A {Ni12}-Wheel-Based Metal-Organic Framework for Coordinative Binding of Sulphur Dioxide and Nitrogen Dioxide

Air pollution by SO2 and NO2 has caused significant risks on the environment and human health. Understanding the mechanism of active sites within capture materials is of fundamental importance to the development of new clean-up technologies. Here we report the crystallographic observation of reversible coordinative binding of SO2 and NO2 on open Ni-II sites in a metal-organic framework (NKU-100) incorporating unprecedented {Ni-12}-wheels; each wheel exhibits six open Ni-II sites on desolvation. Immobilised gas molecules are further stabilised by cooperative host-guest interactions comprised of hydrogen bonds, pi...pi interactions and dipole interactions. At 298 K and 1.0 bar, NKU-100 shows adsorption uptakes of 6.21 and 5.80 mmol g(-1) for SO2 and NO2, respectively. Dynamic breakthrough experiments have confirmed the selective retention of SO2 and NO2 at low concentrations under dry conditions. This work will inspire the future design of efficient sorbents for the capture of SO2 and NO2.