长链β-二酮环金属铂配合物的紫外-可见吸收光谱和三阶非线性光学系数的理论研究

Theoretical Studies on UV-Vis Absorption Spectra and the Third-Order Nonlinear Optical Coefficients of Cyclometalated Platinum Complexes with Long Chain β-Diketonate Ancillary Ligands

采用含时密度泛函理论(TDDFT)B3LYP对6个长链β-二酮环金属铂配合物分子的紫外-可见吸收光谱进行理论计算。结果表明,基态到第一激发态的跃迁来源于金属到配体和配体到配体的混合跃迁。该6个分子的最大吸收波长均在402～405nm范围内,属于近紫外区。使用有限场(FF)方法对6个配合物分子的三阶非线性光学(NLO)系数的理论计算。结果显示,该类配合物分子具有较好的三阶非线性光学系数(为105数量级)。并在C1～C14范围内增加β-二酮碳链的长度以及在配体苯环或吡啶环上分别引入甲基供电子基,均有利于增大配合物的三阶NLO性质。

The time-dependent density functional theory（TD-DFT） B3LYP method is used to investigate the UV-vis absorption spectra of six cyclometalated platinum complexes with long-chain β-diketonate ancillary ligands.The results indicate that the electronic transition from the ground state to the first excited state is ligand-to-ligand charge transfer（LLCT） and metal-to-ligand charge transfer（MLCT） transition.The maximum absorption wavelength of the six compounds is around in the range of 402～405 nm due to the near ultraviolet region.The finite field（FF） method is used to investigate the third-order nonlinear optical properties of the six complexes.The results show that these complexes display good third-order nonlinear optical coefficients（in 105 order of magnitude）.From one to fourteen carbon atoms range,increasing β-diketonate carbon chain length and introducing methyl respectively in the ligands benzene or pyridine are both conducive to increase the third-order nonlinear optical properties.