Organic Ammonium Salts Research Articles

Effect of organic reagents on high temperature rheological characteristics of organic rectorite modified asphalt

The molecular structure of organic reagents has a great effect on properties of organic rectorite (OREC) modified asphalt binder. This paper aims at comparing the influence of molecular chain length and benzyl group on the high temperature rheological characteristics of OREC modified binder. Here, three organic quaternary ammonium salts, including dodecyl trimethyl ammonium chloride (DTAC), dodecyl dimethyl benzyl ammonium chloride (DBAC) and octadecyl trimethyl ammonium chloride (OTAC), were selected as REC modifiers to prepare ORECs. These ORECs were then employed to modify base binder, respectively. The X-ray diffraction (XRD) test and thermogravimetric (TG) test were conducted to study the structure characteristics and thermal behavior of ORECs and corresponding modified binders. The high temperature rheological behavior, rutting and stress susceptibilities of OREC modified binders were evaluated by the temperature and frequency sweep tests, multiple stress creep recovery (MSCR) test. Results indicate that, the organic reagent affects the rheological behavior of OREC modified binder not only by enlarging the basal spacing of REC (specific surface area), but also directly by specific functional groups (e.g. benzyl group). Moreover, the organic reagent with longer molecular chains (18 carbon atoms) or containing benzyl groups is conductive to the improvement in elastic property and stiffness, and reduction in rutting and stress susceptibilities of OREC modified binder. The comparison demonstrates that DBAC containing benzyl groups exhibits better effect. Therefore, organic reagents containing benzyl groups are preferred to obtain OREC modified binder with excellent high temperature property.

Harnessing Dielectric Confinement on Tin Perovskites to Achieve Emission Quantum Yield up to 21.

Tin perovskite nanomaterial is one of the promising candidates to replace organic lead halide perovskites in lighting applications. Unfortunately, the performance of tin-based systems is markedly inferior to those featuring toxic Pb salts. In an effort to improve the emission quantum efficiency of nanoscale 2D layered tin iodide perovskites through fine-tuning the electronic property of organic ammonium salts, we came to unveil the relationship between dielectric confinement and the photoluminescent properties of tin iodide perovskite nanodisks. Our results show that increasing the dielectric contrast for organic versus inorganic layers leads to a bathochromic shift in emission peak wavelength, a decrease of exciton recombination time, and importantly a significant boost in the emission efficiency. Under optimized conditions, a leap in emission quantum yield to a record high 21% was accomplished for the nanoscale thienylethylammonium tin iodide perovskite (TEA2SnI4). The as-prepared TEA2SnI4 also possessed superior photostability, showing no sign of degradation under continuous irradiation (10 mW/cm2) over a period of 120 h.

Salting out assisted liquid-liquid extraction for liquid chromatography tandem-mass spectrometry determination of amphetamine-like stimulants in meconium

In the last decade there has been a dramatic increase in the availability and abuse of synthetic cathinones – new amphetamine-like stimulants. Even though their abuse during pregnancy could have serious adverse effects on the fetus, cathinones are not readily included in neonatal toxicological screenings. Meconium (first neonatal stool) is the specimen of choice to reveal long term drug exposure, however as it is a highly complex matrix, the sample preparation is a critical step before the instrumental analysis.The aim of this work was to develop a suitable meconium sample extraction technique using the advantages of salting-out assisted liquid-liquid extraction (SALLE) and using only MS-friendly organic ammonium salts. We further developed and validated liquid chromatography tandem-mass spectrometry method for the determination of ‘traditional’ stimulants (methamphetamine, amphetamine, MDMA) and cathinones (mephedrone, methylenedioxypyrovalerone (MDPV), α-pyrrolidinopentiophenone (α-PVP), methylone, butylone, flephedrone, and naphyrone).Matrix-matched calibration was prepared in the concentration range 10–2000 ng/g. The limits of quantification were determined as 10 ng/g, recoveries ranged from 48.2% to 94.3% and the matrix effect was between 60.2% and 101.4%. Accuracy (86.1–114.5%) and precision (4.9–14.9%) were determined and all validation criteria were met for all analytes except for naphyrone. Finally, our analytical method was tested on a set of real meconium samples, which were found positive for amphetamine, methamphetamine and methylone, thus demonstrating the validity of the method.

