Synthesis, characterization, crystal structures, QSAR study and antibacterial activities of organotin bisphosphoramidates

Abstract

Organotin complexes of bisphosphoramidates were prepared by the reaction of SnR1R2R3Cl (where R = alkyl/aryl/Cl) and Ph2P(O)XP(O)Ph2 ligands (where X = diamine). All the compounds were characterized by NMR and IR spectroscopy. X-Ray crystallography confirms that the bridging ligand produces binuclear complexes with SnPh3Cl acceptors in Ca3 and Ca4 and offers a polymeric structure toward SnMe2Cl2 in Cc5. The synthesized compounds were screened for the antibacterial activity against B. cereus and E. coli. Based on the MIC test, the ligands are devoid of antibacterial activity. Notably, among the complexes, triphenyltin adducts exhibited a marked activity only against Gram-positive bacterium B. Cereus (IC50 = 0.78 μg/mL for Ca3 and Ca5). DFT–QSAR models revealed that the descriptor of the electrophilicity (ω) parameter is correlated with the inhibition activity on B. cereus. The correlation matrix of QSAR models and docking analysis confirmed that the electrophilicity parameter controls the influence of the net charge (QSn) and polarizability of Sn atom of complexes on the inhibition of B. cereus.