具有樟脑基衍生物作为立体位阻β-二酮的环金属铂配合物:一种有效降低分子间π-π相互作用和Pt-Pt相互作用的新途径

Cyclometalated platinum(II)complexes with sterically bulky Camphor-Derived groups as β-diketonate ancillary ligand: A new route to efficiently reducing π-π interactions and Pt-Pt interactions

合成了一类以立体位阻樟脑基衍生物作为辅助配体的环金属铂(II)配合物并对它们的化学结构、晶体结构和发光性质进行了表征.这类新化合物的结构简式为:ppyPt(O^O),ppy表示主配体(2-苯基吡啶),O^O表示在樟脑基3位上具有不同乙酰取代基团的位阻β-二酮.单晶结构研究表明,虽然这些配合物同其他具有简单β-二酮(如乙酰丙酮等)的环金属铂(II)配合物一样具有正方形的平面构形,同时配合物分子间也具有平面堆积模式,但是,由于配合物中的樟脑基团具有很大的空间位阻,致使配合物的分子平面之间产生相互错动,配合物分子中的芳香环基团不能产生有效的重叠,所以这些配合物具有非常弱的π-π相互作用.分子平面的相互错动也使得金属铂之间产生很大的距离(Pt-Pt最短距离超过6?).这些结果都表明在β-二酮中引入樟脑基团能够有效降低分子间π-π相互作用和Pt-Pt相互作用.溶液发光光谱的研究表明,除配合物2外,这些化合物具有较高的磷光效率.同时,这些配合物的固体发光光谱具有结构发射特征,最大发射波长仅比相应的溶液发光光谱相差几个纳米,表明分子间没有激基复合物产生.分子间非常弱的π-π相互作用、有结构的固体发光性质和较高的磷光效率表明在掺杂磷光发光器件甚至在非掺磷光发光杂器件中,这类磷光材料都具有潜在的应用价值.

A new series of mono-cyclometalated square planar platinum（II）complexes which have the general formula, ppyPt（O^O）, where ppy is 2-phenylpyridyl, and O^O are fl-diketonate ancillary ligands with acyl substituent group in 3 position of （D）-（＋）-camphor, were synthesized and the single-crystal X-ray structures of complex 1 and 2 were determined. Although, like the many square-planar geometry of Pt（II） complexes, these complexes have plane stacking modes in crystal structure, the sterically bulky camphor-derived groups compel extensively slipping of the molecular stacking planes each other, resulting in the negligible overlapping of the aromatic ring fragments between molecules and the considerable Pt-Pt distance. The resolved spectra and a little shifted emissions in solid state of complexes also show that there is significant reducing of π-π interactions and Pt-Pt interactions and suggest these complexes can be as good candidates of the doped phosphorescent organic light emitting diodes （PhOLEDs）and even as candidates of the nondoped PhOLEDs.