1-(2-Aminoethyl)-1-dodecyl-2-undecyl-4,5-dihydro-1H-imidazol-1-ium chloride, 1-(2-Aminoethyl)-1-dodecyl-2-tridecyl-4,5-dihydro-1H-imidazol-1-ium chloride as Corrosion Inhibitors for Carbon Steel in Oil Wells Formation Water

Abstract Introducing1-(2-aminoethyl)-1-dodecyl-2-undecyl-4,5-dihydro-1H-imidazol-1-ium chloride (LQI), 1-(2-aminoethyl)-1-dodecyl-2-tridecyl-4,5-dihydro-1H-imidazol-1-ium chloride (MQI) as two organic structures quaternary ammonium salts, which have been made and analyzed by FTIR, 1H NMR spectroscopic methods. (X-65) carbon steel’s corrosion in naturally formed rocks’ oil wells formation water in the nonappearance (Blank) and using a wide range of concentrations (50, 100, 200, 300, 400, 500 ppm) of these cationic surfactants, as inhibition blockers using direct current (DC), alternative current (AC) electrochemical ways. To sum up, the inhibition efficiency grew with up the gradual rise in the inhibitor content till having peaked at (500 ppm) registered (94.83%) for (MQI). Specifically, carbon steel’s morphology was closely inspected with the aid of highly automated scanning electron microscopy, and energy dispersive X-ray facilities. As a matter of fact, quantum chemical calculations enriched the theoretical study of the (LQI, MQI) compounds depend on energy levels’, energy maps, and 3D structures consideration.

Organic ammonium salt surface treatment stabilizing all-inorganic CsPbI<sub>2</sub>Br perovskite

All-inorganic perovskite cesium lead halides with superior stability, suitable bandgap and high absorption efficient have become a promising candidate for photovoltaic application. In all-inorganic cesium lead halide perovskites, CsPb<i>X</i><sub>3</sub> (<i>X</i> = Br, I) exhibits excellent photoelectric properties, which are similar to those of organic-inorganic hybrid perovskites. The CsPbI<sub>3</sub> faces a challenge of unideal tolerant factor for perovskite phase while CsPbI<sub>3–<i>x</i></sub>Br<i><sub>x</sub></i> has better tolerant factor. Among them, CsPbI<sub>2</sub>Br is one of most popular candidates because of its good thermal stability. Nevertheless, CsPbI<sub>2</sub>Br shows instability due to the phase transition caused by moisture and lower efficiency because of defects. For all inorganic perovskite devices, the alkyl chain length of surface treatment agent should be taken into account when using organic cationic passivation method. In this paper, CsPbI<sub>2</sub>Br perovskite is treated with different organic ammonium salts to enhance its phase stability. The experimental results show that <i>α</i>-phase CsPbI<sub>2</sub>Br is more stable with the increase of the alkyl chain length. Butylamine iodine (BAI) among three kinds of surface treating agents is proved to have the best defect passivation and phase stabilization effect. With the increase of alkyl chain length, the hydrophobicity of the organic molecular layer increases, which plays a crucial role in protecting optically active CsPbI<sub>2</sub>Br. Meanwhile, it is found that the stability of perovskite is enhanced with the concentration of the BAI solution increasing. This should be related to the organic cation termination formed on the surface of CsPbI<sub>2</sub>Br film. Solar cell devices based on the CsPbI<sub>2</sub>Br thin films treated with different concentrations of BAI are assembled and then the effect of organic ion surface treatment on the photoelectric performance of batteries is further explored. The experimental results show that when the concentration of BAI is relatively high (4 mg/mL and 8 mg/mL), the device’s photovoltaic performance decreases especially the photocurrent obviously decreases, while the post-treatment process using 2 mg/mL BAI will enhance not only the phase stability but also the photovoltaic parameters after defect passivation. Considering both humidity resistance and device efficiency, this work demonstrates that the CsPbI<sub>2</sub>Br thin film with suitable BAI treatment can improve the wet stability of perovskite, and enhance the photovoltaic performance.

