Stacked ring-like coordination complex molecules threaded by infinite water tapes

Crystals of {[Cu2(mal)2(bpfp)2(H2O)2]·10H2O}n (1, mal = malonate, bpfp = bis(4-pyridylformyl)piperazine) were prepared by slow diffusion of an ethanolic solution of bpfp into an aqueous solution of copper malonate. Single-crystal X-ray diffraction showed the presence of supramolecular stacks of ring-like [Cu2(mal)2(bpfp)2(H2O)2] neutral coordination complex molecules threaded by unique infinite water molecule tapes with a T6(6)4(4)4(3)4(3)A(2) classification. These feature six-membered chair conformation rings, four-membered rings, and are decorated by single water molecules. Hydrogen bonding acceptance by the formyl groups of the bpfp ligands proved critical in stabilizing the water molecule tapes within the nanotubular incipient channels.