The ligand N,N′-diformylhydrazine (DFH) is a resonance hybrid of its keto-and enol-forms. The resonance structures indicate enolisation of one as well as both the carbonyl groups. This indicates the presence of dissociable protons in the molecule. Equilibrium studies carried out with DFH indicate the presence of one dissociable proton. The solid complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) with DFH have been synthesized, and have been characterized by elemental analysis, magnetic susceptibility, IR, Far-IR, 1 H NMR, TGA, FAB and reflectance spectra. IR and 1 H NMR spectra of the complexes indicate deprotonation of both the enol protons upon complexation. Elemental and TG analyses of Mn(II), Ni(II), Zn(II) DFH complexes indicate 1 : 1 metal to ligand composition. The dimeric nature of the Mn(II)-DFH complex is supported by its FAB spectrum.

Potentiometric titrations were carried out with 2-(2'-hydroxy)phenyl benzothiazoline (HPBT) in various 50%v/v aquo-organic media (dioxan-water, acetone-water, methanol-water, and ethanol-water) and in different percentages of dioxan. The results indicated that the ligand is a monoprotic acid with pKa corresponding to the hydroxyl group. The pKa value of HPBT determined in various aquo-organic media followed the regular order of the reciprocal of dielectric constant. The solid metal complexes employing HPBT were synthesized and characterized. Spectral studies of these metal complexes [M(II) = Co, Ni, Cu and Zn] complexes indicated ring cleavage and formation of bis benzylidene disulphide (BBDS) during complex formation.

Alkaloids are a category of molecules in nature around the globe with a relatively large occurrence. These are chemicals and biomolecules that are very complex. Alkaloids are compounds of a very diverse class of secondary plant metabolites; alkaloids, such as anticholinergic, antitumor, diuretic, antiviral, antihypertensive, antiulcer, analgesic, and anti-inflammatory, have been linked to extensive list of biological activities. The basic character of alkaloids allows salts to be formed with mineral acids or organic acids, alkaloid salts are usually soluble in water and dilute alcohols, and are not soluble in organic solvents except in rare cases. This research is carried out mainly in the context and classification of alkaloids and alkaloids pharmacological practices.