Precise Synthesis of Poly(thioester)s with Diverse Structures by Copolymerization of Cyclic Thioanhydrides and Episulfides Mediated by Organic Ammonium Salts.

The precise synthesis of poly(thioester)s with diverse structures is still a significant challenge in the polymeric materials field. Herein, we report a novel approach to the synthesis of well-defined poly(thioester)s by the controlled alternating copolymerization of cyclic thioanhydrides and episulfides induced by simple organic ammonium salts. Both the cation and anion have strong effects on the copolymerization. [PPN]OAc ([PPN]=bis(triphenylphosphine)iminium) with a bulky cation was proven to be efficient in initiating this polymerization, yielding poly(thioester)s with a completely alternating structure, controlled molecular weight, and narrow polydispersity. The poly(thioester) obtained from succinic thioanhydride and propylene sulfide is a typical semicrystalline material, possessing a high refractive index of up to 1.78. Because it uses readily available monomers, this method is expected to open up a new route to poly(thioester)s with diverse structures and properties.

Precise Synthesis of Poly(thioester)s with Diverse Structures by Copolymerization of Cyclic Thioanhydrides and Episulfides Mediated by Organic Ammonium Salts

AbstractThe precise synthesis of poly(thioester)s with diverse structures is still a significant challenge in the polymeric materials field. Herein, we report a novel approach to the synthesis of well‐defined poly(thioester)s by the controlled alternating copolymerization of cyclic thioanhydrides and episulfides induced by simple organic ammonium salts. Both the cation and anion have strong effects on the copolymerization. [PPN]OAc ([PPN]=bis(triphenylphosphine)iminium) with a bulky cation was proven to be efficient in initiating this polymerization, yielding poly(thioester)s with a completely alternating structure, controlled molecular weight, and narrow polydispersity. The poly(thioester) obtained from succinic thioanhydride and propylene sulfide is a typical semicrystalline material, possessing a high refractive index of up to 1.78. Because it uses readily available monomers, this method is expected to open up a new route to poly(thioester)s with diverse structures and properties.

Evidence for the Importance of Semivolatile Organic Ammonium Salts in Ambient Particulate Matter.

The gas/particle phase partitioning behavior of NH3/NH4+ and other semivolatile constituents was measured by a custom-designed Denuder-MOUDI-Denuder integrated sampling system in Toronto, Canada. In this setup, upstream denuders were used to capture alkaline and acidic gaseous components, and particle phase components were captured by the filters on MOUDI stages. Downstream denuders captured any alkaline and acidic gases that exited the MOUDI apparatus, likely representing semivolatile constituents. In the ambient gas phase HCOOH was the most abundant acidic gas, with an average mixing ratio ∼2-3 times higher than that of SO2 and HNO3. It was found that the majority (49-96%) of filter-collected NH4+ volatilized during collection. NO3- volatilization could only explain 0.9-15% of NH4+ loss from the filters. Instead, a strong correlation and nearly 1:1 molar ratio between downstream HCOO- and NH4+ indicated that most of the semivolatile NH4+ was originally balanced by organic acids in the ambient particle phase. The thermodynamic properties of HCOOH/HCOO- suggest that it should not have been present at high levels in the ambient particle phase, and we interpret its detection in the downstream denuder as evidence for larger organic acids that reacted to generate HCOOH prior to our offline measurement.

