Syntheses and Crystal Structures of Copper(II) Coordination Polymers Comprising Discrete Helical Chains

Three CuII helical complexes, [Cu(H2O)4(dpa)]n (1), [Cu(4,4‘-bipy)(dpa)]n (2), and [Cu(dpe)(dpa)]n (3)
(H2dpa = diphenic acid, 4,4‘-bipy = 4,4‘-bipyridine, and dpe = 1,2-di(4-pyridyl)ethylene), have been synthesized
and characterized by X-ray crystal structure determination. 1 is a one-dimensional helical chain of pseudo square-planar Cu(H2O)4 bridged by bis-monodentate dpa. The hydrogen-bonding interactions extend the helical chain forming
a two-dimensional layer structure. 2 and 3 are three-dimensional coordination polymers composed of Cu−dpa helical
chains bridged by 4,4‘-bipy and dpe, respectively. The longer spacer between coordination sites in dpe results in a
2-fold-interpenetration of the three-dimensional framework in 3. The helical pitches in 1−3 are 7.632, 11.425, and
16.022 Å, respectively.