The photophysical properties of N-(1-naphthyl)-carbazole (1-NACZ), N-(2-naphthyl)-carbazole (2-NACZ), N-(1-naphthyl)-benzimidazole (1-NABI) and N-(2-naphthyl)-benzimidazole (2-NABI) were studied. The emission wavelengths of 1-NACZ and 2-NACZ were very sensitive to the polarity of solvents. The magnitude of change in the dipole moment was calculated based on the Lippert-Mataga equation. 1-NACZ and 2-NACZ had higher change in the dipole moment than that of 1-NABI and 2-NABI. The optical properties, including fluorescence quantum yield and fluorescence decay times, were determined in different polarity solvents. These gave the evidence about the intramolecular charge transfer character in the excited singlet state of 1-NACZ and 2-NACZ. (c) 2006 Elsevier B.V. All rights reserved.