Copper-based metal-organic framework for the facile ring-opening of epoxides

A simplified, facile route was applied for the synthesis of Cu(bpy)(H2O)2(BF4)2(bpy) [Cu-MOF] from Cu(BF4)2⋅H2O and 4,4′-bipyridine in aqueous ethanol. The Cu-MOF catalyst was characterized by XRD, elemental analysis, N2 adsorption, SEM, TEM, and electron diffraction. The crystalline Cu-MOF is an efficient catalyst in the ring-opening reactions of epoxides with alcohols and aniline under ambient, solvent-free conditions. The catalytic activity of Cu-MOF was comparable to that of the homogeneous catalyst Cu(BF4)2⋅H2O in the case of methanolysis, but the relative activity dropped significantly with increasing steric bulkiness of the alcohol, indicating the location of active sites in micropores. Although the catalyst was found to be truly heterogeneous and recyclable with no loss of activity, XRD revealed some restructuring due to interaction with methanol. This restructuring is attributed to the partial replacement of the structural water molecules by methanol, leading to significant changes in the H-bonding system of Cu-MOF.