Adrianna Szulc

A homologous series of but-2-ene-1,4-bis(N-alkyl-N,N-dimethylammonium bromides) containing C12, C14, C16, and C18 alkyl chains was investigated to determine the influence of hydrophobic-chain length and a semi-rigid unsaturated spacer on aggregation and antimicrobial properties. The critical micelle concentration decreased from the C12 to the C16 derivative, whereas further chain elongation to C18 resulted in an increase in CMC, indicating that micellization is governed not only by hydrophobicity but also by molecular packing effects. Negative standard Gibbs energies confirmed spontaneous micellization. Antimicrobial activity showed the opposite trend: the C12 derivative was the most active compound against all tested microorganisms, with MIC (minimum inhibitory concentration) values as low as 0.06 mM (12-4ene-12 against C. albicans). Increasing alkyl-chain length markedly reduced activity, particularly against Escherichia coli, for which the MIC increased from 0.12 mM for C12 to over 62.5 mM for C18, demonstrating a pronounced cut-off effect. Staphylococcus aureus remained more susceptible to longer-chain homologues than E. coli, while notable activity was also observed against yeast and filamentous fungi. DFT calculations further indicated that spacer unsaturation affects the electronic properties of the molecules. Overall, the results demonstrate a strong relationship between alkyl-chain length, micellization, spacer rigidity, and antimicrobial performance.

A homologous series of but-2-ene-1,4-bis(N-alkyl-N,N-dimethylammonium bromides) containing C12, C14, C16, and C18 alkyl chains was investigated to determine the influence of hydrophobic-chain length and a semi-rigid unsaturated spacer on aggregation and antimicrobial properties. The critical micelle concentration decreased from the C12 to the C16 derivative, whereas further chain elongation to C18 resulted in an increase in CMC, indicating that micellization is governed not only by hydrophobicity but also by molecular packing effects. Negative standard Gibbs energies confirmed spontaneous micellization. Antimicrobial activity showed the opposite trend: the C12 derivative was the most active compound against all tested microorganisms, with MIC (minimum inhibitory concentration) values as low as 0.006 mM. Increasing alkyl-chain length markedly reduced activity, particularly against Escherichia coli, for which the MIC increased from 0.012 mM for C12 to >125 mM for C18, demonstrating a pronounced cut-off effect. Staphylococcus aureus remained more susceptible to longer-chain homologues than E. coli, while notable activity was also observed against yeast and filamentous fungi. DFT calculations further indicated that spacer unsaturation affects the electronic properties of the molecules. Overall, the results demonstrate a strong relationship between alkyl-chain length, micelliza-tion, spacer rigidity, and antimicrobial performance.

This feature article reviews the strategies and principles underlying the construction of amino acid-derived supramolecular assemblies, covering both non-covalent and dynamic covalent approaches.

The petroleum industry faces intensifying challenges related to the depletion of easily accessible reservoirs and the growing energy demand, necessitating the adoption of advanced chemical agents that can operate under extreme conditions. Cationic gemini surfactants, characterized by their unique dimeric architecture consisting of two hydrophilic head groups and two hydrophobic tails, have emerged as superior alternatives to conventional monomeric surfactants due to their enhanced interfacial activity and physicochemical resilience. This review provides a comprehensive analysis of the literature concerning the molecular structure, synthesis, and functional applications of cationic gemini surfactants across the entire oil value chain, from extraction to refining. The analysis reveals that gemini surfactants exhibit critical micelle concentrations significantly lower than their monomeric analogs and maintain stability in high-temperature and high-salinity environments. They demonstrate exceptional efficacy in enhanced oil recovery through ultra-low interfacial tension reduction and wettability alteration, while simultaneously serving as effective drag reducers, wax inhibitors, and dual-action biocidal corrosion inhibitors in transportation pipelines. Cationic gemini surfactants represent a transformative class of multifunctional materials for the oil industry.

The petroleum industry faces intensifying challenges related to the depletion of easily accessible reservoirs and the growing energy demand, necessitating the adoption of ad-vanced chemical agents that can operate under extreme conditions. Cationic gemini sur-factants, characterized by their unique dimeric architecture consisting of two hydrophilic head groups and two hydrophobic tails, have emerged as superior alternatives to con-ventional monomeric surfactants due to their enhanced interfacial activity and physico-chemical resilience. This review provides a comprehensive analysis of the literature concerning the molecular structure, synthesis, and functional applications of cationic gemini surfactants across the entire oil value chain, from extraction to refining. The analysis reveals that gemini surfactants exhibit critical micelle concentrations signifi-cantly lower than their monomeric analogues and maintain stability in high-temperature and high-salinity environments. They demonstrate exceptional efficacy in enhanced oil recovery through ultra-low interfacial tension reduction and wettability alteration, while simultaneously serving as effective drag reducers, wax inhibitors, and dual-action bio-cidal corrosion inhibitors in transportation pipelines. Cationic gemini surfactants repre-sent a transformative class of multifunctional materials for the oil industry.

