以2,3-二苯基吡嗪(H2dpp) 、5-甲基-2,3-二苯基吡嗪(H2mdpp)和2,3-二苯基喹喔啉(H2dpq)为配体,乙酰丙酮(Hacac)为辅助配体,合成了一类单核和双核金属铂配合物[Pt(Hdpp)(acac)](1)、[Pt2(dpp)(acac)2] (2)、[Pt(Hmdpp)(acac)] (3)和[Pt(Hdpq)(acac)](4),并且得到了配合物2、3和4的晶体结构数据.通过对单核配合物1的类似物配合物3和双核配合物2的配位平面、分子扭曲程度等的晶体结构分析,我们合理地推断以2,3-二苯基吡嗪为配体的双核配合物2具有比相应的单核配合物1更加扭曲的分子平面.通过对配合物1和2的紫外-可见吸收光谱和激发光谱的比较,发现由于双核配合物2在激发态的构型变化造成了激发光谱中最低能带比相应的最低能量吸收带光谱红移了18 nm.因此,尽管双核配合物2具有与单核配合物1类似的紫外-可见吸收光谱,最低能吸收带仅比单核配合物1红移5 nm,但是双核配合物2的最大发射峰值λmax为609 nm,比单核配合物1(λmax=546 nm)红移了63 nm.双核配合物2的发射光谱红移现象与配合物的分子构型直接相关.分子扭曲程度更大的双核配合物2在激发态可能发生了一个向平面性更好的构型转变过程,从而进一步降低了激发态能量,造成了发射光谱的红移.%Luminescent mononuclear platinum(Ⅱ) complexes,[Pt (Hdpp)(acac)] (1),[Pt (Hmdpp)(acac)] (3) and [Pt(Hdpq)(acac)] (4) and dinuclearnum(Ⅱ) complex,[Pt2(dpp)(acac)2] (2) were obtained by using 2,3-diphenylpyrazine (H2dpp),5-methyl-2,3-diphenylpyrazine (H2mdpp) and 2,3-diphenylquinoxaline (H2dpq) as ligands.It is noted that the maximal emission peak value for dinuclear complex 2 is at 609 nm,which has red-shift of about 63 nm compared with its analogue mononuclear complexes 1 and 3,although they seem somewhat analogue in lowest energy absorption band.To examine the cause of anomalous lower emission for dinuclear complex 2,the single crystals for complexes 2,3 and 4 were grown from dichloromethane and methanol solution.It is found that dinuclear platinum(Ⅱ) complexes 2 incorporating 2,3-diphenylpyrazine-based bridging ligand has more twisted conformation in the ground than its mononuclear analogue,complexes 3,which has similar structure with complex 1.Furthermore,lowest energy band for dinuclear complex 2 in exciting spectrum shows red-shift of 18 nm compared with its absorption spectrum.The twisted geometry in ground and red-shifted exciting spectrum make us infer reasonably that dinuclear complex 2 may undergo a more profound change from twisted geometry to planar conformation before emission,which led a lower triplet excited sate,resulting in the red-shifted emission of the dinuclear complex 2.CCDC:1517500,2;1517502,3;1517501,4.
展开▼
