Chain Ammonium Research Articles

Membrane-anchoring selenophene viologens for antibacterial photodynamic therapy against periodontitis via restoring subgingival flora and alleviating inflammation

Antibacterial photodynamic therapy (aPDT) has emerged as a promising strategy for treating periodontitis. However, the weak binding of most photosensitizers to bacteria and the hypoxic environment of periodontal pockets severely hamper the therapeutic efficacy. Herein, two novel oxygen-independent photosensitizers are developed by introducing selenophene into viologens and modifying with hexane chains (HASeV) or quaternary ammonium chains (QASeV), which improve the adsorption to bacteria through anchoring to the negatively charged cell membrane. Notably, QASeV binds only to the bacterial surface of Porphyromonas gingivalis and Fusobacterium nucleatum due to electrostatic binding, but HASeV can insert into their membrane by strong hydrophobic interactions. Therefore, HASeV exhibits superior antimicrobial activity and more pronounced plaque biofilm disruption than QASeV when combined with light irradiation (MVL-210 photoreactor, 350–600 nm, 50 mW/cm2), and a better effect on reducing the diversity and restoring the structure of subgingival flora in periodontitis rat model was found through 16S rRNA gene sequencing analysis. The histological and Micro-CT analyses reveal that HASeV-based aPDT has a better therapeutic effect in reducing periodontal tissue inflammation and alveolar bone resorption. This work provides a new strategy for the development of viologen-based photosensitizers, which may be a favorable candidate for the aPDT against periodontitis.

Effects of alkyl chain length and halide anion on hydrogen bonding, electrochemical transport properties and double layer capacitance in eutectic solvents

Eutectic solvents (ESs) have been widely studied due to their tunable solvation and physical properties. The properties of eutectic solvents that are formed from mixtures of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are governed by a complex hydrogen (H) bonded network among their constituents. However, an understanding of the key factors effecting the H-bonding structure and dynamics, and the resulting physical and electrochemical properties at interfaces is still in its infancy. In this study, the influence of the cation’s alkyl chain length and the anion chemical identity on the characteristics of the H-bonding network in eutectic solvents were examined. In particular, ESs formed from mixtures of tetraalkylammonium salts as HBAs and ethylene glycol as the HBD were studied. Complementary spectroscopic studies revealed the changes in the solvation environment as a function of the ammonium chain length (C1, C2, C3, and C4) and the anion type (Cl−, Br−, I−). With an increase in the alkyl chain length or a decrease in the electronegativity of halide anions (X−), it was found that the O–H bond length shortens and the H···X− bond elongates in the H-bond (O–H···X−) structure, thus resulting in an increase of the solvated ion size and a decrease in the bulk ionic conductivity. Further, double layer capacitance measurements showed that increased capacitance was correlated with shorter H-bonds in anion solvates.

Antimicrobial polyurethane foams blown by CO 2 adducts from polyethylenimines grafted with alkyl quaternary ammonium groups

Based on previous endeavors on antimicrobial polyurethane (PU) foams and CO2-releasing environment-friendly blowing agents, we explored a series of modified polyethylenimine (PEI)–CO2 adducts, serving as both blowing and antimicrobial agents for PUs. For this purpose, a quaternary ammonium chain with a C12 alkyl (C12+), either alone or together with neutral (C8 and C12) alkyls, was grafted onto branched PEI (Mn = 25,000 Da) backbones prior to saturation with CO2. The resultant four CO2 adducts, 5C12+5C8-, 5C12+5C12-, 10C12+- and 15C12+-PEI-CO2 (where the number indicates grafting rate in percentage of each side chain), all can well disperse into PU foaming mixtures, generating flexible PU foams with antimicrobial activity. 15C12+-PEI-CO2 displays the best dispersibility and highest foaming efficiency, while 10C12+-PEI-CO2 is the most antimicrobial toward both Gram positive and negative bacteria. The relatively high grafting rate in 15C12+-PEI-CO2 drives the formation of micelle-like particles in the foaming system; the outermost hydrophobic chains can somewhat prevent the internal quaternary ammoniums from accessing to the negatively charged cell membrane of bacteria, causing a reduction in antimicrobial efficacy compared with that of 10C12+-PEI-CO2. The developed PEI–CO2 adducts might replace the traditional ozone depletion and/or global warming blowing agents, and would show prolonged antimicrobial activity over rapidly leachable small molecule antimicrobial agents.

