Synthesis, Characterization, Biocide and Toxicological Activities of Di-n-butyl- and DiphenyltinIV-Salicyliden-(beta)-Amino Alcohol Derivatives

The one pot reaction of salicylaldehyde 1, (beta)-amino alcohols 2a-2c, and di-n-butyltinIV oxide 3a or diphenyltinIV oxide 3b produced five diorganotinIV compounds, 4a-4c, 5a, and 5c, in good yields. All compounds were characterized by IR, 1H, 13C, and 119Sn NMR spectroscopy, and elemental analysis; furthermore, compounds 4b, 4c, 5a, and 5c were characterized by X-ray diffraction analysis. After the structural characterization, all of the compounds were tested in vitro against Bacillus subtilis (Gram-positive, strain ATCC 6633), Escherichia coli (Gram-negative, strain DH5(alpha)), Pseudomonas aeruginosa (Gram-negative, strain BH3), Desulfovibrio longus (strain DSM 6739), and Desulfomicrobium aspheronum (strain DSM 5918) to assess their antimicrobial activity. Compounds 4 and 5 demonstrated a wide range of bactericidal activities against the tested aerobic (one Gram-positive and two Gram-negative subtypes) and anaerobic bacteria (two sulfate-reducing bacteria, SRB). Compound 5 had better bactericidal performances than compound 4. For all of the compounds, the acute toxicity was measured using luminescent bacteria toxicity (LBT-Microtox) tests to track their further environmental impact. According to these results and in order to fulfill environmental regulations, the toxicity of the compounds studied herein can be modulated through the proper selection of the disubstituted tinIV moiety.