Nitrogen-rich cobalt (II) MOFs as efficient bifunctional catalysts for single or tandem oxidation and CO2 conversion reactions

The development of efficient catalysts that include the advantages of homogeneous and heterogeneous catalysts is a challenge that can be achieved with metal-organic frameworks (MOFs) since they can incorporate different functionalities in their structure that make them promising catalysts for different processes. Herein, two new isoreticular nitrogen-rich naphthalene cobalt-MOFs, Co-NDTz and Co-NDPhTz, were successfully prepared under solvothermal conditions from the corresponding linkers (H2NDTz=2,6-naphthaleneditetrazole and H2NDPhTz=2,6-bis(4-(1H-tetrazol-5-yl)phenyl)naphthalene). These Co-tetrazole-based MOFs combine Lewis acid and redox functionalities and good CO2 adsorption and after being thermally activated resulted to be excellent efficient catalysts for the epoxidation of alkenes and CO2 cycloaddition to epoxides yielding cyclic carbonates, reaching turnover numbers up to 2500. Furthermore, these two reactions take place following a highly desired one-pot tandem process and a cyclic carbonate was obtained from styrene and CO2 under solvent-free conditions. In addition, the heterogeneous catalysts are easily recycled without noticeable loss of catalytic activity and without important structural deterioration.