Analysis of the parameters of Franck–Condon and Herzberg–Teller interactions the molecules of substituted diphenylbutadienes

Abstract

Abstract.We have done quantitative analysis of parameters FranckCondon and Herzberg-Teller interactions of substituted diphenylbutadiene with general formula all-trans-X-Ph-(C = C)2-Ph-Y (X, Y = H, NO2, N(CH3)2, NH2 various combinations). The research shows the influence of substituents on the vibronic parameters of characteristic bands, which describe the state (vibrations, types of deformation under excitation) of the phenyl ring and the polyene bridge at the diphenylbutadiene molecule. Results described impact of the substituent's nature on the parameters of intra-and intermolecular interactions presents for the studied compounds.The methods of site-selective spectroscopy are very powerful for investigations of interand intra-molecular processes in complex organic dye doped solids (see e.g. [1-4] and references therein). In particular a lot of information about intramolecular interactions can be obtained by joint analysis of absorption and luminescence electronic-vibrational spectra of organic compounds. [5][6][7][8] In the majority works, which devoted to the spectra of substituted polyenes with trans-configuration, for the same substituted compounds there is considerable overlap between the general characteristic vibrational bands locations and these interpretations.It is known that the substituents in the para position (in this study -nitro and amino groups) irrespective of their electronic nature violate uniform distribution of electron density in the molecule of DPB [9]. It should affect by the quantification of intramolecular interactions. Therefore, it was interest to produce comparative analysis of the spectral properties and quantification of the contribution of intramolecular interactions in the formation of the fine-structure spectra. The relative intensities of bands in the spectra of were calculated by the procedure described in [7,8]. Based on the modern theory of molecular spectra in the adiabatic approximation ,which makes it possible to simultaneously take into account the influence of the Franck-Condon and Herzberg-Teller interactions on the shape of optical bands [10], we calculated the parameters а and α (of the FC and HT interactions, respectively) for each vibronic transition of the studied molecules.In this study, the basic oscillations for substituted compounds were correlated with the interpretation of similar value 1,4-diphenylbutadiene, which spectral properties have been studied previously [11][12][13]. We shown to considered acceptors and donors, and besides the