Alkylammonium Salts Research Articles

Influence of tetraalkylammonium salts on the adsorption kinetics of bovine serum albumin in aqueous solutions at the air-liquid interface

Bovine serum albumin adsorption dynamics in water and in aqueous solutions of tetramethylammonium bromide, hexyltrimethylammonium bromide octyltrimethylammonium bromide, decyltrimethylammonium bromide, and dodecyltrimethylammonium bromide at the air-liquid interface was studied at a temperature of 298.15 K.The kinetics of the adsorption process of the biomolecule in water and in the aqueous alkylammonium solutions was investigated following the changes in surface tension with time. The measurements were performed on a high-precision drop volume tensiometer.The surface pressure data were adjusted with two of the most used semi-empirical kinetic models that describe the process of adsorption and allow the determination of the equilibrium adsorption parameters.The results in water and in the aqueous solutions containing tetraalkylammonium salts show that the adsorption kinetics is well described by a model consisting of three steps in which the transport of the protein in the initial stage is diffusion controlled. After some time, the rate is determined by the adsorption and the penetration of the protein at the air-liquid interface and the rearrangement of the protein at the interface; the evolution of both processes is described by steps that follow first-order rate equations.The results indicate that the overall adsorption process of bovine serum albumin BSA in water and the aqueous alkylammonium salts solutions is controlled by the second step which is the slowest of the three steps; it corresponds to the adsorption and penetration of the biomolecule at the air-liquid interface.

Alkyl ammonium salt with different chain length for high-efficiency and good-stability 2D/3D hybrid perovskite solar cells

Recently, 2D/3D halide perovskites solar cells (PSCs) attract extensive attention due to simultaneous improved efficiency and stability. However, the types of alkyl ammonium salts, including the type of functional groups, the number of carbon atoms in the hydrocarbon chain, as well as the arrangement and distribution of the molecular structure, have a great impact on the performance and stability of films and devices. Herein, we compare the passivation capacity and moisture resistance of 2D capping layer based on three structurally similar alkyl ammonium salts (Butyl Ammonium Iodide (BAI), Propyl Ammonium Iodide (PAI), Ethyl Ammonium Iodide (EAI)) on triple cation perovskite thin films. As the number of carbon atoms in the alkane increases, the water contact angle gradually increases. Moreover, the defect state density is reduced to a certain extent compared to untreated 3D perovskite. The optimal PSCs with PAI-based 2D capping layer exhibit a power conversion efficiency (PCE) of 21.22% and remain 79.5% of initial PCE after 720 h. In addition, the reduced defect state density and improved crystallinity can be attributed to the hydrogen bonding interaction between the amine group and the [PbI 6 ] 4- framework. The emergence and development of 2D/3D perovskites have brought greater hope to commercialize the PSCs. • The NH · · · I hydrogen bond could reduce defects and inhibit ion migration. • PAI-based 2D/3D PSC achieved a PCE of 21.22%. • PAI-based 2D/3D PSC maintains 79.50% of the initial efficiency after 720 h. • The length of alkyl ammonium salts affects the humidity stability of perovskite.

Anion Binding by Fluorescent Ureido-Hexahomotrioxacalix[3]arene Receptors: An NMR, Absorption and Emission Spectroscopic Study.

Fluorescent receptors (4a–4c) based on (thio)ureido-functionalized hexahomotrioxacalix[3]arenes were synthesised and obtained in the partial cone conformation in solution. Naphthyl or pyrenyl fluorogenic units were introduced at the lower rim of the calixarene skeleton via a butyl spacer. The binding of biologically and environmentally relevant anions was studied with NMR, UV–vis absorption, and fluorescence titrations. Fluorescence of the pyrenyl receptor 4c displays both monomer and excimer fluorescence. The thermodynamics of complexation was determined in acetonitrile and was entropy-driven. Computational studies were also performed to bring further insight into the binding process. The data showed that association constants increase with the anion basicity, and AcO−, BzO− and F− were the best bound anions for all receptors. Pyrenylurea 4c is a slightly better receptor than naphthylurea 4a, and both are more efficient than naphthyl thiourea 4b. In addition, ureas 4a and 4c were also tested as ditopic receptors in the recognition of alkylammonium salts.

