Complexes of a tridentate ONS Schiff base. Synthesis and biological properties

• Published in: Transition metal chemistry (Weinheim) 2000-08, Vol.25 (4), p.456-460
• Main Authors: Tarafder, M Tofazzal, H, Ali, Manaf A, Wee, D Juan, Azahari, Kasbollah, Silong, Sidik, Crouse, Karen A
• Format: Article
• Language: English
• Subjects: Aspergillus ochraceous; Bacillus cereus; Bacteria; Candida albicans; Pseudomonas aeruginosa
• ISSN: 0340-4285; 1572-901X
• DOI: 10.1023/A:1007062409973

Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=Ni^sup II^, Cu^sup II^, Cr^sup III^, Sb^sup III^, Zn^sup II^, Zr^sup IV^ or U^sup VI^ with X = H^sub 2^O, Cl]. The ligand produced a bis-chelated complex of composition [Th(ONS)^sub 2^] with Th^sup IV^. Square-planar structures are proposed for the Ni^sup II^ and Cu^sup II^ complexes. Antimicrobial tests indicate that the Schiff base and five of the metal complexes of Cu^sup II^, Ni^sup II^, U^sup VI^, Zn^sup II^ and Sb^sup III^ are strongly active against bacteria. Ni^sup II^ and Sb^sup III^ complexes were the most effective against Pseudomonas aeruginosa (gram negative), while the Cu^sup II^ complex proved to be best against Bacillus cereus (gram positive bacteria). Antifungal activities were also noted with the Schiff base and the U^sup VI^ complex. These compounds showed positive results against Candida albicans fungi, however, none of them were effective against Aspergillus ochraceous fungi. The Schiff base and its zinc and antimony complexes are strongly active against leukemic cells (CD^sub 50^ = 2.3-4.3 μg cm^sup -3^) while the copper, uranium and thorium complexes are moderately active (CD^sub 50^ = 6.9-9.5 μg cm^sup -3^). The nickel, zirconium and chromium complexes were found to be inactive.[PUBLICATION ABSTRACT]