Single-crystal-to-single-crystal (SCSC) structural transformation induced by light, heat and guest removal have received considerable interest in recent years, particularly, light-triggered SCSC transformations, which are displayed in several coordination polymers. Photochemical solid-state [2+2] cycloaddition reaction is the most studied reaction in solid-state chemistry and crystal engineering. Although the criteria for photochemical solid-state [2+2] cycloaddition reactions have been well established, it is still a challenge to stack a pair of C=C bonds in the crystal lattice by design. A pair of olefin groups brought closely in parallel in various organic crystals, coordination polymers (CPs) and MOFs. Many CPs have been shown exotic photoreactivity properties via SCSC transformation. However, molecular-ladder CPs have attracted chemists’ much attention due to their unique optical, electronic and magnetic properties. Although one-dimensional ladder CPs topology is uncommon, ladder CPs are considered some of the best-known assemblies to orient olefinic C=C double bonds in infinite pairs for photochemical [2+2] cycloaddition reaction via SCSC manner. The photoreactivity of three parallel aligned C=C bonds in ladder or triple ladder CPs were rarely studied. In this talk, we will discuss how to design photoreactive hydrogen-bonded triple-ladder CP which displays photoreactivity via SCSC transformation and such SCSC transformation is observed for the first time in our triple-stranded ladder. Further, we will present our strategies to achieve 100 % photoreactivity via grinding. The quantitative photoreaction can only be explained due to the mechanically-induced large molecular movement of ladders in the crystal lattice, further photoirradiation formed cyclobutane products in up to 100% yield.

Photodimerization reaction of triple-stranded ladder coordination polymer via single-crystal-to-single-crystal transformation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.