Photoexcited States in the Diimine Platinum(II) Metal Complex and the Stacking Interaction

本文研究了Ipt（II）（dpphen）CN_（21）（dpphen= 4，7-二苯基邻菲咯啉）晶体的发光行为和多晶型。在N，N-二甲基甲酰胺（DMF）中重结晶得到了两种具有不同发光行为的针状和片状晶体（Ipt（dpphen）（CN）_210.5H_2O）。在500 nm附近显示三重态配体中心（Ipt（dpphen）（CN）_21 0.5DMF）发射，但在820 nm附近显示非常宽的红色发射，这与在浓溶液中观察到的准分子样发射相似。测定了它们的X射线晶体结构。在两种晶体中，分子平面均为堆积结构，间距为3.3-3.5A，为紧密的Pt-phen环或phen-CN基团重叠位，但没有Pt-Pt相互作用位。在平板型晶体中，没有分子间邻菲咯啉重叠位点，这似乎是由于芳环重叠而引起的激基缔合物相互作用。 ...更多信息 为了阐明在溶液和晶体中产生类激基缔合的主要相互作用因素，采用密度泛函理论（DFT）方法对化合物的电子结构进行了计算.计算得到的优化结构与晶体结构符合较好。该复合物的最低激发态是^3MLCT和^3LC的混合态，由于在窄能量范围内存在着对^3LC性质贡献不同的多个态，因此该复合物是复杂的。为了考虑状态能量如何随着环境或缔合/堆叠而变化，通过改变化合物周围环境的介电常数进行量子化学计算。有趣的结果是^3MCT的贡献最低。在较低介电常数的环境中，激发态变得显著。这表明晶体中CT结构的增加伴随着缔合物的堆积，并被认为是解释类准分子发射的线索。但是，不能排除杂质的轻微可能性。少

Emission behavior and polymorphism of Ipt(II)(dpphen)CN_2l (dpphen= 4,7-diphenyl-pheuanthroline) in the crystal has been studied. Two kinds of crystals (needle and plate types) of this compound were obtained by recrystallization from N,N-dimethylformamide (DMF), and show different emission behavior Needle crystal (Ipt(dpphen)(CN)_2l0.5H_2O). Shows triplet ligand centered (^3LC) emission around 500 nm, but plate crystal (Ipt(dpphen)(CN)_2l 0.5DMF) shows very broad red emission around 820 nm which is similar with excimer-like emission as observed in concentrated solution. Their X-ray crystal structures have been determined. In both crystal, the molecular planes are in stacking structure with a space-distance of 3.3-3.5A, which are close Pt-phen ring or phen-CN group overlapping sites, but there is no Pt-Pt interaction site. In the plate type crystal, there is no intermolecular phenanthrolines-overlapping site that seems to cause excimer interaction due to aromatic-ring overlap.In order t … More o clarify a main interaction factor that brings excimer-like association in solution and in crystal, .the electronic structure calculation of the compound by the density functional theory (DFT) method also performed. The optimized strtrcture obtained by calculation was is good agreement with the crystal structure. The lowest excited state of the eomplex is the mixed state of ^3MLCT and ^3LC, and is complicated, because there are so many states with different contribution in ^3LC nature within narrow energy. To consider how the state energy changes with an environment or association/stacking, quantum-chemical calculation was performed by changing the dielectric constant of the surroundings of the compound. The interesting result that a contribution of ^3MCT in the lowest. Excited state become remarkable is the case of surrounding with lower dielectric constant have been obtained. This suggests the increase of CT structure accompanied by association ar stacking in the crystal, and is considered that the clue explaining an excimer-like emission. However, slight possibility of an impurity cannot be excluded. Less