TY  - JOUR
A1  - Michalik-Onichimowska, Aleksandra
A1  - Kern, Simon
A1  - Riedel, Jens
A1  - Panne, Ulrich
A1  - King, Rudibert
A1  - Maiwald, Michael
T1  - "Click" analytics for "click" chemistry - A simple method for calibration-free evaluation of online NMR spectra
JF  - Journal of magnetic resonance
N2  - Driven mostly by the search for chemical syntheses under biocompatible conditions, so called "click" chemistry rapidly became a growing field of research. The resulting simple one-pot reactions are so far only scarcely accompanied by an adequate optimization via comparably straightforward and robust analysis techniques possessing short set-up times. Here, we report on a fast and reliable calibration-free online NMR monitoring approach for technical mixtures. It combines a versatile fluidic system, continuous-flow measurement of H-1 spectra with a time interval of 20 s per spectrum, and a robust, fully automated algorithm to interpret the obtained data. As a proof-of-concept, the thiol-ene coupling between N-boc cysteine methyl ester and ally] alcohol was conducted in a variety of non-deuterated solvents while its time-resolved behaviour was characterized with step tracer experiments. Overlapping signals in online spectra during thiol-ene coupling could be deconvoluted with a spectral model using indirect hard modeling and were subsequently converted to either molar ratios (using a calibration free approach) or absolute concentrations (using 1-point calibration). For various solvents the kinetic constant k for pseudo-first order reaction was estimated to be 3.9 h(-1) at 25 degrees C. The obtained results were compared with direct integration of non-overlapping signals and showed good agreement with the implemented mass balance. (C) 2017 Elsevier Inc. All rights reserved.
KW  - NMR spectroscopy
KW  - Reaction monitoring
KW  - Automated data evaluation
KW  - Thiol-ene click chemistry
Y1  - 2017
U6  - https://doi.org/10.1016/j.jmr.2017.02.018
SN  - 1090-7807
SN  - 1096-0856
VL  - 277
SP  - 154
EP  - 161
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Harmanli, İpek
A1  - Tarakina, Nadezda
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - "Giant" nitrogen uptake in ionic liquids confined in carbon pores
JF  - Journal of the American Chemical Society
N2  - Ionic liquids are well known for their high gas absorption capacity. It is shown that this is not a solvent constant, but can be enhanced by another factor of 10 by pore confinement, here of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimOAc) in the pores of carbon materials. A matrix of four different carbon compounds with micro- and mesopores as well as with and without nitrogen doping is utilized to investigate the influence of the carbons structure on the nitrogen uptake in the pore-confined EmimOAc. In general, the absorption is most improved for IL in micropores and in nitrogen-doped carbon. This effect is so large that it is already seen in TGA and DSC experiments. Due to the low vapor pressure of the IL, standard volumetric sorption experiments can be used to quantify details of this effect. It is reasoned that it is the change of the molecular arrangement of the ions in the restricted space of the pores that creates additional free volume to host molecular nitrogen.
Y1  - 2021
U6  - https://doi.org/10.1021/jacs.1c00783
SN  - 0002-7863
SN  - 1520-5126
VL  - 143
IS  - 25
SP  - 9377
EP  - 9384
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Liebig, Ferenc
A1  - Sarhan, Radwan Mohamed
A1  - Prietzel, Claudia Christina
A1  - Reinecke, Antje
A1  - Koetz, Joachim
T1  - "Green" gold nanotriangles: synthesis, purification by polyelectrolyte/micelle depletion flocculation and performance in surface-enhanced Raman scattering
JF  - RSC Advances
N2  - The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering.
Y1  - 2016
U6  - https://doi.org/10.1039/c6ra04808k
SN  - 2046-2069
VL  - 6
SP  - 33561
EP  - 33568
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Sinha, Shreya
A1  - Saalfrank, Peter
T1  - "Inverted" CO molecules on NaCl(100)
BT  - a quantum mechanical study
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Somewhat surprisingly, inverted ("O-down") CO adsorbates on NaCl(100) were recently observed experimentally after infrared vibrational excitation (Lau et al., Science, 2020, 367, 175-178). Here we characterize these species using periodic density functional theory and a quantum mechanical description of vibrations. We determine stationary points and minimum energy paths for CO inversion, for low (1/8 and 1/4 monolayers (ML)) and high (1 ML) coverages. Transition state theory is applied to estimate thermal rates for "C-down" to "O-down" isomerization and the reverse process. For the 1/4 ML p(1 x 1) structure, two-dimensional and three-dimensional potential energy surfaces and corresponding anharmonic vibrational eigenstates obtained from the time-independent nuclear Schrodinger equation are presented. We find (i) rather coverage-independent CO inversion energies (of about 0.08 eV or 8 kJ mol(-1) per CO) and corresponding classical activation energies for "C-down" to "O-down" isomerization (of about 0.15 eV or 14 kJ mol(-1) per CO); (ii) thermal isomerization rates at 22 K which are vanishingly small for the "C-down" to "O-down" isomerization but non-negligible for the back reaction; (iii) several "accidentally degenerate" pairs of eigenstates well below the barrier, each pair describing "C-down" to "O-down" localized states.
Y1  - 2020
U6  - https://doi.org/10.1039/d0cp05198e
SN  - 1463-9076
SN  - 1463-9084
VL  - 23
IS  - 13
SP  - 7860
EP  - 7874
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Dolya, Natalya
A1  - Rojas, Oscar
A1  - Kosmella, Sabine
A1  - Tiersch, Brigitte
A1  - Koetz, Joachim
A1  - Kudaibergenov, Sarkyt
T1  - "One-Pot" in situ frmation of Gold Nanoparticles within Poly(acrylamide) Hydrogels
JF  - Macromolecular chemistry and physics
N2  - This paper focuses on two different strategies to incorporate gold nanoparticles (AuNPs) into the matrix of polyacrylamide (PAAm) hydrogels. Poly(ethyleneimine) (PEI) is used as both reducing and stabilizing agent for the formation of AuNPs. In addition, the influence of an ionic liquid (IL) (i.e., 1-ethyl-3-methylimidazolium ethylsulfate) on the stability of the nanoparticles and their immobilization in the hydrogel is investigated The results show that AuNPs surrounded by a shell containing PEI and IL, synthesized according to the one-pot approach, are much better immobilized within the PAAm hydrogel. Hereby, the IL is responsible for structural changes in the hydrogel as well as the improved stabilization and embedding of the AuNPs into the polymer gel matrix.
KW  - gold nanoparticles
KW  - immobilization
KW  - ionic liquids
KW  - poly(acrylamide) hydrogels
Y1  - 2013
U6  - https://doi.org/10.1002/macp.201200727
SN  - 1022-1352
VL  - 214
IS  - 10
SP  - 1114
EP  - 1121
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Weber, Nancy
A1  - Tiersch, Brigitte
A1  - Unterlass, Miriam M.
