Unsymmetric Ru(II) complexes with N-heterocyclic carbene and/or terpyridine ligands: synthesis, characterization, ground- and excited-state electronic structures and their application for DSSC sensitizers.
Unsymmetric Ru(II) complexes with N-heterocyclic carbene and/or terpyridine ligands: synthesis, characterization, ground- and excited-state electronic structures and their application for DSSC sensitizers.
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DOI：
10.1021/ic100325c
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发表时间：
2010-07
影响因子：
4.6
通讯作者：
Hee-Jun Park;Kyeong Ha Kim;S. Choi;Hyeong-Mook Kim;W. Lee;Youn K. Kang;Y. Chung
中科院分区：
文献类型：
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作者：
Hee-Jun Park;Kyeong Ha Kim;S. Choi;Hyeong-Mook Kim;W. Lee;Youn K. Kang;Y. Chung
三种Ru(II)与N-杂环卡宾或NHC/2，2‘：6’，2‘-三联吡啶杂化配体，bis[2，6-bis(3-methylimidazol-3-ium-1-yl)pyridine-4-carboxylic酸]Ru(II)(Bcn)，[2，6-bis(3-methylimidazolium-1-yl)pyridine-4-carboxylic酸](2，2’；合成了6‘2’-联吡啶Ru(II)和[2，6-bis(3-methylimidazol-3-ium-1-yl)pyridine](2，2‘；6’2‘’-terpyridine-4‘-carboxylic酸Ru(II)(CTN)，并用核磁共振氢谱、高分辨质谱和元素分析对其结构进行了表征。用X-射线结晶学测定了TCN络合物的分子几何构型。这些配合物的电子吸收光谱分别在紫外区和可见光区域呈现典型的pi-pi*和金属-配体电荷转移带。BCN、TCN和CTN的最低能量吸收峰分别为430、448和463 nm，摩尔消光系数分别为28、100、15、400和7400M(-1)cm(-1)。伏安数据表明，这三个络合物的最高占据分子轨道(HOMO)的能级位于10 meV窗口内，尽管组成配体的电子效应程度不同。用密度泛函理论(DFT)计算这些配合物的电子结构表明，前者的三个HOMO和最低的三个空位MoS(Lumos)分别是以金属和配体为中心的。含时密度泛函(TD-DFT)计算表明，每个络合物的最低能量吸收带由多个单电子激发组成。TD-DFT计算还表明，光谱红移的背景很可能源于未被占据的MO的稳定，而不是被占据的MO的失稳。这些络合物的染料敏化太阳能电池系统的总效率分别为0.48%、0.14%和0.10%，而商用bis(4，4‘-dicarboxylato-2，2’-bipyridine)-bis(isothiocyanoto)ruthenium(II)(N719)系统的效率为6.34%。
Three ruthenium(II) complexes with N-heterocyclic carbene (NHC) or NHC/2,2':6',2''-terpyridine (tpy) hybrid ligands, bis[2,6-bis(3-methylimidazol-3-ium-1-yl)pyridine-4-carboxylic acid]ruthenium(II) (BCN), [2,6-bis(3-methylimidazolium-1-yl)pyridine-4-carboxylic acid](2,2';6'2''-terpyridine)ruthenium(II) (TCN), and [2,6-bis(3-methylimidazol-3-ium-1-yl)pyridine](2,2';6'2''-terpyridine-4'-carboxylic acid)ruthenium(II) (CTN), have been synthesized and characterized by (1)H and (13)C NMR, high-resolution mass spectrometry, and elemental analysis. The molecular geometry of the TCN complex was determined by X-ray crystallography. Electronic absorption spectra of these complexes exhibit typical pi-pi* and metal-to-ligand charge transfer bands in the UV and visible regions, respectively. The lowest energy absorption maxima were 430, 448, and 463 nm with molar extinction coefficients of 28,100, 15,400, and 7400 M(-1)cm(-1) for BCN, TCN, and CTN, respectively. Voltammetric data suggest that energy levels of the highest occupied molecular orbitals (HOMOs) of the three complexes reside within a 10 meV window despite the varying degrees of electronic effect of the constituent ligands. The electronic structures of these complexes calculated via density functional theory (DFT) indicate that the three HOMOs and the three lowest unoccupied MOs (LUMOs) are metal and ligand centered in character, for the former and the latter, respectively. Time-dependent DFT (TD-DFT) calculation predicts that the lowest energy absorption bands of each complex are comprised of multiple one-electron excitations. TD-DFT calculation also suggests that the background of spectral red shift stems most likely from the stabilization of unoccupied MOs rather than the destabilization of occupied MOs. The overall efficiencies of the dye-sensitized solar cell systems of these complexes were found to be 0.48, 0.14, and 0.10% for BCN, TCN, and CTN, respectively, while that of a commercial bis(4,4'-dicarboxylato-2,2'-bipyridine)-bis(isothiocyanoto)ruthenium(II) (N719) system was 6.34%.