Structure Variation from One-Dimensional Chain to Three-Dimensional Architecture: Effect of Ligand on Construction of Lanthanide Coordination Polymers

Abstract

Four lanthanide coordination polymers were constructed from mixed ligands of phenanthroline derivative and flexible polydentate ligands, [Gd2(1,3-BDC)3(MOPIP)2]n⋅nH2O (1), [Gd(1,4-BDC)1.5(MOPIP)]n (2), [Yb(1,4-BDC)1.5(MOPIP)]n (3) and [Sm(1,4-BDC)1.5(MOPIP)]n (4), (MOPIP = 2-(4-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, 1,3-BDC = benzene-1,3- dicarboxylic acid, 1,4-BDC = benzene-1,4-dicarboxylic acid). The polymers have been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 possesses one-dimensional chain structure, and expands into the three-dimensional supramolecular architecture by π⋯π stacking and hydrogen-bonding interactions. Meanwhile, compounds 2–4 exhibit three-dimensional frameworks with pcu topology (4 12⋅6 3). The structural differences among such compounds show that the steric hindrances of benzene dicarboxylic acid ligands play a key role in the assembly and the structures of the title compounds. Compounds 1 and 2 act as efficient Lewis acid catalysts for the cyanosilylation of benzaldehyde in high yields, due to the strong Lewis acidity. A series of four 3-dimensional (3D) lanthanide coordination polymers were prepared which exhibit different structures and excellent catalytic activity in the cyanosilylation of benzaldehyde.