The Synthesis, Self-Assembled Structures, and Microbicidal Activity of Cationic Gemini Surfactants with Branched Tridecyl Chains

Martin Pisárčik,Lukáš Hubčík,Miloš Lukáč,Branislav Horváth,Marián Bukovský,Matúš Pupák,Ferdinand Devínsky

doi:10.3390/molecules24234380

Martin Pisárčik, Lukáš Hubčík + Show 5 more

Open Access

https://doi.org/10.3390/molecules24234380

Copy DOI

Abstract

Cationic gemini surfactants with polymethylene spacer and linear alkyl chains containing an even number of carbon atoms have been extensively studied in the recent past, with the emphasis put on the determination of their aggregation behaviour in aqueous solution and their biological properties. However, the information on the aggregation of branched gemini surfactants with an odd number of carbon atoms in their alkyl chains is only sparsely reported in the literature. To help cover this gap in the research of cationic gemini surfactants, a series of branched bisammonium cationic gemini surfactants with an odd number of carbon atoms in alkyl chains (tridecane-2-yl chains) and a polymethylene spacer with a variable length ranging from 3 to 12 carbon atoms have been synthesized and investigated. Critical micelle concentration, which was determined by three methods, was found to be in the order 10−4 mol/L. A comparison of the obtained data of the novel series of tridecyl chain geminis with those of gemini surfactants with dodecyl chains and an identical spacer structure revealed that structural differences between both series of gemini surfactants result in different aggregation and surface properties for surfactants with 6 and 8 methylene groups in the spacer (N,N’-bis(tridecane-2-yl)-N,N,N’,N’-tetramethylhexane-1,6-diaminium dibromide and N,N’-bis(tridecane-2-yl)-N,N,N’,N’-tetramethyloctane-1,8-diaminium dibromide) with the cmc values 8.2 × 10−4 mol/L and 6.5 × 10−4 mol/L, respectively, as determined by surface tension measurements. Particle size analysis showed the formation of small stable spherical micelles in the interval between 2.8 and 5 nm and with zeta potential around +50 mV, which are independent of surfactant concentration and increase with the increasing spacer length. Microbicidal activity of 13-s-13 gemini surfactants was found to be efficient against Gram-positive, Gram-negative bacteria and yeast.

Highlights

Gemini cationic bisammonium surfactants with various structural modifications both in the spacer part and in alkyl chains continue to attract broad interest from the scientific community as well as Molecules 2019, 24, 4380; doi:10.3390/molecules24234380 www.mdpi.com/journal/moleculesMolecules 2019, 24, 4380 various industrial branches and applications over several decades [1,2]
The purpose of this paper is to report aggregation in the bulk and surface behaviour at the air/water interface of cationic bisammonium gemini surfactants with the odd number of carbon atoms and branched hydrophobic chains and a polymethylene spacer of variable length, which
The present study provides information about the synthesis, physicochemical aggregation, and microbicidal activity of a series of branched bisammonium cationic gemini surfactants 13-s-13 with tridecane-2-yl chains and a variable spacer length

Summary

Introduction

Gemini cationic bisammonium surfactants with various structural modifications both in the spacer part and in alkyl chains continue to attract broad interest from the scientific community as well as Molecules 2019, 24, 4380; doi:10.3390/molecules24234380 www.mdpi.com/journal/moleculesMolecules 2019, 24, 4380 various industrial branches and applications over several decades [1,2]. Cationic gemini bisammonium surfactants play an important role in modern nanotechnologies as modifiers of silica nanosheets [21], dispersants of carbon nanotubes [22], or efficient stabilisers of silver [23,24,25] and gold nanoparticles [26,27] Due to their molecular structure consisting of two hydrophobic chains and two ammonium polar heads connected with a spacer, aggregation properties of gemini surfactants are superior to those of conventional single-chain surfactants. Cationic bisammonium gemini surfactants with simple polymethylene spacer belong to one of the most studied groups of cationic geminis Their aggregation properties strongly depend on the length of polymethylene spacer, i.e. on the number of methylene groups that compose the spacer [35,36,37,38,39,40]. In the field of nonionic systems, they interact with cyclodextrins [49,50]

Objectives

Methods

Results

Conclusion