Two scandium-based coordination polymers: rapid ultrasound-assisted synthesis, crystal transformation, and catalytic properties

A scandium-based coordination polymer (Sc-CP), Sc(ox)1.5(H2O)2·4H2O (1) (H2ox = oxalic acid), with a two-dimensional (2D) layered structure was prepared by both hydrothermal synthesis and ultrasound-assisted heating methods using glutaric acid as a modulator. Then, the single crystal of 1 as a precursor was transformed into another 2D Sc-CP, Sc(ox)1.5(H2O)2·H2O (2), by increasing the temperature. Due to the difference in hydrogen bond interactions between the host framework and guest water molecules, 2 showed good tolerance to various solvents, while 1 exhibited poor stability even exposed in air. After activation, 2 could be used as a heterogeneous Lewis acid catalyst for two classic C–C bond formation reactions, the cyanosilylation reaction and Strecker reaction at room temperature, showing excellent catalytic activity and selectivity.