Unsymmetrical borole complexes as biocides: synthetic, structural and biological aspects

Triisopropoxyborane on treatment with catechol in equimolar ratio in excess of benzene affords the formation of 2-isopropoxybenzo-1,3-dioxa-2-borole [OC6H4OB(OPri)]. The interaction of [OC6H4OB(OPri)] with benzothiazolines, prepared by the condensation of [1-(2-thienyl)ethanone], [1-(2-pyridinyl)ethanone], [1-(2-furanyl)ethanone], and [1-(2-naphthenyl)ethanone] with 2-mercaptoaniline, yields complexes that have B--O, B--S, and B<--N bonds. The unsymmetrical borole complexes were subjected to microestimations and spectral analyses comprised of UV, IR, proton-1, boron-11, and carbon-13 nuclear magnetic resonance studies. The spectral studies point to a tetracoordinated environment around boron because the stereochemically active lone pair is also included in the coordination sphere. X-ray powder diffraction of a representative complex also has been carried out. In the quest for better fungicides and bactericides, studies were conducted to assess the growth-inhibiting potential of the synthesized complexes along with the ligands against various fungal and bacterial strains. The studies demonstrate that the concentrations reach levels that are sufficient to inhibit and kill the pathogens. Furthermore, the results achieved from biological activity also have been compared with the conventional fungicide, Bavistin, and conventional bactericide, Streptomycin.