A chiral porous cobalt–organic framework based on reinforced sinusoidal-like SBUs involving in situ-generated formate

Abstract

The assembly of Co(NO₃)₂·6H₂O and achiral isonicotinic acid (HIN) under solvo(hydro)thermal conditions yields a three-dimensional chiral Co-based MOF, {[Co₆(μ₃-OH)₂(IN)₄(HCOO)₆]·4DMF·5H₂O}_n (1). Polymer 1 consists of a reinforced sinusoidal-like hydroxyl–formate–carboxylate mixed-bridged chain as a rod-shaped secondary building unit (SBU), which is constructed from two types of asymmetric triangular Co₃ clusters. This compound also has open irregular channels in the framework and presents a severely distorted pcu net based on two different Co₃ clusters of SBUs as six connected nodes. The presence of a few drops of water in the DMF reaction solution is important in in situ HCOO⁻ generation, which is beneficial for the formation of 1. Compound 1 is further characterized by IR, EA, PXRD, TGA-DSC, N₂ adsorption, and magnetic measurement.