Rational Design of a 3D Mn-Metal-Organic Framework Based on a Nonmetallated Porphyrin Linker for Selective Capture of CO2 and One-Pot Synthesis of Styrene Carbonates

A 3D Mn-II-porphyrin metal-organic framework (MOF), [{Mn-2(TCPP).2H(2)O}.DMF] (MOF1) (TCPP=5,10,15,20-tetrakis(4-benzoate)porphyrin), was constructed; it exhibits an interesting 3D framework structure with two types of 1D channels of dimensions of 3.94x8.37 angstrom(2) and 4.66x4.93 angstrom(2) running along the crystallographic a axis. Owing to the presence of a nonmetallated porphyrin cavity, MOF1 exhibits selective storage of CO2 with an isosteric heat of adsorption value of 32.1 kJ mol(-1), which is further supported by theoretical calculations with the calculated binding energy (BE) of 29.78 kJ mol(-1). Interestingly, the nonmetallated nature of the porphyrin ligand was exploited for implantation of coordinatively unsaturated Fe-III ions to generate a Fe-III@MOF1 framework, which acts as an efficient recyclable catalyst for the oxidation of styrenes to the corresponding epoxides in the presence of PhIO as an oxidant at room temperature. Moreover, the one-pot synthesis of styrene carbonates from styrenes and CO2 was also achieved using Fe-III@MOF1 as a catalyst. The rational design of a porous Mn-II-porphyrin MOF for the selective capture of CO2 and the one-pot synthesis of styrene carbonates at mild conditions is reported.