4,6-O-Phenylethylidene Acetal Protected D-Glucosamine Carbamate-Based Gelators and Their Applications for Multi-Component Gels.

The self-assembly of carbohydrate-based low molecular weight gelators has led to useful advanced soft materials. The interactions of the gelators with various cations and anions are important in creating novel molecular architectures and expanding the scope of the small molecular gelators. In this study, a series of thirteen new C-2 carbamates of the 4,6-O-phenylethylidene acetal-protected D-glucosamine derivatives has been synthesized and characterized. These compounds are rationally designed from a common sugar template. All carbamates synthesized were found to be efficient gelators and three compounds are also hydrogelators. The resulting gels were characterized using optical microscopy, atomic force microscopy, and rheology. The gelation mechanisms were further elucidated using 1H NMR spectroscopy at different temperatures. The isopropyl carbamate hydrogelator 7 formed hydrogels at 0.2 wt% and also formed gels with several tetra alkyl ammonium salts, and showed effectiveness in the creation of gel electrolytes. The formation of metallogels using earth-abundant metal ions such as copper, nickel, iron, zinc, as well as silver and lead salts was evaluated for a few gelators. Using chemiluminescence spectroscopy, the metal–organic xerogels showed enzyme-like properties and enhanced luminescence for luminol. In addition, we also studied the applications of several gels for drug immobilizations and the gels showed sustained release of naproxen from the gel matrices. This robust sugar carbamate-derived gelator system can be used as the scaffold for the design of other functional materials with various types of applications.

Nucleation Effect of the Chemical Structure of Alkylammonium Salt on the Crystallization Behavior of Poly(Vinylidene Fluoride)

We investigated the effect of the chemical structure of alkylammonium salt on the crystallization behavior of poly(vinylidene fluoride) (PVDF) by DSC, optical microscopy, light scattering, and FT-IR. The nonisothermal and isothermal crystallizations of PVDF were accelerated by adding alkylammonium salt consisting of short alkyl chains and small anion species, and the spherulite size and the ordering in the spherulite became smaller due to the nucleation agent effect. The FT-IR spectra revealed that electroactive γ-phase was preferentially formed by adding alkylammonium salts though the accelerated crystallization was suppressed due to the steric hindrance effect by the long alkyl chain and large anion species. On the other hand, the formation of the γ-phase was suppressed when the dispersion of the salt in the PVDF matrix was poor due to the high melting temperature.

Erratum to: Successive Modification of Montmorillonite with Quaternary Alkylammonium Salts of Various Structures as a Method of Preparing Nanofillers for in situ Synthesis of Polymer Nanocomposites (SILAR)-Deposited CuO Thin Films of Nitrobenzene

Erratum to: Successive Modification of Montmorillonite with Quaternary Alkylammonium Salts of Various Structures as a Method of Preparing Nanofillers for in situ Synthesis of Polymer Nanocomposites (SILAR)-Deposited CuO Thin Films of Nitrobenzene

Successive Modification of Montmorillonite with Quaternary Alkylammonium Salts of Various Structures as a Method of Preparing Nanofillers for in situ Synthesis of Polymer Nanocomposites

Successive Modification of Montmorillonite with Quaternary Alkylammonium Salts of Various Structures as a Method of Preparing Nanofillers for in situ Synthesis of Polymer Nanocomposites

Designing the structure and relevant properties of semiclathrate hydrates by partly asymmetric alkylammonium salts.

Semiclathrate hydrates are host-guest materials that form from ionic guests and water. There are numerous options for ionic guests, such as quaternary ammonium salts, to tune the functional properties of these materials such as melting temperature, fusion heat, and gas capacity and selectivity. To design these materials, the stabilization mechanism of the side chains of quaternary ammonium salts must be understood based on both thermodynamic and crystallographic properties and relevant host-guest dynamics. In this paper, we studied semiclathrate hydrates formed from n-propyl, tri-n-butylammonium bromide (N3444Br) and tri-n-butyl, n-pentylammonium bromide (N4445Br). Their cation side chains are decremented or incremented from tetra-n-butylammonium (N4444 or TBA), which is one of the best fits for semiclathrate hydrate structures. The use of the widely used tetra-n-butylammonium bromide (N4444Br or TBAB) as an ionic guest, an increment of the carbon chain, i.e., N4445Br, caused disorders in its hydrate structure due to the oversizing of the cation. This suitably oversized cation selectively stabilized the orthorhombic structure, whose hydration number is relatively high. As a result, the fusion heat at the congruent composition of the hydrate phase was higher than that of the widely used N4444Br (TBAB) hydrates. The N3444Br hydrate showed both significantly decreased melting temperature and fusion heat compared to the N4444Br (TBAB) hydrates. The phase behaviour of the N3444Br hydrate was found to be analogous to that of the N4444Br (TBAB) hydrates. It was demonstrated that the semiclathrate hydrate structures and relevant properties can be modified by adjusting the alkyl side chain length of quaternary ammonium salts.

