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首页> 外文期刊>Chemistry: A European journal >Complete photochromic structural changes in ruthenium(II)-diimine complexes, based on control of the excited states by metalation
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Complete photochromic structural changes in ruthenium(II)-diimine complexes, based on control of the excited states by metalation

机译：钌（II）-二亚胺络合物的完全光致变色结构变化，基于通过金属化控制激发态

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摘要

The thermal and photochemical reactions of a newly synthesized complex, [Ru~(II)(TPA)(tpphz)]~(2+) (1; TPA=tris(2-pyridylmethyl)amine, tpphz=tetrapyrido[3,2-a:2,3-c:3′,2′-h: 2′,3′-j] phenazine), and its derivatives have been investigated. Heating a solution of complex 1 (closed form) and its derivatives in MeCN caused the partial dissociation of one pyridylmethyl moiety of the TPA ligand and the resulting vacant site on the Ru~(II) center was occupied by a molecule of MeCN from the solvent to give a dissociated complex, [Ru~(II)(η ~3-TPA)(tpphz)(MeCN)]~(2+) (1, open form), and its derivatives, respectively, in quantitative yields. The thermal dissociation reactions were investigated on the basis of kinetics analysis, which indicated that the reactions proceeded through a seven-coordinate transition state. Although the backwards reaction was induced by photoirradiation of the MLCT absorption bands, the photoreaction of complex 1 reached a photostationary state between complexes 1 and 1 and, hence, the recovery of complex 1 from complex 1 was 67 %. Upon protonation of complex 1 at the vacant site of the tpphz ligand, the efficiency of the photoinduced recovery of complex 1+H~+ from complex 1+H~+ improved to 83 %. In contrast, dinuclear μ-tpphz complexes 2 and 3, which contained the Ru~(II)(TPA)(tpphz) unit and either a Ru~(II)(bpy)_2 or Pd~(II)Cl_2 moiety on the other coordination edge of the tpphz ligand, exhibited 100 % photoconversion from their open forms into their closed forms (2→2 and 3→3). These results are the first examples of the complete photochromic structural change of a transition-metal complex, as represented by complete interconversion between its open and closed forms. Scrutinization by performing optical and electrochemical measurements allowed us to propose a rationale for how metal coordination at the vacant site of the tpphz ligand improves the efficiency of photoconversion from the open form into the closed form. It is essential to lower the energy level of the triplet metal-to-ligand charge-transfer excited state (~3MLCT) of the closed form relative to that of the triplet metal-centered excited state (~3MC) by metal coordination. This energy-level manipulation hinders the transition from the ~3MLCT* state into the ~3MC* state in the closed form to block the partial photodissociation of the TPA ligand. Ru being served? Photochromic structural changes of Ru~(II)/TPA (TPA=tris(2- pyridylmethyl)amine) complexes that contain a diimine ligand are reported. Further metal coordination to the diimine ligand allows interconversion between its open/closed forms (see scheme).
机译：新合成的配合物[Ru〜（II）（TPA）（tpphz）]〜（2+）（1; TPA = tris（2-吡啶基甲基）胺，tpphz = tetrapyrido [3,2- a：2,3-c：3'，2'-h：2'，3'-j]吩嗪）及其衍生物已得到研究。加热络合物1（封闭形式）及其衍生物在MeCN中的溶液导致TPA配体的一个吡啶甲基甲基部分部分解离，Ru〜（II）中心上的空位被溶剂中的MeCN分子占据分别以定量收率得到解离的配合物[Ru〜（II）（η〜3-TPA）（tpphz）（MeCN）]〜（2+）（1，开放式）及其衍生物。在动力学分析的基础上对热解离反应进行了研究，结果表明该反应经历了七坐标过渡态。尽管通过MLCT吸收带的光辐照引起向后反应，但是配合物1的光反应在配合物1和1之间达到光平稳状态，因此，从配合物1回收配合物1为67％。在tpphz配体的空位上使复合物1质子化后，从复合物1 + H〜+中光诱导回收复合物1 + H〜+的效率提高到83％。相反，双核μ-tpphz配合物2和3包含Ru〜（II）（TPA）（tpphz）单元，而Ru〜（II）（bpy）_2或Pd〜（II）Cl_2部分tpphz配体的配位边缘表现出100％的光转化，从开放形式变为封闭形式（2→2和3→3）。这些结果是过渡金属配合物完全光致变色结构变化的第一个例子，以其开放和闭合形式之间的完全相互转化为代表。通过进行光学和电化学测量的详细审查使我们能够提出一个原理，以说明tpphz配体的空位处的金属配位如何提高从开放形式到封闭形式的光转化效率。通过金属配位，相对于三重金属中心激发态（〜3MC），必须降低封闭形式的三重态金属-配体电荷转移激发态（〜3MLCT）的能级。这种能级操纵阻碍了从〜3MLCT *状态到封闭形式〜3MC *状态的转变，从而阻止了TPA配体的部分光解离。茹被送达了吗？报道了含有二亚胺配体的Ru〜（II）/ TPA（TPA =三（2-吡啶基甲基）胺）配合物的光致变色结构变化。与二亚胺配体的进一步金属配位允许其开放/封闭形式之间的相互转化（参见方案）。

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