A series of coordination polymers constructed from in situ amidation ligands: syntheses, structures and luminescent properties

Abstract

From the hydrothermal in situ amidation reactions of aromatic polycarboxylates and hydrazine hydrate (N₂H₄·H₂O), four complexes, dinuclear [Cu(μ₂-H₃bbch)(H₂O)]₂·2H₂O (1), 3-D grid-like [Fe₃(μ₅-Hbbch)₂(μ₂-H₂O)₂(H₂O)₂]·2H₂O (2), 2-D layer [Zn(μ₂-H₂bbh)(μ₂-N₂H₄)_1/2(H₂O)]·2H₂O (3) and 3-D supramolecular structure [Cd(H₂bch)₂(2,2′-bpy)(H₂O)₂][Cd(μ₂-H₂bch)(2,2′-bpy)(H₂O)₂](H₂bch) (4) have been prepared. The two different in situ amidated ligands in 1, 2 and 3, benzene-4,5-bicarboxylate-1,2-hydrazide (H₄bbch) and benzene-1,2,4,5-bihydrazide (H₄bbh), were formed through adjusting the ratios of pyromellitic acid (PMA) and N₂H₄·H₂O, of which H₄bbch was generated through hydrothermal in situ amidation reactions for the first time. Benzene-4-carboxylate-1,2-hydrazide (H₃bch), displaying three new coordination modes in 4, was also an in situ amidation product of benzene-1,2,4-tricarboxylic acid (H₃btca) and N₂H₄·H₂O. 1–4 were characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Their structures were determined by single-crystal X-ray diffraction. The fluorescence properties of compounds 1, 3 and 4 were also investigated.