Photoreactive coordination polymers are important platforms for the implementation of tailored solid-state photochemical reactions. These crystalline compounds can also be employed as photo-controlled intelligent materials for the design and manufacture of advanced devices. Herein, a comb-like photoreactive coordination polymer, formulated as {[Zn(5-Cl-1,3-bdc)(H₂O)(2,3-ppe)]·H₂O}_n (1), was prepared based on the hydrothermal reaction between Zn(NO₃)₂·6H₂O, 5-chlorobenzene-1,3-dicarboxylic acid (5-Cl-1,3-H₂BDC) and 1-(2-pyridyl)-2-(3-pyridyl)-ethylene (2,3-ppe). Upon irradiation with sunlight, the ¹H NMR spectroscopy, UV-vis absorption spectroscopy and single crystal X-ray diffraction analyses results indicated that 1 can undergo a [2 + 2] photocycloaddition reaction and thus generate a unique ladder-like coordination chain {[Zn(5-Cl-1,3-bdc)(H₂O)(2,3-bpbpcb)_0.5]·H₂O}_n (1a, 2,3-bpbpcb = 1,3-bis(2-pyridyl)-2,4-bis(3-pyridyl)cyclobutane) via single-crystal to single-crystal (SCSC) transformation. Upon irradiation of UV light with a wavelength of 254 nm, the newly formed coordination chain 1a can undergo a reversible cycloreversion reaction and return to 1. The reversible photo-controllable cycloaddition–cycloreversion reaction between 1 and 1a also exhibits an interesting behavior of photo-switchable fluorescence. The reversible structural transformation and fluorescence switching behavior of 1 make it a potential photo-controlled intelligent material for optical information storage, optical anti-counterfeiting, fluorescence sensors and other fields.

中文翻译：

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配位梳和分子量标准之间的可逆单晶到单晶光反应显示可光切换荧光


光反应性配位聚合物是实施定制固态光化学反应的重要平台。这些结晶化合物还可以用作光控智能材料，用于设计和制造先进器件。本文为梳状光反应配位聚合物，配制成 {[Zn（5-Cl-1,3-bdc）（H₂O）（2,3-ppe）]·H₂O}_n （1），基于 Zn（NO₃）₂·6H₂O，5-氯苯-1,3-二羧酸 （5-Cl-1,3-H₂BDC） 和 1-（2-吡啶基）-2-（3-吡啶基）-乙烯 （2,3-ppe） 之间的水热反应制备。在阳光照射下，¹H NMR光谱、紫外-可见吸收光谱和单晶X射线衍射分析结果表明，1可以发生[2 + 2]光环加成反应，从而产生独特的梯形配位链{[Zn（5-Cl-1,3-bdc）（H₂O）（2,3-bpbpcb）_0.5]·H₂O}_n （1a， 2,3-bpbpcb = 1,3-双（2-吡啶基）-2,4-双（3-吡啶基）环丁烷）通过单晶到单晶 （SCSC） 转化。在波长为 254 nm 的紫外光照射下，新形成的配位链 1a 可以发生可逆的环反转反应并返回 1。1 和 1a 之间的可逆光控环加成-环反转反应也表现出光开关荧光的有趣行为。 1 的可逆结构转变和荧光开关行为使其成为光学信息存储、光学防伪、荧光传感器等领域的潜在光控智能材料。