A viologen derivative- and a carboxylic acid-based one-dimensional (1D) cocrystal Zn(II) coordination polymer, {[Zn(bcbpy)₂][Zn(sip)Cl]·4H₂O}_n (1, bcbpy = 1,1′-bis(3-carboxybenzyl)-4,4′-bipyridinium, sip = 5-sulfoisophthalate), has been produced solvothermally and structurally characterized. Complex 1 comprises two cationic chains (Chain-1) and one anionic chain (Chain-2) that cross each other and grow into a 3D supramolecular structure through hydrogen bonding interactions. Notably, under UV 365 nm irradiation, 1 showed a noteworthy photochromic transition between colorless and deep blue, which should be attributed to the generation of viologen radicals. Interestingly, it exhibited a two-step coloring phenomenon when heated, with the color changing to yellow and brown at 230 °C and 250 °C, respectively. Furthermore, 1 demonstrated selective gas-chromic behavior toward ethylamine (EA), and it is recoverable by washing with MeCN. Furthermore, 1 can be deposited on filter paper and demonstrates a potential application as an inkless print material. Interestingly, when complex 1 is removed from liquid nitrogen, as the temperature rises from 80 to 290 K, it exhibits a yellow green afterglow. In addition, the production of polyvinyl alcohol (PVA) film, 1-PVA, has made the photochromism of 1 practical in ink-free printing, UV detection, and information anti-counterfeiting, and it is confirmed that the photochromic properties of viologen complex can be improved in PVA medium.

中文翻译：

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在紫精基配位聚合物中加入一维富电子链，以实现超光致变色性能并改善聚乙烯醇薄膜的光学应用

紫精衍生物和羧酸基一维（1D）共晶Zn( II )配位聚合物，{[Zn(bcbpy) ₂ ][Zn(sip)Cl]·4H ₂ O} _n ( 1 , bcbpy = 1,1'-双(3-羧基苄基)-4,4'-联吡啶鎓，sip = 5-磺基间苯二甲酸酯)已通过溶剂热法生产并进行了结构表征。配合物1包含两条阳离子链（Chain-1）和一条阴离子链（Chain-2），它们相互交叉并通过氢键相互作用生长成3D超分子结构。值得注意的是，在 UV 365 nm 照射下，1显示出无色和深蓝色之间值得注意的光致变色转变，这应归因于紫精自由基的产生。有趣的是，它在加热时表现出两步着色现象，分别在230℃和250℃时颜色变为黄色和棕色。此外，1对乙胺 (EA) 表现出选择性气致变色行为，并且可以通过用 MeCN 洗涤来回收。此外，1可以沉积在滤纸上，并展示出作为无墨印刷材料的潜在应用。有趣的是，当配合物1从液氮中取出时，随着温度从80升至290 K，它呈现出黄绿色余辉。此外，聚乙烯醇（PVA）薄膜1-PVA的生产，使1的光致变色在无墨印刷、紫外检测、信息防伪等方面得到实用化，并证实紫精络合物的光致变色性能在 PVA 介质中可以得到改善。