Torsional Motion in (tert‐Butyl)ammonium Hemispheraplexes: Rotational Barriers and Energy of Binding

The ADPs (ADPs=atomic anisotropic displacement parameters) from the single‐crystal X‐ray studies of nine related TBA⁺ (TBA⁺=(tert‐butyl)ammonium) hemispheraplexes are analyzed, and the results compared to the free energy of binding of this guest by the nine hosts. The lipophilic hosts (Fig. 1) were synthesized over a number of years, with increasing pre‐organization for and specificity of binding. Structural studies for six of the complexes have been published, but the remaining three structures, including those of the strongest binders of TBA⁺, are disordered and have only now been completed. New area‐detector data has been analyzed for the TBA⁺ClO complexes of 5 and of 8 at two temperatures, while the original data for 9 ?TBA⁺SCN^? has been treated with a disorder model. In addition, improved models are presented for the complexes of 6 and 7 . Methods for assessing the precision of the ADP analyses are discussed. Although most of the structures are imprecise, the TBA⁺ groups do demonstrate some of the characteristics of independent motion. The general trend in calculated libration amplitudes for the TBA⁺ group suggests that the guests with the greatest free energy of binding, and the shortest distances from N⁺ to the ligand plane, are those with the highest barriers to internal rotation.     

Thermal latency of novel chelating borate catalysts as latent catalysts for epoxy–phenolic resins

Novel quaternary ammonium bis(2‐oxybenzoyloxy)borate salts ( 1a – 1c ) or quaternary ammonium bis(1,2‐benzenedioxy)borate salts ( 2a and 2b ) with tetra‐n‐butylammonium (TBA⁺), tetra‐n‐octylammonium (TOA⁺), or bis(triphenylphosphoranylidene)ammonium (PNP⁺) cations were synthesized as latent catalysts of epoxy/phenol–novolac resins by the complexation between boric acid and salicylic acid or catechol, followed by neutralization with quaternary ammonium hydroxide. Polyaddition reactions of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐bisphenol F (44BPF) or bisphenol F (BPF‐D) with the ammonium borates were investigated as model reactions of epoxy/phenol–novolac resin systems with respect to the thermal latency and storage stability of the catalyst. The polyaddition of DGEBA/44BPF with 1a – 1c in diglyme at 150 °C for 6 h proceeded up to 85–96% conversions and gave polymers with number‐average molecular weights of 4180–10,500, whereas the polyaddition at 80 °C for 6 h gave less than 8% conversions. However, the polyaddition with 2a containing TBA⁺ cation proceeded to only a 32% conversion at 150 °C for 6 h in diglyme and to a 64% conversion even at 180 °C for 6 h in triglyme and only gave low molecular weight oligomers, and no reaction proceeded in the polyaddition at 80 °C. However, polyaddition with 2b containing PNP⁺ cation proceeded up to a 96% conversion at 150 °C for 6 h in diglyme and gave a higher molecular weight polymer with a number‐average molecular weight of 8050, whereas the polyaddition at 80 °C for 6 h gave only a 5% conversion. The catalytic activity of ammonium borates 1a – 1c and 2a and 2b depended on the borate anion structure: 1a and 1c with bis(2‐oxybenzoyloxy)borate anion revealed higher activity than 2a and 2b with bis(1,2‐benzenedioxy)borate anion, respectively. In comparison with tetra‐n‐butylammonium bromide (TBAB) as a conventional ammonium salt or tetra‐n‐butylammonium tetrakis(benzoyloxy)borate (TBA‐TBB), 1a – 1c and 2b revealed better thermal latency. The catalytic activity of ammonium borates also depended on the bulkiness of the ammonium cation, and the order of activity was 1c (PNP⁺) > 1b (TOA⁺) ≧ 1a (TBA⁺) and 2b (PNP⁺) > 2a (TBA⁺). The storage stability of DGEBA/BPF‐D with the ammonium borate catalysts 1a – 1c and 2a and 2b in bulk at 40 °C was much better than that with TBAB and TBA‐TBB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2702–2716, 2002     

