Antimicrobial activity of organotin(IV) compounds: a review

Equimolar reactions of dibutyltin(IV) oxide with Schiff bases derived from amino-acids led to the formation of a new series of dibutyltin(IV) complexes of general formula, Bu2SnL [L=dianion of tridentate Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde or acetyl acetone with glycine (L-1), L-β-alanine (L-2), DL-valine (L-3), DL-4-aminobutyric acid (L-4), L-methionine (L-5), L-leucine (L-6) and phenylglycine (L-7)]. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analyses, conductance measurements and electronic, IR, multinuclear magnetic resonance (1H, 13C and 117Sn) and 119Sn Mossbauer spectral studies. The complexes have been tested against various bacteria [Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus penicillin resistance (2500 units)] and fungi (Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii,Trichophyton mentagrophytes and Aspergillus fumigatus). All the complexes showed moderate activity. The cytotoxicity of a few compounds has been screened in vitro against seven human tumour cell lines, viz. MCF-7, EVSA-T, WiDr, IGROV, M19 MEL, A498 and H226. The activities found experimentally were better than those obtained for cisplatin and carboplatin © 1997 John Wiley & Sons, Ltd.

Synthesis, characteristic spectral studies and in vitro antimicrobial and antitumour activities of organotin(IV) complexes of Schiff bases derived from amino-acids

Synthesis, characterization, biological screenings and interaction with calf thymus DNA as well as electrochemical studies of adducts formed by azomethine [2-((3,5-dimethylphenylimino)methyl)phenol] and organotin(IV) chlorides

The reactions of phenylmercury(II) acetate with a series of alkyl, aryl and heterocyclic thiosemicarbazones in ethanol formed novel phenylmercury(II) derivatives of stoichiometry [HgPhL] [HL = RN3N2HC1(S)N1H2 = cyclopentanone 1, cyclohexanone 2, benzaldehyde 3, 2-hydroxybenzaldehyde 4, 4-methoxybenzaldehyde 5, pyrrole-2-carbaldehyde 6, thiophene-2-carbaldehyde 7 or furan-2-carbaldehyde 8 thiosemicarbazone], characterised with the help of analytical data, physical properties, IR, far-IR, multinuclear NMR (1H, 13C, 199Hg) spectroscopy and X-ray crystallography of complexes 1, 5 and 6. The 1H and 13C NMR data suggest that the N2H group is deprotonated during reaction with phenylmercury(II) acetate and co-ordination occurs via the N3,S atoms in a chelating mode. The 199Hg NMR data suggest symmetrisation phenomenon for complexes 3 and 5, 2[HgPhL] ⇌ HgPh2 + [HgL], which is supported also by 1H and 13C NMR data. The δ(Hg) values reveal that shielding of Hg with the change of organic group in the thiosemicarbazones decreases in the order: 2-hydroxybenzene ⋙  furan > benzene > 4-methoxybenzene  thiophene ≈ cyclohexanone ≈ cyclopentanone > pyrrole and the Lewis basicity of the thiosemicarbazones varies in the opposite order. The 1H and 13C NMR data reveal that 7 and 8 show isomerism. There are two strong [Hg–C 2.063(7) 1, 2.069(10) 5, 2.049(11) 6; Hg–S 2.382(2) 1, 2.357(3) 5, 2.377(3) A 6] and one weak bond [Hg–N3 2.489(6) 1, 2.611(7) 5, 2.492(9) A 6], with CPh–Hg–S bond angles of 162.9(2), 174.2(3), 165.8(3)° respectively. The weak intermolecular interactions via Hg · · · N2 [3.001(6) A] in 1 and via Hg · · · S in 5 [3.518(3) A] and 6 [3.528(3) A] form centrosymmetric dimers and Hg formally acquires four-co-ordination with two strong (Hg–C, Hg–S), one weak (Hg · · · N3) and one secondary (Hg · · · N2 or S) bonds. The preferred dimer formation via N2 nitrogen in 1, rather than via sulfur atoms (5 and 6) despite Hg · · · S affinity represents an unusual bonding mode. From the low-temperature 1H NMR studies of some selected complexes, the energy barrier (ΔGTc*, Tc is coalescence temperature) to rotation of the amino group about the C1–N1 bond was calculated and correlated with bonding parameters of the thioamide group in the solid state.

Symmetrisation, isomerism and structural studies on novel phenylmercury( II ) thiosemicarbazonates: correlation of the energy barrier to rotation of the amino group with the bonding parameters of the thioamide group

The toxicology and biomedical aspects and applications of organotin compounds are discussed. Factors affecting toxicity are considered first and then the mechanisms of toxicity are described and assessed. A review of the main biomedical applications then follows, covering biochemical, agricultural and other biocidal uses, and recent developments in the field of anticarcinogenesis.

A.J. Crowe

Papers

Synthesis and spectroscopic studies on organotin derivatives of biologically active Schiff bases

X-ray diffraction, Mössbauer spectral and related studies on some tin(IV) complexes with various nitrogen, oxygen and sulphur donor ligands