A1  - Heilig, Anneliese
A1  - Tauer, Klaus
T1  - "Schizomorphic" Emulsion Copolymerization Particles
JF  - Macromolecular rapid communications
N2  - Cryo-electron microscopy, atomic force microscopy, and light microscopy investigations provide experimental evidence that amphiphilic emulsion copolymerization particles change their morphology in dependence on concentration. The shape of the particles is spherical at solids content above 1%, but it changes to rod-like, ring-like, and web-like structures at lower concentrations. In addition, the shape and morphology of these particles at low concentrations are not fixed but very flexible and vary with time between spheres, flexible pearlnecklace structures, and stretched rods.
KW  - amphiphilic particles
KW  - emulsion polymerization
KW  - morphology
Y1  - 2011
U6  - https://doi.org/10.1002/marc.201100491
SN  - 1022-1336
VL  - 32
IS  - 23
SP  - 1925
EP  - 1929
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Vishnevetskaya, Natalya S.
A1  - Hildebrand, Viet
A1  - Niebuur, Bart-Jan
A1  - Grillo, Isabelle
A1  - Filippov, Sergey K.
A1  - Laschewsky, Andre
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - "Schizophrenic" Micelles from Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylmethacrylamide) Diblock Copolymers
JF  - Macromolecules : a publication of the American Chemical Society
Y1  - 2017
U6  - https://doi.org/10.1021/acs.macromol.7b00356
SN  - 0024-9297
SN  - 1520-5835
VL  - 50
SP  - 3985
EP  - 3999
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Paz, Cristian
A1  - Becerra, Jose
A1  - Silva, Mario
A1  - Cabrera-Pardo, Jaime
A1  - Burgos, Viviana
A1  - Heydenreich, Matthias
A1  - Schmidt, Bernd
T1  - (-)-8-Oxohobartine a New Indole Alkaloid from Aristotelia chilensis (Mol.) Stuntz
JF  - Records of Natural Products
N2  - The fruit of Aristotelia chilensis is considered a "super fruit" due to its high concentration of polyphenols displaying exceptional antioxidant capacities ORAC. From maqui berries have been reported several anthocyanins and glycosylated flavonoids, those benefits increase the attention to restudy the plant. From the leaves of A. chilensis several indole alkaloids have been reported, we in addition to aristoteline, aristone, aristoquinoline and 3-fromylindole report the spectroscopic elucidation of 8-oxo-9-dehydromakomakine (1), hobartine (2) and a new alkaloid named 8-oxohobartine (3). Compound 1 to 3 did not show bactericidal activity against E. coli and S. aureus till 200 mu g.
KW  - Aristotelia chilensis
KW  - indole alkaloids
KW  - 8-oxohobartine
Y1  - 2016
SN  - 1307-6167
VL  - 10
SP  - 68
EP  - 73
PB  - ACG Publications
CY  - Gebze-Kocaeli
ER  - 
TY  - JOUR
A1  - Paz, Cristian
A1  - Becerra, Jose
A1  - Silva, Mario
A1  - Burgos, Viviana
A1  - Heydenreich, Matthias
A1  - Schmidt, Bernd
A1  - Thu Tran, 
A1  - Vetter, Irina
T1  - (-)-Pentylsedinine, a New Alkaloid from the Leaves of Lobelia tupa with Agonist Activity at Nicotinic Acetylcholine Receptor
JF  - Natural product communications : an international journal for communications and reviews
N2  - Lobelia tupa, also called devil's tobacco, is a native plant from the center-south of Chile which has been used by the native people of Chile as a hallucinogenic and anesthetic plant. A new piperidine alkaloid, called pentylsedinine, which comprises five carbons in the side chain, was isolated from the aerial part of L. tupa, along with lobeline and lobelanidine. The structure was established on the basis of 1D and 2D NMR spectroscopy. While lobeline is a neutral antagonist at alpha 3 beta 2/alpha 3 beta 4 nAChR and alpha 7 nAChR, both lobelanidine and pentylsedinine act as partial agonists at nAChR
KW  - Lobelia tupa
KW  - Piperidine alkaloid
KW  - nAChR
KW  - Pentylsedinine
Y1  - 2015
SN  - 1934-578X
SN  - 1555-9475
VL  - 10
IS  - 8
SP  - 1355
EP  - 1357
PB  - NPC
CY  - Westerville
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - (Anti)aromaticity of dehydroannulenes of various ring size proved by the ring current effect in H-1 NMR spectra
JF  - Tetrahedron
N2  - The spatial magnetic properties (Through-Space NMR Shieldings-TSNMRS) of already synthesized dehydro[n]annulenes of various ring size (from C-12 to C-20) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, and were examined subject to present (anti)aromaticity. For this purpose the thus quantified ring current effect of the macro cycles on proximate protons in proton NMR spectra was employed.
KW  - Dehydro[n]annulenes
KW  - (Anti)aromaticity
KW  - TSNMRS
KW  - H-1 NMR spectroscopy
KW  - Anisotropic effect
KW  - Theoretical calculations
KW  - ICSS
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2012.12.019
SN  - 0040-4020
VL  - 69
IS  - 5
SP  - 1481
EP  - 1488
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Titov, Evgenii
A1  - Kopp, Tristan
A1  - Hoche, Joscha
A1  - Humeniuk, Alexander
A1  - Mitrić, Roland
T1  - (De)localization dynamics of molecular excitons
BT  - comparison of mixed quantum-classical and fully quantum treatments
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2  - Molecular excitons play a central role in processes of solar energy conversion, both natural and artificial. It is therefore no wonder that numerous experimental and theoretical investigations in the last decade, employing state-of-the-art spectroscopic techniques and computational methods, have been driven by the common aim to unravel exciton dynamics in multichromophoric systems. Theoretically, exciton (de)localization and transfer dynamics are most often modelled using either mixed quantum-classical approaches (e.g., trajectory surface hopping) or fully quantum mechanical treatments (either using model diabatic Hamiltonians or direct dynamics). Yet, the terms such as "exciton localization" or "exciton transfer" may bear different meanings in different works depending on the method in use (quantum-classical vs. fully quantum). Here, we relate different views on exciton (de)localization. For this purpose, we perform molecular surface hopping simulations on several tetracene dimers differing by a magnitude of exciton coupling and carry out quantum dynamical as well as surface hopping calculations on a relevant model system. The molecular surface hopping simulations are done using efficient long-range corrected time-dependent density functional tight binding electronic structure method, allowing us to gain insight into different regimes of exciton dynamics in the studied systems.
