An Unusual 3D Coordination Polymer Based on Bridging Interactions of the Nucleobase Adenine

The first 3D coordination polymer containing a nucleobase as a bridging ligand, {[Cu2(μ-ade)4(H2O)2][Cu(ox)(H2O)]2·∼14H2O}n (1), has been synthesized by reaction of adenine (Hade) with a basic solution of K2[Cu(ox)2]·2H2O (ox = oxalato dianion). Compound 1 crystallizes in the trigonal space group R3̄ with a = b = 31.350(1) Å, c = 14.285(1) Å, V = 12158.7(10) Å3, and Z = 9. X-ray analysis shows a covalent 3D network in which the copper(II) centers are bridged by tridentate μ-N3,N7,N9 adeninate ligands. The compound has relatively large, nanometer-sized tubes associated with the self-assembly process directed solely by metal−ligand interactions. The covalent 3D framework remains intact upon removal of the guest water molecules trapped in the nanotubes. Magnetic measurements indicate an overall antiferromagnetic behavior of the compound.