Hybridization of Oligonucleotide Probes in Aqueous Solutions: Washing in Buffers Containing Quaternary Ammonium Salts.

In this protocol, hybridization is first performed in conventional aqueous solvents at a temperature well below the melting temperature, and the hybrids are then washed at higher stringency in buffers containing quaternary alkylammonium salts. TMACl is used with probes that are 14-50 nt in length, whereas TEACl is used with oligonucleotides that are 50-200 nt in length.

Towards purely inorganic clusters in medicine: Biocompatible divalent cations as counterions of cobaltabis(dicarbollide) and its iodinated derivatives

Monovalent cations, Cs+, and alkylammonium ([NR4]+) salts have traditionally been used to precipitate the anions of boranes, carborane and metallocarborane clusters. In contrast, in the body and in living organisms in general, divalent cations have a special relevance. In this work, we isolate for the first time the cobaltabis(dicarbollide) salts of the biocompatible divalent cations of biological importance that can have application both in biology and in materials science. The preparation of Ca2+, Mg2+ and Fe2+ salts of anionic iodinated nido-[C2B9H12]− and cobaltabis(dicarbollide) as well as its di-, tetra- and octa-iodinated derivatives are reported. Ca2+ and Mg2+ are hard Lewis acids and thus forms aqua ions if water is present in the synthetic process. All solid Ca2+ and Mg2+ salts studied in this work contained water molecules coordinated that have been detected by IR and TGA/DSC. Fe2+ is a medium hard Lewis acid and Fe3+ is a hard one. In acetone they do not coordinate to cobaltabis(dicarbollide) anion, but are solvated by acetone. The studied Ca2+ salts of iodinated cobaltabis(dicarbollide) are basically inorganic small molecules that provide at once the biocompatible divalent Ca2+ cation and and iodinated anions thus simultaneously providing an X-ray contrast agent and/or bone defect repairing agent in regenerative medicine.

Crystallization of Zeolites in the Presence of Diquaternary Alkylammonium Salts Derived from Dimethylethanolamine

Crystallization of Zeolites in the Presence of Diquaternary Alkylammonium Salts Derived from Dimethylethanolamine

Structural, Vibrational, Thermal, Phase Transitions, and Properties Review of Alkylammonium, Alkylenediammonium, and Aminoacid Hexafluorosilicate Salts

Structural, Vibrational, Thermal, Phase Transitions, and Properties Review of Alkylammonium, Alkylenediammonium, and Aminoacid Hexafluorosilicate Salts

Hygroscopicity of secondary marine organic aerosols: Mixtures of alkylammonium salts and inorganic components

