Tetraethylammonium Cations Research Articles

97/03817 Synthesis of Na-zeolites from fly ash

An aluminosilicate system containing mixed bases (tetraethylammonium and sodium cations) at 423 K initially formed gmelinite and later transformed into analcime after 312 h. Solid-state 29Si and 27Al MAS n.m.r. spectroscopic results indicated that the transformation takes place with an increase in the relative intensity of the Si (1Al) peak and some distortion in the Al nucleus. An increase in (Si/Al) n.m.r. from gmelinite to analcime was also observed. These synthetic gmelinite and analcime samples were also more siliceous. Results from thermal analysis indicated a decrease in occlusion of organics with the increase in the gmelinite crystallinity. No occlusion of the organics was observed in the case of analcime. Deammoniation of ammonium-exchanged gmelinite also leads to transformation into analcime. Framework i.r. spectra were also in agreement with the phase transformation. Sorption experiments indicated the presence of stacking faults developed in the gmelinite during synthesis. Analcime sorbed only water, whereas gmelinite sorbed methanol, n-hexane, and cyclohexane in addition to water.

Study of ion transfer across phospholipid monolayers adsorbed at micropipette ITIES

Abstract The transfer of tetraethylammonium cations across phospholilpid monolayers deposited at a micropipette ITIES (interface between two immiscible electrolyte solutions) was studied using short potential step techniques. The observed current transients consisted of a capacitive and a faradaic current component, which were separated using a non-linear fit to a model function. Fits were very good. From the capacitive component, the surface coverage of lipids was calculated by applying a simple model for the monolayer configuration. It appeared that the coverage varied between 80 and 99%. The rate of ion transfer was increased slightly after the lipid addition, but no significant variations between different lipids were found. The transfer mechanism is discussed briefly.

The Influence of Tetraalkylammonium Counterions on the Drainage and Stability of Thin Films and Foams Stabilized by Dilute Aqueous Solutions of Sodium Dodecyl Sulfate

It was demonstrated that the presence of tetraalkylammonium counterions in aqueous foams and thin film lamella stabilized by sodium dodecyl sulfate (at concentrations below the CMC) can act either to promote or to prevent foam stability. The increase in stability was explained by the congenial incorporation of the smaller and more hydrophilic counterions (tetraethylammonium cations and, to some extent, tetrabutylammonium cations) into the interfacial anionic layers. It was suggested that this increased the interfacial cohesive interaction and resiliency within the thin film lamella. This causes regular thin film drainage rates (within reasonable agreement with Reynold's theory) and was shown to promote black films at low surfactant concentrations in model horizontal thin film lamella. Also, high bulk foam lifetimes were observed, as determined by handshaking. The decrease in stability was associated with rapid drainage rates and was explained by the penetration of larger more hydrophobic tetrapentylammonium cations in the layers. This could disrupt and weaken the molecular interactions (less cohesion). This result is quite different from previously reported studies describing the action of tetraalkylammonium counterions on sodium dodecyl sulfate (at concentrations above the CMC). At these higher surfactant concentrations, a defoaming action was generally observed and could be explained in terms of a reduction in the dynamic stability (Gibbs surface elasticity).

Crystal structure and X-ray investigation of phase transition of tetraethylammonium tetrachloroantimonate N(C2H5)4SbCl4

The anionic sublattice of N(C2H5)4SbCl4 consists of isolated Sb4Cl4- 16 units built of four SbCl3- 6 distorted octahedra. There are two crystallographically inequivalent disordered tetraethylammonium cations in crystal structure. The disorder is realized by presence of two positions for all methylene carbon atoms. N(C2H5)4SbCl4 has at 298 K orthorhombic Fddd space group with a = 12.824 (3), b = 24.050 (4), c = 39.739 (4) Å, V = 12256 Å3, Z = 32. Refinement of the atomic parameters by the least square methods gave R = 0.040, wR = 0.036 for 1830 independent reflections with F > 4[sgrave](F). Temperature dependencies of lattice parameters between 170 K and 310 K were determined. The presence of the phase transition of first order at Tc = 272 K was confirmed. The broadening and then splitting of the reflections below 272 K was observed which indicates that this transition take place to phase of lower than orthorhombic symmetry.

