against a methoxyphenyl substituent in the para position causes a maximal reduction of the activation barrier by approximately 1.7 kcal/mol, resulting in a fivefold increased reactivity.},
  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{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{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{DemetriouPashalidisNicolaidesetal.2013,
  author    = {Demetriou, Antri and Pashalidis, Ioannis and Nicolaides, Athanassios V. and Kumke, Michael Uwe},
  title     = {Surface mechanism of the boron adsorption on alumina in aqueous solutions},
  series = {Desalination and water treatment : science and engineering},
  volume    = {51},
  journal   = {Desalination and water treatment : science and engineering},
  number    = {31-33},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {1944-3994},
  doi       = {10.1080/19443994.2013.764354},
  pages     = {6130 -- 6136},
  year      = {2013},
  abstract  = {The adsorption of boron (boric acid) from aqueous solutions on alumina has been investigated at pH 8.0, I=0.1M NaClO4, T=22 +/- 3 degrees C, and under normal atmospheric conditions. The characterization of the adsorbed species was performed by Raman spectroscopy and the spectroscopic speciation was assisted by theoretical DFT calculations. Evaluation of the spectroscopic data points to the formation of inner-sphere surface complexes and indicates the formation of two different types of adsorbed boron species. The theoretical calculations corroborate the spectroscopic data and indicate that at low boron concentration the monodentate surface species dominates, whereas increased boron concentration favors the formation of a bidentate surface species. Assuming low coverage, the conditional formation constant for the monodentate surface species has been evaluated to be log=4.1 +/- 0.1.},
  language  = {en}
}
@article{SzatmariHeydenreichKochetal.2013,
  author    = {Szatmari, Istvan and Heydenreich, Matthias and Koch, Andreas and Fulop, Ferenc and Kleinpeter, Erich},
  title     = {Unexpected isomerization of new naphth[1,3]oxazino[2,3-a] isoquinolines in solution, studied by dynamic NMR and supported by theoretical DFT computations},
  series = {Tetrahedron},
  volume    = {69},
  journal   = {Tetrahedron},
  number    = {35},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2013.06.094},
  pages     = {7455 -- 7465},
  year      = {2013},
  abstract  = {Through the reactions of 1-aminomethyl-2-naphthol and substituted 1-aminobenzyl-2-naphthols with 3,4-dihydroisoquinoline or 6,7-dimethoxy-3,4-dihydroisoquinoline under microwave conditions, naphth[1,2-e][1,3]oxazino[2,3-a]-isoquinoline derivatives were prepared in good yields. The latter reaction was extended by using 2-aminoarylmethyl-1-naphthols, leading to isomeric naphth-[2,1-e][1,3]oxazino[2,3-a] isoquinolines. Beside the detailed NMR spectroscopic and theoretical study of both stereochemistry and dynamic behaviour of these new conformational flexible heterocyclic ring systems an unexpected dynamic process between two diastereomers was observed in solution, studied by variable temperature H-1 NMR spectroscopy and the mechanism proved by theoretical DFT computations.},
  language  = {en}
}