Luminescent Properties of Mercury-taining Diethynylfluorene Derivatives*

Excited state structures and spectroscopic properties of mercury(II) complexes, Hg-TFT(1) and its electron-withdrawing substituents Hg-TFOT (2), Hg-TFCNT (3), where TFT = diethynylfluorenyl, TFOT = diethynyl-fluorenone, and TFCNT = diethynyl-[9-(dicyanomethylene) fluorene], were studied using singlet excitation configuration interaction (CIS) and time-dependent density functional theory(TDDFT) methods. The results of the theoretical calculations indicate that the electron-withdrawing substitutions lead to a significant decrease in the energy gap between the ground state and the first excited states. In the case of Hg-TFCNT, the second singlet excited state (S2) may contribute to the luminescence because of its large S1-S2 separation.