Waterland Mark R, Howell Sarah L, Gordon Keith C, Burrell Anthony K
MacDiarmid Institute for Advanced Materials and Nanotechnology, Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
J Phys Chem A. 2005 Oct 6;109(39):8826-33. doi: 10.1021/jp052954n.
The structural changes that occur when Cu(pqx)(PPh(3))(2) (pqx is 2-(2'-pyridyl)quinoxaline) undergoes excitation through a metal-to-ligand charge-transfer (MLCT) transition are investigated using resonance Raman excitation profiles coupled with density functional theory (DFT). The DFT calculations predict bond lengths to within 3 pm and absolute deviations of 7 cm(-1) for the vibrational frequencies of Cu(pqx)(PPh(3))(2). TD-DFT calculations of oscillator strengths (f = 0.089) and band positions (419 nm) showed close agreement with experiment (f = 0.07, 431 nm). Resonance Raman spectra show the 527 cm(-1) (nu(29)) and 1476 cm(-1) (nu(75)) modes undergo the largest dimensionless displacement (Delta = 1.5 and 1.1, respectively) following photoexcitation into the MLCT Franck-Condon region. The solvent couples strongly to the MLCT transition and resonance Raman intensity analysis (RRIA) gives a solvent reorganization energy of 3400 cm(-1) for dichloromethane and 2800 cm(-1) for chloroform solutions. A large inner-sphere reorganization of 3430 cm(-1) in dichloromethane solution (3520 cm(-1) in chloroform solution) was found for Cu(pqx)(PPh(3))(2), indicating that the molecule as a whole undergoes significant distortion following MLCT excitation.
利用共振拉曼激发谱结合密度泛函理论（DFT），研究了[Cu(pqx)(PPh(3))(2)]⁺（pqx为2-(2'-吡啶基)喹喔啉）通过金属到配体电荷转移（MLCT）跃迁发生激发时所发生的结构变化。DFT计算预测[Cu(pqx)(PPh(3))(2)]⁺的键长在3 pm以内，振动频率的绝对偏差为7 cm⁻¹。振子强度（f = 0.089）和能带位置（419 nm）的TD-DFT计算结果与实验值（f = 0.07，431 nm）显示出密切的一致性。共振拉曼光谱表明，在光激发进入MLCT弗兰克-康登区域后，527 cm⁻¹（ν₂₉）和1476 cm⁻¹（ν₇₅）模式经历了最大的无量纲位移（分别为Δ = 1.5和1.1）。溶剂与MLCT跃迁强烈耦合，共振拉曼强度分析（RRIA）给出二氯甲烷溶液的溶剂重组能为3400 cm⁻¹，氯仿溶液为2800 cm⁻¹。发现[Cu(pqx)(PPh(3))(2)]⁺在二氯甲烷溶液中有3430 cm⁻¹的大内球重组（氯仿溶液中为3520 cm⁻¹），这表明该分子在MLCT激发后整体发生了显著畸变。
