Oxotitanium(IV) complexes of some bis-unsymmetric Schiff bases: Synthesis, structural elucidation and biomedical applications

A number of oxotitanium(IV) complexes of the type TiOL with bis-unsymmetric dibasic tetradentate Schiff base (LH2) containing ONNO donor atoms have been synthesized. Mono-Schiff base (OPD-HNP) was prepared by the condensation of 1:3 molar ratio of 2-hydroxy-1-naphthaldehyde (HNP) with o-phenylenediamine (OPD). Dibasic unsymmetric tetradentate diamine Schiff bases were prepared by the reaction of OPD-HNP with 2-hydroxyacetophenone, 2-hydroxypropeophenone, benzoylacetone, acetylacetone and ethylacetoacetate. Further, titanylacetylacetonate was reacted with these ligands to obtain their metal complexes. On the basis of analytical and physiochemical data, the formation of complexes as TiOL was suggested having square pyramidal geometry. Quantum mechanical approach also confirmed this geometry. The assessment of the synthesized ligands and their complexes showed that some behave as good inhibitors of mycelial growth against selected phytopathogic fungi but weak inhibitors against some selected bacteria. A few of them also showed antioxidant properties.