Effects of hydrophilic and hydrophobic counterions on the Coulombic interactions in perfluorosulfonate ionomers

Attenuated total reflectance FTIR spectroscopy was used to compare the influence of hydrophilic and hydrophobic counterions on the vibrational behavior of the sulfonate and perfluoroether groups in 1100 equivalent weight (EW) Nafion^® and 808 EW Dow perfluorosulfonate ionomer membranes. For dry, Na⁺-form membranes, the infrared band attributed to the —SO₃^? symmetric stretching vibration was found to shift to higher frequencies with an increase in the degree of neutralization. In contrast, neutralization with tetrabutlyammonium ions caused the —SO₃^? vibrational band to shift to lower frequencies with increasing neutralization. This behavior is attributed to a diminished polarization of the —SO₃^? groups by the hydrophobic and diffusely charged TBA⁺ cations, relative to the strong polarization observed with Na⁺ ions. Vibrational bands attributed to perfluoroether groups in close proximity to the sulfonate groups were also found to be influenced by Coulombic interactions within the clusters. The frequency shifts of these bands followed a trend that was virtually identical to that observed for the —SO₃^? symmetric stretch. This behavior is attributed to a combination of through-space, dipolar field effects, and through-bond inductive effects, from the neighboring ionic groups. In Nafion^®, the ether groups directly attached to the backbone are shielded from the Coulombic interactions within the clusters, while the ether groups within three bonds of the terminal ionic groups are very sensitive to the state of polarization of the sulfonate anion. ©1995 John Wiley & Sons, Inc.     

Sensitive Electrochemical Determination of NADH Using an Electrode Fabricated by Intercalation of Tetrabutylammonium Ions Into Graphite Electrode

In this study, we present a strategy for the specific electrochemical detection of NADH in human blood serums using modified electrode fabricated by intercalation of tetrabutylammonium ions (TBA⁺) into pencil graphite electrode (TBA⁺/PGE). In order to implement this protocol, a modification process in the potential range (−0.2) to (−2.75) V was performed in DMSO containing 0.1 M TBAP by CV method. The characterization processes of the prepared sensor were carried out using CV, EIS, FT-IR, XPS, and SEM methods. The electrode fabricated by intercalation of TBA⁺ was found to be able to analyze NADH at +0.32 V applied potential by the amperometric method. The LOD was detected as 0.46 μM. The analysis results of human blood serums which are taken from healthy individuals show that TBA⁺/PGE can be used for real samples. The results indicated that TBA⁺/PGE can be easily fabricated by one-step and one-pot electrochemical method and TBA⁺/PGE can be used as a potential sensor for the NADH determination.     

Zeolite synthesis from tetraalkylammonium silicate gels

Siliceous zeolite synthesis gels containing tetraalkylammonium (TAA⁺) and sodium cations were studied using X-ray diffraction, elemental analysis, ion exchange, ²⁹Si magic-angle spinning nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The TAA⁺ cations are encapsulated in silicate cages, and silicalite is formed via the rearrangement of these cages by the breaking and reformation of siloxane bonds. Tetrabutylammonium (TBA⁺) cations promote silicalite growth, but not as effectively as tetrapropylammonium (TPA⁺) because the larger TBA⁺ cations do not conform as well to the silicalite lattice, thus forming an intergrowth of the silicalite-1 and silicalite-2 structures. The time to nucleate silicalite is not affected by the TBA⁺ content of the gel, but the rate of silicalite crystal growth increases with increasing TBA⁺ in the gel. The TBA⁺ occupies all the channel intersections of the silicalite formed. Tetraethylammonium (TEA⁺) cations are encapsulated in silicate cages, but not to the same extent as TPA⁺ and TBA⁺, because TEA⁺ is not as hydrophobic. No silicalite forms in the TEA⁺ silicate gel. The addition of tripropylamine (TriPA) to a TPA⁺ silicate gel has no effect on the kinetics of silicalite formation. TriPA does not incorporate into the gel because it is neutral and, therefore, does not experience a coulombic attraction to the negatively charged surface of the gel.     

