D-π-A'-π-A chromophores with quinoxaline core in the π-electron bridge and charged heterocyclic acceptor moiety: Synthesis, DFT calculations, photophysical and electro-chemical properties

Abstract

Chromophores with charged heterocyclic acceptor moiety in combination with divinylquinoxaline conjugated π-bridge show a significant solvatochromic shift, small energy gap value (determined by various methods), and large values of the first hyperpolarizability estimated by DFT. A quinoxaline-based chromophore with an indolium acceptor exhibits an outstanding solvatochromic shift (0.38 eV), probably a record one for D-π-A chromophores with a dialkyl aniline donor moiety. A good correlation between the above characteristics and the calculated NBO π-charge on the aniline nitrogen atom has been found. A change in the trend by opposite one in the characteristics in the series of quinolinium /benzothiazolium/ indolium chromophores is exhibited when passing from gas to solvent.