Synthesis and characterization of some coordinated metal and charge transfer complexes of isonicotinic acid hydrazide ligand with 2-hydroxyacetophenonylidene.

A new series of coordinated metal (Fe(III), Co(II) and Cu(II)) and charge transfer complexes of Schiff base isonicotinic acid (2-hydroxy acetophenonylidene) hydrazide (L) have been synthesized. The ligand (L), its metals and CT complexes were characterized by UV-Vis spectra, FT-IR, HNMR and elemental analysis as well as conductance measurements. The pK of L was determined in universal buffer solutions (20% v/v EtOH-HO) with varying pH's values. The molar conductivity measurements prove the non-electrolytic nature of all metal complexes. Furthermore, the thermogravimetry (TG) and differential thermal analysis (DTA) of the synthesized complexes were carried out in the range of 30-1000 °C. In addition, interaction of (L) as an electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as π-type electron acceptor has been studied and characterized. The observed new band at 585 nm might be assigned as charge transfer (CT) absorption band. The electronic absorption spectrum of L-DDQ interaction is found to be dependent on time. The IR spectra of L with the coordinated metals and CT-complexes revealed new main IR bands, which strongly support the formation of complexes. The stoichiometry of the complexes was determined from photometric titration methods which are in accordance with the results of elemental analyses. The ratio were found to be 1:2 (metal:L) and 1:1 (L:DDQ). The spectra of L, its coordinated metals and CT complexes are fully discussed.