ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of the critical micelle concentration and thermodynamic parameters of phenylcarbamic acid derivatives using a fluorescence method

Eva Salanci, Ivan Malík, Róbert Šandrik, Daniel Pecher, and Fils Andriamainty

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic

E-mail: salanci@fpharm.uniba.sk

Received: 10 September 2020  Accepted: 25 January 2021

Abstract:

Critical micelle concentration (CMC) values of 1-[3-(2-alkoxyphenylcarbamoyloxy)-2-hydroxypropyl]-4-(4-fluorophenyl)piperazin-1-ium-chlorides (alkoxy = methoxy to propoxy; 6a–c) were determined by a fluorescence method using pyrene as a probe over a temperature interval T = 293.15–313.15 K. The dependence of CMC on T turned out forming the U-shape. The curve was drawn by fitting of observed values using a second-degree polynomial function and so-called power-law equation, minimum of the curve was observed at T = 298.15 K. Thermodynamic parameters of micellization, i.e., molar Gibbs energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), respectively, were calculated according to a phase separation model. Following the observations, the enthalpy (ΔH°) and entropy contributions

(−TΔS°) to the molar Gibbs energy (ΔG°) were calculated. It was found that contribution of enthalpy increased with the increase in temperature, and entropy contribution decreased within chosen range of the temperature. Finally, the enthalpy–entropy compensation and the compensation temperature (T_c) were determined.

Keywords: Critical micelle concentration; Micellization; Thermodynamic parameters; Fluorescence study

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01539-5

Chemical Papers 75 (7) 3081–3090 (2021)