Research on single-crystal-to-single-crystal photoaddition and extension of Schmidt's rule in topological chemistry

In this article, we report the synthesis of a MOF containing multiple C.C bonds geometrical features by adjusting the reactant ratio of the synthetic system. The photochemical addition studies revealed that the ligand 1,4-bis[2-(4-pyridyl) ethenyl]benzene can undergo photoisomerization under UV irradiation, and the. angle between the C.C bonds can be changed by about 85 degrees, so that the C.C pairs that do not conform to Schmidt's rule can be transformed into the conforming state, and then the 2 + 2 photoaddition can occur. We found that the. angle range suitable for photoaddition includes not only the 0-15 degrees range, but also the potential 85 +/- 15 degrees range. Furthermore, it is not the C.C pair that best conforms to Schmidt's rule that gives priority to the photoaddition, but the one that enables the lowest total energy in the crystal to occur.

Automated summary

In this article, the synthesis of a MOF with multiple C.C bond geometrical features was achieved by adjusting the reactant ratio. Photochemical studies showed that the ligand 1,4-bis[2-(4-pyridyl) ethenyl]benzene undergoes photoisomerization under UV irradiation, resulting in a change of about 85 degrees in the angle between the C.C bonds. This allows the transformation of non-conforming C.C pairs into conforming pairs, enabling 2 + 2 photoaddition. Interestingly, the most favorable C.C pair for photoaddition is not necessarily the one that best conforms to Schmidt's rule, but the one that leads to the lowest total energy in the crystal.