Cationic gemini surfactants, which constitute a unique class of amphiphilic molecules composed of two hydrophilic ammonium groups and two hydrocarbon tails connected by a spacer, have emerged as highly versatile functional agents with superior interfacial activity and self-assembly behavior compared to conventional monomeric analogs. Their structural tunability enables precise control over physicochemical properties, making them attractive for applications across diverse scientific and industrial domains. In biomedical sciences, gemini surfactants act as potent antimicrobial and anti-biofilm agents, as well as efficient carriers for drug and gene delivery. In nanotechnology and optoelectronics, they facilitate the synthesis and stabilization of nanoparticles, quantum dots, and perovskite nanocrystals, leading to improved colloidal stability, enhanced photophysical performance, and extended material lifetimes. Within the petroleum industry, gemini surfactants have proven effective in enhanced oil recovery (EOR) by reducing interfacial tension and in crude oil transportation as drag-reducing agents (DRAs), significantly lowering viscosity, turbulence, and pipeline energy losses. This review summarizes recent advances in the chemistry, mechanisms of action, and applications of gemini surfactants, highlighting their multifunctionality and emphasizing their potential in the development of next-generation sustainable technologies.

Cationic surfactants, accounting for approximately 7% of the global surfactant market, are widely used in applications such as fabric softeners, biocides, and corrosion inhibitors. Recently, gemini surfactants—comprising two amphiphilic units linked by a spacer—have attracted significant interest due to their superior surface activity, lower critical micelle concentrations, and strong antimicrobial properties. However, their poor biodegradability, resulting from their complex molecular structure, has raised environmental concerns. To address this, researchers have developed ester-based gemini surfactants incorporating biodegradable bonds. This study aimed to investigate the relationship between the structure of ester-based gemini surfactants (hydrophobic chain length and spacer type) and their antimicrobial activity against bacteria and fungi. Three series of compounds featuring different functional groups in the spacer were synthesized, along with a trimeric surfactant for comparative purposes. The results demonstrated that both the hydrophobic chain length and the presence of additional cationic groups significantly influence the CMC and antimicrobial performance. Quantum mechanical calculations were also performed to search for correlations between electronic properties and chemical reactivity of compounds. These findings highlight that ester-based gemini surfactants combine high surface and antimicrobial activity with the potential for improved biodegradability, making them promising candidates for use in environmentally friendly applications.

Cationic gemini surfactants are used due to their broad spectrum of activity, especially surface, anticorrosive and antimicrobial properties. Mixtures of cationic and anionic surfactants are also increasingly described. In order to investigate the effect of anionic additive on antimicrobial activity, experimental studies were carried out to obtain MIC (minimal inhibitory concentration) against E. coli and S. aureus bacteria. Two gemini surfactants (12-6-12 and 12-O-12) and two single quaternary ammonium salts (DTAB and DDAC) were analyzed. The most commonly used commercial compounds of this class, i.e., SDS and SL, were used as anionic additives. In addition, computer quantum mechanical studies were also carried out to confirm the relationship between the structure of the mixture and the activity. The obtained results of microbiological tests and quantum mechanical calculations are in agreement with each other and show the lack of synergism in catanionic mixtures in the case of antibacterial activity.

Cationic gemini surfactants are used due to their broad spectrum of activity, especially surface, anticorrosive and antimicrobial properties. Mixtures of cationic and anionic surfactants are also increasingly described. In order to investigate the effect of anionic additive on antimicrobial activity, experimental studies were carried out to obtain MIC (minimal inhibitory concentration) against E. coli and S. aureus bacteria. Two gemini surfactants (12-6-12 and 12-O-12) and two single quaternary ammonium salts (DTAB and DDAC) were analyzed. The most commonly used commercial compounds of this class, i.e. SDS and SL, were used as anionic additives. In addition, computer quantum-mechanical studies were also carried out to confirm the relationship between the structure of the mixture and the activity.

Organic corrosion inhibitors are one of the five ways, besides material selection, design, cathodic protection and coatings, to protect materials against corrosion. Corrosion is an ubiquitous phenomena that deteriorates all materials, metals, plastics, glass and concrete. The costs of corrosion are tremendous and amounts to 4.0% of gross domestic product (GDP) in USA. The similar losses of GDP are noted in all countries around the world. At this point of time, there is no way to completely stop the corrosion processes. Some new solutions can only slow this process. Organic corrosion inhibitors are widely used in industry because of their effectiveness at wide range of temperatures, compatibility with protected materials, good solubility in water, low costs and relatively low toxicity. Organic corrosion inhibitors adsorb on the surface to form protective film which displace water and protect it against deteriorating. Effective organic corrosion inhibitors contain nitrogen, oxygen, sulfur and phosphorus with lone electron pairs as well can contain structural moieties with π-electrons that interact with metal favoring the adsorption process. This review presents mechanisms and monitoring of corrosion, laboratory methods for corrosion study, relationship between structure and efficacy of corrosion inhibitions, theoretical approach to design new inhibitors and some aspects of biocorrosion.