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Pivnenko, N. S.; Vashchenko, V. V.; Kutulya, L. A.; Дорошенко, А. О.; Chepeleva, L. V.

doi:10.1023/a:1013082417885

Cited by 8 publications

(10 citation statements)

References 10 publications

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“…1,12 Obviously, an essential spatial contiguity of˛-equatorial substituent and the aryl fragment in molecules of the types under consideration is decisive for their conformational states. As an indirect confirmation of that, only one example is known up to now showing the presence of chair conformers with an equatorial methyl group in the p-menthanone ring 23 (but only to 20-25%). This is the 1R,4R-Z-isomer 6 having methyl and aryl groups more strongly separated than for compounds 1-5.…”

Section: Resultsmentioning

confidence: 90%

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Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Pivnenko

Drushlyak

Kutulya

et al. 2002

Magnetic Reson in Chemistry

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Based on1 H NMR spectral analysis combined with molecular simulation, conformational states of the cyclohexanone ring were studied for some 1R,4S-2-(4-X-benzylidene)-p-menthan-3-ones (X = COOCH 3 or C 6 H 5 ) in CDCl 3 and C 6 D 6 . The co-existence of chair conformers with an axial orientation of both alkyl substituents and twist-boat forms was established for the compounds studied at room temperature (22-23• C). The substituent X does not influence appreciably the ratio of these conformers, but the fraction of twist-boat forms increases noticeably in benzene solutions as compared with CDCl 3 solutions. Rotameric states of the isopropyl fragment were also characterised for the compounds studied. Distinctions in conformational states for the 1R,4S-2-arylidene-p-menthan-3-ones and (−)-menthone were revealed and are discussed.

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Section: Resultsmentioning

confidence: 90%

“…An approach using 1 H NMR spectra combined with theoretical conformational analysis was shown 22,23 to be useful for investigating the conformational equilibrium of six-membered cyclic compounds.…”

Section: Introductionmentioning

confidence: 99%

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Pivnenko

Drushlyak

Kutulya

et al. 2002

Magnetic Reson in Chemistry

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“…1 -5 Recently, we have succeeded in the study of conformational equilibria for E-and Z-isomers of some 1R,4R-2-arylidene-p-menthan-3-ones (3R,6R-2-arylidene-3-methyl-6-isopropylcyclohexanones) 6 and also for several of their 1R,4S-diastereomers, 7 using 1 H NMR spectral analysis combined with theoretical molecular simulations.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, a dependable approach based on the analysis of the proton spin-spin couplings was applied to ascertain conformational states for 3R-methyl-6-(4-phenylbenzylidene)cyclohexanone (1) (Scheme 1) and some 2,6-bis(arylidene)-3R-methylcyclohexanones (2) similar to that described by Pivnenko et al 7 We intended to compare the results obtained with those for 1R,4R-p-menthan-3-one derivatives (3) investigated in previous studies. 6,7 It can be expected that some common peculiarities and distinctions revealed in such a comparison will assist in clarifying the structural factors which are responsible for both the 'twisting' properties of chiral˛,ˇ-unsaturated ketones of types 1-3 and their trend to exhibit mesomorphic behaviour.…”

Section: Introductionmentioning

confidence: 99%

“…The arylidene proton in E-isomers lies in the region of essential deshielding by the carbonyl group, and its resonance is usually observed at 6.9-7.8 ppm, whereas in alternative Zforms this proton is substantially remote from this group and, therefore, its signal is shifted upfield (υ 6.0-6.3 ppm). 6,17,18 Results of the theoretical simulation for 1 are presented in Table 3. Both methods used describe its molecular geometry, particularly for the aliphatic fragment of the cyclohexanone ring, essentially similarly (see torsion angles 1 -3 and CH 3 ).…”

Section: Introductionmentioning

confidence: 99%

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Study of molecular structures for arylidene derivatives of 3R‐methylcyclohexanone by ¹H NMR and molecular simulation

