Promazine π-mers formation at a 1,2-dichloroethane/water interface

The behavior of promazine in 1,2-dichloroethane was studied using cyclic voltammetry at the ITIES and UV–vis spectrophotometry. The analysis of voltammograms and spectra obtained varying promazine concentration, pH, nature and concentration of organic electrolyte and applying positive polarisation at the interface allowed us to postulate a reaction scheme consisting in a first step of promazine partition to organic phase, followed by a charge transfer complex (CTC) formation with 1,2-dichloroethane. This CTC induces the oxidation of promazine to the corresponding radical cation which is stabilised in organic phase by π-mers formation. π-mer complexes form ion pairs with the anions of the organic base electrolyte. Similar results were found using methotrimeprazine, another phenothiazine derivative, with a methoxyl group attached to the ring. Chlorpromazine, triflupromazine, perphenazine and fluphenazine were stable in 1,2-dichloroethane.