Evidence of CO2 molecule acting as an electron acceptor on a nanoporous metal–organic-framework MIL-53 or Cr3+(OH)(O2C–C6H4–CO2)

Abstract

The adsorption mode of CO₂ at low coverage in the nanoporous metal benzenedicarboxylate MIL-53(Cr) or Cr³⁺(OH)(O₂C–C₆H₄–CO₂) has been identified using IR spectroscopy; the red shift of the ν₃ band and the splitting of the ν₂ mode of CO₂ in addition to the shifts of the ν(OH) and δ(OH) bands of the MIL-53(Cr) hydroxyl groups provide evidence that CO₂ interacts with the oxygen atoms of framework OH groups as an electron-acceptor via its carbon atom; this is the first example of such an interaction between CO₂ and bridged OH groups in a solid.