TWISTED INTRAMOLECULAR CHARGE-TRANSFER OF PARA-(N,N-DIMETHYLAMINO)BENZONITRILE - AN APPROXIMATE QUANTUM-MECHANICAL STUDY INCLUDING SOLVATION EFFECTS

被引:63
作者
MAJUMDAR, D [1 ]
SEN, R [1 ]
BHATTACHARYYA, K [1 ]
BHATTACHARYYA, SP [1 ]
机构
[1] INDIAN ASSOC CULTIVAT SCI,DEPT PHYS CHEM,CALCUTTA 700032,W BENGAL,INDIA
关键词
D O I
10.1021/j100164a028
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The twisted intramolecular charge-transfer (TICT) phenomenon of p-(N,N-dimethylamino)benzonitrile (DMABN) is studied by using the CNDO-S/CI method for calculating transition energies. The ground state geometry is fully optimized by the MNDO method. The solvent is treated as a continuous dielectric. The TICT state is found to correspond to a state of perpendicular geometry and large dipole moment (18.656 D). The "nonpolar" emission is ascribed to either of two nearly degenerate states at nearly planar geometry having relatively small dipole moments. The calculations indicate that the TICT emission should be observed only if the dielectric constant of the medium exceeds 2.2. The model also provides reasonably good estimates for the activation barrier for the TICT process. Finally, the energy difference between the TICT emission and the nonpolar emission turns out to be predominantly due to the energy difference between the excited states, the energies of the two ground-state conformations (planar and perpendicular) being very nearly the same.
引用
收藏
页码:4324 / 4329
页数:6
相关论文
共 43 条