Influence of Hydrogen Bond Formation on the Photophysics of N-(2,6-Dimethylphenyl)-2,3-naphthalimide

Abstract

The photophysics of N-(2,6-dimethylphenyl)-2,3-naphthalimide (DMPN) has been investigated in the presence of methanol or fluorinated aliphatic alcohols in n-hexane and carbon tetrachloride solvents. Consecutive two-step hydrogen bonded complex formation is observed in the presence of alcohols. Equilibrium constants are determined for the formation of singly and doubly complexed species. The UV absorption and fluorescence spectra for the singly and doubly complexed DMPN are derived from the measured absorption and fluorescence spectra, respectively, by means of the equilibrium constants. It is concluded from the results that the spectroscopic properties (singlet excitation energy and Stokes shift) of the complexed species are significantly influenced by the Gibbs energy change in the complexation reaction. Quantitatively, a linear relationship is found between the difference of singlet excitation energy of the complexed and uncomplexed species on one hand and the Gibbs energy change in the complexation rea...