Monodentate function of the 4,4′-bipyridine that systematically occurs in the 4-sulfobenzoate manganese(ii) complexes: syntheses, crystal structures, and properties

Abstract

In this presentation, three topologically diverse complexes based on the Mn²⁺/4-sulfobenzoate/4,4′-bipyridine system, [Mn(4,4′-bipy)₂(H₂O)₄](Hsb) (1), [Mn(4,4′-bipy)₂(H₂O)₄](sb)(4H₂O) (2), and {[Mn(4,4′-bipy)(sb)(H₂O)₃](2H₂O)}_n (3) [4,4′-bipy = 4,4′-bipyridine; sb = 4-sulfobenzoate dianion], have been prepared and characterized by single-crystal X-ray analyses, elemental analyses, IR spectra, TG analyses, and photoluminescence studies. The structures of complexes 1 and 2 are cation–anion species whereas complex 3 is a 1-D polymer. In all three complexes 4,4′-bipyridine ligands feature a monodentate coordination mode and the uncoordinated nitrogen donor of each 4,4′-bipyridine engages in the intermolecular hydrogen bonding, which blocks the metal–metal bridging by 4,4′-bipyridine. In contrast to monodentate 4,4′-bipyridine-containing complexes occasionally reported in the literature, the monodentate function for 4,4′-bipyridine ligands in complexes 1–3 systematically occurs, suggesting the sulfonate group can adjust the competitive coordination between the carboxylate and 4,4′-bipyridine ligands. Extensive hydrogen-bonding interactions including hydrogen-bonded 4,4′-bipyridine in these three complexes control their crystal packings and give rise to 3-D extended supramolecular architectures.