Interfacial engineering of quasi-2-D formamidinium lead iodide nanosheets for perovskite solar cell by mechanochemical approach

Solvent-free synthetic protocols for the formation of nanoarchitectures continues to attract a great attention amoung the wide class of synthetic chemists in order to overcome the harsh reaction conditions. In the current work we demonstrate, for the first time, solvent-free synthesis of dodecylammonium formamidinium lead iodide (DDA)2 [FAPbI3]n−1PbI4, a quasi-two-dimensional (2D) red-light-emitting perovskite nanosheet, where DDA is dodecylammonium, a long chain ammonium cation, and FA is a formamidinium cation. By varying the amount of DDA, we controlled the dual emission of quasi-2D perovskite comprising of both 2D and three-dimensional perovskite layers. The optical properties have manifested the effect of DDA on the structure of perovskite nanosheets. As a proof-of-concept demonstration the material has been explored in perovskite solar cell. The compound containing least amount of DDA exhibited open-circuit voltage (VOC) of 0.961 V, short-circuit current density (JSC) of 23.41 mA cm−2, and PCE of 15.23% under one-sun illumination conditions.

Highly dispersed Ni-La catalysts over mesoporous nanosponge MFI zeolite for low-temperature CO2 methanation: Synergistic effect between mesoporous and microporous channels

The mesoporous nanosponge MFI silicate zeolite was facilely fabricated by employing the long chain ammonium as the structure-directing agent. The zeolite with both mesoporous and microporous channels were selected as the support of Ni-La catalysts for methanation of CO2. Various techniques were used to characterize the catalysts systematically. The effects of the La2O3 promotor and pore morphology of the support on the catalytic performance were carefully investigated. Our study demonstrated that La promoter could be beneficial to the increase of the surface basicity and the enhancement of the metallic Ni dispersion. This would intensify the processes of the CO2 chemisorption and H2 dissociation in CO2 methanation. Besides, we also found that the catalyst supported on mesoporous nanosponge MFI zeolite performed higher activity and better long-term stability than the reference catalysts supported on bulk MFI and MCM-48, suggesting that the synergistic effect between the mesoporous and microporous channels displayed unique advantages. Kinetic study revealed that both the nanosponge structure and La2O3 promoter contributed to decreasing the reaction activation energy. Therefore, the present highly dispersed Ni-La catalyst over mesoporous nanosponge MFI zeolite promised a potential catalyst candidate for low-temperature CO2 methanation reaction.

Deep catalytic oxidative desulfurization process catalyzed by TBA-PWFe@NiO@BNT composite material as an efficient and recyclable phase-transfer nanocatalyst

The production of high-quality fuel with substantially lowered sulfur level has attracted a great deal of attention in recent years. Developing high-performance and recyclable catalysts for the desulfurization process remains largely a challenge. In this study, an efficient catalytic oxidative desulfurization (CODS) strategy has been developed using a new phase-transfer nanocatalyst. The TBA-PWFe@NiO@BNT nanocatalyst was fabricated from the mono Fe-substituted phosphotungstate with tetra (n-butyl) ammonium chains (TBA-PWFe), nickel oxide (NiO), and sodium activated bentonite (BNT) for the first time. The TBA-PWFe@NiO@BNT composite was utilized as a recyclable nanocatalyst for the desulfurization of simulated fuels and real gasoline using acetic acid/hydrogen peroxide (VCH3COOH/VH2O2 = 1/2). The best desulfurization results were attained with the TBA-PWFe@NiO@BNT phase-transfer nanocatalyst at 35 °C after just 60 min, showing identical CODS performance under mild reaction conditions. The total sulfur removal efficiency of real gasoline achieved a remarkable 98% and the concentration of mercaptans (RSH; R = alkyl group) was reduced from 98 to 3 ppm. On the other hand, thiophenes (Ts), benzothiophenes (BTs), and dibenzothiophenes (DBTs) were near completely removed from the simulated fuels phase with efficiencies of 96, 97, and 99%, respectively. Finally, the recycling capacity of TBA-PWFe@NiO@BNT nanocatalyst was confirmed for five consecutive desulfurization runs without remarkably decreases in its catalytic performance. The overall results obtained have been discussed in detail.

