Electronic spectra and (hyper)polarizabilities of ketocyanine dye complexes with metal ions

The interaction of a ketocyanine dye, an example of donor–acceptor–donor (D–A–D) chromophore, and its parent merocyanine (D–A) dye with metal ions have been investigated using density functional theory. Time dependent density functional theory (TDDFT) is employed to target the lowest singlet excited dipole allowed states of optimized structures of dye–metal ion complexes in acetonitrile solution. The calculated excitation energies are in good agreement with absorption spectra obtained in experiment. We have also calculated the linear and static first hyperpolarizabilities of those dye–ion complexes and found these complexes to be promising in the field of nonlinear optoelectronics.