Critical role of chloride in organic ammonium spacer on the performance of Low-dimensional Ruddlesden-Popper perovskite solar cells

Low-dimensional Ruddlesden-Popper (LDRP) perovskites attracted remarkable attention due to their technologically relevant intrinsic photo- and chemical-stability, suppressed ion migration, and ultralow self-doping effect over their 3D counterpart. The power conversion efficiency over 14% was recently achieved since the initial demonstration of LDRP perovskite solar cells (PSCs) in 2014. However, further improvements require a fundamental understanding on the components functionality in LDRP perovskites, e.g., bulky organic ammonium spacer and halogen ions, which are critical for designing efficient LDRP PSCs. Here, we report the critical role of the chloride that are derived from halogenated organic ammonium salts on the LDRP perovskite film crystallization, growth, opto-electric properties, and device performance. We found that the expected improvements in perovskite morphology with increased grain size, enhanced crystallinity, and uniform and smooth surface were revealed no matter which introduced chloride either by bulky organic ammonium or methyl ammonium salts. We also unambiguously demonstrated that photocurrent and photovoltage of LDRP PSCs are highly related to the position of chloride on organic ammonium salts. Moreover, the films and devices maintain excellent stability by the introduction of chloride due to the excellent film quality. The resulting LDRP PSCs exhibited best efficiency of 12.78%, which is two times enhancement compared to all iodide-contained device (6.52%) commonly used in previous reports. These findings demonstrated that chloride plays a significant role in LDRP perovskite and detected a key parameter for the development of future LDRP perovskite absorbers and relevant optoelectronic devices.

Redox reaction process between hydrocarbon and adsorbed NOx over lean NOx trap catalyst

In this study, we investigated the redox reaction between a hydrocarbon (HC) and adsorbed NOx over CuPtBa/Al2O3 lean NOx trap (LNT) catalyst. Experimental characterizations included temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), in situ diffuse reflectance Fourier transform spectroscopy (in situ DRIFTs) and Raman spectroscopy. Density functional theory (DFT) calculations were also performed. The model C3H6 first adsorbed to the catalyst surface, and the resulting C3H6-adsorbed species reacted with adsorbed NOx species to form various intermediates such as: carboxylates, enolic compounds, carbonato complexes, Pt-carbonyls, acid anhydrides, basic hydroxyls, nitrogen-containing organic species, acyl chlorides, and ammonium salts. These intermediates participated in subsequent reactions and finally produced the effluent gases CO2, N2, NH3, and H2O. The decomposition ability of adsorbed NOx species indicated that the NOx species participated in the C3H6 oxidation in the order: adsorbed N2O4 > monodentate nitrates > free ionic nitrates > bulk free ionic nitrates. Carbonaceous materials were generated during the C3H6 oxidation process and were consumed as intermediates by gaseous NOx released upon decomposition of the adsorbed NOx species. In summary, the redox reaction between C3H6 and adsorbed NOx followed the Langmuir–Hinshelwood mechanism, and three reaction routes were proposed for the redox process over the studied catalyst. The activation energy barriers determined by DFT + U calculations for the three routes indicated that the initial dissociation of NO3− species in R(2) occurred more easily than the oxidation of C3H6 species in R(1), delivering the active oxygen species that participated in R(1) and R(3). As the reactions proceeded, the higher energy barrier for the complete dissociation of NO2* indicated that the temperature determined the further decomposition of adsorbed NOx species, and R(1) and R(3) were constrained owing to the limited surface active oxygen species from R(2).

