Synthesis, characterization, thermal stability, reactivity, and antimicrobial properties of some novel lanthanide(III) complexes of 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Abstract

Two series of new lanthanide(III) complexes of the type [Ln(HSAT) 2 (H 2 O) 3 Cl 3 ] and [Ln(HSAT) 2 (NO 3 ) 3 ], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Tm, Yb, or Lu, and HSAT = 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene, are synthesized by the reaction of LnCl 3 or Ln(NO 3 ) 3 with the title ligand in ethanol. The complexes are characterized by elemental analysis, magnetic moment values, molar conductivity, IR, UV-Vis, and 1 H NMR spectral data. Two selected complexes are subject to thermogravimetric analysis, and their kinetic parameters are estimated using Coats-Redfern equation. The complex [La(HSAT) 2 (NO 3 ) 3 ] underwent facile transesterification when refluxed in methanol. The ligand and some selected complexes are screened for their antimicrobial properties. Antimicrobial activities of the ligand increase on coordination with the metal ion.