Structure determination of [tetraethylammonium]-[(1,3-dithiole-2-one-4,5-dithiolato)diphenyl-(thiocyanato-N)stannate

The title compound (3) has been synthesised and its molecular structure has been elucidated by single crystal X-ray diffraction. Refinement of the complex in space groupP21/c witha=11.535(4),b=9.831(2),c=25.217(1) and β=94.23(5)° converged atR=0.064. The geometry at the tin center in the anion is trigonal bipyramidal, with the thiocyanato N atom and a dithiolato S atom in the axial sites. The tetraethylammonium cation exhibtis normal geometry.

Cholesterol modulates organic cation transport activity and lipid fluidity in rat renal brush-border membranes

The role of cholesterol in organic cation transport was studied in rat renal brush-border membranes. H + gradient-dependent uptake of the organic cation tetraethylammonium in brush-border membrane vesicles was stimulated by cholesterol enrichment in a dose-dependent manner. The dissipation rate of the H + gradient, a driving force for organic cation transport in brush-border membranes, was reduced by cholesterol enrichment. Tetraethylammonium uptake in the absence of H + gradient was also stimulated by cholesterol enrichment. These findings indicate that cholesterol modulates tetraethylammonium uptake by affecting the intrinsic activity of the organic cation transporter and the H + gradient dissipation rate. Therefore, cholesterol content should be an important determinant for organic cation transport in renal brush-border membranes.

Peculiarities Associated with the Adsorption of Alkyne Peroxides from Dimethyl Formamide/Water Solutions on to the Mercury Electrode in the Presence of Tetraethylammonium Cations

The adsorption of alkyne peroxides on to the surface of a mercury electrode from dimethyl formamide (DMFA)/water solutions in the presence of tetraethylammonium perchlorate [(C2H5)4NClO4] has been investigated by polarography and electrocapillarity techniques. It has been shown that the interfacial activity of these peroxides is determined by products arising from associative interactions both between these peroxides and DMFA and tetraethylammonium cations. Comparable estimations of the interfacial activity of various alkyne peroxides in the solutions studied have been made.

Syntheses of diethyleneoxy bridged cryptophanes and their complexing abilities with alkali metal and alkylammonium cations

Abstract The anti- and syn-diethyleneoxy bridged cryptophanes (3a and 3b) were prepared by the direct trimerization of 1,5-bis[(4-hydroxymethyl)-2-methoxyphenoxy]-3-oxapentane, which was obtained by the reaction of diethyleneglycol ditosylate with vanillyl alcohol and/or by stepwise methods from vanillyl alcohol. The syn isomer (3b) showed highly selective complexing abilities for cesium, and the tetraethylammonium and triethylmethylammonium cations as compared with those of the anti isomer (3a).

Proton induced reduction of WO 42− under sulfide-polysulfide environment: A new route to the synthesis of complexes containing {W 2VS 2(μ-S) 2} 2+, {W 2O 2(μ-S) 2} 2+ and {W 2O 2(μ-S)} 6+ cores

Acidification of an alkaline solution containing tungstate, polysulfide and tetraethylammonium chloride afforded the products (Et 4N) 2[W 2S 2(μ-S) 2(S 4) 2] ( 1), (Et 4N) 2[W 2O 2(μ-S)(S 2) 4] ( 2) and (Et 4N) 2[W 2O 2(μ-S) 2(S 4) 2] ( 3) depending on the pH of the solution. This method is a new rational and general method of the syntheses of binuclear sulfur bridged oxo- or sulfido-compounds of tungsten (V) or (VI). The X-ray crystal structure of 1 has been determined. The structure consists of disordered tetra-ethylammonium cations and binuclear units of the complex anion [W 2S 12] 2− with the metal atoms displaying distorted square pyramidal geometry. The structural features of all the complexes are supported or revealed by the IR, electronic and FAB mass spectroscopic data. Cyclic voltammetric study of ( 1) shows two irreversible single step metal centred reduction waves in the potential range −1.0 to −1.8 V.

