Series of Microporous Redox-Active Pillared Metal-Organic Frameworks Based On Alloxazine Ligands

Two series of robust pillared metal-organic frameworks (MOFs) are obtained under solvothermal conditions by combining a metal salt with either H₂bpdc, biphenyl-4,4'-dicarboxylic acid, or H₂pda, 1,4-phenylenediacrylic acid, forming 2D layers, which are pillared by L, an alloxazine derivative of 1,4-di(pyridin-4-yl)benzene using a one-pot three-component strategy. Crystallographic studies reveal the formation of two isomorphous series of compounds, namely 1-M (from H₂bpdc with M = Co, Ni, Cu, and Zn) and 2-M (from H₂pda with M = Co or Cu). The multifunctional compounds have high decomposition temperatures, and their sorption properties were measured, revealing relatively low surface areas. Furthermore, 1-Zn displays a moderate uptake of CO₂ and C₂H₄ at high pressures. In addition, for 1-M (M = Co, Cu or Zn), solid-state electrochemistry reveals redox behavior for the MOF, centered on the ligand. This study provides evidence for the first account of a one-pot formation of redox-active pillared MOFs, which exhibit gas sorption abilities before the reduction.