Friedländer, Knoevenagel, and Michael Reactions Employing the Same MOF: Synthesis, Structure, and Heterogeneous Catalytic Studies of ([Zn(1,4-NDCA)(3-BPDB)0.5]·(DMF)(MeOH) and [Cd4(1,4-NDCA)4(3-BPDB)4]·2(DMF)

Abstract

Two new inorganic–organic coordination polymers, namely, ([Zn(1,4-NDCA)(3-BPDB)0.5]·(DMF)(MeOH) (I) and [Cd4(1,4-NDCA)4(3-BPDB)4]·2(DMF) (II), were synthesized by employing naphthalene dicarboxylic acid and 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-BPDB) ligands. Both the compounds have a three-dimensional structure and exhibit Lewis acidic as well as basic characters. The Lewis acid character was explored by using the Friedländer reaction involving the condensation of amino benzaldehyde and ketones. The Lewis basic character was investigated by employing a three-component condensation that combines Knoevenagel and Michael reactions. Both the Lewis acid and Lewis base reactions were found to proceed well, giving rise to the expected products with good and comparable yields of ∼80%. The catalysts were found to be active for up to three cycles.