Abstract:
Three new 3D lanthanide-based metal–organic frameworks (MOFs), [Ln2(ImBDC)3(2H2O)]n (where
Ln = Tb3+ (1)/Sm3+ (2)/Eu3+ (3), ImBDC = 2-(imidazol-1-yl)terephthalic acid), have been synthesized
solvothermally and characterized with single-crystal X-ray diffraction and other physicochemical
methods. MOFs1–3 are isostructural and feature a 3D framework structure with 1D channels of dimension
3.91 5.27 Å2 decorated with basic imidazole groups. Owing to imidazole functionalized pores, MOF1
exhibits selective adsorption properties for CO2 with a high interaction energy (Qst) of 37.1 kJ mol 1. The
activated samples of the MOFs act as efficient heterogeneous catalysts for the cycloaddition reaction
of CO2 to epoxides to generate value-added cyclic carbonates. Interestingly, due to the narrow pore
channels of the MOFs, preferential conversion of smaller size epoxides over the larger epoxides
is observed. Furthermore, the MOF catalyst could be recycled and reused for up to five cycles without
significant reduction in the catalytic activity. Thus the present study demonstrates size-selective catalytic
activity for the conversion of smaller epoxides to cyclic carbonates under mild reaction conditions.
