Three-dimensional amino acid backbone Cu-aspartate metal–organic framework as a catalyst for the cycloaddition of propylene oxide and CO2

Three-dimensional amino acid backbone Cu-aspartate metal organic frameworks {[Cu(l-asp)(1,4-bpy)0.5].H2O}n (CuAspBpy) were prepared from copper salt, l-aspartic acid linker, and 4,4′-bipyridyl cross-linker by solvothermal and microwave methods. The synthesized CuAspBpy was characterized and used as a catalyst for the synthesis of propylene carbonate (PC) by the cycloaddition of CO2 with propylene oxide (PO). An efficient catalytic process for PC synthesis was developed via the synergistic role of CuAspBpy and the quaternary ammonium bromide co-catalyst. Computational studies based on density-functional theory (DFT) were utilized to propose a mechanistic pathway for the reaction. The heterogeneous catalyst was reused four times without any considerable loss in the activity.