Imidazolium-based zwitterionic surfactants: characterization of normal and reverse micelles and stabilization of nanoparticles.

This paper presents the physicochemical properties of micellar aggregates formed from a series of zwitterionic surfactants of the type 3-(1-alkyl-3-imidazolio)propane-sulfonate (ImS3-n), with n = 10, 12, 14, and 16. The ImS3-n dipolar ionic surfactants represent a versatile class of dipolar ionic compounds, which form normal and reverse micelles. Furthermore, they are able to stabilize nanoparticles in water and in organic media.

Simultaneous nondestructive analysis of palladium, rhodium, platinum, and gold nanoparticles using energy dispersive X-ray fluorescence.

A selective method is proposed for the determination of palladium, gold, and sulfur in catalytic systems, by direct liquid analysis using energy dispersive X-ray fluorescence (EDXRF), under an atmosphere of helium or air. This method allows a nondestructive analysis of palladium, rhodium, platinum, and gold nanoparticulate catalysts stabilized by imidazolium propane sulfonate based zwitterionic surfactants, allowing the samples to be reused for catalytic studies. The signals from palladium, rhodium, platinum, and gold samples in the presence of imidazolium propane sulfonate-based zwitterionic surfactants obtained using EDXRF before (Pd(2+), Rh(2+), Pt(2+), and Au(3+)) and after (Pd(0), Rh(0), Pt(0), and Au(0)) formation of nanoparticles are essentially identical.

A bio-inspired sensor based on surfactant film and Pd nanoparticles.

A bio-inspired complex, [(bpbpmp)Fe(III)(m-OAc)(2)Cu(II)](ClO(4)), was combined with a zwitterionic surfactant (ImS3-14) stabilizing pre-formed palladium nanoparticles and coated on a glassy carbon electrode (GCE). This bio-inspired surfactant film was capable of catalyzing redox reactions of dihydroxybenzenes, thus allowing the simultaneous electrochemical quantification of CC and HQ in cigarette residue samples by square-wave voltammetry (SWV). The best experimental conditions were obtained using phosphate buffer solution (0.

The chameleon-like nature of zwitterionic micelles: effect of cation binding.

Addition of salts, especially perchlorates, to zwitterionic micelles of SB3-14, C(14)H(29)NMe(2)(+)(CH(2))(3)SO(3)(-), induces anionic character and uptake of H(3)O(+) by SB3-14 micelles. Thus, the addition of alkali metal perchlorates accelerates the acid hydrolysis of 2-(p-heptoxyphenyl)-1,3-dioxolane, HPD, in the presence of SB3-14 micelles, which depends on the local proton concentration at the micelle surface. The addition of metal chlorides to solutions of such perchlorate-modified SB3-14 micelles decreases both the negative zeta potential of the micelles and the observed rate constant for acid hydrolysis of HPD.

pKa determinations of xanthene derivates in aqueous solutions by multivariate analysis applied to UV-Vis spectrophotometric data.

Xanthenes form to an important class of dyes which are widely used. Most of them present three acid-base groups: two phenolic sites and one carboxylic site. Therefore, the pKa determination and the attribution of each group to the corresponding pKa value is a very important feature.