Impact of double-chain surfactant stabilizer on the free active surface sites of gold nanoparticles

Positive and negative charged stabilizing ligands, for example, ammonium surfactants and citrate, influence the catalytic activity of AuNPs greatly, due to their different electrostatic attraction ability with substrates. However, as for the more decisive factor in AuNPs catalyzed reactions, the free active surface sites of AuNPs influenced by different kinds of ammonium surfactants has not been studied yet. In this work, we prepared double chain and mono chain ammonium surfactants capped gold nanoparticles, DDAB-Au and CTAB-Au, and put them into the reduction reaction of uranine by NaBH4. Compared to CTAB-Au, DDAB-Au favors the adsorption of BH4− and generation of metal hydride on the active sites. As a result, DDAB-Au catalyzed reduction of uranine could give shorter induction time. We attribute this phenomenon to a weaker binding affinity of DDAB to the active sites of AuNPs, resulting from the more flexible, less polar and low charge-to-molecular weight ratio properties of DDAB. Fast responding time is one of important criteria in analytical chemistry and sensor chemistry. With dramatic fluorescence changes, some DDAB-Au catalyzed reactions would facilitate the related studies in the fields of catalysis, analysis and biosensors.

The adsorption characteristics and mechanism of montmorillonite with different layer charge density for alkyl ammonium with different carbon chain length

The crystal chemical properties of montmorillonite and the length and amount of straight alkyl ammonium chain affect the adsorption characteristics of alkyl ammonium on montmorillonite.

Overriding Intrinsic Reactivity in Aliphatic C-H Oxidation: Preferential C3/C4 Oxidation of Aliphatic Ammonium Substrates.

The site-selective C-H oxidation of unactivated positions in aliphatic ammonium chains poses a tremendous synthetic challenge, for which a solution has not yet been found. Here, we report the preferential oxidation of the strongly deactivated C3/C4 positions of aliphatic ammonium substrates by employing a novel supramolecular catalyst. This chimeric catalyst was synthesized by linking the well-explored catalytic moiety Fe(pdp) to an alkyl ammonium binding molecular tweezer. The results highlight the vast potential of overriding the intrinsic reactivity in chemical reactions by guiding catalysis using supramolecular host structures that enable a precise orientation of the substrates.

Surface Regulation of CsPbBr3 Quantum Dots for Standard Blue‐Emission with Boosted PLQY

AbstractIt is demonstrated that, via surface treatment of CsPbBr3 perovskite quantum dots (PeQDs) by introducing small amount of organic ammonium chlorides possessing short alkyl chain (C ≤ 4) in methyl acetate in the typical purification process, the emission can be tuned from green to blue region with boosted photoluminescence quantum yield (PLQY). The Cl− mainly works on the surface of PeQDs to fill bromide vacancy, which generates a passivated mixed‐halide surface and avoids formation of defects deep within bandgap. Meanwhile, the replacement of initial long‐chain ligands with short chain ammonium moiety benefits the film PLQY. Accordingly, a standard blue emission of 461 nm with a high film PLQY of 52% is accessed and the corresponding colloidal shows a PLQY of 80% at 456 nm. This method is also proved to be a versatile tool to boost the PLQY of PeQDs by using short chain ammonium halides bearing the same X with the initial CsPbX3. A near‐unity colloidal PLQY of 97% and 98% is achieved for CsPbBr3 and CsPbI3 respectively. Quantum dots light‐emitting diode (QLED) with treated CsPbBr3 affords a standard blue electroluminescence of 459 nm and a maximum external quantum efficiency of 0.3%.

