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The synthesis of several diorganotin(IV) dicarboxylate compounds, including acetates and nicotinates as well as diorganotin(IV) dichloride complexes of the ligands phen, dione and dppz were undertaken. Several difficulties in either the syntheses or complexation reactions with the organic ligands were encountered. The diorganotin(IV) dichloride complexes of the ligands (R2SnCl2·L where R = Me, n-Bu or Ph and L = phen, dione or dppz) were tested against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The dibutyltin(IV) derivatives exhibited the broadest range of activity in comparison to the dimethyltin(IV) or diphenyltin(IV) derivatives. The addition of the nicotinate group did not promote activity against any of the bacteria. Furthermore, only in the case of Ph2SnCl2·dione was there improved activity compared to the organic ligand itself.

We report the synthesis, antibacterial evaluation of a series of thiourea-containing compounds. 1-(3,5-Bis(trifluoromethyl)phenyl)-3-((S)-(6-methoxyquinolin-4-yl)-((1S,2S,4S,5R)-5-vinylquinuclidin-2-yl)methyl)thiourea 5, was the most active against a range of Gram-positive and Gram-negative bacteria, and exhibited bacteriostatic activity against methicillin resistant Staphylococcus aureus (MRSA) comparable to that of the well-known antibacterial agent vancomycin. Quinoline thiourea 5 was subjected to a detailed structure–activity relationship study, with 5 and its derivatives evaluated for their bacteriostatic activity against both Gram-negative and Gram-positive bacteria. A number of structural features important for the overall activity of quinoline thiourea 5 have been identified. A selection of compounds, including 5, was also evaluated for their in vivo toxicity using the larvae of the Greater wax moth, Galleria mellonella. Compound 5, and a number of derivatives, were found to be non-toxic to the larvae of Galleria mellonella. A new class of antibiotic can result from the further development of this family of compounds.