Some heteroleptic boron derivatives and their isomers derived from Schiff bases and glycol: Synthesis, characterization and antimicrobial activities

Abstract

Some new heteroleptic boron derivatives of the type [where R=CH3, R′=(CH2)2(2a); (CH2)3(2b); CH(CH3)CH2(2c), R=C6H5, R′=(CH2)2(2d); (CH2)3(2e); CH(CH3)CH2(2f)] have been synthesized by the reactions of tri-isopropyl borate with bifunctional tridentate Schiff bases and 2,2-dimethyl propane 1,3-diol in 1:1:1 molar ratio in refluxing benzene. Four isomers of corresponding heteroleptic derivatives 2a, 2b, 2e and 2f having the general formula [where R=CH3, R′=(CH2)2 (3a); (CH2)3 (3b), R=C6H5, R′=(CH2)3 (3e); CH(CH3)CH2 (3f) have also been synthesized by adopting different synthetic two-step processes. All these compounds have been characterized by elemental analyses, and their tentative structures have been proposed on the basis of IR, 1H, 13C, 11B NMR spectroscopic and FAB mass spectrometric studies. Schiff base ligands and their corresponding heteroleptic boron derivatives (2a-f) have also been screened for antimicrobial activities against pathogenic bacteria and fungi.