Structural changes and band gap tunability with incorporation of n-butylammonium iodide in perovskite thin film

The current work presents structural change and band gap tunability using hybrid organic-inorganic perovskite with the incorporation of long chain ammonium halide. Thin films of MAPbI3 with different ratio of n-butylammonium iodide (BAI) have been successfully deposited on the substrate using a single step coating technique. X-ray diffraction scans revealed the transition of the 3D structure of MAPbI3 to quasi-2D perovskite structure when BAI loading increase with a crystallite size range approximately 16 nm. This structural changeis reflected in the band gap as it increased from 1.59 eV for bulk crystal MAPbI3 to 2.13 eV for BAI and MAPbI3 ratio of 1:1. Correspondingly, photoluminescence measurement showed a blue shift in perovskite emission due to the transition of 3D to 2D layered structure perovskite. Raman spectra confirm that all fabricated films are of pristine quality and no corresponding degradation peaks of PbI2 is observed. These characteristics are important to address the single step deposition method of hybrid perovskite for perovskite solar cells application.

Quasi-2D organic cation-doped formamidinium lead bromide (FAPbBr3) perovskite light-emitting diodes by long alkyl chain

Abstract Organic-inorganic hybrid perovskites (OIHP) are promising materials for high efficiency light emitting diode (LEDs) due to their high color purity, their high photo-luminescence quantum yield and their bandgap tuneability. Introducing long chain ammonium halide in a perovskite films can result in energy funneling from a distribution of two-dimensional perovskite nanosheets to three-dimensional nanocrystals through energy cascade from high bandgap energy states (nanosheets) to lower bandgap energy states (nanocrystals), or enhance the passivation of the 3D nanocrystals. Thus, the electrical charge injection in the emitter site is enhanced or the non-radiative recombination rate is reduced. Here we report on the doping of a FAPbBr3 green-emitter with n-BABr (butyl ammonium bromide). Upon addition of a small amount of n-BABr (0.2 wt%) in a non-stoichiometric perovskite solution, the photoluminescence intensity of thin films and current efficiency of PeLEDs increase by about an order of magnitude, from 1.2 Cd/A without to 13.5 Cd/A with n-BABr doping.

Fabrication of Organic Probe Decorated Water-Soluble Polymer Chains on Natural Fibers for Selective Detection and Efficient Removal of Hg2+ Ions in Pure Aqueous Media

Developing dual-functional materials that can simultaneously detect and remove toxic heavy metal ions is of practical importance but still remains a challenging task. Herein, an ion-recognizable material, MA–SAPQA@NFs, was facilely fabricated through covalent grafting of salicylaldehyde-containing polymeric quaternary ammonium (SAPQA) chains onto the lotus seedpod-derived natural fibers (NFs), followed by decoration with 2-mercaptoaniline (MA). Several remarkable features for MA–SAPQA@NFs, which could rarely be achieved in previous studies, were integration of good hydrophilicity, high content of organic probe units, and specific visual recognition ability toward Hg2+, making it an excellent candidate as a dual-functional platform for simultaneous detection and removal of Hg2+ under completely aqueous conditions. The distinctive color change as result of Hg2+ binding to MA–SAPQA@NFs could be detected easily by the naked eye and allowed quantitative determination of Hg2+ in simulated and real water samples...

Sodium Ion Modifying In Situ Fabricated CsPbBr3 Nanoparticles for Efficient Perovskite Light Emitting Diodes

AbstractAll‐inorganic perovskite has attracted much attention because of the higher stability. Many organic additives such as alkyl chain ammonium and polymers are usually introduced into perovskite to improve their performance. However, the long chain ammonium cations in perovskite may restrain the carrier transfer ability and ultimately deteriorate the performance of light‐emitting diodes (LEDs). In this work, the CsPbBr3 nanoparticles (NPs) are in situ fabricated by the synergistic effect of poly(ethylene oxide) and phenethylammonium bromide (PEABr). Particularly, sodium bromide (NaBr) with better conductivity is successfully introduced into CsPbBr3 NPs to substitute PEA partially, ultimately to passivate the defect and promote the carrier transfer ability. Besides, the addition of NaBr results in a better promotion for electron mobility than for hole mobility leading to a more balanced charge transport in devices. It enables NaBr based CsPbBr3 NPs green LEDs to exhibit a maximum external quantum efficiency (EQEmax) of 17.4%, which presents obvious enhancement compared to the LEDs without NaBr (EQEmax = 12%). Further, NaBr based CsPbBr3 NPs LEDs with a large area of 108 mm2 still show a high maximum EQE of 10.2%. Above all, this work provides a feasible way of adding metal additive in perovskite films to improve the performance of perovskite LEDs.