Y1  - 2022
U6  - https://doi.org/10.1039/d2cp00586g
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 20
SP  - 12136
EP  - 12148
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bois, Juliana
A1  - Körzdörfer, Thomas
T1  - 0 How Bond Length Alternation and Thermal Disorder Affect the Optical
Excitation Energies of pi-Conjugated Chains: A Combined Density
Functional Theory and Molecular Dynamics Study
JF  - Journal of chemical theory and computation
N2  - We dissect the sources of error leading to inaccuracies in the description of the geometry and optical excitation energies of pi-conjugated polymers. While the ground-state bond length alternation is shown to be badly reproduced by standard functionals, the recently adapted functionals PBEh* and omega PBE* as well as the double hybrid functional XYGJ-OS manage to replicate results obtained at the CCSD(T) level. By analysis of the bond length alternation in the excited state, a sensitive dependence of the exciton localization on the long-range behavior of the functional and the amount of Hartree-Fock exchange present is shown. Introducing thermal disorder through molecular dynamics simulations allows the consideration of a range of thermally accessible configurations of each oligomer, including trans to cis rotations, which break the conjugation of the backbone. Thermal disorder has a considerable effect when combined with functionals that overestimate the delocalization of the excitation, such as B3LYP. For functionals with a larger amount of exact exchange such as our PBEh* and omega PBE*, however, the effect is small, as excitations are often localized enough to fit between twists in the chain.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.jctc.5b01070
SN  - 1549-9618
SN  - 1549-9626
VL  - 12
SP  - 1872
EP  - 1882
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Awad, Duha Jawad
A1  - Conrad, Franziska
A1  - Koch, Andreas
A1  - Schilde, Uwe
A1  - Poeppl, Andreas
A1  - Strauch, Peter
T1  - 1,10-phenanthroline-dithiolate mixed ligand transition metal complexes : synthesis, characterization and EPR spectroscopy
N2  - A series of new N2S2 mixed ligand transition metal complexes, where N-2 is phenanthroline and S-2 is 1,2- dithiooxalate (dto) or 1,2-dithiosquarate (dtsq), has been synthesized and characterized. IR spectra reveal that the 1,2- dithiolate ligands are coordinated via the sulfur atoms forming a N2S2 coordination sphere. The copper(II) complex [Cu(phen)(dto)] was studied by EPR spectroscopy as a diamagnetically diluted powder. The diamagnetic dilution resulted from doping of the copper complex into the isostructural host lattice of the nickel complex [Ni(phen)(dto)]. The electronic situation in the frontier orbitals of the copper complex calculated from the experimental data is compared to the results of EHT and DFT calculations. Furthermore, one side product, chlorobis(1,10-phenanthroline)copper(I) ethanol solvate hydrate [(phen)(2)CuCl]center dot C2H5OH center dot H2O, was formed by a reduction process and characterized by X-ray diffraction. In the crystal packing one-dimensional columns of dimers are formed, stabilized by significant pi-pi interactions.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/00201693
U6  - https://doi.org/10.1016/j.ica.2010.01.021
SN  - 0020-1693
ER  - 
TY  - JOUR
A1  - Kammer, Stefan
A1  - Starke, Ines
A1  - Pietrucha, Andreas
A1  - Kelling, Alexandra
A1  - Mickler, Wulfhard
A1  - Schilde, Uwe
A1  - Dosche, Carsten
A1  - Kleinpeter, Erich
A1  - Holdt, Hans-Jürgen
T1  - 1,12-Diazaperylene and 2,11-dialkylated-1,12-diazaperylene iridium(III) complexes [Ir((CN)-N-boolean AND)(2)((NN)-N-boolean AND)]PF6: new supramolecular assemblies
JF  - Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry
N2  - A series of new monocationic iridium(III) complexes [Ir((CN)-N-boolean AND)(2)((NN)-N-boolean AND)]PF6 with "large-surface" alpha,alpha'-diimin ligands (NN)-N-boolean AND (dap = 1,12-diazaperylene, dmedap = 2,11-dimethyl-1,12-diazaperylene, dipdap = 2,11-diisopropyl-1,12-diazaperylene) and different cyclometalating ligands (CN)-N-boolean AND (piq = 1-phenylisoquinoline, bzq = benzo[h]quinoline, ppz = 1-phenylpyrazole, thpy = 2-(2-thienyl)pyridine, ppy = 2-phenylpyridine, meppy = 2-(4-methylphenyl)pyridine, dfppy = 2-(2,4-difluorophenyl)pyridine) were synthesized. The solid structures of the complexes [Ir(piq)(2)(dap)]PF6, [Ir(bzq)(2)(dap)]PF6, [Ir(ppy)(2)(dipdap)]PF6, [Ir(piq)(2)(dmedap)]PF6, [Ir(ppy)(2)(dap)]PF6 and [Ir(ppz)(2)(dap)]PF6 are reported. In [Ir(piq)(2)(dap)]PF6, the dap ligand and one of the piq ligands of each cationic complex are involved in pi-pi stacking interactions forming supramolecular channels running along the crystallographic c axis. In the crystalline [Ir(bzq)(2)(dap)]PF6 pi-pi stacking interactions between the metal complexes lead to the formation of a 2D layer structure. In addition, CH-pi interactions were found in all compounds, which are what stabilizes the solid structure. In particular, a significant number of them were found in [Ir(piq)(2)(dap)]PF6 and [Ir(bzq)(2)(dap)]PF6. The crystal structures of [Ir(ppy)(2)(dipdap)]PF6 and [Ir(ppy)(2)(dmedap)]PF6 are also presented, being the first examples of bis-cyclometalated iridium(III) complexes with phenanthroline-type alpha,alpha'-diimin ligands bearing bulky alkyl groups in the neighbourhood of the N-donor atoms. These ligands implicate a distorted octahedral coordination geometry that in turn destabilized the Ir-N-N boolean AND N bonds. The new iridium (III) complexes are not luminescent. All compounds show an electrochemically irreversible anodic peak between 1.15 and 1.58 V, which is influenced by the different cyclometalated ligands. All of the new complexes show two reversible successive one-electron "large-surface" ligand-centred reductions around -0.70 V and -1.30 V. Electrospray ionisation mass spectrometry (ESI-MS) and collision induced decomposition (CID) measurements were used to investigate the stability of the new complexes. Thereby, the stability agreed well with the order of the Ir-N-N boolean AND N bond lengths.
Y1  - 2012
U6  - https://doi.org/10.1039/c2dt30412k
SN  - 1477-9226
VL  - 41
IS  - 34
SP  - 10219
EP  - 10227
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Schwarze, Thomas
A1  - Sprenger, Tobias
A1  - Riemer, Janine
T1  - 1,2,3-Triazol-1,4-diyl-Fluoroionophores for Zn2+, Mg2+ and Ca2+ based on Fluorescence Intensity Enhancements in Water
JF  - ChemistrySelect
N2  - Herein, we represent cation-responsive fluorescent probes for the divalent cations Zn2+, Mg2+ and Ca2+, which show cation-induced fluorescence enhancements (FE) in water. The Zn2+-responsive probes Zn1, Zn2, Zn3 and Zn4 are based on o-aminoanisole-N,N-diacetic acid (AADA) derivatives and show in the presence of Zn2+ FE factors of 11.4, 13.9, 6.1 and 8.2, respectively. Most of all, Zn1 and Zn2 show higher Zn2+ induced FE than the regioisomeric triazole linked fluorescent probes Zn3 and Zn4, respectively. In this set, ZN2 is the most suitable probe to detect extracellular Zn2+ levels. For the Mg2+-responsive fluorescent probes Mg1, Mg2 and Mg3 based on o-aminophenol-N,N,O-triacetic acid (APTRA) derivatives, we also found that the regioisomeric linkage influences the fluorescence responds towards Mg2+ (Mg1+100 mM Mg2+ (FEF=13.2) and Mg3+100 mM Mg2+ (FEF=2.1)). Mg2 shows the highest Mg2+-induced FE by a factor of 25.7 and an appropriate K-d value of 3 mM to measure intracellular Mg2+ levels. Further, the Ca2+-responsive fluorescent probes Ca1 and Ca2 equipped with a 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) derivative show high Ca2+-induced FEs (Ca1 (FEF=22.1) and Ca2 (FEF=23.0)). Herein, only Ca1 (K-d=313 nM) is a suitable Ca2+ fluorescent indicator to determine intracellular Ca2+ levels.