Affinity interactions in counterion‐polyelectrolyte systems: Competition between different counterions

Non‐bonding, specific interactions between linear polyelectrolytes and different species of counterions (of equal or different valence) are considered in the framework of the counterion condensation theory. It is assumed that these interactions are of short distance nature and that, within our theoretical approach, they apply only to the counterions territorially associated (condensed) to the polyion, which are free to move within the condensation volume V_p around it. It is found that a simple additive term in the total free energy is sufficient to account for this interaction, resulting in a modulation of the polyelectrolytically determined population of territorially bound counterions. The distribution of free and condensed counterions as well as its variation with the physicochemical variables of the solution can be readily calculated. Analysis of literature data on titrations of poly(methacrylic acid) and dextran sulfate in aqueous solution with different species of monovalent and divalent counterions show that both polyanions appear to have a modest affinity free energy (of about RT) for Ca⁺⁺ counterions when compared with Na⁺. On the other hand, polyion interactions with the Mg⁺⁺/Na⁺ pair are well described by bare polyelectrolytic interactions.     

The role of cations in homogeneous succinoylation of mulberry wood cellulose in salt-containing solvents under mild conditions

The role of two cations [tetraethylammonium⁺ (TEA⁺) and tetrabutylammonium⁺ (TBA⁺)] in the homogeneous succinoylation of mulberry wood (MW) cellulose in dimethyl sulfoxide (DMSO)/tetraethylammonium chloride (TEACl) and DMSO/tetrabutylammonium fluoride (TBAF) was investigated using the intrinsic viscosity and two-dimensional nuclear Overhauser effect NMR spectroscopy (2D NOESY). The intrinsic viscosity of MW cellulose solution strongly depends on the salt dosage for both TEACl and TBAF, indicating that the increase in the hydrodynamic size of cellulose chains was caused by the interactions between salts and cellulose, which promotes the solvation process of cellulose in solution. Two-dimensional NOESY spectra reveal that cations bind to cellobiose in DMSO by the interactions between α-methylene groups of TEA⁺ (or TBA⁺) and C1/C1′ groups of cellobiose, and the intensities of the respective crosspeaks increase with increasing TEACl dosage from 5 to 10 mg/ml, but no change was present with TBAF at the same concentration range. Taking cellobiose as a model compound for cellulose, it can be expected that TEA⁺ (or TBA⁺) and cellulose form polyelectrolyte-like complexes. The degree of substitution (DS) of homogeneous succinoylation of MW cellulose benefits from the interactions between TEA⁺ (or TBA⁺) and cellulose evidenced by FT-IR spectra and CP/MAS ¹³C NMR spectra. The DS of the succinylated cellulose declines at TBAF concentrations higher than 11 wt% probably because of the steric hindrance effects of TBA⁺.     

Effect of Acetic Acid on Polymerization of Butylcyanoacrylate by Tetrabutylammonium Acetate in Tetrahydrofuran

Butylcyanoacrylate (BCA) was polymerized in tetrahydrofuran by tetrabutylammonium acetate (TBA⁺ Ac^-) in the presence of acetic acid. Large concentrations of acetic acid, several times the concentration of the initiator, TBA⁺ Ac^- did not stop the polymerization of BCA but showed an overall rate which decreased with increasing concentrations of the acid. The molecular weight of polymers, measured by gel permeation chromatography, decreased with increasing concentration of acetic acid. The corresponding molecular weight distribution is high but comparable to the value from acid-free polymerization. A retardation period, caused by methane sul-fonic acid for BCA polymerized by TBA⁺Ac^-, was extended in the presence of acetic acid. This is explained as arising from an enhanced equilibrium concentration of methane sulfonic acid from acetic acid protonated sulfonyl anions.     

