Quaternary Salts Research Articles

Facile Functionalization of Charcoal by a Green Approach

The ability of charcoal, a low-cost material derived from biomass pyrolysis, to be functionalized via cation exchange in an aqueous solution, providing new interesting fillers with possible antimicrobial and flame-retardant properties, is discussed here. The adducts obtained through this sustainable procedure, show a significant uptake of close to 30% by weight of well-known quaternary phosphonium salts, tetraphenyl phosphonium bromide, and dodecyl triphenyl phosphonium bromide. The new functionalized materials were characterized by elemental analysis, wide-angle X-ray diffraction, infrared spectroscopy, and thermogravimetry. Additionally, a study of changing the ratio between the reagents for both adducts was performed to improve salt uptake and optimize the cationic exchange. Dispersibility tests showed the ability of functionalization to deeply change the polarities of the carbon materials to modify the compatibility and improve the possible interactions with different media, such as different polymer matrices.

Preparation and characterization of functionalized chitosan/polyvinyl alcohol composite films incorporated with cinnamon essential oil as an active packaging material

In this study, amphiphilic chitosan (NPCS-CA) was synthesized by grafting quaternary phosphonium salt and cholic acid onto the chain of chitosan, aiming to develop an active edible film based on NPCS-CA and polyvinyl alcohol (PVA) incorporated with cinnamon essential oil (CEO) by the casting method. The chemical structure of the chitosan derivative was characterized by FT-IR, 1H NMR and XRD. Through the characterization of FT-IR, TGA, mechanical and barrier properties of the composite films, the optimal proportion of NPCS-CA/PVA was determined as 5/5. And, the tensile strength and elongation at break of the NPCS-CA/PVA (5/5) film with 0.4 % CEO were 20.32 MPa and 65.73 %, respectively. The results revealed that the NPCS-CA/PVA-CEO composite films exhibited an excellent ultraviolet barrier property at 200–300 nm and significantly reduced oxygen permeability, carbon dioxide permeability and water vapor permeability. Furthermore, the antibacterial property of film-forming solutions against E. coli, S. aureus, and C. lagenarium was distinctly improved with the increase of NPCS-CA/PVA proportion. And, the multifunctional films effectively extended the shelf-life of mangoes at 25 °C based on the characterization of surface changes and quality indexes. The NPCS-CA/PVA-CEO films could be developed as biocomposite food packaging material.

Proton conduction in tetra-n-butylammonium bromide semiclathrate hydrate

Clathrate hydrate as well as ice has been spotlighted as promising materials to investigate the properties of hydrogen-bonded networks formed by the water molecules. In the semiclathrate hydrate (SCH, a kind of clathrate hydrate) consisting of host water molecules and guest quaternary onium salts, the anion takes part in the hydrogen-bonded networks with the water molecules. In the present study, we measured the electrical conductivity and electrical relaxation time in the single-crystalline tetra-n-butylammonium bromide (TBAB) SCH by electrochemical impedance spectroscopy. The results clearly revealed that the conduction carrier was proton. The electrical relaxation time of proton conduction in TBAB SCH was similar to the reorientation time of the water molecules in TBAB SCH estimated by the results of nuclear magnetic resonance.

Synthesis of arsonium salts and betaines based on triphenylarsine and ω-bromoalkanoic acids

The reactions between Ph3As and ω-bromoalkanoic acids with the length of polymethylene fragment n = 5, 7, 9 afford quaternary arsonium salts. Their treatment with alkali gives biologically active arsenobetaines. Solvent-free reactions of Ph3P or Ph3As with 2,3-dibromopropionic acid lead to the corresponding arsonium and phosphonium salts bearing (CH2)2COOH substituent.

First Synthesis of DBU-Conjugated Cationic Carbohydrate Derivatives and Investigation of Their Antibacterial and Antifungal Activity

The emergence of drug-resistant bacteria and fungi represents a serious health problem worldwide. It has long been known that cationic compounds can inhibit the growth of bacteria and fungi by disrupting the cell membrane. The advantage of using such cationic compounds is that the microorganisms would not become resistant to cationic agents, since this type of adaptation would mean significantly altering the structure of their cell walls. We designed novel, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)-derived amidinium salts of carbohydrates, which may be suitable for disturbing the cell walls of bacteria and fungi due to their quaternary ammonium moiety. A series of saccharide-DBU conjugates were prepared from 6-iodo derivatives of d-glucose, d-mannose, d-altrose and d-allose by nucleophilic substitution reactions. We optimized the synthesis of a d-glucose derivative, and studied the protecting group free synthesis of the glucose-DBU conjugates. The effect of the obtained quaternary amidinium salts against Escherichia coli and Staphylococcus aureus bacterial strains and Candida albicans yeast was investigated, and the impact of the used protecting groups and the sugar configuration on the antimicrobial activity was analyzed. Some of the novel sugar quaternary ammonium compounds with lipophilic aromatic groups (benzyl and 2-napthylmethyl) showed particularly good antifungal and antibacterial activity.

NiAs-derived cyanamide (carbodiimide) structures – a group-theoretical view

Abstract The cyanamide and carbodiimide anions are complex nitrogen-derived one-dimensional species of the type NCN2− (hence, resembling O2− but more covalently bonding) that form a huge number of salt-like phases with a variety of metal cations stemming from the whole Periodic Table. Depending on the coloring (binary, ternary and quaternary salts are known), the cationic size and charge as well as covalent contributions, different distortion (tilting in particular) and/or vacancy ordering variants of cyanamides/carbodiimides occur. Herein we summarize those cyanamide/carbodiimide structures that derive from the aristotype NiAs. The crystal chemistry is discussed on the basis of group-subgroup schemes (Bärnighausen trees).

Influence of Reinforcing Efficiency of Clay on the Mechanical Properties of Poly(butylene terephthalate) Nanocomposite

In contrast to traditional fillers, clay, in particular, natural smectite clay, represents an environmentally significant alternative to improve the properties of polymers. Compared to conventional nanofillers, smectite clay can effectively enhance the physical and mechanical properties of polymer nanocomposites with a relatively small amount of addition (<5 wt%). The present study focuses on investigating the reinforcing efficiency of different amounts (up to 5 wt%) of a natural Brazilian smectite clay modified (MBClay) on the mechanical properties of poly(butylene terephthalate) (PBT) nanocomposites and also evaluates the correlation between MBClay addition and the mechanical and thermal behaviors of the PBT/MBClay nanocomposites. Natural Brazilian clay modified by the addition of quaternary salt and sodium carbonate (MBClay) was infused into the PBT polymer by melt extrusion using a twin-screw extruder. It was found that the best properties for PBT were obtained at 3.7 wt% of modified BClay. Tensile strength at break exhibited increased by about 60%, flexural strength increased by 24%, and flexural modulus increased by 17%. In addition, an increase in the crystallinity percentage of PBT/BClay nanocomposite was confirmed by DSC and XRD analysis, and a gain of about 45% in HDT was successfully achieved due to the incorporation of 3.7 wt% of MBClay.

Synthesis, Characterization, DFT Studies of Novel Phase Transfer Catalyst and Application in O-Propargylation Reaction

The present work reports the synthesis and characterization of 1-benzyl-1,4- diazoniabicyclo[2.2.1]hepta-2,4(7)-diene dibromide for phase transfer catalyst (PTC) applications. The derived quaternary salt was characterized by UV, FTIR and NMR spectral techniques. The structure has been optimized by density functional theory (DFT) in water and diethyl ether solvation conditions. The DFT outcomes showed the good chemical potential of the compound between 2.15 eV and 6.8 eV in both media. Extended research examined the nature of phase transfer by adjusting dosage, temperature and solvents in the O-propargylation reaction under normal conditions for useful precursor synthesis. The kinetic data revealed that the novel bisite quaternary amine bromide salt was effective in a variety of conditions. The chlorobenzene and water biphasic system yielded 88% of bioactive molecule precursor when compare to other immiscible systems.

Synthesis of 2-aminopropyl benzopyran derivatives as potential agents against triple-negative breast cancer.

Synthesis of three series of 2-aminopropyl derivatives containing a benzopyran nucleus was performed to evaluate their performance against triple-negative breast cancer cell lines (MDA-MB-231 and MDA-MB-436) and normal breast epithelial cells (MCF10A). For the three series, the cytotoxic activity was as follows: N-methylated derivatives (tertiary amines) 5b, 6b, and 7b > secondary amine benzopyrans 5, 6, and 7 > quaternary amine salts 5c, 6c, and 7c > free phenolic derivatives 5a, 6a, and 7a. The structure-activity relationship showed the importance of the presence of an amine group and a p-fluorobenzyloxy substituent in the chromanol ring (IC50 values from 1.5 μM to 58.4 μM). In addition, 5a, 5b, 6a, and 7b displayed slight selectivity towards tumor cells. Compounds 5, 5a, 5b, 6, 6a, 6c, 7, and 7b showed apoptotic/necrotic effects due to, at least in part, an increase in reactive oxygen species generation, whereas 5b, 5c, 6b, 7a, and 7c caused cell cycle arrest in the G1 phase. Further cell-based mechanistic studies revealed that 5a, 6a, and 7b, which were the most promising compounds, downregulated the expression of Bcl-2, while 5b downregulated the expression of cyclins CCND1 and CCND2. Therefore, 2-aminopropyl benzopyran derivatives emerge as new hits and potential leads for developing useful agents against breast cancer.

One-pot synthesis of quaternary pyridinium salts of lupane triterpenoids and their antimicrobial properties

C30-quaternized derivatives of lupane triterpenoids (31 examples) were synthesized with a yield of 85–95% via a one-pot functionalization of a double bond under the action of organic tribromides and pyridines.

Brønsted acid-mediated tandem cyclization of triarylphosphines and in situ generated ortho-alkynyl quinone methides: access to heterocyclic quaternary phosphonium salts.

Heterocyclic Quaternary Phosphonium Salts (HQPS) have emerged as promising chemicals for organic synthesis and medicinal chemistry. However, the present synthetic methodology of this type of compound is still limited. Here, we report a deconstructive reorganization strategy based on Brønsted acid-mediated tandem 1,4 addition/intramolecular cyclization of triphenylphosphine derivatives and in situ generated o-AQMs for the first time. This protocol provides a novel approach to heterocyclic quaternary phosphonium salts. The method also features a non-metal catalyst, mild reaction conditions, high efficiency and wide substrate scope. Moreover, a series of obtained heterocyclic phosphonium salts can be converted to isotopically labelled 2-benzofuran compounds directly by simple deuteration reactions.

α-КАРБОКСИЛАТНЫЕ ФОСФАБЕТАИНЫ В РЕАКЦИЯХ АЛКИЛИРОВАНИЯ И КОМПЛЕКСООБРАЗОВАНИЯ

Alkylation reactions of α-carboxylate phosphabetaines were carried out and studied to enhance the biological activity of previously synthesized carboxylate phosphabetaines. As a result of these reactions, the original structure was destroyed with the formation of quaternary salts of phosphonium triiodide. The structure and composition were confirmed by a complex of physical research methods, including NMR, IR spectroscopy, and elemental analysis. The bactericidal and antimycotic activity of the synthesized salts was assessed. The compounds showed activity similar to that of commercial drugs. The reactions of complexation of these structures were also investigated. In the reactions with nickel and copper chloride, complexes were isolated and characterized. The structure of the nickel complex was unambiguously confirmed by the data obtained with the help of single-crystal X-ray diffraction analysis.

The role of organoclay in the diffusion of epoxy‐amine oligomers and in the cross‐linking density of the resulting network

AbstractEpoxy nanocomposites are promising for adhesive applications due to their high performance. In this work, an organoclay (PO), prepared by cationic exchanging using a quaternary phosphonium salt or a silylated PO (SPO) was added to an epoxy‐amine resin‐based adhesive to reduce its dripping. PO and SPO were dispersed in the epoxy network on a nanometric scale, mainly in an intercalated structure. A liquid‐to‐gel transition occurs at 4–6 wt% PO due to forming a continuous organoclay network throughout the epoxy volume, eliminating its dripping. The PO addition accelerates the curing reaction initially, and cured nanocomposites with over 3 wt% PO show a drastic reduction in the glass transition temperature (Tg). Moreover, a broadening of the secondary relaxation observed by DMA indicates an interaction between the epoxide‐amine oligomers with the silicate surface. This interaction, associated with forming a continuous organoclay network at 4–6 wt% PO, reduces the epoxy‐amine oligomers diffusion, resulting in their partial curing and consequent Tg decreasing. EPOXY_SPO nanocomposites show Tg values similar to or higher than that observed for the epoxy‐amine network attributed to the forming of covalent bonds between the glycidyloxypropyl end groups in the SPO surface and the hardener amine.

