Department of Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg (Sweden).
Chemphyschem. 2014 Apr 14;15(6):1154-63. doi: 10.1002/cphc.201301193. Epub 2014 Mar 19.
Two series of Ru(II) polypyridyl compounds with formulas (bpy)2RuL2 and (deeb)2RuL2, where bpy is 2,2'-bipyridine, deeb is 4,4'-diethylester-2,2'-bpy, and L is one of several substituted 9'-(1,3-dithiole-2-ylidene)-4',5'-diazafluorene ligands, were studied as potential photosensitizers for TiO2. These compounds possess notably high extinction coefficients (≥40,000 M(-1) cm(-1) @470 nm) which are shown by time-dependent density functional theory (TD-DFT) calculations to result from overlapping metal-to-ligand charge transfer (MLCT) and ligand-localized transitions. Low-temperature absorption and photoluminescence measurements were suggestive of a short-lived MLCT excited state. When adsorbed onto TiO2 thin films, both the free ligands (L) and their corresponding (deeb)2RuL complexes exhibited rapid excited-state electron injection into TiO2; in the case of the complexes, this was followed by rapid (k>10(8) s(-1)) hole transfer from Ru(III) to the 1,3-dithiole ring of the L ligand. Observation of diffusion-limited reductive quenching of the Ru(bpz)3* (bpz is 2,2'-bipyrazine) excited state by the L ligands in solution supported the occurrence of intramolecular hole transfer following electron injection by the TiO2-anchored complexes.
研究了两种钌（II）多吡啶配合物系列，其化学式为(bpy)2RuL2 和 (deeb)2RuL2，其中 bpy 是 2,2'-联吡啶，deeb 是 4,4'-二乙酯-2,2'-联吡啶，L 是几种取代的 9'-(1,3-二硫杂环戊烯-2-亚基)-4',5'-二氮杂芴配体之一，它们被用作 TiO2 的潜在光催化剂。这些化合物具有显著高的消光系数（≥40,000 M(-1) cm(-1) @470nm），这通过时间依赖密度泛函理论（TD-DFT）计算表明是由重叠的金属到配体电荷转移（MLCT）和配体局域化跃迁引起的。低温吸收和光致发光测量表明存在短寿命的 MLCT 激发态。当吸附在 TiO2 薄膜上时，游离配体（L）及其相应的(deeb)2RuL配合物都表现出快速将激发态电子注入 TiO2；在配合物的情况下，随后发生从 Ru(III)到 L 配体的 1,3-二硫杂环戊烯环的快速（k>10(8) s(-1)）空穴转移。在溶液中观察到 Ru(bpz)3*（bpz 是 2,2'-联吡嗪）激发态被 L 配体扩散限制还原猝灭，这支持了 TiO2 锚定的配合物注入电子后发生分子内空穴转移。
