文献类型：期刊文献

英文题名：Theoretical Studies on Molecular and Structures of Mono- and Binuclear Chromium Carbazole Derivatives for Optoelectronics

作者：Sun, Haitao[1,2];Tian, Xiaohui[1,2];Wang, Jun[1,2];Zhang, Jian[3];Yuan, Yizhong[1,2];Sun, Zhen-Rong[3]

机构：[1]E China Univ Sci & Technol, Key Lab Ultrafine Mat, Minist Educ, Shanghai 200237, Peoples R China;[2]E China Univ Sci & Technol, Key Lab Mat Phys Shanghai, Sch Mat Sci & Engn, Shanghai 200237, Peoples R China;[3]E China Normal Univ, Dept Phys, Shanghai 200062, Peoples R China

年份：2011

卷号：115

期号：50

起止页码：14495

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY A

收录：;EI(收录号：20115214636201);WOS:【SCI-EXPANDED(收录号:WOS:000297947300030)】；

基金：We gratefully acknowledge the support of the National High Technology Research and Development Program of China (0099AA03500), Shanghai Key Project for Basic Research (No. 09JC1404300), Shanghai Leading Academic Discipline Project (B502), and Shanghai Key Laboratory Project (08DZ2230500).

语种：英文

外文关键词：Chromophores - Density functional theory - Metals - Charge transfer - Continuum mechanics - Ligands - Self assembly - Polycyclic aromatic hydrocarbons - Computation theory - Electronic properties - Molecular orbitals - Oscillators (electronic)

摘要：Studies on the molecular geometries, electronic properties and second-order nonlinearities of a series of mono- and binuclear chromium carbazole complexes: (N-vinylcarbazole)Cr(CO)(3) (MI), (N-vinylcarbazole)Cr(CO)(2)PPh3 (M2), (CO)(3)Cr(N-vinylcarbazole)Cr(CO)(3) (B1), and (CO)(3)Cr(N-vinylcarbazole)Cr(CO)(2)PPh3 (B2) were carried out, using the density functional theory (DFT) at the B3LYP//LanL2DZ/6-31G(d) level. The experimental singlet metal-to-ligand charge transfer ((MLCT)-M-1) spectra of these complexes can also be well simulated and discussed by the time-dependent DFT (TDDFT) at the B3LYP//LanL2DZ/6-311+G(d) level associated with the polarizable continuum model (PCM). The computational results show that an unusual characteristic of chromium carbazole structures is explained in terms of interaction between frontier molecular orbitals of the metal and its ligands. The highest occupied molecular orbitals (HOMOs) of these complexes are composed of a set of distorted degenerated Cr 3d orbitals, whereas the lowest unoccupied molecular orbitals (LUMOs) are predominantly the N-vinylcarbazole ligand pi* orbitals. The HOMO-LUMO energy gaps decrease in the order NVC > M1 > B1 > M2 > B2. The considerable coupling between the carbazole and (CO)(3) in MI creates an asymmetric environment about the chromium atom, leading to modest second-order responses. The PPh3 ligand is acting as a donor which increases the donating strength of the d, orbitals in chromium carbazole species, resulting in the large electronic asymmetry in M2. As for the binuclear chromium carbazole chromophores, a wide-range (MLCT)-M-1 band and large oscillator strength are found, allowing for the electronic interactions between two metal centers which can be modified by altering the ligand bound to the metals to induce peculiar asymmetry. Essentially, Cr(CO)(3) acceptor and Cr(CO)(2)PPh3 donor units in B2 make significant contribution to the charge-transfer process or NLO responses via conventional push pull chromophoric architecture.