45498
2016
2016
eng
1675
1685
11
72
article
Elsevier
Oxford
1
--
--
--
Y-aromaticity - existing: yes or no? An answer given on the magnetic criterion (TSNMRS)
The spatial magnetic properties (Through Space NMR Shieldings - TSNMRS) of a number of Y-shaped structures possessing 4n+2 pi-electrons (i.a. the trimethylenemethane ions TMM2+, TMM2-, the guanidinium cation, substituted and hetero analogues) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, were examined subject to present Y-aromaticity and the results compared with energetic and geometric criteria obtained already. (C) 2016 Elsevier Ltd. All rights reserved.
Tetrahedron
10.1016/j.tet.2016.02.020
0040-4020
wos2016:2019
WOS:000372375500006
Kleinpeter, E (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Golm, Germany., ekleinp@uni-potsdam.de
importub
2020-03-22T19:02:01+00:00
filename=package.tar
ff61982ecad3c10a4caf249dedf893bb
Erich Kleinpeter
Andreas Koch
eng
uncontrolled
Y-aromaticity
eng
uncontrolled
pi-Electron delocalization
eng
uncontrolled
Theoretical calculations
eng
uncontrolled
ICSS
eng
uncontrolled
TSNMRS
Institut für Chemie
Referiert
Import
45344
2016
2016
eng
2402
2410
9
72
article
Elsevier
Oxford
1
--
--
--
Synthesis and stereochemistry of new naphth[1,3]oxazino[3,2-a] benzazepine and naphth[1,3]oxazino[3,2-e]thienopyridine derivatives
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.
Tetrahedron
10.1016/j.tet.2016.03.058
0040-4020
wos2016:2019
WOS:000375164000005
Fulop, F (reprint author), Univ Szeged, Hungarian Acad Sci, Inst Pharmaceut Chem, Eotvos 6, H-6720 Szeged, Hungary.; Fulop, F (reprint author), Univ Szeged, Hungarian Acad Sci, MTA SZTE Stereochem Res Grp, Eotvos 6, H-6720 Szeged, Hungary.; Kleinpeter, E (reprint author), Univ Potsdam, Dept Chem, Karl Liebknecht Str 24-25, D-14476 Golm, Germany., fulop@pharm.u-szeged.hu; ekleinp@uni-potsdam.de
Bolyai Janos Fellowship
importub
2020-03-22T17:45:01+00:00
filename=package.tar
1c9b29f645fcdfcccfd21b675c172927
Petra Barta
Istvan Szatmari
Ferenc Fueloep
Matthias Heydenreich
Andreas Koch
Erich Kleinpeter
eng
uncontrolled
Modified Mannich reaction
eng
uncontrolled
Thienopyridine
eng
uncontrolled
Benzazepine
eng
uncontrolled
NMR spectroscopy
eng
uncontrolled
Stereochemistry
eng
uncontrolled
Theoretical calculations
Institut für Chemie
Referiert
Import
45151
2016
2016
eng
6364
6373
10
40
article
Royal Society of Chemistry
Cambridge
1
--
--
--
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
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.
New journal of chemistry
10.1039/c6nj00901h
1144-0546
1369-9261
wos2016:2019
WOS:000385869600088
Rasovic, A (reprint author), Univ Belgrade, Ctr Chem ICTM, Studentski Trg 16,POB 473, Belgrade 11000, Serbia., arasovic@chem.bg.ac.rs
Ministry of Education, Science and Technological Development of the Republic of Serbia [172020]
importub
2020-03-22T16:08:01+00:00
filename=package.tar
0a72b3febfe566911ba7d59dd0ac8261
Aleksandar Rasovic
Vladimir Blagojevic
Marija Baranac-Stojanovic
Erich Kleinpeter
Rade Markovic
Dragica M. Minic
Institut für Chemie
Referiert
Import
44997
2016
2016
eng
277
289
13
86
article
Elsevier
Amsterdam
1
--
--
--
The effects of conformation and zwitterionic tautomerism on the structural and vibrational spectral data of anserine
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.
Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy
10.1016/j.vibspec.2016.08.003
0924-2031
1873-3697
wos2016:2019
WOS:000384865000036
Balci, K (reprint author), Istanbul Univ, Fac Sci, Dept Phys, TR-34134 Istanbul, Turkey., kbalci@istanbul.edu.tr
Istanbul University (IU BAP) [N-3341, N-1650]; Scientific and Technological Research Council of Turkey (TUBITAK) [Bidep 2221]
importub
2020-03-22T14:51:01+00:00
filename=package.tar
bdfc570e2cbbb7d079a03270def8311b
K. Balci
Y. Akkaya
S. Akyuz
W. B. Collier
M. C. Stricker
D. D. Stover
G. Ritzhaupt
Andreas Koch
Erich Kleinpeter
eng
uncontrolled
Anserine
eng
uncontrolled
Matrix IR spectrum
eng
uncontrolled
Tautomerism
eng
uncontrolled
SQM-FF
eng
uncontrolled
Dual scale factors
Institut für Chemie
Referiert
Import
44895
2016
2016
eng
4985
4990
6
article
Wiley-VCH
Weinheim
1
--
--
--
Twisted C=C Double Bonds with Very Low Rotational Barriers in Dioxanediones and Isoxazolones Determined by Low-Temperature Dynamic NMR Spectroscopy and Computational Chemistry
European journal of organic chemistry
10.1002/ejoc.201600931
1434-193X
1099-0690
wos2016:2019
WOS:000386920600010
Wentrup, C (reprint author), Univ Queensland, Sch Chem & Mol Biosci, Brisbane, Qld 4072, Australia.; Koch, R (reprint author), Carl von Ossietzky Univ Oldenburg, Inst Chem, POB 2503, D-26111 Oldenburg, Germany.; Koch, R (reprint author), Carl von Ossietzky Univ Oldenburg, Ctr Interface Sci, POB 2503, D-26111 Oldenburg, Germany.; Kleinpeter, E (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Golm, Germany., wentrup@uq.edu.au; rainer.koch@uni-oldenburg.de; ekleinp@uni-potsdam.de
Deutsche Forschungsgemeinschaft (DFG); Fonds der Chemischen Industrie; Center for Scientific Computation at the University of Oldenburg; University of Queensland
importub
2020-03-22T14:00:01+00:00
filename=package.tar
458e6681ee80ee981f0ea6ca9fc22841
Curt Wentrup
Rainer Koch
Erich Kleinpeter
eng
uncontrolled
NMR spectroscopy
eng
uncontrolled
Twisted double bonds
eng
uncontrolled
Push-pull effect
eng
uncontrolled
Density functional calculations
Institut für Chemie
Referiert
Import
39452
2016
2016
eng
6364
6373
10
postprint
1
--
2016-05-10
--
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
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 C[double bond, length as m-dash]C double bond to quantify the push–pull effect in biologically important 2-alkylidene-4-oxothiazolidines. While olefinic proton chemical shifts and differences in 13C NMR chemical shifts of the two carbons constituting the C[double bond, length as m-dash]C 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 (ΔS‡, ΔH‡ and ΔG‡), 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 ΔG‡ 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 C[double bond, length as m-dash]C bond lengths and corroborate the applicability of ΔG‡ for estimation of the strength of the push–pull effect in these and related systems.
urn:nbn:de:kobv:517-opus4-394523
online registration
Au-028171
New J.Chem. (2016) Nr. 40, S. 6364-6373. - DOI: 10.1039/C6NJ00901H
Keine öffentliche Lizenz: Unter Urheberrechtsschutz
Aleksandar Rasovic
Vladimir Blagojevic
Marija Baranac-Stojanovic
Erich Kleinpeter
Rade Markovic
Dragica M. Minic
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
322
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
RSC
Universität Potsdam
https://publishup.uni-potsdam.de/files/39452/pmnr322_online.pdf