Stepwise Host–Guest [2 + 2] Photoreaction in a Hydrogen-Bonded One-Dimensional Coordination Polymer to a Two-Dimensional Layered Structure

Abstract

Two hydrogen-bonded interdigitated one-dimensional (1D) coordination polymers (CPs) were synthesized from Cd(II) nitrate and 1,4-benzenedicarboxylate (bdc) with two 4-styrylpyridine (4spy) derivatives. In the solid state structure of 1D CP containing 2′-fluorostyrylpyridine (2F-4spy), a guest 2F-4spy was sandwiched between the terminal 2F-4spy ligands and the C═C bonds of all the 2F-4spy are well-aligned in host–guest-host–host-guest–host- sequence infinitely. From time-dependent photoreaction studies, it has been found that the [2 + 2] photocycloaddition occurs between host–guest molecules first followed by host–host pairs in a two-step process, which resulted in the quantitative conversion of C═C bond pairs to cyclobutane rings. It is a rare quantitative photoreaction between the host and guest molecules. Further, solvothermal crystallization of the final photoproduct furnished an interesting three-dimensional CP with bcg topology. Interestingly, 2NO2-4spy also furnished a similar hydrogen-bonded 1D CP ...