KW  - calcium
KW  - fluorescence
KW  - magnesium
KW  - probes
KW  - zinc
Y1  - 2020
U6  - https://doi.org/10.1002/slct.202003695
SN  - 2365-6549
VL  - 5
IS  - 41
SP  - 12727
EP  - 12735
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Kirpichenko, Svetlana V.
A1  - Kleinpeter, Erich
A1  - Shlykov, Sergey A.
A1  - Osadchiy, Dmitriy Yu
A1  - Chipanina, Nina N.
A1  - Oznobikhina, Larisa P.
T1  - 1,3-Dimethy1-3-silapiperidine - synthesis, molecular structure, and conformational analysis by gas-phase electron diffraction, low temperature NMR, IR and Raman Spectroscopy, and quantum chemical calculations
JF  - The journal of organic chemistry
N2  - The first Si-H-containing azasilaheterocycle, 1,3-dimethyl-3-silapiperidine 1, was synthesized, and its molecular structure and conformational properties were studied by gas-phase electron diffraction (GED), low temperature NMR, IR and Raman spectroscopy and quantum chemical calculations. The compound exists as a mixture of two conformers possessing the chair conformation with the equatorial NMe group and differing by axial or equatorial position of the SiMe group. In the gas phase, the SiMeax conformer predominates (GED: ax/eq = 65(7):35(7)%,Delta G = 0.36(18) kcal/mol; IR: ax/eq = 62(5):38(5)%,Delta G = 0.16(7) kcal/mol). In solution, at 143 k the SiMeeq conformer predominates' in the frozen equilibrium (NMR: ax/eq = 31.5(1.5):68.5(1.5)%, Delta G = -0.22(2) kcal/mol). Thermodynamic parameters of the ring inversion are determined (Delta G(double dagger) = 8.9-9.0 kcal/mol, Delta H-double dagger = 9.6 kcal/mol, Delta S-double dagger = 2.1 eu). High-level quantum chemical calculations :(MP2, G2, CCSD(T)) nicely reproduce the experimental geometry and the predominance of the axial conformer in the gas phase.
Y1  - 2013
U6  - https://doi.org/10.1021/jo400289g
SN  - 0022-3263
VL  - 78
IS  - 8
SP  - 3939
EP  - 3947
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Engelhardt, Ulrike
A1  - Linker, Torsten
T1  - 1,4-cyclohexadienes as mechanistic probes for the Jacobsen epoxidation : evidence for radical pathways
N2  - 1,4-Cyclohexadienes allow a direct comparison of epoxidation and C - H oxidation within the same molecule and give evidence for radical pathways during the Jacobsen epoxidation
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
A1  - Tran Dinh Phien, 
A1  - Shlykov, Sergey A.
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - 1-Methylthio-1-phenyl-1-silacyclohexane: Synthesis, conformational preferences in gas and solution by GED, NMR and theoretical calculations
JF  - Tetrahedron
N2  - 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.
KW  - 1-Methylthio-1-phenyl-1-silacyclohexane
KW  - Conformational analysis
KW  - Gas phase electron diffraction
KW  - Low-temperature C-13 and Si-29 NMR
KW  - DFT and MP2 calculations
Y1  - 2019
U6  - https://doi.org/10.1016/j.tet.2019.130677
SN  - 0040-4020
VL  - 75
IS  - 46
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Pihlaja, Kalevi
A1  - Sinkkonen, Jari
A1  - Stajer, Geza
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - 1-Oxo-1,3-dithiolanes - synthesis and stereochemistry
JF  - Magnetic resonance in chemistry
N2  - 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.
KW  - NMR
KW  - (1)H NMR
KW  - (13)C NMR
KW  - sulfur heterocycles
KW  - conformational analysis
KW  - computational chemistry
Y1  - 2011
U6  - https://doi.org/10.1002/mrc.2764
SN  - 0749-1581
VL  - 49
IS  - 7
SP  - 443
EP  - 449
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Pihlaja, Kalevi
A1  - Sinkkonen, Jari
A1  - Stájer, Gezá
A1  - Koch, Andreas
T1  - 1-Oxo-1,3-dithiolanesùsynthesis and stereochemistry
N2  - 1-Oxo-1,3-dithiolane (4) and its cis- andtrans-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 NaIO4 in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with 1H and 13C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=Oax envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=Oax (30 and 27%) as well as S=Oeq (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of 1H-1H coupling constants and 1H and 13C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data.
Y1  - 2011
SN  - 0749-1581
ER  - 
TY  - JOUR
A1  - Thomas, Steffen
A1  - Brühl, Iris
A1  - Heilmann, Dieter
A1  - Kleinpeter, Erich
T1  - 13 C NMR Chemical shift calculations for some substituted pyridines - a comparative consideration
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
A1  - Fischer, G.
A1  - Askolin, C.-P.
T1  - 13 C NMR, 15 N NMR and quantum-chemical study of the tautomerism of 2-substituted 5-ME-7-OH-1,2,4-triazolo[1,5- a]pyrimidines
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Thomas, Steffen
A1  - Fischer, G.
T1  - 13C and 15N NMR study of 1,2,4-Triazolo[1,5-a]pyrimidines with one tautomerism-introducing substituent
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Poleschner, Helmut
A1  - Heydenreich, Matthias
T1  - 13C NMR chemical shifts of unbranched 2-Alkyn-1-ols, w-Alkyn-1-ols and "internal" Alkyn-1-ols
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Poleschner, Helmut
A1  - Heydenreich, Matthias
A1  - Schilde, Uwe
T1  - 13C, 19F and 77Se NMR study of vicinal (E)-fluoro(organylseleno)olefins and [(E)- fluoroalkenyl]diorganylselenonium salts
N2  - Selenides of the type R1Se-EMe3 (E = Si, Ge, Sn, Pb) react with xenon difluoride by cleavage of the Se-E bond to yield the R1Se-F intermediate and the fluorides Me3E-F, whereas the Se-C bond in PhSe-tBu (E = C) is stable against XeF2. The presence of R1Se-F intermediates is confirmed by addition to acetylenes (4-octyne, 3-hexyne). Thus, the fluoroselenenylation of acetylenes gives fluoro(organylseleno)olefins in preparative yields. In the cases of E = Si, Ge, Sn, and Pb, aryl and n-alkyl groups are suitable as the substituent R1. The X-ray crystal structural analysis of (E)-3- (p-carboxyphenylseleno)-4-fluorohex-3-ene - the first example of an uncharged fluoroselenoolefin synthesized from p- EtO2C-C6H4-Se-SnMe3, XeF2, and 3-hexyne followed by an ester hydrolysis - shows that the addition of the selenenylfluoride intermediate to the acetylene proceeds via a trans-addition, as is known for the R2Se2-XeF2 reagents.
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Poleschner, Helmut
A1  - Heydenreich, Matthias
T1  - 1H and 13C NMR Spectra and One-Bond 13C,13C Coupling Constants of 2-Alken-4-yn-1-ols, (E)-2-Alken-4-yn-1-yl Acetates and (E)-2-Alken-4-yn-1-als
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Lehmann, J.
A1  - Kleinpeter, Erich
T1  - 1H NMR lanthanide-induced shift investigations of highly flexible molecules, part III. Applications to alcohols, aldehydes, esters and amines
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Lehmann, J.
A1  - Kleinpeter, Erich
T1  - 1H NMR Lanthanideinduced Shift (LIS) investigations of highly flexible molecules : a new approach
Y1  - 1993
ER  - 
TY  - JOUR
A1  - Lehmann, J.
A1  - Kleinpeter, Erich
T1  - 1H NMR Lanthanideinduced Shift (LIS) investigations of highly flexible molecules : a new approach ; Part II
Y1  - 1993
ER  - 
TY  - JOUR
A1  - Hilfert, Liane
A1  - Sarodnick, Gerhard
A1  - Kempter, Gerhard
A1  - Kleinpeter, Erich
T1  - 1H, 13C and 15 N NMR study and molecular modelling of 2,3- disubstituted quinoxalines with sterically hinderered aromatic and heteroaromatic substituents
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Starke, Ines
A1  - Koch, Andreas
A1  - Holdt, Hans-Jürgen
A1  - Kleinpeter, Erich
T1  - 1H, 13C, and 15N NMR study of the solution structure of metabridged bis(benzo-15-crown-5-ether)s
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Schreiber, Ulrike
A1  - Hosemann, Benjamin
A1  - Beuermann, Sabine
T1  - 1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP
JF  - Macromolecular chemistry and physics
N2  - Block copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (AC8) were obtained from ARGET ATRP. To obtain block copolymers of low dispersity the PAC8 block was synthesized in anisole with a CuBr(2)/PMDETA catalyst in the presence of tin(II) 2-ethylhexanoate as a reducing agent. The PAC8 block was subsequently used as macroinitiator for copolymerization with butyl and tert-butyl acrylate carried out in scCO(2). To achieve catalyst solubility in CO(2) two fluorinated ligands were employed. The formation of block copolymers was confirmed by size exclusion chromatography and DSC.
KW  - atom transfer radical polymerization (ATRP)
KW  - block copolymers
KW  - fluoropolymers
KW  - supercritical carbon dioxide
Y1  - 2011
U6  - https://doi.org/10.1002/macp.201000307
SN  - 1022-1352
VL  - 212
IS  - 2
SP  - 168
EP  - 179
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kammer, Stefan
A1  - Kelling, Alexandra
A1  - Baier, Heiko
A1  - Mickler, Wulfhard
A1  - Dosche, Carsten
A1  - Rurack, Knut
A1  - Kapp, Andreas
A1  - Lisdat, Fred
A1  - Holdt, Hans-Jürgen
T1  - 2,11-dialkylated 1,12-diazaperylene copper(I) complexes : first supramolecular column assemblies by pi-pi stacking between homoleptic tetrahedral metal complexes, exhibiting low-energy MLCT transitions
N2  - 2,11-Dialkylated 1,12-diazaperylenes (alkyl = Me, Et, iPr) dmedap, detdap and dipdap have been synthesized by reductive cyclization of 3,3-dialkylated 1,1-biisoquinolines 3a-c, resulting in the first copper(I) complexes of a large- surface ligand. The new copper(I) complexes show low-energy MLCT absorptions unprecedented for bis(-diimin)copper(I) complexes. The solid structures of the complexes[Cu(dipdap)2]BF4·CH2Cl2·1.5H2O, [Cu(dipdap)2]OTf·CH2Cl2, [Cu(dipdap)2]I·C2H4Cl2·THF·2H2O, [Cu(dmedap)2]OTf and [Cu(dipdap)2]AQSO3·H2O (AQSO3 = sodium 9,10-dihydro-9,10-dioxo-2- anthracenesulfonate) are reported. In [Cu(dipdap)2]BF4·CH2Cl2·1.5H2O, each copper(I) complex cation interacts with two others by - stacking interactions forming a novel supramolecular column structural motif running along the crystallographic c axis. In the crystalline compound [Cu(dipdap)2]AQSO3·H2O, aggregation between two complex cations and two additional anions by - stacking interactions is observed, leading to a tetrameric assembly. Furthermore, the three complex compounds [Cu(L)2]BF4 (L = dmedap, detdap, dipdap) were tested for sensory applications in aqueous buffer solutions in electrochemical studies of the complex immobilized on glassy carbon electrodes.
Y1  - 2009
UR  - http://www3.interscience.wiley.com/journal/27721/home
U6  - https://doi.org/10.1002/ejic.200900695
SN  - 1434-1948
ER  - 
TY  - JOUR
A1  - Schmidt, Bernd
A1  - Riemer, Martin
A1  - Karras, Manfred
T1  - 2,2 '-Biphenols via protecting group-free thermal or microwave-accelerated suzuki-miyaura coupling in water
JF  - The journal of organic chemistry
N2  - User-friendly protocols for the protecting group-free synthesis of 2,2'-biphenols via Suzuki-Miyaura coupling of o-halophenols and o-boronophenol are presented. The reactions proceed in water in the presence of simple additives such as K2CO3, KOH, KF, or TBAF and with commercially available Pd/C as precatalyst. Expensive or laboriously synthesized ligands or other additives are not required. In the case of bromophenols, efficient rate acceleration and short reaction times were accomplished by microwave irradiation.
Y1  - 2013
U6  - https://doi.org/10.1021/jo401398n
SN  - 0022-3263
VL  - 78
IS  - 17
SP  - 8680
EP  - 8688
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Strehmel, Veronika
A1  - Rexhausen, Hans
A1  - Strauch, Peter
T1  - 2,2,6,6-Tetramethylpiperidine-1-yloxyl bound to the imidazolium ion by an acetamido group for investigation of ionic liquids
N2  - New spin probes bearing the 2,2,6,6-tetramethylpiperidine-1-yloxyl covalently bound to the imidazolium ion via a methylene spacer and an amide group are synthesized. If the anion is bis(trifluoromethylsulfonylimide) instead of iodide, the new spin probe has a similar structure as that of an ionic liquid. Nevertheless, the new spin probes are useful tools to investigate ionic liquids.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/00404039
U6  - https://doi.org/10.1016/j.tetlet.2009.11.124
SN  - 0040-4039
ER  - 
TY  - JOUR
A1  - Dzambaski, Zdravko
A1  - Markovic, Rade
A1  - Kleinpeter, Erich
A1  - Baranac-Stojanovic, Marija
T1  - 2-Alkylidene-4-oxothiazolidine S-oxides - synthesis and stereochemistry
JF  - Tetrahedron
N2  - A series of 5-unsubstituted and 5-substituted 2-alkylidene-4-oxothiazolidine-S-oxides were synthesized by the sulfur-oxidation with m-CPBA. The stereochemistry of 5-substituted sulfoxides was determined by means of NMR spectroscopy and DFT theoretical calculations. It was found that the thermodynamically less stable anti-isomer was initially formed in the course of the oxidation, but it underwent epimerization to the mixture enriched in the more stable syn-isomer, during the work-up process. The higher stability of syn-isomers is ascribed to the stronger hyperconjugative sigma(C-H)->sigma*(S-O) interaction versus the weaker sigma(C-C)->sigma*(S-O) delocalization in their anti-counterparts and to the existence of intramolecular 1,5-CH center dot center dot center dot C hydrogen bonds.
