QUANTITATIVE TREATMENT OF THE SOLVENT EFFECTS ON THE ELECTRONIC ABSORPTION AND FLUORESCENCE-SPECTRA OF ACRIDINES AND PHENAZINES - THE GROUND AND FIRST EXCITED SINGLET-STATE DIPOLE-MOMENTS

Electronic absorption and fluorescence excitation and emission spectra of four acridines (acridine, Acridine Yellow, 9-aminoacridine and pro flavine) and three phenazines (phenazine, neutral Red and safranine) a re determined at room temperature (298 K) in several solvents of vario us polarities (dioxane, chloroform, ethyl ether, ethyl acetate, 1-buta nol, 2-propanol, ethanol, methanol, dimethylformamide, acetonitrile an d dimethyl sulfoxide). The effect of the solvent upon the spectral cha racteristics of the above compounds, is studied. In combination with t he ground-state dipole moments of these compounds, the spectral data a re used to evaluate their first excited singlet-state dipole moments b y means of the solvatochromic shift method (Bakhshiev's and Kawski-Cha mma-Viallet's correlations). The theoretical ground and excited single t-stare dipole moments for acridines and phenazines are also calculate d as a vector sum of the pi-component (obtained by the PPP method) and the sigma-component (obtained from sigma-bond moments). For most acri dines and phenazines under study, the experimental excited singlet-sta te dipole moments are found to be higher than their ground state count erpart. The application of the Kamlet-Abboud-Taft solvatochromic param eters to the solvent effect on spectral properties of acridine and phe nazine derivatives is discussed.