Computation studies on Schiff base ligands and equilibrium studies on their metal complexes

Department of Chemistry, Manonmanium Sundaranar University, Abishekapatti, Tirunelveli-627 012,

Tamilnadu, India

E-mail : msnairchem@rediffmail.com

Manuscript received 9 October 2007, revised 8 January 2008, accepted 16 January 2008

Schiff bases of furfural with L-threonine (thr) and L-glutamine (gin) were studied by quantum mechanical method using GAMESS program. Geometry of the Schiff bases was optimized by HF and MP2 methods. The Schiff bases are non-planair. Based on the Mulliken's charge density calculations, furan oxygen, imino nitrogen and carboxylato oxygen atoms were found to be the potential binding sites. Equilibrium studies of Coli, Ni^ll, Cu^II and Zn^II-furfural (A)- L-threonine (thr), L-tryptophane (trp) and L-glutamine (gin) (B) systems were done by batch wise titration method at 25 ºC and ionic strength of 0.1 µ (KNO₃). All the systems have MAB, MAB₂ or MAB₂ types of Schiff base complexes. The results indicate that the Schiff base (AB) binds to the metal ions in terdentate manner through furan oxygen, imino nitrogrn and carboxylato oxygen atoms.