Hydrothermal Synthesis, Structures, and Properties of Manganese(II) and Zinc(II) Coordination Polymers with Different Phenylenediacrylates

Four novel metal-organic coordination polymers, [Zn-2(ppda)(phen)(2)(HCOO)(2)] (1), [Mn(ppda)(phen)(H2O)(2)]center dot DMF (2), [Zn(mpda)(phen)]center dot 1.5H(2)O (3), and [Mn-2(mpda)(2)(phen)(2)] (4), (H(2)ppda = p-phenylenediacrylic acid, H(2)mpda = m-phenylenediacrylic acid, and phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions. Compound 1 consists of two-dimensional (2D) bilayers in which formate-bridged chains are cross-linked by ppda ligands, and the bilayers are sustained by infinite zipper-like pi-pi stacking of the phen ligands. Compounds 2 and 3 are both one-dimensional (1D) coordination polymers, but exhibit different chain shapes due to the different geometry of ppda and mpda. Via O-H center dot center dot center dot O hydrogen bonding and pairwise phen center dot center dot center dot phen pi-pi stacking, the zigzag chains in 2 are assembled into a three-dimensional (3D) diamond network with 3-fold interpenetration, while the helical chains in 3 are packed into a 3D structure through quadruple pi-pi stacking arrays. Compound 4 is composed of double twist chains of binuclear units sustained by double carboxylate bridges and phen center dot center dot center dot phen pi-pi stacking. Magnetic investigations on 2 and 4 have been carried out. Compound 4 exhibits weak intradimer antiferromagnetic exchange mediated through the carboxylate bridges and the possible pi-pi stacking pathway, while much weaker antiferromagnetic exchange is operative through the interchain hydrogen bonding motif in 2.