Template-assisted [6+6] cycloaddition for the construction of photothermally responsive functional materials.

High-order cycloaddition offers a direct and powerful strategy for constructing medium-sized architectures, but it is often limited by low yields and poor stereoselectivity. Here, we report a template- assisted [6+6] photodimerization reaction, which is achieved via the self-assembly of a two-dimensional (2D) coordination polymer (CP) CP1. The coordination template precisely organizes the reactants. Under irradiation with visible light or natural sunlight, the [6+6] photodimerization proceeds in an environmentally friendly and selective manner. To demonstrate the universality and functionality of this strategy, we introduce methoxy-functionalized ligands to construct CP2, which not only undergoes the same [6+6] cycloaddition reactions but also exhibits temperature-responsive properties. The combination of CP1 and CP2 with Poly(vinyl alcohol) (PVA) and MXene (2D transition-metal carbides) further enhances their actuation properties, making them suitable for adaptive materials. This work establishes a milestone in template-assisted cycloaddition reactions, offering an approach to achieving higher-order cycloadditions and expanding the development of crystal adaptronics.