Salting-in and salting-out effects of organic and inorganic ammonium salts on the aqueous polymer solutions

This paper accomplishes a broad survey of the salting effects of different ammonium salts on the aqueous polymer solutions. In order to cover a wide range of hydrophilic and hydrophobic nature of solutes, salts including ammonium chloride (NH4Cl), ammonium bromide (NH4Br), tetraethyl ammonium bromide (TEAB), tetrapropyl ammonium bromide (TPAB), tetrabutyl ammonium bromide (TBAB), tetrabutyl ammonium chloride (TBAC), and dodecyl trimethyl ammonium bromide (DTAB), and polymers polyethylene glycol (PEG400 and PEG10000) and polypropylene glycol (PPG400 and PPG1000) have been used. In the first part of this work, cloud point temperatures (TC) for binary system of PPG1000 in pure water and for ternary systems of PPG1000 in aqueous solutions of ammonium salts have been determined by visual observation. It is shown that while the inorganic ammonium salts (NH4Cl and NH4Br) reduce the TC values of PPG1000 aqueous solutions (salting-out effect), the organic ammonium salts (TEAB, TPAB, TBAB, TBAC, DTAB) because of hydrocarbon portions in their structure favourably interact with PPG1000 and elevate the TC values (salting-in effect). The values of salting coefficient and energetic parameters of clouding process have been calculated. In the second part of this work, the isopiestic equilibrium has been investigated for several ternary {polymer + ammonium salt + water} systems at 298.2 K. Three different types of constant water activity curves deviation from the linear isopiestic relation (LIR) were observed: negative deviations for systems which undergo salting-out phenomenon and phase separation, positive deviations for systems which undergo salting-in effect, and non-deviation for semi-ideal solutions. The effects of type and molar mass of polymers, and type of cation and anion of ammonium salts on the magnitude and type of salting effects have been scrutinized.

Chemical Composition and Reaction Mechanisms for Aged p‐Xylene Secondary Organic Aerosol in the Presence of Ammonia

A laboratory study was carried out to investigate the chemical composition of aged aromatic secondary organic aerosol (SOA) formed from the photoxidation of p‐xylene in the presence of ammonia (NH3). The experiments were conducted by irradiating p‐xylene/CH3ONO/NH3 air mixtures without and with NO in a home‐made smog chamber. The particulate products of aged p‐ xylene SOA in the presence of NH3 were measured by UV–vis spectrophotometry, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, and aerosol laser time‐of‐flight mass spectrometry (ALTOFMS) coupled with the fuzzy C‐means (FCM) clustering algorithm. The experimental results show that NH3 does not alter the gas–particle partitioning in the photoxidation of p‐xylene without NO and that 2,5‐dimethylphenol is the predominant NH3‐aged p‐xylene SOA without NO. However, NH3 has a significant promotional effect on the formation of organonitrogen compounds in the OH‐initiated oxidation of p‐xylene with NO. Organic ammonium salts such as ammonium glyoxylate and p‐methyl ammonium benzoate, which are formed from NH3 reactions with gaseous organic acids, were detected as the major particulate organonitrogen products of NH3‐aged p‐xylene SOA with NO. 1H‐Imidazole, 4‐methyl‐1H‐imidazole, and other imidazole products of the heterogeneous reactions between NH3 and dialdehydes of p‐xylene SOA were newly measured. The possible reaction mechanisms leading to these organonitrogen products are also discussed and proposed. The formation of imidazole products suggests that some ambient particles containing organonitrogen compounds may be the result of this mechanism. The results of this study may provide valuable information for discussing anthropogenic SOA aging mechanisms.

Characterization of brown carbon constituents of benzene secondary organic aerosol aged with ammonia

Nitrogen-containing organic compounds (NOC) formed from secondary organic aerosols (SOA) age via reaction with reduced nitrogen species are a vital class of brown carbon compounds. NOC compounds from ammonia (NH3) gas-aging of benzene SOA were investigated in present study, and the experiments were performed by irradiating benzene/CH3ONO/NO/NH3 air mixtures in a home-made smog chamber. The particulate NOC products of aged benzene SOA in the presence of NH3 were measured by UV-Vis spectrophotometer, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and aerosol laser time-of-flight mass spectrometer (ALTOFMS) coupled with Fuzzy C-Means (FCM) clustering algorithm, respectively. Experimental results demonstrated that NH3 has significant promotion effect on benzene SOA formation. Organic ammonium salts, such as ammonium glyoxylate, ammonium 6-oxo-2,4-hexadienoiclate, which are formed from NH3 reactions with gaseous organic acids were detected as the major particulate NOC products of NH3-aged benzene SOA. 1H–imidazole, 1H–imidazole-2-carbaldehyde and other imidazole products via the heterogeneous reactions between NH3 and dialdehydes of benzene SOA were successfully detected as important brown carbon constituents. The formation of imidazole products suggests that some ambient particles contained organonitrogen compounds may be come from this mechanism. The results of this study may provide valuable information for discussing NH3 deposition and SOA aging mechanisms.

