Studies and applications of organic light emitting display (OLED) have indicated that it is one of the promising technologies of planar display. Metaloquinolates with high stability and high fluorescence quantum efficiency are widely applied in organic EL devices. The experimental and theoretical investigations of these complexes have been widely implemented

while the theoretical study of Liq attracted little attention. The singles configuration interaction (CIS )and the time-dependent density functional theory (TD-DFT) are main methods for theoretical study on molecular excited state and electronic spectrum. In this paper

the frontier molecular orbit and electronic spectrum of Liq and its derivates are calculated by CIS and TD-DFT method. The effect of substituting group on the frontier molecular orbit and the electronic spectrum were analyzed. All this will provide a theoretical basis for the molecular structure design of organic electroluminescent materials. We designed 18 kinds of derivates which were obtained by substitution of three kinds electron-withdrawing group (C

6

H

5

CN or Cl) at different position

respectively. The derivates of 8-hydroxyquioline lithium (Liq) were investigated quantitatively by means of DFT/B3LYP. The most stable substituted derivates (2-C

6

H

5

-Liq

5-CN-Liq and 6-Cl-Liq) were selected according to the lowest energy rule. Basing on that

the absorption spectrum is calculated by TD-DFT

and the structures of excited states were optimized by CIS method. On the optimized-structures of excited states

the emission wavelength was predicted by TD method. And then the effect of substituting group on the frontier molecular orbit and electronic spectrum were discussed. The results indicated that the electronic withdrawing group affected mainly the electron cloud distribution of the frontier molecular orbit

which was correlated to the electronic withdrawing ability of ligand. The electron-withdrawing group on phenoy ring makes the HOMO-LUMO band gap increased. The increase of band gap then leads to a blue shift of electronic spectrum. Substitute position was related to electronic spectrum shift. The electron-withdrawing group on pyriding ring makes the HOMO-LUMO band gap decreased. The decrease of band gap then leads to a red shift of electronic spectrum. The simulative peaks at 269.94

373.26 nm of the UV absorption spectra and the peak at 461.7 nm of emission spectra of Liq are closed to the peaks at 259.8

363.8 nm of the experimental UV absorption spectra and the peak at 452 nm of emission spectra of Liq. It indicates that the TD-DFT method do well in predicting the electronic spectrum of metaloquinolates.