Synthesis of reactive waterborne polyurethane modified with quaternary ammonium chain extender and its color fixation properties

N-Methyl diethanolamine was adopted to react with isophorone diisocyanate to provide a dihydroxyl complex. The obtained complex was further modified by benzyl chloride through alkylation reaction to offer a cationic quaternary ammonium chain extender. Polyether glycol was selected as the soft segment to prepare the waterborne polyurethane (WPU) prepolymer. Then, as-prepared cationic chain extender was blocked into the achieved WPU prepolymer, and the residual NCO groups were tentatively terminated by NaHSO3 at a low temperature to obtain WPU emulsion. The structure of WPU was confirmed by Fourier Transform Infrared spectrometry, Gel permeation chromatography, Thermogravimetric analysis, and scanning electron microscopy. The color fastness of dyed cotton fabrics was obviously promoted after treating by WPU latex, and the wet rubbing fastness of cotton fabrics obviously improved 1.5 grade.

Ammonium salt modified mesoporous silica nanoparticles for dual intracellular-responsive gene delivery

Effective gene delivery system plays an importmant role in the gene therapy. Mesoporous silica nanoparticle (MSN) has become one potential gene delivery vector because of its high stability, good biodegradability and low cytotoxicity. Herein, MSN-based dual intracellular responsive gene delivery system CMSN-A was designed and fabricated. Short chain ammonium group, which is modified with disulfide bond and amide bond simultaneously, is facilely grafted onto the mesoporous silica nanoparticles. As-synthesized CMSN-A is endowed with small size (80–110nm), large conical pores (15–23nm), and moderate Zeta potential (+25±2mV), which behaves high gene loading capacity, good stability and effectively gene transfection. Moreover, CMSN-A exhibits dual micro-environment responsive (lower pH, more reducing substances) due to the redox-sensitive disulfide bond and pH-sensitive amide bond in the short chain ammonium group. The cellular uptake study indicates that CMSN-A could transfer both plasmid DNA (pDNA) and siRNA into different kinds of tumour cells, which demonstrate the promising potential of CMSN-A as effective and safe gene-delivery vectors.

Property investigation of surface-modified MMT on mechanical and photo-oxidative degradation of viton rubber composites

At different time intervals, photo-oxidative degradation of organically modified montmorillonite (OMMT):viton rubber composites were studied under accelerated UV (≥290 nm) irradiation. The changes in properties (mechanical, thermal, and physical) before and after UV exposure were studied using universal testing machine (UTM), thermogravimetric analyzer (TGA) and shore A hardness tester. Meanwhile, surface of montmorillonite (MMT) was modified using column chromatography technique (quaternary long chain ammonium salt as an intercalent), which resulted in uniform exchange of ions between MMT and ion exchange resin; and thus d-spacing increases to 31.5 A. Viton:OMMT nanocomposites were prepared using two roll mill and compression molding machine to obtain a square sheet. Prolonged exposure to UV leads a progressive decrease in mechanical, thermal and physical properties along with the change in behavior of filler–matrix interaction, which was due to decrease in cross-linkage density with increase in the mobility of rubber chains. The increases in carbonyl (>CO), hydroxyl (–OH) functional groups after degradation of OMMT:viton rubber composites at different time intervals (0, 100, 200, 300 h of UV exposure) were studied using Fourier transform infrared spectroscopy (FTIR). Besides this, the change in surface behavior of viton rubber composites before and after degradation was studied using scanning electron microscopy (SEM). Overall, the study shows that the OMMT:viton composites were affected more upon irradiation compared to pristine viton composites and it was more prominent at 12 wt% loading of 300 h of UV exposure.

