Deciphering the role of alkyl chain length on interaction study of antidepressant drug-cationic surfactants in imidazolium based ionic liquid

To study the role of alkyl chain length on the thermodynamics and mixed micellization behavior of amitriptyline hydrochloride (AMT) with dodecyltrimethylammonium bromide (DTAB)/cetyltrimethylammonium bromide (CTAB) in imidazolium based ionic liquid 1-methyl-3-octylimidazolium chloride (Omim.Cl) at various mole fractions and several temperatures (varied: 298–313 K) was carried out by the electrical conductivity measurements. Mixed micellization behavior of CTAB with AMT demonstrates the synergistic interaction while DTAB with AMT favors antagonistic interaction, in the presence of Omim.Cl. The shift in nature of binding interaction from antagonistic to synergistic with increase in the alkyl chain length of cationic surfactant from DTAB to CTAB is elucidated in terms of the divergence in ideal and calculated values of critical micelle concentration ( cmc ) and micellar mole fraction ( X m ) and discussed in an appropriate manner. In addition, the values of various thermodynamic parameters were determined by using the results obtained from conductivity plots. They also support the results obtained from the interaction parameters.