The chemistry and applications of flexible porous coordination polymers

Since the late 1990s, much progress has been made in the field of the chemistry of flexible porous coordination polymers (PCPs). Various PCP architectures have been recognized and several promising applications have been identified, e.g., in the areas of selective gas capture and separation, sensors, and drug carriers. The crystalline and flexible frameworks of PCPs can respond to various external stimuli and then adjust themselves to adapt to new environments in a tuneable fashion (R) behavior that is seldom observed in other porous solids. Over the past decade, following on from developments made in terms of flexible PCP performance, how to accurately build these architectures with the required functions has become a new challenge. In this review, the authors focus on the three aspects of flexible PCPs: 1) classifying the flexible systems with different fashions of pore opening, 2) classifying the flexible PCPs with governing factors of internal structure and external conditions, and 3) introducing, and summarizing, flexibility-and structure-dependent performance. The goal is to present the state-of-art chemistry and application of flexible PCPs and to offer an outlook towards discovering and designing further new materials.