Department of Material and Life Science, Graduate School of Engineering, Osaka University and SORST (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
Chemistry. 2010 Mar 22;16(12):3646-55. doi: 10.1002/chem.200902939.
Novel conglomerates consisting of saddle-distorted Sn(IV)(DPP) (H(2)DPP = dodecaphenylporphyrin) complexes and mu(3)-O-centered and carboxylato-bridged trinuclear Ru(III) clusters linked by pyridine carboxylates were synthesized and characterized. Sn(IV)-DPP complexes with Cl(-), OH(-), and 3- and 4-pyridine carboxylates ligands were characterized by spectroscopic methods and X-ray crystallography. Reactions of [Sn(DPP)(pyridinecarboxylato)(2)] with trinuclear Ru(III) clusters gave novel conglomerates in moderate yields. The conglomerates are stable in solution as demonstrated by (1)H NMR and electrospray ionization mass spectrometry (ESI-MS) measurements, which show consistent spectra with those expected from their structures, and also by electrochemical measurements, which exhibit reversible multistep redox processes. This stability stems from the saddle distortion of the DPP(2-) ligand to enhance the Lewis acidity of the Sn(IV) center that strengthens the axial coordination of the linker. The fast intramolecular photoinduced electron transfer from the Sn(IV)(DPP) unit to trinuclear Ru(III) clusters, affording the electron-transfer (ET) state {Sn(DPP(*+))-Ru(II)Ru(III)(2)}, was observed by femtosecond laser flash photolysis. The lifetimes of ET states of the conglomerates were determined to be in the range 98-446 ps, depending on the clusters and energies of the ET states. The reorganization energy of the electron transfer was determined to be 0.58+/-0.08 eV in light of the Marcus theory of electron transfer. The rate constants of both the photoinduced electron transfer and the back electron transfer in the conglomerates fall in the Marcus inverted region due to the small reorganization energy of electron transfer.
合成并表征了由 saddle-distorted Sn(IV)(DPP)（H(2)DPP = 十二苯基卟啉）配合物和通过吡啶羧酸酯连接的 mu(3)-O 中心和羧酸桥联的三核 Ru(III)簇组成的新型聚集体。用光谱方法和 X 射线晶体学对具有 Cl(-)、OH(-)和 3-和 4-吡啶羧酸配体的 Sn(IV)-DPP 配合物进行了表征。[Sn(DPP)(吡啶羧酸酯)(2)]与三核 Ru(III)簇的反应以中等产率得到了新型聚集体。聚集体在溶液中稳定，这一点通过（1）H NMR 和电喷雾电离质谱（ESI-MS）测量得到了证明，这些测量结果与它们的结构预期的谱图一致，也通过电化学测量得到了证明，这些测量结果显示出可逆的多步氧化还原过程。这种稳定性源于 DPP(2-)配体的 saddle 扭曲，以增强 Sn(IV)中心的路易斯酸度，从而加强了连接体的轴向配位。从 Sn(IV)(DPP)单元到三核 Ru(III)簇的快速分子内光致电子转移，提供了电子转移（ET）态 {Sn(DPP(*+))-Ru(II)Ru(III)(2)}，这是通过飞秒激光闪光光解观察到的。聚集体的 ET 态的寿命范围为 98-446 ps，取决于簇和 ET 态的能量。根据 Marcus 电子转移理论，电子转移的重组能被确定为 0.58+/-0.08 eV。由于电子转移的重组能较小，聚集体中的光致电子转移和反向电子转移的速率常数都落入 Marcus 反转区域。
