M.A. Shashidhar

Vibrational spectra of ortho-, meta and para-fluoroanilines

Abstract The infra-red spectra of ortho -, meta - and para -fluoroanilines in the liquid state have been investigated in the region 650–4000 cm −1 . Tentative assignments of the observed frequencies have been made by assuming C 2 v , symmetry for para -fluoroaniline and C 3 , symmetry for ortho - and meta -fluoroanilines.

A new method for estimating excited state dipole moments of molecules from the solvent effect on their electronic spectra

Abstract Some comments are made on the paper entitled “Excited state dipole moments of some monosubstituted benzenes from the solvent effect on electronic absorption spectra” by Prabhumirashi et al . ( Spectrochim. Acta 39A , 663,1983) and a new method, which has been tested on some molecules and found satisfactory, is suggested for estimating the excited state dipole moment of molecules from the solvent effect on their electronic spectra.

Infrared and electronic absorption spectra of some trisubstituted benzenes

Abstract The electronic absorption spectra of 2,3-, 2,4-, 2,5-, 2,6- and 3,4-difluorobenzonitriles, 3,4-difluoroaniline and 3,4-difluoroanisole in the ultraviolet region in vapour phase have been recorded on medium quartz and Hilger large quartz spectrographs and on a Hitachi model 150-20 UV-VIS ratio recording spectrophotometer. All the molecules investigated have exhibited two π* ← π band systems corresponding to 1 B 2 u ← 1 A 1 g (λ2600 A) and 1 B 1 u ← 1 A 1 g (λ2100 A) systems of benzene. The infrared absorption spectra of all the molecules studied have also been recorded and analysed. These infrared data have been taken to help analyse the u.v. spectra of the molecules studied.

π* ← π systems in the electronic absorption spectra of some trisubstituted benzenes

Abstract The electronic absorption spectra of 2,3-, 2,4-, 2,5- and 3,4-difluorobenzaldehyde in the UV region in vapour have been recorded on medium quartz and Hilger Large Quartz Spectrographs, and on a Hitachi U-3200 UV—vis spectrophotometer and analyzed. All the molecules investigated have exhibited two π* ← π band systems corresponding to 1B2u ← 1A1g (λ 2600 A) and 1B1u ← 1A1g (λ 2100 A) systems of benzene.

Determination of excited state electric dipole moment of a molecule from solvatochromic shift measurements—a new approach

Abstract A new approach to the determination of the electric dipole moment of a molecule in an excited electronic state from the method of solvent-shifts is indicated.

gP∗ ← gP system in the electronic absorption spectra of some disubstituted phenols☆

Abstract Despite the studies on the II∗ ← II band system corresponding to 1 B 2u ← 1 A 1g (γ = 2600 A ) in tri-substituted benzenes (Aralakkanavar et al., Spectrochim. Acta 48A , 983 (1992) and references mentioned therein), the available data are limited. The vapour phase electronic absorption spectra of 2,4-, 2,5-, 3,4- and 3,5-difluorophenols are reported and interpreted.

Electronic absorption spectra of some substituted indoles

Abstract The electronic absorption spectra of 4-chloro-, 5-chloro-, 5-methyl-, 6-methyl- and 5-methoxy indoles have been recorded. The observed spectra lying in the region λ3100 A to λ 2650 A has been identified as a π* ← π transition analogous to the λ 2850 A system of indole. The results are reported and discussed in this paper.

π* ← n and π* ← π absorption spectra of aminopyrazine

Abstract π* ← n and π* ← π absorption spectra of aminopyrazine have been recorded and analysed assuming C s symmetry for the molecule.

Electronic absorption spectra of 2,3- and 2.5-dimethylpyrazines

Abstract The electronic absorption spectra of 2,3- and 2,5-dimethylpyrazines were recorded and analysed considering C 2ν and C 2h symmetry for the molecules, respectively. Vibrational analysis of the electronic spectra of these molecules has shown the existence of a vibronic interaction between two electronic states of both the molecules through an out-of-plane bending mode.

Vibrational and electronic absorption spectra of some trisubstituted benzenes

Abstract Despite our studies on the Π* ← Π systems in some trisubstituted benzenes, the available data are limited, especially concerning two heavy and one light or one heavy and two light substituents. We therefore report and interpret the vapour phase electronic absorption, infrared and Raman spectra of 1-bromo-2,4-difluoro-, 1-bromo-3,4-difluoro-, 1-bromo-3,5-difluoro-, 1,3-dichloro-2-fluoro- and 1,3-dichloro-4-fluoro-benzenes.