The vibrational spectra and force constants of benzylideneaniline and its fluoroderivatives

Kozhevina, L. I.; Prokopenko, E. B.; Рыбаченко, В. И.; Титов, Е. В.

doi:10.1016/0022-2860(93)85007-h

Cited by 20 publications

(20 citation statements)

References 11 publications

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“…As shown previously, distinct structural changes accompanying proton transfer(s) upon oxidation of phenols can be detected by this technique . In the case of BIP-Ph R imines, the IRSEC experiments take advantage of the well-established imine and protonated imine infrared spectra in which the CN vibrational stretching mode is sensitive to the local protonation state of the nitrogen. ,− …”

Section: Results and Discussionmentioning

confidence: 92%

“…33 In the case of BIP-Ph R imines, the IRSEC experiments take advantage of the well-established imine and protonated imine infrared spectra in which the C=N vibrational stretching mode is sensitive to the local protonation state of the nitrogen. 56,[61][62][63][64][65][66][67][68] and C show the IRSEC spectra for the BIP-Ph R imines 2, and 7, respectively, in the 1700-1400 cm -1 region. IRSEC spectra of 3 are shown in the SI ( Figure S35).…”

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confidence: 99%

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Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays

et al. 2018

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Bioinspired constructs consisting of benzimidazole-phenol moieties bearing N-phenylimines as proton-accepting substituents have been designed to mimic the H-bond network associated with the TyrZ-His190 redox relay in photosystem II. These compounds provide a platform to theoretically and experimentally explore and expand proton-coupled electron transfer (PCET) processes. The models feature H-bonds between the phenol and the nitrogen at the 3-position of the benzimidazole and between the 1H-benzimidazole proton and the imine nitrogen. Protonation of the benzimidazole and the imine can be unambiguously detected by infrared spectroelectrochemistry (IRSEC) upon oxidation of the phenol. DFT calculations and IRSEC results demonstrate that with sufficiently strong electron-donating groups at the para-position of the N-phenylimine group (e.g.,-OCH3 substitution), proton transfer to the imine is exergonic upon phenol oxidation, leading to a oneelectron, two-proton (E2PT) product with the imidazole acting as a proton relay. When transfer of the second proton is not sufficiently exergonic (e.g.,-CN substitution), a one-electron, one-proton transfer (EPT) product is dominant. Thus, the extent of proton translocation along the H-bond network, either ~1.6 Å or ~6.4 Å, can be controlled through imine substitution. Moreover, the H-bond strength between the benzimidazole NH and the imine nitrogen, which is a function of their relative pKa values, and the redox potential of the phenoxyl radical/phenol couple are linearly correlated with the Hammett constants of the substituents. In all cases, a high potential (~1 V vs SCE) is observed for the phenoxyl radical/phenol couple. Designing and tuning redox-coupled proton wires is important for understanding bioenergetics and developing novel artificial photosynthetic systems.

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Section: Results and Discussionmentioning

confidence: 92%

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confidence: 99%

Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays

et al. 2018

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“…Because no spectral data are available in the vapor phase, the vibrational frequencies observed in the liquid phase were used in the normal coordinate analysis. The assignments of vibrational spectra have been reported in the literature. ,,, Some assignments were, however, corrected by referring to the assignments of the observed frequencies of related molecules such as tBA, − anisole, , benzene derivatives, − and saturated hydrocarbons. , Assignments were confirmed by normal coordinate calculations.…”

Section: Methodsmentioning

confidence: 99%

“…The force constants of MBBA have not been reported. Therefore, harmonic force constants were determined by modifying the force constants transferred from those of tBA, − , ethers, , alkyl benzenes, 32 and saturated hydrocarbons 35 so as to reproduce the observed vibrational frequencies of MBBA. The local symmetry coordinates are defined in Table S3 and Figure S1 in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Gas-Phase Molecular Structure of MBBA (4-Methoxybenzylidene-4‘-n-butylaniline), a Mesogen, by Electron Diffraction Combined with ab Initio Calculations

