Construction of homo- and heterometallic-pyridine-2,3-dicarboxylate metallosupramolecular networks with structural diversity: 1D T5(2) water tape and unexpected coordination mode of pyridine-2,3-dicarboxylate

Abstract

Five new homo and heterometallic Cu(II), Cd(II), Cu(II)–Ag(I), Cu(II)–Cd(II) supramolecular networks with pyridine-2,3-dicarboxylate (pydc), {[Cu(μ-pydc)(dmpen)₂]}_n (1), [Cu₂(μ-pydc)₂(emim)₄]·2H₂O (2), [Cd(μ-pydc)(emim)₂]_n (3), [Cu(en)₂(H₂O)₂][Ag₂(pydc)₂(μ-en)]·6H₂O (4) and {[Cd(H₂O)₄Cu(μ-pydc)₂]·2H₂O}_n (5) have been synthesized and structurally characterized (en = ethylenediamine, dmpen = 1,3-diamino-2,2-dimethylpropane and emim = 2-ethyl-4-methyl-imidazole). Owing to diverse binding modes and conformations of the pydc ligand and the different diamine or imidazole-containing coligands, these complexes exhibit structural and dimensional diversity. Complex 1 exhibits a new unexpected coordination mode of pydc, which is known as a chelating ligand, leading to the formation of a 1D coordination polymer. Complex 2 is the first dinuclear copper(II)–pydc complex containing a dinuclear metalloligand. Complex 3 is a one dimensional coordination polymer and the Cd(II) ion is six-coordinated in a distorted octahedral geometry. Complex 4 is the first 3d–4d heterometallic complex and shows two different coordination behaviors of the ethylenediamine ligand: common chelate mode and rare bridging mode. The most striking feature of 4 is the existence of a infinite T5(2) water tape. Complex 5 is the first 3d–4d heteropolynuclear complex obtained from a polynuclear metalloligand. Neighboring metalloligand double-chains bind to Cd(II) ions to form a two dimensional (2D) layered structure. Complex 4 exhibits weak emission due to the quenching effect of Cu(II) ions. Complexes 3 and 5 exhibit rare green emission and blue photoluminesence, respectively. Atomically detailed simulations were used to assess the potential of complexes in gas storage and gas separation applications. The antimicrobial properties of the complexes were also investigated by the broth dilution method (MIC). Complexes 4 and 5 are determined to be highly effective for antimicrobial activity.