Hydrothermal synthesis and characterisation of BIS (4- Hydroxybenzaldehyde) - P - Phenylenediamine zinc (ii) phosphate

Abstract

The condensation of a para-phenylenediamine and two equivalent of para-hydroxybenzaldehyde in the presence of Zn²⁺ ions yielded a metallo-ligand of composition [ZnL₂Ph(NH₃)₂(H₂O)₂] I. Compound I melts at 126^oC and is soluble in common organic solvents such as ethanol  (C₂H₅OH), dimethylformamide (DMF) and dimethylsulphoxide (DMSO). The scanning electron micrograph of compound I reveals a rectangular block crystals. The metalloligand synthesized was reacted with ortho-phosphoric acid under hydrothermal conditions at 105^oC to obtain colourless crystals of compound II with composition [Zn₄L₂(HPO₄)₆(H₂O)₃]. Compound II is insoluble in common organic solvents and melts above 300^oC. The structure of compounds I and II have been studied with the help of Infrared and UV- visible spectroscopy. The complexes show broad band absorption in the region 3760 – 3765.71 cm^-1 due to the symmetric stretching vibration of the co-ordinated water molecule.

Keywords: Hydrothermal reaction, metalloligand,  parahydroxybenzaldehyde, para-phenylenediamine, zinc phosphate.