Field studies have identified alkylammonium salts as important components of secondary marine organic aerosols. In this work, we study the hygroscopic behavior of laboratory-generated alkylammonium aerosol particles, including monomethylammonium chloride (MMACl), dimethylammonium chloride (DMACl), trimethylammonium chloride (TMACl), diethylammonium chloride (DEACl), and their mixtures with inorganic salts containing ammonium sulfate (NH4)2SO4, sodium chloride NaCl, calcium nitrate Ca(NO3)2 and sodium sulfate Na2SO4 at different dry mass ratios with a hygroscopicity tandem differential mobility analyzer (HTDMA). The hygroscopic growth of pure alkylammonium salt particles (except for DEACl) reveals gradual water uptake over the whole studied range of relative humidities (RHs). In general, the impact of the presence of alkylammonium chloride on the phase behavior and hygroscopic growth of mixtures depends on the chemical composition of particles and volume fraction of the alkylammonium chloride in the mixtures. For alkylammonium/(NH4)2SO4 mixed particles (except for TMACl/(NH4)2SO4), the hygroscopic growth shows a smooth growth tendency when the organic content is high, while the deliquescence transition is observed for alkylammonium salt/NaCl mixtures at all mass ratios. Regarding the different mixtures of alkylammonium/Ca(NO3)2 particles, continuous water uptake without phase transition is observed over the studied RH range, indicating that alkylammonium salts impose no effect on the liquid-like state of calcium nitrate. The alkylammonium/Na2SO4 mixtures show obvious particle shrinkage prior to the deliquescence point. A similar behavior is also observed for alkylammonium salt/NaCl mixtures. The observed diameter reduction can be attributed to the transformation of porous or irregularly shaped solid particles into more compact near-spherical particles. In the following, measured growth factors (GFs) are compared with values predicted with the Zdanovskii–Stokes–Robinson (ZSR) mixing rule and ideal solution model. The ZSR predictions for different alkylammonium/inorganic mixtures are similar to the measured GFs as long as the mixed particles are in a liquid-like state.

Fluorinated interphase enables reversible aqueous zinc battery chemistries.

Metallic zinc is an ideal anode due to its high theoretical capacity (820 mAh g-1), low redox potential (-0.762 V versus the standard hydrogen electrode), high abundance and low toxicity. When used in aqueous electrolyte, it also brings intrinsic safety, but suffers from severe irreversibility. This is best exemplified by low coulombic efficiency, dendrite growth and water consumption. This is thought to be due to severe hydrogen evolution during zinc plating and stripping, hitherto making the in-situ formation of a solid-electrolyte interphase (SEI) impossible. Here, we report an aqueous zinc battery in which a dilute and acidic aqueous electrolyte with an alkylammonium salt additive assists the formation of a robust, Zn2+-conducting and waterproof SEI. The presence of this SEI enables excellent performance: dendrite-free zinc plating/stripping at 99.9% coulombic efficiency in a Ti||Zn asymmetric cell for 1,000 cycles; steady charge-discharge in a Zn||Zn symmetric cell for 6,000 cycles (6,000 h); and high energy densities (136 Wh kg-1 in a Zn||VOPO4 full battery with 88.7% retention for >6,000 cycles, 325 Wh kg-1 in a Zn||O2 full battery for >300 cycles and 218 Wh kg-1 in a Zn||MnO2 full battery with 88.5% retention for 1,000 cycles) using limited zinc. The SEI-forming electrolyte also allows the reversible operation of an anode-free pouch cell of Ti||ZnxVOPO4 at 100% depth of discharge for 100 cycles, thus establishing aqueous zinc batteries as viable cell systems for practical applications.

Vermiculite modified with alkylammonium salts: characterization and sorption of ibuprofen and paracetamol

In this work, the clay mineral vermiculite (VT) was treated using the bromide form of quaternary alkylammonium salts—ethylhexadecyldimethylammonium (EHDDMAB), hexadecyltrimethylammonium (HDTMAB), tetradecyltrimethylammonium (TDTMAB) and tetrabutylammonium (TBAB), in order to obtain the organo-vermiculites (OVT) named as VT-EHDDMA, VT-HDTMA, VT-TDTMA and VT-TBA, respectively. These sorbents and the precursor VT were characterized using several techniques which allowed to infer the intercalation of the alkylammonium salts in the interlayer space of VT, except VT-TBA, and these materials were evaluated as sorbents for ibuprofen and paracetamol. VT and OVT presented no significant interactions with paracetamol and sorbed less than 10% of the initial concentration. On the other hand, two OVT sorbents demonstrated high efficiency in the sorption of ibuprofen, and the maximum percent removal was higher than 92% for VT-EHDDMA and VT-HDTMA, with a maximum sorption capacity of 52 ± 2 mg g−1 (VT-EHDDMA) and 54 ± 2 mg g−1 (VT-HDTMA), whereas 16 ± 2 mg g−1 was observed for VT. These results suggest that the low-cost OVT could be considered as appropriate sorbent for ibuprofen removal from aqueous medium, and probably as a promising sorbent for drugs of a wide polarity range, with neutral, acid and basic characteristics.

Tetraoctylammonium, a Long Chain Quaternary Ammonium Blocker, Promotes a Noncollapsed, Resting-Like Inactivated State in KcsA.