et al. 1999

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The molecular structure of a typical mesogen, 4-methoxybenzylidene-4′-n-butylaniline (MBBA, CH 3 O-C 6 H 4 -CHdN-C 6 H 4 -(CH 2 ) 3 -CH 3 ), has been studied by gas-phase electron diffraction (GED). The nozzle temperature was about 150°C. Structural constraints in the GED data analysis were obtained by the ab initio MO calculation at the HF/4-21G(*) level of theory. Vibrational amplitudes and shrinkage corrections were calculated from the harmonic force constants given by a normal coordinate analysis. The phenylene ring attached to the C(dN) atom and the azomethine group (-CHdN-) are essentially on the same plane, i.e., the dihedral angle is 0(12)°. The phenylene ring bonded to the nitrogen atom is found to be out of the plane of the azomethine group and the determined value of the dihedral angle, 48(9)°, in the gas phase is larger than that in the crystalline state. This is mainly due to the steric interaction between the hydrogen atoms of the azomethine group and the phenylene ring. In the gas phase the four rotational conformers with respect to the configurations of the n-butyl group were assumed to exist. Their conformational abundance was fixed, as calculated from the ab initio relative energies. The principal bond distances and angles (r g /Å and ∠ R /deg) determined by GED are r(NdC) ) 1.290 (12), r(C-N) ) 1.413 (12), r(C az -C ring ) ) 1.467 (3), 〈r(C ring -C ring )〉 ) 1.400 (6), ∠C-NdC ) 119.0(18), ∠NdC-C ) 121.6(13), ∠NC ring C 14 ) 128.5(25), ∠C az C ring C 4 ) 121.2 (dependent), 〈CCC ring 〉 ) 120.0(3), 〈∠CCC butyl 〉 ) 116.2(11), ∠C 5 C ring O )129.3 (16), where C az , C ring , and C butyl denote the carbon atoms of the azomethine, phenylene and butyl groups, respectively. C 14 and C 4 are the C atoms of the rings synclinal to the C(dN) atom and cis to the H az atom, and C 5 is the C atom of the ring cis to the C atom of the methoxy group. The values in parentheses are three times the standard deviations. The notation 〈 〉 represents the average value. The transition temperature from the nematic to liquid phases was discussed on the basis of the determined molecular structure.

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“…And the interpretations for the vibrational spectra of the XBAY and 4,4′‐disubstituted XBAY were given. In 1993, Kozhevina et al explored the vibrational spectra of XBAY and its fluoroderivatives, and they found that the fluorination of the aniline or benzylidene rings did not exercise much influence on the ν (C═N) bond position but caused a significant change in the intensity. In 2002, Güner and Bayari discussed the interpretation of the substituent effect on the infrared data of XBAYs.…”

Section: Introductionmentioning

confidence: 99%

Substituent effects on the stretching vibration of C═N in multi‐substituted benzylideneanilines

Wang

Cao

2019

J of Physical Organic Chem

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Forty-nine samples of 3,4′/4,3′/3,3′-disubstituted benzylideneanilines (XBAYs) and 52 samples of multi-substituted XBAYs were synthesized, and their infrared absorption spectra were recorded in this paper. On the basis of the stretching vibration frequencies ν C═N of C═N bridging bond of 158 samples of substituted XBAYs (including 57 samples of 4,4′-disubstituted XBAYs from reference and 101 samples of substituted XBAYs synthesized in this paper), an extensional research of substituent effects on the ν C═N values from 4,4′-disubstituted XBAYs to multi-substituted XBAYs was made. A modified equation for quantifying the ν C═N values of multi-substituted XBAYs was obtained (shown as Equation (3)). Equation (3) indicates that the excitedstate substituent constant of Y and the substituent specific cross-interaction effect between X and X cannot be ignored for the quantitative regression analysis of the ν C═N values of multi-substituted XBAYs. Compared with Equation (1), Equation (3) has a wider application and more accuracy in quantifying the ν C═N values of substituted XBAYs.

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The vibrational spectra and force constants of benzylideneaniline and its fluoroderivatives

Cited by 20 publications

References 11 publications

Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays

Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays

Gas-Phase Molecular Structure of MBBA (4-Methoxybenzylidene-4‘-n-butylaniline), a Mesogen, by Electron Diffraction Combined with ab Initio Calculations

Substituent effects on the stretching vibration of C═N in multi‐substituted benzylideneanilines

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