Study of electronic and spectroscopic properties on a newly synthesized red fluorescent material

The ground state (S(0)) and the lowest singlet excited state (S(1)) of a newly synthesized red fluorescent material, 2-3-(2-{4-(2-Hydroxy-ethyl)-methyl-amino]-phenyl}-vinyl)-5,5-dimethyl-cyclohex-2-enylidene]-malononitrile (A31), are investigated. The S(0) and S(1) geometries are optimized at the ab initio Hartree-Fock and the singles configuration interaction (CIS) levels of theory, respectively. The CIS and semiempirical Zerner's Intermediate Neglect of Differential Overlap (ZINDO) methods provide the results for the absorption (S(0)-->S(1)) and emission (S(1)-->S(0)) transition energies. The Stokes shifts calculated at the CIS and ZINDO levels of theory are obtained. The absorption spectra in various solvents are calculated using the time-dependent density-functional theory method in combination with the polarized continuum model, which are in very good agreement with our experimental measurements. The solvent effects are discussed.