Chemical analysis of particulate products of aged 1,3,5-trimethylbenzene secondary organic aerosol in the presence of ammonia

Ammonia (NH3) gas-aging of secondary organic aerosol (SOA) results in the formation of organonitrogen compound is an important class of brown carbon. The particulate products of aged 1,3,5-trimethylbenzene (135-TMB) SOA in the presence of NH3 were measured by UV–Vis spectrophotometer, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and aerosol laser time-of-flight mass spectrometer (ALTOFMS) in present study. Experimental results indicated that NH3 has significant promotion effect on 135-TMB SOA formation. Organic ammonium salts, such as ammonium methyl glyoxylate, ammonium 3,5-dimethylbenzoate, which are formed from NH3 reactions with gaseous organic acids were detected as the principal particulate products of NH3-aged 135-TMB SOA. 4-methyl-imidazole-2-acetaldehyde, 4-methyl- 1H-imidazole and other imidazole products via the heterogeneous reactions between NH3 and dialdehydes of 135-TMB SOA were newly measured. The formation of imidazole products suggests that some ambient particles contained organonitrogen compounds may be come from this mechanism. The results of this study may provide valuable information for discussing SOA aging mechanisms and new route for NH3 deposition.

Ambient and laboratory observations of organic ammonium salts in PM1.

Ambient measurements of PM1 aerosol chemical composition at Cabauw, the Netherlands, implicate higher ammonium concentrations than explained by the formation of inorganic ammonium salts. This additional particulate ammonium is called excess ammonium (eNH4). Height profiles over the Cabauw Experimental Site for Atmospheric Research (CESAR) tower, of combined ground based and airborne aerosol mass spectrometric (AMS) measurements on a Zeppelin airship show higher concentrations of eNH4 at higher altitudes compared to the ground. Through flights across the Netherlands, the Zeppelin based measurements furthermore substantiate eNH4 as a regional phenomenon in the planetary boundary layer. The excess ammonium correlates with mass spectral signatures of (di-)carboxylic acids, making a heterogeneous acid-base reaction the likely process of NH3 uptake. We show that this excess ammonium was neutralized by the organic fraction forming particulate organic ammonium salts. We discuss the significance of such organic ammonium salts for atmospheric aerosols and suggest that NH3 emission control will have benefits for particulate matter control beyond the reduction of inorganic ammonium salts.

Recurrent supramolecular scenarios within complex 3-D hydrogen bond networks derived from organic ammonium salts of (4-amino-1-hydroxybutylidine)-1,1-bisphosphonic acid

Reactions of (4-amino-1-hydroxybutylidine)-1,1-bisphosphonic acid (LH5) with organic amines or diamines in aqueous solution yields crystalline compounds of the general formula [(RN)H]2[LH3] or [(R'N)H2][LH3].

