基于羧苄基紫精配体构筑的三种多重响应配合物

以羧苄基紫精配体1，1''-双（4-羧苄基）-4，4''-联吡啶二氯化物（（H₂Bpybc） Cl₂）为功能主体，引入辅助配体1，3，5-苯三甲酸（H₃BTC），与不同金属离子自组装反应，合成了3个配合物{[Cd （Bpybc）_0.5（HBTC）（H₂O）]·0.6H₂O}_n （1）、[Ni （Bpybc）_0.5（HBTC）（H₂O）₄]（2）和[Co （Bpybc）_0.5（HBTC）（H₂O）₄]（3）。其中，配合物1为2D结构，而配合物2和3为0D结构。同时，3种配合物表现出不同的变色性能。配合物1是由于产生紫精自由基而具有光致变色行为，而配合物2和3的光致变色行为是光诱导形成紫精自由基及金属离子的氧化反应共同导致的。此外，配合物2还表现出由电子转移而导致的热致变色行为，而配合物3表现出脱水和吸水引起的可逆结构改变而导致的颜色变化。这些结果表明，金属离子对紫精配合物的结构及变色性能具有明显的调控作用。

Three Multiple-Responsive Complexes Based on a Carboxybenzyl Viologen Ligand

A carboxybenzyl viologen ligand 1,1''-bis(4-carboxybenzyl)-4,4''-bipyridinium dichloride ((H₂Bpybc)Cl₂) was used as the functional ligand, and the auxiliary ligand 1,3,5-benzene tricarboxylic acid (H₃BTC) was introduced to self-assemble with different metal ions to synthesize three complexes:{[Cd(Bpybc)_0.5(HBTC)(H₂O)]·0.6H₂O}_n (1), [Ni(Bpybc)_0.5(HBTC)(H₂O)₄] (2), and [Co(Bpybc)_0.5(HBTC)(H₂O)₄] (3). The three complexes display different structural features, including a 2D structure of 1 and 0D structures of 2 and 3. Furthermore, these three complexes displayed different chromic properties. Complex 1 was photochromic only due to the generation of viologen radicals, while complexes 2 and 3 were photochromic originating from the photo-induced formation of viologen radicals accompanying the redox activity of metal ions. In addition, complex 2 showed thermochromic behavior, which is associated with the radical formation through electron transfer, while complex 3 exhibited a color change accompanying a reversible structural transformation due to dehydration and rehydration. These results suggest that metal ions play a significant role in regulating the structure and chromic behavior of viologen complexes.