Syntheses and Properties of One–Three-Dimensional Coordination Polymers Constructed by Metallohelicates of Purin-Containing Carboxylate

Abstract

An acetate-functionalized purine-containing ligand, 2-(6-oxo-6,9-dihydro-1H-purin-1-yl) acetic acid (H2L), and its six new one–three-dimensional (1–3D) coordination polymers, [La(HL)2(NO3)(H2O)2]n (1), [Ce(HL)2(NO3)(H2O)2]n (2), [Pb(HL)2(H2O)2]n (3), [Cd(HL)2(H2O)2]n (4), [Cd(L)]n (5), and [Zn(L)]n (6), were synthesized and characterized. Single-crystal X-ray diffraction analyses reveal that the architectures of complexes 1–6 are built from the metal–organic helixes of ligands H2L. The overall structures range from the double helical chains of 1 and 2, and the 2D helical networks of 3 and 4, to the 3D coordination polymers of 5 and 6, containing 2D homochiral layers based on 1D metal–organic helixes. In those meso compounds, ligands H2L display differently anionic states, bridge modes, and especially unsymmetrical configurations with the sharp distortion between the acetate and purin in favor of constructing helical assemblies as expected. The plentiful hydrogen-bonding sites and π···π interactions origin...