A series of phenyl sulfonate metal coordination polymers as catalysts for one-pot Biginelli reactions under solvent-free conditions

Three new metal coordination polymers, namely, [Co(DPP)(2)(H2O)(2)]center dot(BS)(2)center dot 2H(2)O (1), [Co(DPP)(2)(H2O)(2)]center dot(ABS)(2)center dot 2H(2)O (2) and [Co(DPP)(2)(MBS)(2)] (3) [DPP = 1,3-di(pyridin-4-yl) propane, BS = phenyl sulfonic acid, ABS = p-aminobenzene sulfonic acid, MBS = p-methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1-3 were structurally characterized using X-ray single-crystal diffraction, XRD and IR spectroscopy. Both complexes 1 and 2 display a 1D tape structure. Meanwhile, complex 3 exhibits a 2D layer and further stacks via C-H center dot center dot center dot pi interactions to generate a three-dimensional supramolecular architecture. These three metal coordination polymers have been applied as catalysts for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions through the Biginelli reaction. Interestingly, the catalysis products have been obtained in high yields under eco-friendly synthesis conditions.