Abstract The absorption and emission characteristics of five hydroxytetrahydrochrysenes substituted with acceptor groups (nitro, cyano, methylketone, 1° amide and methyl ester) (THC‐NO2, THC‐CN, THC‐COCH3, THC‐CONH2 and THC‐CO2CH3, respectively) were investigated in an extensive set of solvents. The order of absorption and fluorescence bathochromicity are: THC‐NO2 > THC‐COCH3 > THC‐CN ≥ THC‐CO2CH3 > THC‐CONH2 and THC‐NO2 >> THC‐COCH3 > THC‐CO2CH3 > THC‐CN > THC‐CONH2, respectively. The emission spectra of these compounds are sensitive to the solvent polarity (ET scale) in the order: THC‐NO2 > THC‐COCH3 > THC‐CO2CH3 > THC‐CONH2 > THC‐CN. The response of the emission maxima of these compounds to the solvent polarity and hydrogen‐bond donor/acceptor properties (π*/α/β and acity/basity scales) was also determined. The emission energies of THC‐NO2 were most sensitive to π*, β, acity, and basity of the solvent; those of the amide were least sensitive to the solvent π*, β, and basity. The ground‐ and excited‐state dipole moments were determined by semiempirical molecular orbital calculations and the absorption/fluorescence solvent‐shift method, respectively. THC‐NO2 had the largest ground‐ and excitedstate moments. The ester and amide had the smallest ground‐ and excited‐state moments, respectively. In general, unsatisfactory results were obtained for correlations of the emission and absorption energies, fluorescence solvatochromism and the ground‐ and excited‐state dipole moments with the Hammett substituent constants of the five acceptor groups. Acceptable correlations were obtained for the absorption and emission energies and the fluorescence solvatochromism with the substituent constants if the cyano compound was excluded.
|Original language||English (US)|
|Number of pages||10|
|Journal||Photochemistry and Photobiology|
|State||Published - Dec 1993|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry