Recent advance in porous coordination polymers from the viewpoint of crystalline-state transformation

Recently, research of crystalline-state transformation involving the removal/inclusion of guest molecules in porous coordination polymers (PCPs) was underway. Crystalline-state transformation, especially, single-crystal to single-crystal (SC-SC) transformation as new method for the direct observation of host-guest chemistry, can reveal the intrinsic relevance and interaction between the framework and guest molecules. This review describes our work concerning PCPs and recent investigations of others, within the last four years, from the viewpoint of crystalline-state transformations of PCPs on guest removal or inclusion processes. Ligand substitution reaction and postsynthetic modification of PCPs in SC-SC fashion which were distinguished from conventional crystalline-state transformation triggered by guest removal or exchange were highlighted in this review. The research status of crystalline-state transformation in China was briefly introduced as well. Series of structure analysis techniques including single-crystal X-ray diffraction, powder X-ray diffraction, neutron diffraction, inelastic neutron scattering as well as the application of synchrotron radiation light source will inevitably promote the advance of study of crystalline-state transformation. And as a hotspot, deep investigations of crystalline-state transformation also help us to overcome the challenge of achieving multifunction and the correlation among them, such as sorption, magnetism, optical or electrical properties simultaneously in PCPs and contribute to design stimulate-oriented porous intelligent materials in the future.