Pivnenko

Krivoshey

Kutulya

2003

Magnetic Reson in Chemistry

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Conformational states of the cyclohexanone ring were established for 3R-methyl-6-(4-phenylbenzylidene) cyclohexanone and several 2,6-bis(4-X-benzylidene)-3R-methylcyclohexanones (X = Br, OCOCH 3 and C 6 H 5 ) by 1 H NMR spectroscopy combined with molecular simulation using the semi-empirical methods AM1 and PM3. The first compound studied contains only one arylidene group, and exists predominantly in a chair conformation of the cyclohexanone ring with an equatorial orientation of the methyl substituent in C 6 D 6 and CDCl 3 solutions at room temperature (22-23• C). In contrast, the 2,6-bis(arylidene) derivatives of 3R-methylcyclohexanone preferentially adopt conformations with an axially oriented methyl group. The extent of twisting of enone fragments was also characterized for the compounds studied based on simulation results and comparison of chemical shifts for the arylidene protons of appropriate model compounds.

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Fluorescent properties and spontaneous Raman spectroscopy of new ketocyanine probes in organic solvents

2006

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The position of their electronic spectra depends strongly on the polarity of the solvent. We measured the dipole moments of the dyes in the equilibrium ground state and the Franck-Condon excited state. In mixtures of neutral nonpolar toluene with aprotic polar dimethylsulfoxide, we observe inhomogeneous broadening of the electronic spectra for the indicated compounds, due to fluctuations in solution of the intermolecular interaction energy. The time-resolved characteristics of fluorescence obtained suggest formation of an intermolecular hydrogen bond between the dye and the surrounding medium in a toluene-ethanol mixture. We measured the Raman spectra of CPET and CPMR in different organic solvents. The most intense lines in the 1582-1591 cm -1 region can be assigned to stretching of the phenyl rings of the molecules; the lines in the 831-842 cm -1 region can be assigned to a cyclopentanone ring mode; the lines at 1186-1195 cm -1 can be assigned to stretching of the =C-C-bond of the phenyl ring and rocking of the H atoms of the phenyl ring. We have observed that the position and width of the lines for the stretching vibrations of the ketocyanines depend substantially on the polarity of the surrounding medium.The studied dyes can be used as probes for studying different biological systems by site-selective laser spectroscopy and Raman spectroscopy. The fact that these two methods can be used simultaneously for diagnostics of biosystems is an important advantage of ketocyanine dyes compared with other known probes.Key words: fluorescence spectroscopy, spontaneous Raman scattering, ketocyanine dyes, inhomogeneous broadening of spectra, hydrogen bond.Introduction. Fluorescent probes have been increasingly intensively used for more and more diverse purposes in physics, chemistry, biology, and medicine, since such probes make it possible to solve a number of complicated and important problems [1]. The fluorescent probes themselves have also been perfected, and new spectral effects are used for analysis of the microcharacteristics of the environment. Fluorescent probes have been previously synthesized containing distinct electron density donor and acceptors, most often amino and carbonyl groups. Many such dipolar compounds (naphthalenes, phthalimides, anthracenes, etc.) have found broad application in analysis of molecular structure relaxation in simple solutions and biological macromolecules [2][3][4][5]. The indicated compounds are characterized by a significant change in the charge distribution in the excited electronic state, occurring on a femtosecond to nanosecond time scale. From the position of the fluorescence spectrum, its Stokes shift, the lifetime of the excited state, the emission anisotropy kinetics, and other characteristics, we can obtain information about the polarity, viscosity, dynamics of nearest-neighbor molecules and their segments in the environment of the probe, the presence, nature, and size of the charge on the ions.

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Cited by 8 publications

References 10 publications

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Study of molecular structures for arylidene derivatives of 3R‐methylcyclohexanone by ¹H NMR and molecular simulation

Fluorescent properties and spontaneous Raman spectroscopy of new ketocyanine probes in organic solvents

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Cited by 8 publications

References 10 publications

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by 1H NMR spectroscopy and molecular simulation

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by 1H NMR spectroscopy and molecular simulation

Study of molecular structures for arylidene derivatives of 3R‐methylcyclohexanone by 1H NMR and molecular simulation

Fluorescent properties and spontaneous Raman spectroscopy of new ketocyanine probes in organic solvents

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Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Conformational analysis of some 1R,4S‐2‐arylidene‐p‐menthan‐3‐ones by ¹H NMR spectroscopy and molecular simulation

Study of molecular structures for arylidene derivatives of 3R‐methylcyclohexanone by ¹H NMR and molecular simulation