Influence of the Organophilisation Process on Properties of the Bentonite Filler and Mechanical Properties of the Clay/Epoxy Nanocomposites

Abstract In this comparative study, the influence of the organophilisation process on the properties of resulting organobentonite fillers and their capability to improve the mechanical properties of clay/polymer nanocomposites were investigated. The organobentonites were obtained by activation with the use of two organic quaternary ammonium salts (QAS) with alkyl chains of significantly different lengths. The organophilisation resulted in an increase in the interlayer space of clays, which was confirmed by XRD analysis. The obtained organofillers were used to produce nanoclay/epoxy resin composites and the effects of alkyl chain length on the resulting properties of composites were compared based on the examination of mechanical behaviour and morphology, and a composite filled with the non organophilised bentonite was used as a reference material. It was demonstrated that the organophilisation process using distearyldimethyl ammonium chloride salt with a longer alkyl chain (C18-C20) created a more superior conditions for the compatibility of nanofiller with a polymer matrix, resulting in a 25 % increase in the bending strength of the epoxy composite material filled with 3 %wt of the organophilised bentonite, comparing to neat epoxy.

Cation-Anion Interactions and Synergistic Catalysis by Supramolecular Polyoxometalate Complexes [C10H18N]n[XM12O40

A series of novel organic ammonium salts of Keggin [XM12O40]n− (X=P, Si, B; M=W, Mo) was synthesized and fully characterized using ESI-MS and X-ray crystallography. The solid-state structure of the title compounds [C10H18N]n[XM12O40] was unveiled by X-ray crystallography that hydrogen bonds are formed between the nitrogen center of amantadine and the bridging oxygen atoms of POM in addition to Coulombic attractions and by MS/MS that consecutive proton-transfer reactions from [C10H18N]+ to [XM12O40]n− were observed in the gas-phase fragmentations of the dimeric clusters {(C10H18N)m[XM12O40]2}(2n−m)−. A comparative study on the catalytic property of [XM12O40]n− in methyl phenyl sulfide (MPS) oxidation with aqueous hydrogen peroxide in MeCN was performed and the effect of counterions ([C10H18N]+ and TBA+, etc) on the catalytic performance has been investigated. The best catalytic activity of [C10H18N]3[PMo12O40] in MPS oxidation illustrates the explicit role of cations on promoting catalytic activity of polyoxoanions.

Effect of Carbon Chain Length of Organic Salts on the Thermodynamic Stability of Methane Hydrate

This study presents the phase equilibrium conditions for methane hydrate with one of the following organic ammonium salts differing in carbon chain length: tetramethylammonium bromide (TMAB), tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPrAB), tetrabutylammonium bromide (TBAB), and tetrapentylammonium bromide (TPeAB). The hydrate phase equilibrium measurements were conducted for a temperature range of 278.94–291.85 K and pressure range of 4.79–14.32 MPa using the step-heating pressure search method. The addition of TBAB or TPeAB shifts the phase equilibria of the semiclathrate hydrates (SCHs) of CH4 to a lower pressure and higher temperature zone. At a given temperature, increasing the mole fraction of TBAB and TPeAB from 0.294 mol % to 0.620 mol % made the shift in phase equilibrium conditions greater. At a given dosage, TBAB consistently outperformed TPeAB in thermodynamically promoting methane hydrate formation. TMAB, TEAB, or TPrAB slightly shifts the phase equilibrium conditions t...

Ion-Directed Synthesis of Indium-Derived 2,5-Thiophenedicarboxylate Metal–Organic Frameworks: Tuning Framework Dimensionality

Template directed synthesis of metal–organic frameworks (MOFs) is of increasing interest. Herein we report the synthesis of six new MOFs synthesized from 2,5-thiophenedicarboxylic acid (TDC) and InCl3. The new frameworks are formally two- (YCM-21) and one-dimensional (YCM-22) anionic, as well as three-dimensional neutral (YCM-23). YCM-22 contains an unprecedented dianionic [InCl3(κ2-O2CAr)2]2– node. The structural diversity represented by these materials is entirely controlled by addition of organic ammonium salts during the synthesis process. The role of the additives is briefly discussed with observed correlations of (1) hydrogen bonding and cation−π interactions influencing MOF dimensionality and (2) the presence of anionic chlorides creating a chlorine-rich metal center leading to a one-dimensional framework.