Grimes Tom, Omary Mohammad A, Dias H V Rasika, Cundari Thomas R
Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas, Denton, 76203-5070, USA.
J Phys Chem A. 2006 May 4;110(17):5823-30. doi: 10.1021/jp0605146.
The interactions present in cyclic trinuclear coinage metal pyrazolates were studied computationally. Cuprophilic interaction was found to bind the singlet ground state of the dimer of trimers Cu(Pz), overcoming electrostatic repulsion. The large variation in intertrimer separations found in the literature for coinage metal pyrazolates is consistent with the relatively weak metallophilic interaction. The emissive triplet excited-state geometry of M(Pz) is predicted by density functional calculations to show major geometric distortion caused by Jahn-Teller instability and excimeric M-M bonding. Large calculated Stokes' shifts, which are also observed for experimental models, are consistent with significant excited-state distortions for these materials. The major finding derived from the present study is that the intertrimer M...M contraction in the emissive T(1) state is much more than the intratrimer contraction in all M(Pz) models, giving rise to a lower T(1) --> S(0) phosphorescence energy in these models than in analogous monomer-of-trimer models. The observations made here point to a great potential for rationally tuning the emission properties of trinuclear coinage metal complexes through choice of the metal and ligands.
通过计算研究了环状三核货币金属吡唑盐中的相互作用。发现亲铜相互作用能结合三聚体[[Cu(Pz)]₃]₂二聚体的单重基态，克服静电排斥。文献中报道的货币金属吡唑盐三聚体间间距的巨大变化与相对较弱的亲金属相互作用是一致的。密度泛函计算预测[[M(Pz)]₃]₂的发射三重激发态几何结构会显示出由 Jahn - Teller 不稳定性和准分子 M - M 键引起的主要几何畸变。计算得到的大斯托克斯位移在实验模型中也有观察到，这与这些材料显著的激发态畸变是一致的。本研究的主要发现是，在所有[[M(Pz)]₃]₂模型中，发射 T₁态下三聚体间 M...M 收缩比三聚体内收缩大得多，导致这些模型中 T₁→S₀磷光能量低于类似的三聚体单体模型。此处的观察结果表明，通过选择金属和配体来合理调节三核货币金属配合物的发光性质具有很大潜力。
