Intramolecular charge transfer, solvatochromism and hyperpolarizability of compounds bearing ethenylene or ethynylene bridges

Abstract

Emission or both absorption/emission solvatochromic effects induced by intramolecular charge transfer (ICT) have been used to determine the excited-state dipole moments of the locally excited μe(LE) and the polar-solvent induced μe(ICT) states and the first hyperpolarizability parameter βCT of six asymmetric distyrylbenzene analogues, two 9,10-(diarylethynyl)anthracene derivatives and two 2,7-(diarylethynyl)fluorene analogues. The change in dipole moment under excitation (Δμeg) was also evaluated by theoretical calculations and compared with experimental data. All compounds display more or less remarkable positive solvatochromism which leads to relatively high hyperpolarizabilities and makes them interesting candidates for applications associated with photoinduced ICT. The structural effect on the transfer is also briefly discussed and related to the relaxation properties (previously investigated) of these compounds.