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, {[Cu-2(mu-ade)(4)(H2O)(2)][Cu(OX)(H2O)](2).similar to14H(2)O}(n) (1), has been synthesized by reaction of adenine (Hade) with a basic solution of K-2[Cu(OX)(2)].2H(2)O (ox = oxalato dianion). Compound 1 crystallizes in the trigonal space group R3 with a = b = 31.350(1) Angstrom, c = 14.285(1) Angstrom, V = 12158.7(10) Angstrom(3), and Z= 9. X-ray analysis shows a covalent 3D network in which the copper(11) centers are bridged by tridentate mu-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.