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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Ruthenium(II) dichloro or dithiocyanato complexes with 4,4′:2′, 2″:4″,4?-quaterpyridinium ligands: Towards photosensitisers with enhanced low-energy absorption properties
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Ruthenium(II) dichloro or dithiocyanato complexes with 4,4′:2′, 2″:4″,4?-quaterpyridinium ligands: Towards photosensitisers with enhanced low-energy absorption properties

机译：具有4,4'：2'，2″：4″，4′-四吡啶鎓配体的二氯或二硫氰酸钌（II）配合物：朝着具有增强的低能量吸收特性的光敏剂的方向发展

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摘要

Fourteen new complexes of the form cis-[Ru~(II)X_2(R _2qpy~(2+))_2]~(4+) (R_2qpy ~(2+) = a 4,4′:2′,2″:4″,4?- quaterpyridinium ligand, X = Cl- or NCS-) have been prepared and isolated as their PF_6 ~- salts. Characterisation involved various techniques including 1H NMR spectroscopy and +electrospray or MALDI mass spectrometry. The UV-Vis spectra display intense intraligand π → π* absorptions, and also metal-to-ligand charge-transfer (MLCT) bands with two resolved maxima in the visible region. Red-shifts in the MLCT bands occur as the electron-withdrawing strength of the pyridinium groups increases, while replacing Cl- with NCS- causes blue-shifts. Cyclic voltammograms show quasi-reversible or reversible RuIII/II oxidation waves, and several ligand-based reductions that are irreversible. The variations in the redox potentials correlate with changes in the MLCT energies. A single-crystal X-ray structure has been obtained for a protonated form of a proligand salt, [(4-(CO _2H)Ph)_2qpyH~(3+)][HSO_4] _3·3H_2O. Time-dependent density functional theory calculations give adequate correlations with the experimental UV-Vis spectra for the two carboxylic acid-functionalised complexes in DMSO. Despite their attractive electronic absorption spectra, these dyes are relatively inefficient photosensitisers on electrodes coated with TiO_2 or ZnO. These observations are attributed primarily to weak electronic coupling with the surfaces, since the DFT-derived LUMOs include no electron density near the carboxylic acid anchors.
机译：十四种新的顺式[Ru〜（II）X_2（R _2qpy〜（2 +））_ 2]〜（4+）（R_2qpy〜（2+）= a 4,4'：2'，2''制备并分离出了：4″，4′-季吡啶鎓配体，X ＝ Cl-或NCS-），并分离为它们的PF 6-6-盐。表征涉及多种技术，包括1H NMR光谱和+电喷雾或MALDI质谱。 UV-Vis光谱显示强烈的配体内π→π*吸收，以及金属到配体的电荷转移（MLCT）带，在可见光区域具有两个分辨的最大值。 MLCT谱带中的红移随着吡啶鎓基团的吸电子强度的增加而发生，而用NCS-取代Cl-则引起蓝移。循环伏安图显示准可逆或可逆RuIII / II氧化波，以及几种不可逆的基于配体的还原。氧化还原电势的变化与MLCT能量的变化相关。已获得配体配体盐[（4-（CO _2H）Ph）_2qpyH〜（3 +）] [HSO_4] _3·3H_2O的质子化形式的单晶X射线结构。随时间变化的密度泛函理论计算为DMSO中两种羧酸官能化的配合物的实验UV-Vis光谱提供了足够的相关性。尽管它们具有吸引人的电子吸收光谱，但这些染料在涂有TiO_2或ZnO的电极上是效率相对较低的光敏剂。这些观察结果主要归因于与表面的弱电子耦合，因为DFT衍生的LUMO在羧酸锚附近不包含电子密度。

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