Alkylammonium salts have been used extensively to study the structure and function of potassium channels. Here, we use the hydrophobic tetraoctylammonium (TOA+) to shed light on the structure of the inactivated state of KcsA, a tetrameric prokaryotic potassium channel that serves as a model to its homologous eukaryotic counterparts. By the combined use of a thermal denaturation assay and the analysis of homo-Förster resonance energy transfer in a mutant channel containing a single tryptophan (W67) per subunit, we found that TOA+ binds the channel cavity with high affinity, either with the inner gate open or closed. Moreover, TOA+ bound at the cavity allosterically shifts the equilibrium of the channel’s selectivity filter conformation from conductive to an inactivated-like form. The inactivated TOA+–KcsA complex exhibits a loss in the affinity towards permeant K+ at pH 7.0, when the channel is in its closed state, but maintains the two sets of K+ binding sites and the W67–W67 intersubunit distances characteristic of the selectivity filter in the channel resting state. Thus, the TOA+–bound state differs clearly from the collapsed channel state described by X-ray crystallography and claimed to represent the inactivated form of KcsA.

Synthesis of α,δ-Disubstituted Tetraphosphates and Terminally-Functionalized Nucleoside Pentaphosphates.

The anion [P4O11]2-, employed as its bis(triphenylphosphine)iminium (PPN) salt, is shown herein to be a versatile reagent for nucleophile tetraphosphorylation. Treatment under anhydrous conditions with an alkylamine base and a nucleophile (HNuc1), such as an alcohol (neopentanol, cyclohexanol, 4-methylumbelliferone, and Boc-Tyr-OMe), an amine (propargylamine, diethylamine, morpholine, 3,5-dimethylaniline, and isopropylamine), dihydrogen phosphate, phenylphosphonate, azide ion, or methylidene triphenylphosphorane, results in nucleophile substituted tetrametaphosphates ([P4O11Nuc1]3-) as mixed PPN and alkylammonium salts in 59% to 99% yield. Treatment of the resulting functionalized tetrametaphosphates with a second nucleophile (HNuc2), such as hydroxide, a phenol (4-methylumbelliferone), an amine (propargylamine and ethanolamine), fluoride, or a nucleoside monophosphate (uridine monophosphate, deoxyadenosine monophosphate, and adenosine monophosphate), results in ring opening to linear tetraphosphates bearing one nucleophile on each end ([Nuc1(PO3)3PO2Nuc2]4-). When necessary, these linear tetraphosphates are purified by reverse phase or anion exchange HPLC, yielding triethylammonium or ammonium salts in 32% to 92% yield from [PPN]2[P4O11]. Phosphorylation of methylidene triphenylphosphorane as Nuc1 yields a new tetrametaphosphate-based ylide ([Ph3PCHP4O11]3-, 94% yield). Wittig olefination of 2',3'-O-isopropylidene-5'-deoxy-5'-uridylaldehyde using this ylide results in a 3'-deoxy-3',4'-didehydronucleotide derivative, isolated as the triethylammonium salt in 54% yield.

Synthesis of Silver Nanoparticles with Gemini Surfactants as Efficient Capping and Stabilizing Agents

The scientific community has paid special attention to silver nanoparticles (AgNPs) in recent years due to their huge technological capacities, particularly in biomedical applications, such as antimicrobials, drug-delivery carriers, device coatings, imaging probes, diagnostic, and optoelectronic platforms. The most popular method of obtaining silver nanoparticles as a colloidal dispersion in aqueous solution is chemical reduction. The choice of the capping agent is particularly important in order to obtain the desired size distribution, shape, and dispersion rate of AgNPs. Gemini alkylammonium salts are named as multifunctional surfactants, and possess a wide variety of applications, which include their use as capping agents for metal nanoparticles synthesis. Because of the high antimicrobial activity of gemini surfactants, AgNPs stabilized by this kind of surfactant may possess unique and strengthened biocidal properties. The present paper presents the synthesis of AgNPs stabilized by gemini surfactants with hexadecyl substituent and variable structure of spacer, obtained via ecofriendly synthesis. UV-Vis spectroscopy and dynamic light scattering were used as analyzing tools in order to confirm physicochemical characterization of the AgNPs (characteristic UV-Vis bands, hydrodynamic diameter of NPs, polydispersity index (PDI)).

