Preparation and characterization of two new metal–organic coordination polymers with 3,3′-azodibenzoic acid under N-donor auxiliary chelating ligand intervention

Abstract

Reactions of 3,3′-azodibenzoic acid (H₂azdc) with Mn(II) and Cd(II) in the presence of 1,10-phenanthroline (phen) yield two new metal–organic coordination polymers, {[Mn(azdc)(phen)(DMF)(H₂O)]}_n (1) and {[Cd(azdc)(phen)]}_n (2), which display 1-D azdc-bridged coordination arrays with different topology. 1 was synthesized under ambient conditions and exhibits a zigzag chain structure, further extending into a 2-D supramolecular double layer through C–Hπ and C–HO hydrogen bonds. Solvothermally 2 was obtained and shows a double-chain structure. Adjacent double chains are linked by C–HN hydrogen bonds to give a 2-D supramolecular wavy double layer. Distinct extended 3-D supramolecular network architectures are further constructed with weak secondary interactions, especially aromatic stacking and hydrogen bonding as supramolecular driving forces. The coordination modes of azdc²⁻ and crystalline architectures of the complexes depend on the central metal ions. The desolvation–resolvation behavior of 1 has been explored. Thermal stabilities of 1 and 2 have been studied. Solid-state fluorescence of 2 has been investigated.

Keywords:

• Coordination polymers
• Synthesis
• Crystal structures
• Fluorescence
• Desolvation–resolvation property

Acknowledgments

We gratefully acknowledge the Natural Science Foundation of Jiangsu Province (BK2012680), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Analysis and Test Center of Yangzhou University, and the Key Laboratory of Environmental Material and Environmental Engineering of Jiangsu Province.

Disclosure statement

No potential conflict of interest was reported by the authors.