Spectral studies of Charge transfer (CT) Complexes for Schiff bases derived from 3- methoxy-4-hydroxybenzaldehyde with various acceptors molecules and the stability of these bases in different medium.

Abstract

Five Schiff bases have been synthesized by condensation of molar quantities (2:1) from 3-methoxy-4-hydroxy benzaldehyde with five diaminoalkane. The molecular structures of these Schiff bases were characterized by available methods; melting points, elemental analysis, infrared and electronic spectral measurements. The physical parameters of these compounds(1-5) as donor molecules the ionization potential(Ip), the dissociation energies of the excited state(W) and their charge- transfer complexes such as the equilibrium constant (KCT), the molar extinction coefficient (εCT), the energy of complexes (hνCT) and the free energy of complex (ΔG) with different electron acceptors 2,3,5,6-tetrachloro-p- benzoquinone (p-CA), 2,3-dichloro-5,6-dicyano p-benzoquinone (DDQ), phenyl fluorine (PF), 2,4,6-trinitro phenol (TNP) and tetra hydroxy p-benzoquinon (THQ) in CH₂Cl₂ solution have been estimated from the electronic spectrum at λmax absorption of their CT complexes. The study also includes the hydrolysis of the Schiff bases in different media (50 % C₂H₅OH, 30% HCl and gla. CH₃COH) beside the hydrolysis in different pH values (3.5 -11.0.)