Theoretical Study of Molecular Orbital of Cyclometalated Phenylpyridine Ir(III) Complexes Using Density Functional Theory

• Main Authors: Wei-Lin Su, 蘇煒林
• Other Authors: Shao-Pin Wang
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/52411023164031111269

碩士 === 國立成功大學 === 化學系碩博士班 === 94 === The photophysical properties of a series of cyclometalated Ir(III) complexes Ir(ppy)2(CN)2- (1), Ir(ppy)2(NCS)2- (2), and Ir(ppy)2(NCO)2- (3) (where ppy = 2-phenyl pyridine, CN = cyanide, NCS = isothiocyanate, and NCO = isocyanate) have been reported. It is concluded that time-dependent density functional theory (TD-DFT) calculations supply theoretical interpretation of the triplet excited states and the nature of photophysical behaviors reported in literature. Combined with conductive polarizable continuum model (CPCM) the calculations are valid in examining the solvent effect on excitation energies. Analysis of highest occupied molecular orbital (HOMO) and lowest unoccupied orbital (LUMO) obtained by B3LYP functional reveals effects of p-donating and/or p-accepting properties of three pseudohalogens on optical orbitals in complexes 1, 2, and 3. The origin of HOMO tuning up, results in the blue, green and yellow photoluminescence observed in experiments, can be interpreted by interaction between the lone pairs perturbed p-p*(NC) system with metal dp orbitals. We have modified the Hoffman’s orbital interaction diagram to demonstrate effects of sulfur or oxygen atoms on the energy of p(NC). The degree of HOMO tuning-up is parallel to the lone-pair contribution to the perturbed p (NC) analyzed by the natural bonding orbital (NBO) method.