Synthesis and Spectral Characterization of Lanthanide Complexes Containing Bidentate Schiff Base Derived From Pyridine-2-Carbaldehyde and 2-Hydrazinylquinoline

Abstract

A series of new rare earth complexes of La(III) of the type [Ln(L) 2 (H 2 O) 2 ]Cl 3 where Ln= La(III), Pr(III), Nd(III), Sm(III) and Tb(III) and L=Schiff base ligand, 2-[2-(pyridin-2-ylmethylidene)hydrazinyl]quinoline (PCQH). These complexes have been characterized on the basis of elemental analysis (Ln, C, H, N, and Cl), melting point, IR, 1 H-NMR and UV-Vis spectral data. X-ray powder diffraction study of two of the complex [Nd(L) 2 (H 2 O) 2 ]Cl 3 and Pr(L) 2 (H 2 O) 2 ]Cl 3 was found to be on powder diffraction with Cu-K α1 radiation (λ = 1.5406 Å) showing monoclinic crystal system. The complexes were found to be colored solid and were soluble only in DMF and DMSO. INTRODUCTION Compounds which contain pyridine and its derivatives or Schiff bases as ligands have occupied a central role in the development of coordination chemistry and biochemistry. Schiff base ligands form a stable complex with different transition metal ions. Schiff bases having multidentate coordination sites are known to form complexes with transition metal ions readily [1-6]. In particular, the transition metal complexes have been the subject for thorough investigation because of their extensive application in wide ranging areas from material science to biological sciences [7-9]. The formation of Schiff base intermediate in reactions of biological importance is well documented [10]. Schiff base and their metal complexes have a variety of applications in biological, clinical and analytical fields. Many potent antibacterial and antifungal Schiff base compounds of heterocyclic compounds were reported [11-14]. Some heterocyclic Schiff bases can act as antibacterial agent and antifungal agent [15-16]. Chemical properties of quinoline and its derivatives are of interest due to their biological Activity [17], coordination capacity [18], and their use as metal extracting agents [19]. The coordination chemistry, novel structural features and biological activity of the Schiff bases have also attracted attention. The quinoline skeleton is often used for the design of many synthetic compounds with diverse pharmacological properties such as, anti-inflammatory [20], antimicrobial agents [21], cytotoxic activity [22], antidotal and antibacterial [23], antitumor activity [24], antimalarial [25]. Additionally, quinoline derivatives find use in the synthesis of fungicides [2], virucides, biocides, alkaloids, rubber