Oligomerisations electro-assistees —II: Dimerisation de la phenyl-1-pentene-2-one-3

With Li⁺ or TBA⁺ as counter ion the electrodimerization of phenylpent-2-en-3-one occurs by a 0.2 F initiation. This reaction is regio- and stereospecific with Li⁺, the radical autocatalytic reaction gave 100% yield of a new dimer. If TBA⁺ is used the primary step is an ion-substrate reaction giving two isomers in equal proportion. All reaction products were structurally determined by 2D-NMR (SECSY or COSY and NOESY sequence).     

Synthesis and Characterization of Novel Gold(III) Complexes of Asymmetrically Aryl‐Substituted 1,2‐Dithiolene Ligands Featuring Potential‐Controlled Spectroscopic Properties

The tetrabutylammonium (TBA⁺) salts of square‐planar monoanionic gold complexes of the unsymmetrically substituted Ar,H‐edt^2? 1,2‐dithiolene ligands (Ar,H‐edt^2?=arylethylene‐1,2‐dithiolato; Ar=phenyl ( 1 ^?), 2‐naphthyl ( 2 ^?), and 1‐pyrenyl ( 3 ^?)) were synthesized and characterized by spectroscopic and electrochemical methods and the corresponding neutral species ( 1 , 2 , and 3 , respectively) were obtained in CH₂Cl₂ solution at room temperature by diiodine oxidation. The single‐crystal X‐ray diffraction structural data collected for (TBA⁺)( 2 ^?), supported by DFT theoretical calculations, are consistent with the ene‐1,2‐dithiolate form of the ligand and the Au^III oxidation state. All complexes feature intense near‐IR absorptions (at about 1.5 μm) in their neutral states and Vis‐emitting properties in the 400–550 nm range, the energy of which is controlled by the charge of the complex in the case of the 3 ^?/ 3 couple. The spectroscopic and electrochemical features of 1 ^x? and 2 ^x? (x=0, 1), both in their cis and trans conformations, were investigated by means of DFT and time‐dependent (TD) DFT calculations.     

Enrichment and distribution of counterions in spherical polyelectrolyte brushes probed by SAXS

The spatial correlation of counterions [Li⁺, Na⁺, Rb⁺, Cs⁺, NH₄⁺, (CH₃)₄N⁺] with spherical polyelectrolyte brushes (SPBs), which consist of a PS core and chemically grafted PSS chains, was comprehensively studied through a combination of SAXS, DLS, and Zeta potential. Results show that the SAXS intensity profiles of the brush appears to be “insensitive” to the concentration of Na⁺. By contrast, introducing salt ions with a density lower than sodium [NH₄⁺, (CH₃)₄N⁺ and Li⁺] into the brush layer will cause a decrease in the scattering intensity while introducing those with a higher density than sodium (Rb⁺ and Cs⁺) will cause the opposite result. As verified by the combined results of SAXS, DLS, and Zeta potential, the collapse of the brush and the enrichment of the counterions in the brush layer occur simultaneously. It was further demonstrated that the concentration of counterions enriched in the innermost layer of the brush shell can be enhanced up to hundreds of times compared with the bulk concentration, and the counterion distribution in SPB shell follows a radial attenuation distribution. SAXS is confirmed to be powerful in probing the enrichment and distribution of counterions within SPB. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 738–747     

Ionic transport in a sulfonated polystyrene–polyethylene copolymer

The conductivity of a grafted copolymer composed of 21% sulfonated polystyrene and 79% polyethylene has been investigated as a function of temperature and absorbed moisture for membranes containing the monovalent counterions H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs, and Ag⁺. The mobility of Ag⁺ was measured directly in an experiment analogous to that used for the mobility of F-centers in alkali halides. The mobility and density of free counterions depend on the amount of absorbed water, but only the mobility and not the density of free counterions is a thermally activated process. Current is carried by both intrinsic counterions and, in samples containing absorbed water with greater than 1.5 V applied, by protonic carriers created when the absorbed water is electrolyzed. Thermal depolarization studies indicate that persistent polarization observed is the result of homogeneous volume polarization, due to the orientation of sulfonic acid side groups.     

