Solvent dependence of structure and electronic properties in the ground and first excited singlet state of 4-dimethylamino-4′-nitrostilbene (DANS) – semiempirical calculations Original Research Article

Ground and excited state properties of trans-4-dimethylamino-4′-nitrostilbene (DANS) in different solvents are calculated with the semiempirical SAM1 Hamiltonian. The solvent is treated as a continuum with the conductor-like screening model. Singlet excited-state conformations at various stages of relaxation, their optical transitions, and triplet states for these geometries are reported for the first time. Relaxation pathways are suggested which may be distinguished by characteristic optical spectra and which explain why fluorescence, intersystem crossing, and internal conversion strongly depend on the solvent.