Interplay of Ionic Species in Salts of Homoleptic Quaternary Phosphonium Cations Bearing Linear Biphenyl Moieties

Quaternary phosphonium salts are popular candidates used in many chemical transformations and synthetic chemistry, notably in catalysis. We have examined the single crystals of two bulky phosphonium compounds, tetra([1,1′-biphenyl]-4-yl) phosphonium dicyanamide (C48H36P+·N(CN)2−, compound 1), and tetra([1,1′-biphenyl]-4-yl) phosphonium bromide hydrate (C48H36P+·Br−, CH3CN, H2O, compound 2), and herein report the structural properties for the compounds with an emphasis on the influence of the ion-ion interaction towards self-assembly; the overall self-assembly for both structures is very similar, with subtle differences in the cell parameters. The symmetrical tetra ([1,1′-biphenyl]-4-yl) phosphonium cations in both compounds self-assembled to form robust stacked columns in the solid-state, with voids occupied by anions or solvent molecules. Quantitative examination of intermolecular interactions using Hirshfeld surface analysis found that classical and non-classical hydrogen bonding appears to be the dominant contributor in stabilizing the self-assembly in both cases. The present work can not only benefit in understanding the mutual interaction between the sterically encumbered tetra ([1,1′-biphenyl]-4-yl) phosphonium cations and between counterions, but also provide insights for the self-assembled arrays in the solid-state.

Ultra-transparent, hard and antibacterial coating with pendent quaternary pyridine salt

Pathogenic microbes are ubiquitous, and they can proliferate quickly on wood surface under the suitable conditions to pose a huge hidden threat to public health security and safety. To impart wood surface with outstanding antibacterial activity, we synthesized a pyridine quaternary ammonium (PQAS) monomer by nucleophilic addition reaction between 4-vinylpyridine and 1-bromododecane, and then prepared the cationic antibacterial polymer (CAP) by radical copolymerization. After that, the antibacterial composite emulsion was obtained after uniformly mixing CAP with a commercialized polyacrylate emulsion (PAE). Finally, we obtained an ultra-transparent, hard and antibacterial CAP/PAE coating by brushing CAP/PAE emulsion on the wood surface and then drying at 80 °C for 3 h. And the optimum mixing ratio of coating was explored and explained by using zeta potentialaccording to the theory of polymeric emulsion. Moreover, the chemical structure, antibacterial activity, physicochemical properties, and cytotoxicity of this coating were investigated systematically. The experimental results indicated that the antibacterial activity of CAP/PAE coating against E. coli and S. aureus were greater than 99.9 % without releasing antibacterial components. Even after being irradiated with ultraviolet light at 254 nm for 100 h, its antibacterial rates still reached 97.12 % (E. coli) and 99.35 % (S. aureus), respectively, which are much higher than the required antibacterial rate of Grade 1 (the highest-grade), and superior to most of the reported work. In addition, the CAP/PAE coating exhibited 5H hardness, ultra-transparent, enhanced mechanical properties and low cytotoxicity. Hence, we have developed a facile approach to fabricate multifunctional coating that has potential application in vehicle glass, mobile screens, building wall, furniture and other fields to endow outstanding and rapid bactericidal activity without compromising their appearance physicochemical properties or biocompatibility.

Organophosphine as an Alkyl Transfer Shuttle for the Direct β-Alkylation of Chalcones Using Alkyl Halides.

We report an efficient alkyl transfer strategy for the direct β-alkylation of chalcones using commercially available alkyl bromides as alkyl reagents. In this transformation, the ortho-phosphanyl substituent in the chalcones is crucial for controlling their reactivity and selectivity. It also serves as a reliable alkyl transfer shuttle to transform electrophilic alkyl bromides into nucleophilic alkyl species in the form of quaternary phosphonium salts and transfer the alkyl group effectively to the β-position of the chalcones. This alkyl transfer strategy can be further extended to the alkenylation of ortho-phosphanyl benzaldehydes to assemble functionalized polyenes.

Regulating Alkyl Chain Length on Quaternization TiO2 for Boosting Photocatalytic Performance: Synergism of Promoting Photogenerated Charge Separation and Improving Reactant Adsorption.

To explore the effect of surface charge properties of a photocatalyst on photocatalytic activity, quaternization TiO2 particles with different alkyl chain lengths (CT-X/P25) are first synthesized to boost the photocatalytic activity. The effect of a quaternary ammonium group with different alkyl chain lengths on the photocatalytic activity of CT-X/P25 is investigated. Interestingly, the introduction of a quaternary ammonium group on CT-X/P25 not only contributes to improving the photodegradation efficiency of anionic dyes due to enhancing of adsorption capacity through electrostatic attraction, but also it can improve the photodegradation efficiency of cationic dyes. Therefore, there seems to be another factor affecting the photocatalytic activity. The results of photoelectric characterization show that the photogenerated charge separation of CT-X/P25 is greatly enhanced, which is beneficial to improve the photocatalytic activity. Simultaneously, the results show that the difference in the photocatalytic activity of CT-X/P25 is mainly related to the charge intensity of -N+(CH3)2- in the quaternary amine salt. According to X-ray photoelectron spectroscopy, the charge intensity of -N+(CH3)2- in CT-X/P25 gradually increases with the increase in alkyl chain lengths, which is conducive to promoting photogenerated charge separation and improving the adsorption for anionic dyes. The photocatalytic activity has been further enhanced due to the enhancement of this synergy. In summary, the quaternary ammonium salt-modified CT-X/P25 shows an excellent synergistic effect on the process of photodegradation of anionic dyes: promoting photogenerated charge separation and adsorption.