Electrochemical deposition of copper phosphides

Summary Methods for preparation of copper phosphides at ambient temperatures by electrodeposition are presented. From P₄/PCl₃/Acetonitrile/TBA-BF₄/Cu⁺ (solvated) Cu₃P and Cu₃P₂ can be obtained at different deposition potentials.

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Elektrochemische Abscheidung von Kupferphosphiden

Zusammenfassung Es werden Verfahren zur Herstellung von Kupferphosphiden bei ambienten Temperaturen beschrieben. Aus der Anordnung P₄/PCl₃/Acetonitril/TBA-BF₄/Cu⁺ (solvatisiert) können Cu₃P und Cu₃P₂ bei verschiedenen Abscheidungspotentialen erhalten werden.

     

Influence of stereoregularity on binding of counterions by poly(methacrylic acid)

The activity coefficient γ, of sodium ion, in aqueous solutions of both isotactic and conventional poly(methacrylic acid) (PMA) has been studies throughout the whole range of degree of neutralization α with a Beckman Na electrode and membrane electrodes. The results show that the fraction of sodium ions bound to isotactic PMA is higher than that bound to conventional (or syndiotactic) PMA over the entire range of α. The binding of divalent counterions (Mg⁺², Cu⁺², Co⁺², and Ni⁺²) by the two forms of PMA (at α = 0.95) has been evaluated from the release of Na⁺ ions with the Beckman Na electrode. Turbidimetric determinations of the critical amount of various divalent cation chlorides necessary to bring about precipitation of both isotactic and conventional PMA (at α = 0.95) have also been carried out.     

Electrochemical studies of the tetrabutyl- and tetramethyl-ammonium ion transfer across the water-1,2-dichloroethane interface: A comparison with the water—nitrobenzene interface

The results of electrochemical studies on the reaction of tetrabutyl- and tetramethylammonium (TBA⁺ and TMA⁺) ion transfer from water to 1,2-dichloroethane are presented in this paper and are compared with se of the water—nitrobenzene interface. The TMA⁺ ion transfer has been studied by the chronopotentiometric cyclic voltammetry methods and that of the TBA⁺ ion by the chronopotentiometric method only.It has been found that the reactions are diffusion controlled over the current density range up to about 1O μA cm^?2 and at polarization rates up to 0.15V s^?1. Diffusion coefficients of the studied ions have been detemined, as well as their formal potentials with respect to an ion-selective tetrabutylammonium electrode to a partition electrode containing tetraethylammonium picrate whose potential is close to zero. In additon, kinetic parameters of the transfer reaction have been determined for the tetrabutylammonium ion from data obtained at current densities over 10 μA cm^?2 (irreversible range).     

Sorption and conducting properties of perfluorinated MF-4SC membranes in aqueous solutions containing phenylammonium ions

A comparative study of the sorption effect is performed for nitrogen-containing ammonium, phenylammonium (PhA⁺), and tetrabutylammonium (TBA⁺) cations on conducting and hydrophilic properties of protonic form of perfluorinated sulfocationite MF-4SC membrane. Conductometric method was used to study thermodynamic equilibria in the systems of perfluorinated MF-4SC membrane—aniline in the acid solutions of variable composition (PhA⁺/HCl and PhA⁺/H₂SO₄). Concentration constants of ion-exchange equilibrium are calculated for a MF-4SC membrane on the basis of these data. These constants in the solutions of aniline with HCl and H₂SO₄ are 10.3 and 27.0, accordingly. The choice of sulfuric acid as background electrolyte for matrix polyaniline synthesis is substantiated.     

