Synthesis,physicochemical, and biological activities of novel N‐acyl tyrosine monomeric and Gemini surfactants in single and SDS/CTAB–mixed micellar system

A series of single‐chained N‐acyl tyrosine surfactants with varying chain lengths (C₁₀‐C₁₈) and degree of unsaturation, as well as an N‐acyl Gemini tyrosine surfactant with chain length C₁₂, were synthesized, and the structures were confirmed using spectral analysis. The effect of chain length and level of unsaturation on the physicochemical and antibacterial properties of the N‐acyl tyrosine surfactants was evaluated. The C₁₂ derivative displayed the optimum antibacterial activity among the single chain surfactants, and the presence of double bond in the oleoyl derivative enhanced the antibacterial activity over its saturated analogue. The N‐acyl Gemini surfactant displayed the highest antibacterial activity among the series and also showed greater micelle forming ability than its single chain analogue. Mixed micellar behavior of the N‐acyl Gemini surfactant with conventional cationic (CTAB) and anionic (SDS) surfactants in aqueous solution was studied. The negative value of the interaction parameter β₁₂ observed for the N‐acyl Gemini in binary mixture with CTAB surfactant indicated a synergistic interaction within the mixed micellar system. However, the binary mixture with SDS displayed antagonistic behavior. The binary mixture of N‐acyl Gemini surfactant with CTAB displayed better antibacterial activity and foaming properties than with SDS mixtures. Optimum antibacterial activity was observed for N‐acyl Gemini surfactant with mole ratio 0.4 to 0.6 in the CTAB binary mixture, at which the lowest ocular irritation index was observed. Overall, the study showed that the Gemini surfactant in combination with the conventional surfactant CTAB can be used as potential ingredients in detergent and pharmaceutical formulations.     

杂双子咪唑表面活性剂的合成及其表面性能

合成了一系列以两个亚甲基为联接基的杂双子咪唑表面活性剂([C_m-2-C_nim]Br_{2, m, n}=8, 10, 12, 14, 16; m≠n). 用氢谱和质谱对其结构进行了表征. 探索了物料比、反应温度和时间对反应产率的影响. 对合成的杂双子咪唑表面活性剂的表面活性进行了研究,讨论了分子结构的不对称程度对表面活性的影响.     

Surface,micellar, and thermodynamic properties of antidepressant drug nortriptyline hydrochloride with TX‐114 in aqueous/urea solutions

This paper deals with a comprehensive study of the mixed micellization and adsorption behavior of mixed systems enclosing an amphiphilic antidepressant drug nortriptyline hydrochloride (NOT) and Triton X‐114 (TX‐114) (nonionic surfactant) in aqueous/urea (500 mmol·kg^?1 and 1000 mmol·kg^?1) solutions by tensiometric method. The NOT is used for the cure of depression. For comparison purpose cmc value of pure drug NOT was also evaluated by conductimetric technique. Different theoretical models like Clint, Rubingh, and Rosen were used to get information about the nature of interaction between the components in bulk and at the interface. Because of the occurrence of urea increase in the surface charge of the micelles was obtained resulting a delay of the micelles formation. The cmc values of the mixed systems of NOT and TX‐114 were found to be in between the cmc values of pure components, which signify nonideal mixed system having attractive interactions in the absence and presence of urea. Various parameters such as micellar mole fractions of TX‐114 (X₁^m, X₁^σ) in solution and at interface, interaction parameter (β^m/β^σ) in solution and at interface, and activity coefficient in solution and at interface were evaluated and discussed using Rubingh's and Rosen's models. Surface excess (Γ_max) increases that means minimum area per head group (A_min) decreases as mole fraction (α₁) of TX‐114 increases in the absence/presence of urea. Different thermodynamic parameters have been calculated and discussed. The ?G⁰_m values achieved are all negative both in the absence and occurrence of urea.     

Bulk and surface properties of liquid Al-Mg, Au-Sn, and Mg-Tl compound forming alloys

We have used phenomenological models based on statistical mechanics to study the bulk and surface properties of Au-Sn, Al-Mg, and Mg-Tl binary liquid alloys. Our study reveals that the three alloys are weakly ordered systems with the most stable intermetallic complexes at temperatures of 823 K, 1073 K and 923 K been AuSn, Al₃Mg₂ and Mg₄Tl, respectively. An analysis of Warren-Cowley short-range order parameter indicates that the weakest intermetallic compound is Al-Mg while Au-Sn is observed to be more chemically ordered than Mg-Tl. Furthermore, our surface properties calculations shows that Mg-atom and Sn-atom segregate to the surface over the whole concentration range of Al-Mg and Au-Sn alloys, respectively. In Mg-Tl, there is a competing effect between Tl-atom being drawn into the bulk and at the same time Tl-atom wanting to segregate to the surface over the whole concentration range.