No abstract

Solvation-dependent photophysical properties of two push–pull thiophene-based compounds with donor–π–acceptor (D–π–A) structures were investigated using absorption, fluorescence emission and time resolved spectroscopy, and supported by different solvation models.

No abstract

No abstract

No abstract

Solvent effect on the absorption and fluorescence emission spectra of 1-naphthylamine-4-sulfonate (1NA4S) and 2naphthylamine-6-sulfonate (2NA6S) were investigated. Excited state fluorescence decay measurements were also measured in different solvents. The spectral shifts are well correlated with several multiparametric relationships that predict the participation hydrogen bonding interactions (specific) versus non-hydrogen bonding interactions (non-specific) on the photophysical properties. Kamlet-Taft with their three parametric relationship which was then improved by Catalán by splitting the * (dipolarity/polarizability) to parameters namely, solvent"s polarizability) solvent"s dipolarity, and very recently Laurence relationships. The three-parameter relationship by Kamlet-Taft has shown that the absorption energy is mainly controlled by specific interactions while the emission energy is controlled by the non-specific interactions. On the other hand, Catalán"s treatment has shown that non-specific interaction has higher contribution to the emission energy than predicted by Kamlet-Taft treatment. Laurence"s treatment has shown that hydrogen bonding interaction has higher contribution than non-hydrogen bonding interactions to the emission energy for both compounds while they contribute equally to their absorption energy.

Inclusion of 2,4-dihydroxyquinoline in a variety of cyclodextrins with different cavity dimensions is studied. It has been found that excited state proton transfer is strongly affected upon the inclusion of 2,4-dihydroxyquinoline in the nano cavities of cyclodextrin derivatives. Molecular encapsulation of 2,4-dihydroxyquinoline by-, , and methylcyclodextrins in aqueous media has been studied by steady state absorption and fluorescence emission techniques. It has been found that the fluorescence intensity at 360 nm increases in case of inclusion in-CD. On the other hand, the band at 360 nm decreases with concomitant increase of the fluorescence intensity at about 325 nm in case of the inclusion in-CD and M-CD. Calculation of the association constant shows that inclusion in-CD is higher than in case of M-CD and-CD