Synthesis and Characterization of Four Novel Divalent Transition Metal-Dicarboxylate Coordination Polymers With Chelating Aromatic Amine Ligands (Metal = Mn²⁺, Co²⁺, Cu²⁺, Zn²⁺)

Abstract

The hydrothermal reactions between divalent transition metal acetates (metal = Mn²⁺, Co²⁺, Cu²⁺, Zn²⁺), naphthalene-1,4-dicarboxylic acid (NDC), and 1,10-phen (1,10-phen = 1,10- phenanthroline) or 2,2′-bipy (2,2′-bipy = 2,2′-bipyridine) yielded four novel metal-organic frameworks, formulated as [Co(phen) (NDC)]₂·H₂O (1), [Cu(bipy)(NDC)]₂·2H₂O (2), {[Mn(bipy)₂]₂ (NDC)(HNDC)₂}·0.5H₂O (3), and [Zn(H₂O)(phen)(NDC)]·H₂O (4). These four compounds have been characterized structurally using single-crystal diffraction, elemental analysis, FT-IR spectrum, and TG analysis. In 1, the coordination octahedra [CoO₄N₂] are joined by common vertices leading to dimeric units [Co₂O₈N₄], which are bridged by NDC ligands to form a 2D framework with well-proportioned, rectangular-shaped cavities. In 2, two square-pyramids Cu(N₂O₃) share a common edge to form [Cu₂O₄N₄] dimers. These dimers and NDC ligands are alternately connected, resulting in grid structures similar to those found in compound 1. Alternating [MnO₂N₄] octahedra in 3 are linked by carboxylate groups to form an eight-membered ring, which is bridged by NDC ligands leading to an infinite chain. The Zn center in 4 is in a distorted trigonal-bipyramidal environment. The ZnO₃N₂ units are linked by NDC in bis-monodentate fashion, to form a chain of structure.

Keywords:

• coordination polymers
• crystal structure
• polycarboxylate
• transition metal

Acknowledgments

This work was financially supported by the natural science foundation of Henan Institute of Science and Technology.