Single ion transfer entropies in binary mixtures of isodielectric protic ethylene glycol and dipolar aprotic N, N-dimethylformamide vis-à-vis 3D-structuredness of aqueous co-solvents

Abstract

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> Single ion transfer entropies, <i style="">∆S</i>⁰_t(i) of some electrolytes like tetraphenylarsonium picrate, potassium tetraphenylborate, potassium picrate and potassium chloride from protic ethylene glycol to its isodielectric mixtures with 20, 40 and 60 wt % protophilic dipolar aprotic N,N-dimethylformamide have been determined at 25 °C using the Ph₄AsPh₄B TATB reference electrolyte assumption, and solubility of the salts measured at 15°, 20°, 30° and 35°C, and that at 25 °C reported earlier. <i style="">∆S</i>⁰_t(i) of the ions as well as their chemical effects, <i style="">∆S</i>⁰_t,_ch(i) (as obtained after correcting for the cavity effects, <i style="">∆S</i>⁰_t,_cav(i) and ignoring Born-type electrostatic effect <i style="">∆S</i>⁰_t,_Born(i), since the solvent mixtures are isodielectric), exhibit mirror-image behaviour of simple cation like K⁺ and anion like Cl^-, which can be explained in the light of Kundu <i>et al.</i>’s four step transfer process. However, this feature in completely non-aqueous solvent system is strikingly different from that in aquo-cosolvent systems studied earlier, and offers an indirect evidence that the ‘characteristic mirror-image relationship’ of simple cations and anions, in aqueous cosolvent systems, is, as contended earlier, associated with 3D-‘structuredness’ of aqueous cosolvent systems. This reiterates that <i>T</i><i style="">∆S</i>⁰_{t, ch}(i) serves as a useful probe for the 3D-structuredness of aqueous cosolvents. </smarttagtype>