Direct and Indirect Cationization of Cellulose Nanocrystals: Structure-Properties Relationship and Virus Capture Activity.

Due to increasing public concern over hygiene, there have been many studies investigating antimicrobial and antiviral agents recently. With the aim of developing biobased virucidal/virus capture agents, we report a chemical modification of the cellulose nanocrystals (CNCs) surface with poly(2-dimethylamino) ethyl acrylate) methyl chloride quaternary salt (Q-PDMAEA) to introduce the positively charged functional groups. The surface of CNCs was modified through direct and indirect graft polymerization. Subsequently, the direct and indirect cationization effect on the degree of functionalization, thermal stability, crystallinity, and antiviral activity of CNCs was investigated. Indirect cationization produced the highest degree of polymer grafting, increasing particle size and thermal stability. Further, the modified CNCs were tested for their ability to capture nonenveloped bacteriophages PhiX174 (ΦX174) and MS2. We observed a significant (>4.19 log10) reduction in total viral load by specific functionalized CNCs. However, the activity depended on the structure of functional groups, surface charge density, and the type of virus under study. Overall, the direct and indirect cationization of CNC leads to biobased agents with immobilized cationic charge, with good virus capture activity. Such agents can be used for various applications including textiles, packaging, wastewater treatment, etc.

Organic quaternary phosphonium salts intercalated MXene towards controllable amphiphilicity and dispersions

• 1. Ti 3 C 2 was intercalated by quaternary phosphonium salt with different structure. • 2. The modified Ti 3 C 2 show controllable dispersions in different organic solvents. • 3. The thermal stability of Ti 3 C 2 was significantly improved after the intercalation. Two-dimensional Ti 3 C 2 has drawn widespread academic interest in several fields due to its unique physicochemical properties. However, its poor dispersion in organic solvents and easily oxidized in aqueous solution pose a challenge to storage and application. Herein, we intercalated Ti 3 C 2 with a series of quaternary phosphonium salts (QPS) for turning amphiphilicity, thus controlling its dispersion in organic solvents. The effect of molecular structure of QPS on the dispersion of modified Ti 3 C 2 was investigated, including chain type and length. The results showed that the thermal stability and dispersion in organic solvents of Ti 3 C 2 were remarkably enhanced after being intercalated with QPS containing a longer chain. This strategy may pave a new way for rationally designing Ti 3 C 2 with high stability and dispersion and enriching its application.

Preparation and properties of quaternary phosphonium salt containing poly-acrylate emulsion

In this study, methacryloxyhexyl triphenylphosphonium bromide (Br-MHP), a quaternary phosphonium salt monomer, was synthesized and then poly-acrylate emulsion with various Br-MHP contents was prepared through seed emulsion polymerization. The chemical structure of Br-MHP and chemical composition of Br-MHP containing poly-acrylate emulsion were characterized by 1H NMR, 13C NMR, LC-MS and FT-IR, respectively. Effects of Br-MHP content on the stability of emulsion polymerization and micro-structure of the latex particles were investigated. The micro-morphology of the polymer film was observed by SEM. The film performances such as hardness, adhesive, water absorption ratio, thermal stability and antibacterial property were studied. The surface element composition of Br-MHP containing poly-acrylate film was characterized by XPS. The results show that Br-MHP monomer and poly-acrylate emulsion with various Br-MHP contents can be successfully prepared. With the increase of Br-MHP content, the emulsion polymerization stability increases while particle size of latex particles decreases. Besides, the prepared emulsions show excellent storage stability and mechanical stability. The prepared Br-MHP containing poly-acrylate films also present excellent film properties. As the content of Br-MHP increases, the water absorption ratio of the co-polymer film increases, while hardness and thermal stability decreases. Moreover, XPS result show that the quaternary phosphonium salt group is enrich on the polymer film surface, therefore, the Br-MHP containing poly-acrylate resin presents 99.99 % antibacterial efficiency against S. aureus and E. coli when Br-MHP content is only 1 wt% and 2 wt%, respectively.