Progress on defects and interfacial passivation layers in hybrid perovskite solar cells

<p indent=0mm>Perovskite, as a class of semiconductor materials with unique optoelectronic properties, such as low exciton binding energy, long carrier diffusion length and tunable bandgap, is widely studied in many research fields. Particularly, organic–inorganic hybrid perovskite solar cells (PSCs) have attracted wide attention due to their low cost and high power conversion efficiencies. Currently, inherent defects in perovskites are restricting their further development. As is known to all, both deep level defects and shallow level defects play key roles in the dynamic process of carriers and the stability of perovskites. Recombination loss, unfavorable band bending, unwanted surface reaction and ionic migration caused by these defects, can lead to serious damages to the device lifetime and performance. In this review article, the formation processes and physical properties of the defects, including point defects, surface defects and defects around perovskite grain boundaries, as well as their effects on the PSC performances, are carefully summarized and analyzed. According to the previous studies, conduction band and valence band of perovskites and defect energy states in perovskites are all related to the anti-bonding coupling of Pb-s and I-p atom orbitals. Certain anti-site and interstitial defects caused by the wrong ionic bonds as well as the surface states can create deep level defects. Moreover, shallow level defects produced by the point defects and grain boundaries will aggravate the unfavorable ion migration and surface reaction, which will dramatically deteriorate the device lifetime and performance of the PSCs. Therefore, defect passivation is a crucial and powerful route to optimizing the power conversion efficiency and long-term stability of the PSCs. Moreover, recent advances in interfacial layer used for the defect passivation, categorized as Lewis acid, Lewis base, alkylammonium, polymer, metal oxide, 3D perovskite, graphene and inorganic salt, are described in detail. We comprehensively present the passivation mechanisms and significant effects of these materials in this paper. Note that the main passivation mechanisms of these materials have been summarized as following: (1) Reducing the density of surface defects via the interaction between functional groups of the passivation molecules and the defects; (2) forming passivation layer on the surface through <italic>in situ</italic> reaction between the passivation molecules and the perovskite during post-treatment; (3) optimizing the energy level arrangement of the PSCs by molecular dipole to promote the transport and extraction of photo carriers; (4) adding an insulating layer between the active layer and the charge transport layer to improve the stability of the perovskite and the PSCs; (5) controlling the crystallization and wettability of the perovskite film and each function layer through surface interaction to obtain flat and high-quality films. Lastly, some potential design strategies of passivation materials are proposed, such as intentionally integrating multifunction groups, polymerization of small organic molecules and exploring novel inorganic materials. The theoretical understanding of the defects properties and the mechanisms for defect passivation summarized by this review should be very helpful in further developing the PSCs.

Dihomooxacalix[4]arene-Based Fluorescent Receptors for Anion and Organic Ion Pair Recognition.

Fluorescent dihomooxacalix[4]arene-based receptors 5a–5c, bearing two naphthyl(thio)ureido groups at the lower rim via a butyl spacer, were synthesised and obtained in the cone conformation in solution. The X-ray crystal structures of 1,3- (5a) and 3,4-dinaphthylurea (5b) derivatives are reported. Their binding properties towards several anions of different geometries were assessed by 1H-NMR, UV-Vis absorption and fluorescence titrations. Structural and energetic insights of the naphthylurea 5a and 5b complexes were also obtained using quantum mechanical calculations. The data showed that all receptors follow the same trend, the association constants increase with the anion basicity, and the strongest complexes were obtained with F−, followed by the oxoanions AcO− and BzO−. Proximal urea 5b is a better anion receptor compared to distal urea 5a, and both are more efficient than thiourea 5c. Compounds 5a and 5b were also investigated as heteroditopic receptors for biologically relevant alkylammonium salts, such as the neurotransmitter γ-aminobutyric acid (GABA·HCl) and the betaine deoxycarnitine·HCl. Chiral recognition towards the guest sec-butylamine·HCl was also tested, and a 5:2 selectivity for (R)-sec-BuNH3+·Cl− towards (P) or (M) enantiomers of the inherently chiral receptor 5a was shown. Based on DFT calculations, the complex [(S)-sec-BuNH3+·Cl−/(M)-5a] was indicated as the more stable.