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

Four novel metal−organic coordination polymers, [Zn2(ppda)(phen)2(HCOO)2] (1), [Mn(ppda)(phen)(H2O)2]·DMF (2), [Zn(mpda)(phen)]·1.5H2O (3), and [Mn2(mpda)2(phen)2] (4), (H2ppda = p-phenylenediacrylic acid, H2mpda = 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 π−π 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···O hydrogen bonding and pairwise phen···phen π−π 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 π−π stacking arrays. Compound 4 is composed of double twist chains of binuclear units sustained by double carboxylate bridges and phen···phen π−π 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 π−π stacking pathway, while much weaker antiferromagnetic exchange is operative through the interchain hydrogen bonding motif in 2.