Induction Of Chirality In A Metal-Organic Framework Built From Achiral Precursors

Induction of chirality from an achiral assembly system remains a huge challenge related to the origin of life. Here, induction of chirality in a metal-organic framework (MOF) built from achiral precursors has been realized. Assembling achiral H3BTB ligands and Zn-II/Cd-II clusters leads to a 2D coordination polymer (FJI-H16), while introduction of achiral pyridine into such assembly system leads to a 3D chiral MOF (FJI-H27 (M) or (P)). The driven force for chiral generation has been proved to be a pyridine participated kinetic-control assembly process, which can be controlled by changing the amount of pyridine and temperature, from no induction to partial induction to complete induction. The chiral generation process has been identified in detail through a pyridine-involved key intermediate (FJI-H28). The targeted modification of pyridine can selectively lead to FJI-H27 (M) or FJI-H27 (P), making the chiral orientation and distribution of bulk FJI-H27 samples can be controlled. Our work not only represents a new chiral induction process that may relate to the chiral origin in nature, but also firstly reveals how achiral external stimuli generate chirality from achiral precursors, and offers a guide for rational preparation of chiral MOFs.