Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
Inorg Chem. 2011 May 2;50(9):3959-69. doi: 10.1021/ic1023696. Epub 2011 Mar 29.
The reaction of 2,3-di(2-pyridyl)-5,6-diphenylpyrazine (dpdpz) with K(2)PtCl(4) in a mixture of acetonitrile and water afforded mono-Pt complex (dpdpz)PtCl(2)4 in good yield, with two lateral pyridine nitrogen atoms binding to the metal center. Two types of Ru(II)-Pt(II) heterodimetallic complexes bridged by dpdpz, namely, (bpy)(2)Ru(dpdpz)Pt(C≡CC(6)H(4)R) (7-9, R = H, NMe(2), or Cl, respectively) and [(tpy)Ru(dpdpz)Pt(C≡CPh)] (+) (12), were then designed and prepared, where bpy = 2,2'-bipyridine and tpy = 2,2';6',2''-terpyridine. In both cases, the platinum atom binds to dpdpz with a C(∧)N(∧)N tridentate mode. However, the coordination of the ruthenium atom with dpdpz could either be noncyclometalated (N(∧)N bidentate) or cyclometalated (C(∧)N(∧)N tridentate). The electronic properties of these complexes were subsequently studied and compared by spectroscopic and electrochemical analyses and theoretical calculations. These complexes exhibit substantial absorption in the visible to NIR (near-infrared) region because of mixed MLCT (metal-to-ligand-charge-tranfer) transitions from both the ruthenium and the platinum centers. Complexes 7 and 9 were found to emit NIR light with higher quantum yields than those of the mono-Ru complex (bpy)(2)Ru(dpdpz) (5) and bis-Ru complex (bpy)(2)Ru(dpdpz)Ru(bpy)(2) (13). However, no emission was detected from complex 8 or 12 at room temperature in acetonitrile.
2,3-二(2-吡啶基)-5,6-二苯基吡嗪(dpdpz)与 K(2)PtCl(4)在乙腈和水的混合物中反应，以高产率得到单 Pt 配合物(dpdpz)PtCl(2)4，其中两个侧吡啶氮原子与金属中心结合。然后设计并制备了两种由 dpdpz 桥接的 Ru(II)-Pt(II)杂二金属配合物，即(bpy)(2)Ru(dpdpz)Pt(C≡CC(6)H(4)R)（7-9，R = H，NMe(2)或 Cl）和[(tpy)Ru(dpdpz)Pt(C≡CPh)] (+)（12），其中 bpy = 2,2'-联吡啶，tpy = 2,2';6',2''-三联吡啶。在这两种情况下，铂原子与 dpdpz 以 C(∧)N(∧)N 三齿配位模式结合。然而，钌原子与 dpdpz 的配位可以是非环金属化的（N(∧)N 二齿）或环金属化的（C(∧)N(∧)N 三齿）。随后通过光谱和电化学分析以及理论计算研究和比较了这些配合物的电子性质。由于来自钌和铂中心的混合 MLCT（金属到配体电荷转移）跃迁，这些配合物在可见到近红外（NIR）区域显示出显著的吸收。配合物 7 和 9 被发现发射近红外光，其量子产率高于单核 Ru 配合物(bpy)(2)Ru(dpdpz)（5）和双 Ru 配合物(bpy)(2)Ru(dpdpz)Ru(bpy)(2)（13）。然而，在室温下在乙腈中未检测到配合物 8 或 12 的发射。