KW  - 2-Alkylidene-4-oxothiazolidine
KW  - Sulfoxide
KW  - Diastereoselectivity
KW  - Density functional calculations
KW  - CH center dot center dot center dot O hydrogen bonds
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.05.087
SN  - 0040-4020
VL  - 69
IS  - 31
SP  - 6436
EP  - 6447
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kolocouris, Antonios
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Stylianakis, Ioannis
T1  - 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
JF  - Tetrahedron
N2  - 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.
KW  - 2-Substituted adamantane derivatives
KW  - 2,2-Disubstituted adamantane derivatives
KW  - H-1 NMR
KW  - C-13 NMR
KW  - B3LYP/6-31+G(d,p) calculations
KW  - GIAO calculations
KW  - Substituent chemical shifts
Y1  - 2015
U6  - https://doi.org/10.1016/j.tet.2015.01.044
SN  - 0040-4020
VL  - 71
IS  - 16
SP  - 2463
EP  - 2481
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Mutai, Peggoty
A1  - Heydenreich, Matthias
A1  - Thoithi, Grace
A1  - Mugumbate, Grace
A1  - Chibale, Kelly
A1  - Yenesew, Abiy
T1  - 3-Hydroxyisoflavanones from the stem bark of dalbergia melanoxylon -  isolation, antimycobacterial evaluation and molecular docking studies
JF  - Phytochemistry letters
N2  - Two new 3-hydroxyisoflavanones, (S)-3,4',5-trihydroxy-2',7-dimethoxy-3'-prenylisoflavanone (trivial name kenusanone F 7-methyl ether) and (S)-3,5-dihydroxy-2',7-dimethoxy-2 '',2 ''-dimethylpyrano[5 '',6 '':3',4']isoflavanone (trivial name sophoronol-7-methyl ether) along with two known compounds (dalbergin and formononetin) were isolated from the stem bark of Dalbergia melanoxylon. The structures were elucidated using spectroscopic techniques. Kenusanone F 7-methyl ether showed activity against Mycobacterium tuberculosis, whereas both of the new compounds were inactive against the malaria parasite Plasmodium falciparum at 10 mu g/ml. Docking studies showed that the new compounds kenusanone F 7-methyl ether and sophoronol-7-methyl ether have high affinity for the M. tuberculosis drug target INHA.
KW  - Dalbergia melanoxylon
KW  - 3-Hydroxyisoflavanone
KW  - Kenusanone F 7-methyl ether
KW  - Sophoronol-7-methyl ether
KW  - Mycobacterium tuberculosis
KW  - Docking
Y1  - 2013
U6  - https://doi.org/10.1016/j.phytol.2013.08.018
SN  - 1874-3900
SN  - 1876-7486
VL  - 6
IS  - 4
SP  - 671
EP  - 675
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Atilaw, Yoseph
A1  - Heydenreich, Matthias
A1  - Ndakala, Albert
A1  - Akala, Hoseah M.
A1  - Kamau, Edwin
A1  - Yenesew, Abiy
T1  - 3-Oxo-14 alpha, 15 alpha-epoxyschizozygine: A new schizozygane indoline alkaloid from Schizozygia coffaeoides
JF  - Phytochemistry letters
N2  - The stem bark extract of Schizozygia coffaeoides (Apocynaceae) showed moderate antiplasmodial activity (IC50 = 8-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new schizozygane indoline alkaloid, named 3-oxo-14 alpha, 15 alpha-epoxyschizozygine. In addition, two dimeric anthraquinones, cassiamin A and cassiamin B, were identified for the first time in the family Apocynaceae. The structures of the isolated compounds were deduced on the basis of spectroscopic evidence. The schizozygane indole alkaloids showed good to moderate antiplasmodial activities (IC50 = 13-52 mu m). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
KW  - Schizozygia coffaeoides
KW  - Schizozygane indoline alkaloid
KW  - 3-Oxo-14 alpha, 15 alpha-epoxyschizozygine
KW  - Dimeric anthraquinone
KW  - Cassiamin A
KW  - Cassiamin B
Y1  - 2014
U6  - https://doi.org/10.1016/j.phytol.2014.07.003
SN  - 1874-3900
SN  - 1876-7486
VL  - 10
SP  - 28
EP  - 31
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Sarauli, David
A1  - Peters, Kristina
A1  - Xu, Chenggang
A1  - Schulz, Burkhard
A1  - Fattakhova-Rohlfing, Dina
A1  - Lisdat, Fred
T1  - 3D-Electrode architectures for enhanced direct bioelectrocatalysis of pyrroloquinoline quinone-dependent glucose dehydrogenase
JF  - ACS applied materials & interfaces
N2  - We report on the fabrication of a complex electrode architecture for efficient direct bioelectrocatalysis. In the developed procedure, the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase entrapped in a sulfonated polyaniline [poly(2-methoxyaniline-5-sulfonic acid)-co-aniline] was immobilized on macroporous indium tin oxide (macroITO) electrodes. The use of the 3D-conducting scaffold with a large surface area in combination with the conductive polymer enables immobilization of large amounts of enzyme and its efficient communication with the electrode, leading to enhanced direct bioelectrocatalysis. In the presence of glucose, the fabricated bioelectrodes show an exceptionally high direct bioelectrocatalytical response without any additional mediator. The catalytic current is increased more than 200-fold compared to planar ITO electrodes. Together with a high long-term stability (the current response is maintained for >90% of the initial value even after 2 weeks of storage), the transparent 3D macroITO structure with a conductive polymer represents a valuable basis for the construction of highly efficient bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.
KW  - 3D electrode structures
KW  - macroITO
KW  - conductive polymer
KW  - PQQ-GDH
KW  - direct bioelectrocatalysis
KW  - bioelectrochemistry
Y1  - 2014
U6  - https://doi.org/10.1021/am5046026
SN  - 1944-8244
VL  - 6
IS  - 20
SP  - 17887
EP  - 17893
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Derese, Solomon
A1  - Barasa, Leonard
A1  - Akala, Hoseah M.
A1  - Yusuf, Amir O.
A1  - Kamau, Edwin
A1  - Heydenreich, Matthias
A1  - Yenesew, Abiy
T1  - 4 '-Prenyloxyderrone from the stem bark of Millettia oblata ssp  teitensis and the antiplasmodial activities of isoflavones from some Millettia species
JF  - Phytochemistry letters
N2  - The CH2Cl2/MeOH (1: 1) extract of the stem bark of Millettia oblata ssp. teitensis showed antiplasmodial activity (IC50 = 10-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new isoflavone, 4'-prenyloxyderrone (1), together with known isoflavones (8-O-methylretusin, durmillone, maximaisoflavone B, maximaisoflavone H and maximaisoflavone J), a rotenoid (tephrosin) and a triterpene (lupeol). Similar investigation of Millettia leucantha resulted in the identification of the isoflavones afrormosin and wistin, and the flavone chrysin. The identification of these compounds was based on their spectroscopic data. Five of the isoflavones isolated from these plants as well as 11 previously reported compounds from Millettia dura were tested and showed good to moderate antiplasmodial activities (IC50 = 13-53 mu M), with the new compound, 4'-prenyloxyderrone, being the most active (IC50 = 13-15 mu M).
