Charge transfer complexes of chloranil with drugs

The study of charge transfer (CT) complexes of chloranil with drugs (Naproxen, Nerolin, Methyl anthranilate, Isoxsuprine and Nylidrin) showed that there is a significant interaction between the acceptor and donors as evidenced by colour changes and absorption spectra. From the position of CT bands, the ionization potentials (IPs) of donors were evaluated using appropriate equations. The donor’s abilities are in the following order: Naproxen > Nerolin > Methyl anthranilate > Isoxsuprine > Nylidrin. Benesi-Hildebrand plots, Job's variation method indicated the formation of 1:1 complex in each case. The stability constants that varied in the same order as IPs are useful in estimation of the concentration of drugs either in pure form or in formulations and give a guide to the estimation of the drugs in industry and pharmacy. Thermodynamic parameters (-ve values of ∆H) suggest that the formation of complex is exothermic. The -∆S values indicate a decrease in the degree of freedom of molecules upon complexation, while -∆G values indicate that complex formation is spontaneous and the values give a relative estimation of interaction between donors and acceptor.