Copper Phthalate Coordination Polymers Incorporating Kinked Dipyridyl Ligands: An Unprecedented 8-Connected Network and One-Dimensional Chiral Nanobarrels with Hydrophobic Channels Constructed from Septuple Helical Motifs

Abstract

Copper phthalate coordination polymers incorporating the kinked and hydrogen-bonding-capable imines 4,4'-dipyridylketone (dpk) and 4,4'-dipyridylamine (dpa) have been prepared and structurally characterized by single-crystal X-ray diffraction. {[Cu(pht)(dpk)].0.33CH(3)OH}(n) (1; pht = phthalate) possesses helical subunits built from the fusion of [Cu(dpk)](n) 3-fold double helices and [Cu(pht)](n) 3-fold helices with opposite handedness. The resulting achiral [Cu(pht)(dpk)](n) helices are conjoined by bridging phthalate carboxylate oxygen atoms to construct {Cu(2)O(2)} dimeric units, which serve as 8-connected nodes for a three-dimensional (3D) coordination polymer lattice with an unprecedented 3(6)4(12)5(8)6(2) topology, evocative of a 3D Kagome lattice. {[Cu(2)(pht)(2)(dpa)].H(2)O}(n) (2) manifests homochiral septuple left-handed [Cu(2)O(2)(dpa)](n) helices formed by copper ions, phthalate oxygen atoms, and dpa ligands. The septuple helices are bracketed by pht anions to construct chiral one-dimensional nanobarrels with solvent-free "star-shaped" channels. Compounds 1 and 2 display antiferromagnetic [J = -9.85(5) cm(-1)] and ferromagnetic [J = +1.36(3) cm(-1)] coupling across their {Cu(2)O(2)} dimeric units, respectively.