KW  - Millettia oblata ssp teitensis
KW  - Millettia leucantha
KW  - Millettia dura;
Y1  - 2014
U6  - https://doi.org/10.1016/j.phytol.2014.02.001
SN  - 1874-3900
SN  - 1876-7486
VL  - 8
SP  - 69
EP  - 72
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Awad, Duha Jawad
A1  - Schilde, Uwe
A1  - Strauch, Peter
T1  - 4,4 '-Bis(tert-butyl)-2,2 '-bipyridinedichlorometal(II) - Synthesis, structure and EPR spectroscopy
JF  - Inorganica chimica acta : the international inorganic chemistry journal
N2  - Due to the better solubility of the 4,4'-substituted bipyridine ligand a series of 4,4'0-bis(tert-butyl)-2,2'-bipyridinedichlorometal(II) complexes, [M(tbbpy)Cl(2)], with M = Cu, Ni, Zn, Pd, Pt was synthesised and characterised. The blue copper complex 4,4'-bis(tert-butyl)-2,2'-bipyridinedichlorocopper(II) was isolated in two different polymorphic forms, as prisms 1 with a solvent inclusion and solvent-free as needles 2. Both structures were determined by X-ray structure analysis. They crystallise in the monoclinic space group P2(1)/c with four molecules in the unit cell, but with different unit cells and packing motifs. Whereas in the prisms 1, with the unit cell parameters a = 12.1613(12), b = 10.6363(7), c = 16.3074(15) angstrom, eta = 94.446(8)degrees, the packing is dominated by intra-and intermolecular hydrogen bonds, in the needles 2, with a = 7.738(1), b = 18. 333(2), c = 13.291(3) angstrom, beta = 97.512(15)degrees, only intramolecular hydrogen bonds appear and the complex molecules are arranged in columns which are stabilised by p-p-stacking interactions. In both complexes the copper has a tetrahedrally distorted coordination sphere. These copper complexes were also studied by EPR spectroscopy in solution, as frozen glass and diamagnetically diluted powder with the analogue [Pd(tbbpy)Cl(2)] as host lattice.
KW  - 4,4 '-Bis(tert-butyl)-2,2 '-bipyridine
KW  - X-ray structure
KW  - EPR
KW  - Copper(II)
KW  - Transition metals
Y1  - 2011
U6  - https://doi.org/10.1016/j.ica.2010.08.035
SN  - 0020-1693
VL  - 365
IS  - 1
SP  - 127
EP  - 132
PB  - Elsevier
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Lazareva, Nataliya F.
A1  - Shainyan, Bagrat A.
A1  - Kleinpeter, Erich
T1  - 4-Alkyl-2,2,6,6-tetramethyl-1,4,2,6-oxaazadisilinanes : synthesis, structure, and conformational analysis
N2  - 4-Alkyl-2,2,6,6-tetramethyl-1,4,2,6-oxaazadisilinanes RN[CH2Si(Me)2]2O [R = Me (1), i-Pr (2)] were synthesized by two methods which provided good yields up to 84%. Low temperature NMR study of compounds (1) and (2) revealed a frozen ring inversion with the energy barriers of 8.5 and 7.7 kcal/mol at 163 and 143 K, respectively, which is substantially lower than that for their carbon analog, N-methylmorpholine. DFT calculations performed on the example of molecule (1) showed that N-Meax conformer to exist in the sofa conformation with the coplanar fragment C-Si-O-Si-C, and its N-Meeq conformer in a flattened chair conformation.
Y1  - 2010
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/4569
U6  - https://doi.org/10.1002/Poc.1605
SN  - 0894-3230
ER  - 
TY  - JOUR
A1  - Mazurek-Budzyńska, Magdalena
A1  - Behl, Marc
A1  - Neumann, Richard
A1  - Lendlein, Andreas
T1  - 4D-actuators by 3D-printing combined with water-based curing
JF  - Materials today. Communications
N2  - The shape and the actuation capability of state of the art robotic devices typically relies on multimaterial systems from a combination of geometry determining materials and actuation components. Here, we present multifunctional 4D-actuators processable by 3D-printing, in which the actuator functionality is integrated into the shaped body. The materials are based on crosslinked poly(carbonate-urea-urethane) networks (PCUU), synthesized in an integrated process, applying reactive extrusion and subsequent water-based curing. Actuation capability could be added to the PCUU, prepared from aliphatic oligocarbonate diol, isophorone diisocyanate (IPDI) and water, in a thermomechanical programming process. When programmed with a strain of epsilon(prog) = 1400% the PCUU networks exhibited actuation apparent by reversible elongation epsilon'(rev) of up to 22%. In a gripper a reversible bending epsilon'(rev)((be)(nd)()) in the range of 37-60% was achieved when the actuation temperature (T-high) was varied between 45 degrees C and 49 degrees C. The integration of actuation and shape formation could be impressively demonstrated in two PCUU-based reversible fastening systems, which were able to hold weights of up to 1.1 kg. In this way, the multifunctional materials are interesting candidate materials for robotic applications where a freedom in shape design and actuation is required as well as for sustainable fastening systems.
KW  - 4D-actuation
KW  - 3D-printing
KW  - Ink
KW  - Gripper
KW  - Fastener
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtcomm.2021.102966
SN  - 2352-4928
VL  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Senge, Mathias O.
A1  - Ryppa, Claudia
A1  - Fazekas, Marijana
A1  - Zawadzka, Monika
A1  - Dahms, Katja
T1  - 5,10-A2B2-Type meso-Substituted PorphyrinsuA Unique Class of Porphyrins with a Realigned Dipole Moment
JF  - Chemistry - a European journal
N2  - Current applications in porphyrin chemistry require the use of unsymmetrically substituted porphyrins. Many current industrial interests in optics and biomedicine require systems with either pushpull (electron-donating and -withdrawing groups) or amphiphilic systems (hydrophobic and hydrophilic groups). In this context we present the class of 5,10-A2B2-type porphyrins for which two different substituents are positioned in diagonally opposite meso positions. Thus, the intramolecular dipole moment in these tetrapyrroles is positioned along a beta-beta vector passing through two pyrrole rings. This is opposite to the situation of the frequently used 5,15-A2BC porphyrins for which the dipole moment is oriented along a mesomeso axis. We have elaborated syntheses of the 5,10-A2B2 porphyrins by using transition-metal-catalyzed transformations of 5,10-A2 porphyrins or direct substitutions reactions thereof; this gives the target molecules in 2277% overall yields. The compounds exhibit interesting structural, spectroscopic, and optical features and can serve as building blocks for new porphyrin arrays and applications.
