Terpyridine platinum(ii) complexes containing triazine di- or tri-thiolate bridges: structures, luminescence, electrochemistry, and aggregation
作者:Hua-Xin Zhang、Masako Kato、Yoichi Sasaki、Tadashi Ohba、Hiroto Ito、Atsushi Kobayashi、Ho-Chol Chang、Kohei Uosaki
DOI:10.1039/c2dt30997a
日期:——
Dinuclear complexes [Pt(trpy)}2(L)](PF6)2 (trpy = 2,2′:6′,2′′-terpyridine, L = 2-octylthio-1,3,5-triazine-4,6-dithiolate ion (1), L = 2-octadecylthio-1,3,5-triazine-4,6-dithiolate ion (2), L = 2-di-n-butylamino-1,3,5-triazine-4,6-dithiolate ion (3)) and a trinuclear complex [Pt(trpy)}3(L)](PF6)3 (L = 1,3,5-triazine-2,4,6-trithiolate ion (4)) have been synthesized and characterized. The single crystal X-ray analysis revealed that the two Pt(trpy)}2+ fragments in 1 and 3 adopt a syn-configuration. The Pt⋯Pt distances are around 4.3 Å, suggesting no intramolecular Pt⋯Pt interactions. Complexes 1–4 in acetonitrile show broad absorption bands at around 470 nm, assigned to mainly the ligand-to-ligand charge transfer (1LLCT) from triazine thiolates to trpy based on the comparison to the related complexes and the density functional theory (DFT) calculations. The red luminescence of 1–4 in acetonitrile is attributable to emission predominantly from 3LLCT. Cyclic voltammograms of 1–3 exhibit four redox couples from −2.0 V to 0 V vs. Ag/AgCl. The two consecutive processes at around −0.70 V are assigned to the sequential reduction of two trpy ligands. This assignment was further supported by the observation of the anion radical of trpy in spectroelectrochemical experiments. The splitting of the redox potentials of two trpy ligands evidences the moderate electronic coupling interactions mediated by the triazine dithiolate bridges. Complex 2 formed a transparent red gel in CH3CN, whereas 4 produced a gel-like solid in the mixtures of CH3CN and other solvents. The interactions dominating the aggregative behaviours have been discussed based on the results of electronic absorption and emission spectroscopy.
合成并表征了双核配合物 [Pt(trpy)}2(L)](PF6)2(trpy = 2,2′:6′,2′′-三吡啶,L = 2-辛基硫-1,3,5-三嗪-4,6-二硫醋酸根离子 (1),L = 2-十八烷基硫-1,3,5-三嗪-4,6-二硫醋酸根离子 (2),L = 2-二正丁基氨基-1,3,5-三嗪-4,6-二硫醋酸根离子 (3))和三核配合物 [Pt(trpy)}3(L)](PF6)3(L = 1,3,5-三嗪-2,4,6-三硫醋酸根离子 (4)。单晶X射线分析显示,配合物1和3中的两个 Pt(trpy)}2+片段呈现出syn构型。Pt⋯Pt距离约为4.3 Å,表明不存在分子内的Pt⋯Pt相互作用。配合物1-4在乙腈中呈现出约470 nm的宽吸收带,主要归因于三嗪二硫醋酸根到trpy之间的配体间电荷转移(1LLCT),这基于与相关配合物及密度泛函理论(DFT)计算的比较。配合物1-4在乙腈中的红光发射主要源于3LLCT。配合物1-3的循环伏安图显示,从−2.0 V到0 V与Ag/AgCl比较,存在四对氧化还原对。在约−0.70 V处的两个连续过程被归因于两个trpy配体的顺序还原。这一归因在光谱电化学实验中通过观察trpy的阴离子自由基进一步得到了支持。两个trpy配体的氧化还原电势的分裂证明了由三嗪二硫醋酸盐桥介导的适度电子耦合相互作用。配合物2在CH3CN中形成透明红色凝胶,而4则在CH3CN与其他溶剂的混合物中产生类似凝胶的固体。根据电子吸收和发射光谱的结果,讨论了主导聚集行为的相互作用。