Solvatochromism of some hemicyanines

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• 作者：Mallika Panigrahi^a ; Sabita Patel^b ; Bijay K. Mishra^a ; ^{bijaym@hotmail.com}
• 关键词：Hemicyanine ; Solvatochromism ; Solvent parameter ; Stokes shift ; Dipole moment ; Successive exclusion of variable
• 刊名：Journal of Molecular Liquids
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：177
• 期：Complete
• 页码：335-342
• 全文大小：891 K

文摘

Solvatochromism of some hemicyanines dyes (N-alkyl (methyl, hexyl and hexadecyl)-4-[(4-N,N-dimethylamino)styryl] pyridinium halides in 28 organic solvents has been investigated by using absorption and emission spectroscopy. The probes have inbuilt donor-acceptor system and the corresponding charge transfer bands are found to be solvent sensitive. A reversion in the steady solvatochromism has been rationalized through hydrogen bonding of the solvents with the dye and stability of both the excited and ground state species. Accordingly the solvents are classified into hydroxylic and nonhydroxylic groups. For a quantitative solvent-transition energy relationship, the transition energies obtained from absorption and emission spectra have been subjected to multiple regression analysis with 14 different solvent parameters. Optimization of multiparametric regression models has been achieved by successive exclusion of variable technique. The validity of the regression models has been established from the linearity of the plot of calculated and observed transition energy relating to absorption spectra and Stokes shift. The ratio of the dipole moment in excited and ground state has been determined and is found to be around 1.65.