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

研究了IPT(II)(Dpphen)CN_2L(dpphen=4，7-二苯基邻菲咯啉)在晶体中的发射行为和晶型。从N，N-二甲基甲酰胺(DMF)重结晶得到两种不同的针状晶体(IPT(Dpphen)(CN)2L0.5H2O)，表现出不同的发射行为。在500 nm附近有三重态配体中心(^3LC)的发射，而片状晶体(IPT(Dpphen)(CN)_2l 0.5DMF)在820 nm附近有很宽的红光发射，这与在浓溶液中观察到的类准分子发射相似。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，为紧密的铂-邻菲咯环或邻菲咯环重叠位置，但不存在铂-铂相互作用位置。在板状晶体中，由于芳环的重叠，没有分子间邻菲咯啉的重叠位置，这似乎是引起激基缔合作用的原因。为了t…为了阐明在溶液和晶体中产生类准分子缔合的主要相互作用因素，用密度泛函理论(DFT)方法对该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吻合较好。络合物的最低激发态是^3MLCT和^3LC的混合态，并且很复杂，这是因为在窄能量范围内^3LC性质中有许多不同贡献的态。为了考虑状态能量如何随环境或缔合/堆积而变化，通过改变化合物周围环境的介电常数进行了量子化学计算。有趣的结果是^3MCT的贡献最低。当周围的介电常数较低时，激发态变得明显。这表明晶体中伴随着缔合Ar堆积的CT结构的增加，被认为是解释类准分子发射的线索。然而，不能排除有轻微杂质的可能性。较少

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