Synthesis, characterisation and antibacterial activity of novel Ga(III) polypyridyl catecholate complexes.

Ga(III) polypyridyl catecholate complexes of type [Ga(bipy)(O,O)](NO) or [Ga(phen)(O,O)](NO) respectively were readily synthesised on reaction of Ga(NO) in methanol with 1 equivalent of catecholate ligand (2,3-DHBA, 3,4-DHBA, 2,3,4-THBA or CafA) and then 2 equivalents of either bipy or phen. The complexes were characterised in full including by X-ray crystallography, which established that the catecholate ligands coordinate the Ga(III) centres in a bidentate manner the two deprotonated hydroxy groups. All Ga(III) complexes exhibited good antibacterial activity against the Gram-negative pathogenic bacteria , and . The complexes were inactive against the Gram-positive pathogenic bacteria including against a methicillin-resistant strain (MRSA). [Ga(bipy)(2,3-DHBA)](NO)·1.5HO (1) was shown to be non toxic in larvae of at doses up to 2000 μg mL and to offer protection at doses of 100 and 250 μg mL at 48 and 96 h to larvae infected with .