Coordination polymers (CPs) are made by the metal ions connecting the organic molecules at regular intervals in the polymer chain. CPs have high crystallinity, multi-dimensional structures, and are made by self-assembly. For last few decades, this active research area has become very much attractive to materials researchers due to the modular design, interesting properties and potential applications of CPs in catalysis, gas storage, ion exchange, separation, polymerization, magnetism, conductivity, optics, etc. Of these, controlling the reactivity of the CPs is a challenging task, but has potential applications in green synthesis of organic compounds with regio- and stereoselectivity. However, it is now possible to design a reactive solid and conduct a reaction in the solid-state with ease using crystal engineering principles. For the past few years, our research group is actively involved in designing reactive CPs that can undergo structural transformation by [2+2] cycloaddition reactions under UV light as well as sunlight in the solid-state. Here, we present some of the recent results obtained at our laboratory. In addition, the photosalient effect, where crystals leap when exposed to light, is considered a very rare phenomenon. Here, with a one-dimensional (1D) CP that undergoes [2+2] photocycloaddition, we present the evidence of photosalient effect where the crystals undergo popping like popcorn under exposed to UV light as well as sunlight.
[2+2] Cycloaddition, metal complexes, solid-state reactions, Stacking interactions, topochemistry