KW  - macrocycles
KW  - nitrogen heterocycles
KW  - nonlinear optics
KW  - porphyrinoids
KW  - tetrapyrroles
Y1  - 2011
U6  - https://doi.org/10.1002/chem.201101934
SN  - 0947-6539
VL  - 17
IS  - 48
SP  - 13562
EP  - 13573
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Muiva-Mutisya, Lois
A1  - Macharia, Bernard
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Akala, Hoseah M.
A1  - Derese, Solomon
A1  - Omosa, Leonidah K.
A1  - Yusuf, Amir O.
A1  - Kamau, Edwin
A1  - Yenesew, Abiy
T1  - 6 alpha-Hydroxy-alpha-toxicarol and (+)-tephrodin with antiplasmodial activities from Tephrosia species
JF  - Phytochemistry letters
N2  - The CH2Cl2/MeOH (1: 1) extract of the roots of Tephrosia villosa showed good antiplasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 3.1 +/- 0.4 and 1.3 +/- 0.3 mu g/mL, respectively. Chromatographic separation of the extract yielded a new rotenoid, 6 alpha-hydroxy-alpha-toxicarol, along with five known rotenoids, (rotenone, deguelin, sumatrol, 12 alpha-hydroxy-alpha-toxicarol and villosinol). Similar treatment of the extract of the stem of Tephrosia purpurea (IC50 = 4.1 +/- 0.4 and 1.9 +/- 0.2 mu g/mL against D6 and W2 strains of P. falciparum, respectively) yielded a new flavone having a unique substituent at C-7/C-8 [trivial name (+)-tephrodin], along with the known flavonoids tachrosin, obovatin methyl ether and derrone. The relative configuration and the most stable conformation in (+)-tephrodin was determined by NMR and theoretical energy calculations. The rotenoids and flavones tested showed good to moderate antiplasmodial activities (IC50 = 9 +/- 23 mu M). Whereas the cytotoxicity of rotenoids is known, the flavones (+)-tephrodin and tachrosin did not show significant cytotoxicity (IC50 > 100 mu M;) against mammalian African monkey kidney (vero) and human larynx carcinoma (HEp2) cell lines. (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
KW  - Tephrosia villosa
KW  - Tephrosia purpurea
KW  - 6 alpha-Hydroxy-alpha-toxicarol
KW  - (+)-Tephrodin
KW  - Plasmodium falciparum
Y1  - 2014
U6  - https://doi.org/10.1016/j.phytol.2014.09.002
SN  - 1874-3900
SN  - 1876-7486
VL  - 10
SP  - 179
EP  - 183
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Yenesew, Abiy
A1  - Mushibe, E. K.
A1  - Induli, M.
A1  - Derese, Solomon
A1  - Midiwo, Jacob O.
A1  - Kabaru, Jacques M.
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Peter, Martin G.
T1  - 7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoloata
N2  - From the acetone extract of the roots of Derris trifoliata an isollavonoid derivative, named 7a-O- methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isollavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence. Rotenone and deguelin were identified as the larvicidal principles of the acetone extract of the roots of Derris trifoliata. (c) 2005 Elsevier Ltd. All rights reserved
Y1  - 2005
SN  - 0031-9422
ER  - 
TY  - JOUR
A1  - Yenesew, Abiy
A1  - Twinomuhwezi, Hannington
A1  - Kiremire, Bernard T.
A1  - Mbugua, Martin N.
A1  - Gitu, Peter M.
A1  - Heydenreich, Matthias
A1  - Peter, Martin G.
T1  - 8-Methoxyneorautenol and radical scavenging flavonoids from Erythrina abyssinica
N2  - A new pterocarpan (named 8-methoxyneorautenol) was isolated from the acetone ext. of the root bark of Erythrina abyssinica. In addn., the known isoflavonoid derivs. eryvarin L, erycristagallin and shinpterocarpin were identified for the first time from the roots of this plant. The structures were detd. on the basis of spectroscopic evidence. The new compd. showed selective antimicrobial activity against Trichophyton mentagrophytes. The acetone ext. of the root bark of E. abyssinica showed radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The pterocarpenes, 3-hydroxy-9-methoxy-10-(3,3-dimethylallyl)pterocarpene and erycristagallin, were the most active constituents of the roots of this plant and showing dose-dependent activities similar to that of the std. quercetin. [on SciFinder (R)]
Y1  - 2009
UR  - http://www.ajol.info/journal_index.php?jid=120&ab=bcse
SN  - 1011-3924
ER  - 
TY  - JOUR
A1  - Schultze, Christiane
A1  - Foß, Stefan
A1  - Schmidt, Bernd
T1  - 8-Prenylflavanones through microwave promoted tandem claisen rearrangement/6-endo-trig cyclization and cross metathesis
JF  - European journal of organic chemistry
N2  - Prenylated flavanones were obtained from ortho-allyloxy chalcones through a one-pot sequence of Claisen rearrangement and 6-endo-trig cyclization, followed by olefin cross metathesis of the intermediate allyl flavanones with 2-methyl-2-butene. The synthetic utility of this route is illustrated for the synthesis of several naturally occurring prenyl flavanones.
KW  - tandem reactions
KW  - arenes
KW  - oxygen heterocycles
KW  - microwave chemistry
KW  - rearrangement
Y1  - 2020
U6  - https://doi.org/10.1002/ejoc.202001378
SN  - 1434-193X
SN  - 1099-0690
VL  - 2020
IS  - 47
SP  - 7373
EP  - 7384
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Zehm, Daniel
A1  - Fudickar, Werner
A1  - Hans, Melanie
A1  - Schilde, Uwe
A1  - Kelling, Alexandra
A1  - Linker, Torsten
T1  - 9,10-Diarylanthracenes as molecular switches : syntheses, properties, isomerisations and their reactions with singlet oxygen
N2  - A series of 9,10-diarylanthracenes with various substituents at the ortho positions have been synthesised by palladium-catalysed cross-coupling reactions. Such compounds exhibit interesting physical properties and can be applied as molecular switches. Despite the high steric demand of the substituents, products were formed in moderate-to-good yields. In some cases, microwave conditions further improved yields. Bis-coupling afforded two isomers (syn and anti) that do not interconvert at room temperature. These products were easily separated and their relative stereochemistries were unequivocally assigned by NMR spectroscopy and X-ray analysis. The syn and anti isomers exhibit different physical properties (e.g., melting points and solubilities) and interconversion by rotation around the aryl-aryl axis commences at <100 °C for fluoro-substituted diarylanthracenes and at >300 °C for alkyl- or alkoxy-substituted diarylanthracenes. The reactions with singlet oxygen were studied separately and revealed different reactivities and reaction pathways. The yields and reactivities depend on the size and electronic nature of the substituents. The anti isomers form the same 9,10-endoperoxides as the syn species, occasionally accompanied by unexpected 1,4-endoperoxides as byproducts. Thermolysis of the endoperoxides exclusively yielded the syn isomers. The interesting rotation around the aryl-aryl axis allows the application of 9,10-diarylanthracenes as molecular switches, which are triggered by light and air under mild conditions. Finally, the oxygenation and thermolysis sequence provides a simple, synthetic access to a single stereoisomer (syn) from an unselective coupling step.
Y1  - 2008
SN  - 0947-6539
ER  -