Synthesis, Surface Properties and Biological Activity of Long Chain Ammonium Herbicidal Ionic Liquids

Herbicidal ionic liquids exhibit many advantages compared to conventional chemical plant protection agents, which allow for a reduction of the herbicide dose per hectare and decrease of toxicity. Popular herbicides, such as 4-chloro-2-methylphenoxyacetic (MCPA) or 2,4-dichlorophenoxyacetic (2,4-D) acids, can be modified by reaction with long chain ammonium cations in order to obtain novel forms. The aim of this study was to present an alternative method for the synthesis of herbicidal ionic liquids based on a natural cation known as Ethoquad C/12 and to analyze the physicochemical properties and herbicidal activity of the obtained products. New ionic liquids comprising MCPA and 2,4-D as anions were obtained and their chemical as well as thermal stability were evaluated. Furthermore, their biological and surface activity were investigated. The obtained results confirmed that the herbicidal activity has been preserved.

Stable zinc cycling in novel alkoxy-ammonium based ionic liquid electrolytes

High-energy density Zinc-air batteries are currently of interest since they could play a key role in emerging large-scale energy storage applications. However, achieving good rechargeability of such metal-air batteries requires significant further research and development effort. Room Temperature Ionic liquids (RTILs) offer a number of ideal thermal and physical properties as potential electrolytes for large-scale energy storage applications and thus, can help increase the practicality of such electrochemical devices. This paper reports the synthesis and application of three novel quaternary alkoxy ammonium bis(trifluoromethylsulfonyl)amide based RTILs, with two or more ether functional groups designed to interact and solubilize zinc ions, in order to aid in the electrochemical reversibility of the metal. The anion is successfully reduced from, and re-oxidized into, the three alkoxy ammonium RTILs suggesting that they are potential candidates as electrolytes for use in zinc-air batteries. Cyclic voltammetry reveals that the presence of water reduces the activation barrier required to deposit zinc and assists stable charge/discharge cycling in an electrolyte consisting of 0.1M Zn(NTf2)2 in the tri-alkoxy ammonium chain RTIL, [N2(20201)(20201)(20201)] [NTf2], with 2.5wt.% H2O. Further experiments demonstrate that with such electrolyte a Zn electrode can complete at least 750 cycles at a current density of 0.1mA/cm2 at room temperature.

Effects of quaternary ammonium chain length on the antibacterial and remineralizing effects of a calcium phosphate nanocomposite.

Composites containing nanoparticles of amorphous calcium phosphate (NACP) remineralize tooth lesions and inhibit caries. A recent study synthesized quaternary ammonium methacrylates (QAMs) with chain lengths (CLs) of 3–18 and determined their effects on a bonding agent. This study aimed to incorporate these QAMs into NACP nanocomposites for the first time to simultaneously endow the material with antibacterial and remineralizing capabilities and to investigate the effects of the CL on the mechanical and biofilm properties. Five QAMs were synthesized: DMAPM (CL3), DMAHM (CL6), DMADDM (CL12), DMAHDM (CL16), and DMAODM (CL18). Each QAM was incorporated into a composite containing 20% NACP and 50% glass fillers. A dental plaque microcosm biofilm model was used to evaluate the antibacterial activity. The flexural strength and elastic modulus of nanocomposites with QAMs matched those of a commercial control composite (n = 6; P > 0.1). Increasing the CL from 3 to 16 greatly enhanced the antibacterial activity of the NACP nanocomposite (P < 0.05); further increasing the CL to 18 decreased the antibacterial potency. The NACP nanocomposite with a CL of 16 exhibited biofilm metabolic activity and acid production that were 10-fold lesser than those of the control composite. The NACP nanocomposite with a CL of 16 produced 2-log decreases in the colony-forming units (CFU) of total microorganisms, total streptococci, and mutans streptococci. In conclusion, QAMs with CLs of 3–18 were synthesized and incorporated into an NACP nanocomposite for the first time to simultaneously endow the material with antibacterial and remineralization capabilities. Increasing the CL reduced the metabolic activity and acid production of biofilms and caused a 2-log decrease in CFU without compromising the mechanical properties. Nanocomposites exhibiting strong anti-biofilm activity, remineralization effects, and mechanical properties are promising materials for tooth restorations that inhibit caries.