Synthesis, crystal structures and in vitro antibacterial activity of two novel organotin(IV) complexes

Two triorganotin(IV) carboxylates [nBu3SnOL]n (KK1) and [Ph3SnOL]n (KK2) have been prepared by the reactions of (E)-3-(4-(diphenylamino)phenyl)acrylic acid (HL) with n(Bu3Sn)2O and Ph3Sn(OH), respectively. Complexes KK1 and KK2 have been structurally characterized by IR, elemental analysis and X-ray crystallography, confirming that both complexes possess infinite 1D chain structures. It’s exciting to discover that KK1 and KK2 exhibit strong solid-state luminescence emission while the HL almost quenches. Furthermore, both complexes were assayed for in vitro antibacterial activity against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Pseudomonas aeruginosa ATCC 13525 and Escherichia coli ATCC 35218) by MTT method. Complex KK2 exhibited powerful antibacterial activities against S. aureus with MIC value of 0.78 μg/mL, which was superior to the positive controls penicillin G. On the basis of the biological results, structure–activity relationships were discussed.