Pendant arm length control of dimensionality in cobalt dipyridylamine coordination polymers containing meta-benzenedicarboxylate ligands

Hydrothermal synthesis has afforded a pair of divalent cobalt coordination polymers containing meta-substituted benzenedicarboxylate and 4,4′-dipyridylamine (dpa) ligands, in which the length of the pendant arms on the anionic components dictates the overall dimensionality. [Co(1,3-phda)(dpa)(H2O)]n (1, 1,3-phda = 1,3-phenylenediacetate) possesses a ruffled (4,4) rhomboid grid 2-D layered structure with an 5-connected sqp supramolecular net. Use of a meta-substituted benzenedicarboxylate with shorter pendant arms generated {[Co(1,3-bdc)(dpa)]·3H2O}n (2, 1,3-bdc = 1,3-benzenedicarboxylate), which displays a 3-D network structure with 658 topology. Antiferromagnetic coupling, in conjunction with zero-field splitting, was evident across the supramolecular Co–O–H⋯O–Co patterns in 1 and the syn–syn bridged {Co(OCO)}2 dimeric units in 2.