Luminescent compounds diphenylboron analogs of Alq3 and its methyl substituents:: A theoretical investigation of their electronic and spectroscopic properties

The absorption and emission energies for diphenylboron analogs of Alq(3) (Ph(2)Bq) and its methyl substituents (Ph(2)Bmq) were systematically investigated at the Zerner's intermediate neglect of differential overlap (ZINDO), configuration interaction singles (CIS), and time-dependent density functional theory (TD-DFT) levels of theory. The lowest excited-state geometries were optimized at the ab initio CIS level. The TD-DFT method provides the most reliable results for the absorption and emission transition energies, compared with other methods. Moreover, the TD-DFT calculations reliably estimate the changes of absorption and emission lambda(max) values upon methyl substitution, with errors of 1.2% and 1.8%, respectively. The Stokes shifts are well reproduced by TD-DFT calculations. Various density functional theory methods have been tested and the B3LYP functional clearly seems to be the best choice for this class of compounds. (C) 2005 Wiley Periodicals, Inc.