An Asymmetric Supercapacitor–Diode (CAPode) for Unidirectional Energy Storage

A new asymmetric capacitor concept is proposed providing high energy storage capacity for only one charging direction. Size‐selective microporous carbons (w<0.9 nm) with narrow pore size distribution are demonstrated to exclusively electrosorb small anions (BF₄^?) but size‐exclude larger cations (TBA⁺ or TPA⁺), while the counter electrode, an ordered mesoporous carbon (w>2 nm), gives access to both ions. This architecture exclusively charges in one direction with high rectification ratios (RR=12), representing a novel capacitive analogue of semiconductor‐based diodes (“CAPode”). By precise pore size control of microporous carbons (0.6 nm, 0.8 nm and 1.0 nm) combined with an ordered mesoporous counter electrode (CMK‐3, 4.8 nm) electrolyte cation sieving and unidirectional charging is demonstrated by analyzing the device charge‐discharge response and monitoring individual electrodes of the device via in situ NMR spectroscopy.     

Water Soluble Benzimidazole Containing Ionic Palladium(II) Complex for Rapid Microwave‐Assisted Suzuki Reaction of Aryl Chlorides

In this paper a water soluble benzimidazole – Pd complex used for Suzuki reaction under conventional heating and microwave heating. To increase the activity of complex, ionic group change with bulky TBA⁺ and Bmim⁺ groups. To determine whether the reaction is homogeneous or heterogeneous, Hg(0) poisoning tests, hot filtration tests and CS₂ poisoning tests were performed.     

Nano‐ and Microstructure Fabrication by Using a Three‐Component System

Two‐component amphiphiles based on hydrogen‐bonded complexes between terephthaloylbisalanine (H₂TBA) and dodecylamine (DA) are able to self‐assemble into nano‐ and microsized superstructures in an aqueous solvent. It is possible to modulate the morphology of these self‐assembled superstructures by modifying the composition of the complexes, which can be achieved by changing the molar ratio of the two components or by changing the chirality of H₂TBA. For example, right‐handed microhelical ribbon structures were formed with L ‐TBA_1.0DA_2.0, whereas in the case of rac‐TBA_1.0DA_2.0, flat ribbonlike structures were observed. Although L ‐TBA_1.0DA_1.0 exhibited entangled fibrous structures, rac‐TBA_1.0DA_1.0 exhibited wire structures. Different ratios of H₂TBA and DA were self‐assembled into fiber‐, wire‐, and tubulelike superstructures, as well as monoclinic, columnar, and lamellar aggregation patterns. The self‐assembled superstructures of TBA_xDA_y were significantly changed by adding metal ions. Transition metal (Cd^II, Co^II, and Zn^II) complexes with L ‐TBA_xDA_y self‐assembled into rod‐, tubule‐, wire‐, and platelike superstructures. Metal‐ion complexes with rac‐TBA_xDA_y exhibited different superstructures. Our work suggests that it is possible to fabricate a wide variety of nano‐ and microsized superstructures by using two‐ and three‐component amphiphiles.     

Methanol to Gasoline over ZSM-5 Zeolite Treated with Alkaline Mixture with Different Ratios of TBA<Superscript>+</Superscript>/OH<Superscript>–</Superscript>

The influence of ZSM-5 (SiO₂/Al₂O₃ = 50) treatment with a tetrabutylamine hydroxide (TBAOH)/NaOH mixture having different mole ratios on its physicochemical properties and catalytic performance in the reaction of methanol to gasoline (MTG) was investigated. It was found that, with increasing ratio TBA⁺/OH^–, the crystallinities, micropore surface areas, micropore volumes, the amounts of strong acid sites and Brönsted acid sites gradually increased, and the mesopore volumes decreased. The treatment with pure TBAOH (TBA⁺/OH^– = 1.0) ensured the formation of narrow and uniform intracrystalline mesoporosity and the large amounts of strong or Brönsted acid sites on the zeolite, which contribute to the highest liquid hydrocarbon yield in the reaction of MTG.