Voltammetry of carbon dioxide. Part 2. Voltammetry in aqueous solutions on glassy carbon

Variable sweep rate voltammetry of carbon dioxide at a glassy carbon electrode in aqueous solutions containing tetraethylammonium perchlorate gave two successive one-electron kinetically controlled waves. The apparently low peak potentials (−0.74 V vs. SCE at pH 10) were rationalised by consideration of the ionic radius of the tetraethylammonium cation relative to other cations. The rate limiting process appeared to be release of carbon dioxide molecules from aqueous bicarbonate. Equilibrium constants for this process were measured by rotating disc electrode voltammetry and found to be 0.069 at pH 9.1 and 0.076 at pH 10. The rate constant for the formation of carbon dioxide molecules was calculated from Kl 1 2 and found to be k f = 1.6 s −1 at pH 10. However, these data conflicted with published data for this process from homogeneous kinetics. An adsorption model was applied to rationalise the data. The surface coverage was found to be 0.019 at pH 10, in line with published data.

Tetraethylammonium Bis(isothiocyanato)triphenylstannate

The [Sn(C6H5)3(NCS)2]− organotin anion of the title compound, (C8H20N)[Sn(C6H5)3(NCS)2], lies on a crystallographic twofold axis and the trigonal bipyramidal structure has NCS groups in axial and phenyl groups in equatorial positions. The tetraethylammonium cation is disordered over two orientations.

X-Ray diffraction and solid-state nuclear magnetic resonance study of a silicate containing two different nitrogenous cations

Single-crystal X-ray diffraction has been used to determine the structure of a silicate hydrate containing both the tetraethylammonium cation and a cation containing three nitrogen atoms. The structure is monoclinic, space group C2/c, and may be regarded as a host–guest system, with the cations as guests in a hydrogen-bonded framework consisting of a cubic octameric silicate anion, [Si8O20]8–, and water molecules. Magic-angle spinning 13C, 29Si and 1H NMR spectra are consistent with the crystallographic asymmetric unit. The precursor solution, the mother-liquor after crystallisation, and the solution obtained by melting the crystals have also been examined by NMR spectroscopy. The implications for silicate solution equilibria and for zeolite synthesis mechanisms are discussed.

VPI-8: A High-Silica Molecular Sieve with a Novel “Pinwheel” Building Unit and Its Implications for the Synthesis of Extra-Large Pore Molecular Sieves

Relatively large (up to 4 μm), needle-like crystals of the high-silica molecular sieve VPI-8 are synthesized by hydrothermal methods and are subsequently calcined to remove the pore-filling organic TEA+ (tetraethylammonium cation). Numerous physicochemical techniques are used to determine and characterize the structure of organic-free VPI-8. The structure is discussed with the use of two ordered topologies (1a and 1b) and an average structure (1c) that accounts for the possibility of structural disorder in one of the T-atoms (Si1). The symmetry and space group of the ordered structure type 1a (tetragonal, P4̄ (no. 81)) is supported by electron diffraction data and the Rietveld refinement of the synchrotron X-ray powder data based on 1a converges with the lowest agreement factors. The pore system of VPI-8 consists of one-dimensional channels containing 12-membered T-atom rings (12MRs) that run down the c-axis. HRTEM images along [001] confirm the general structure topology (the possible disorder occurs only along c). The structure of VPI-8 contains five unique T-atoms in atomic ratios of 1:4:4:4:4 per unit cell. These number densities are consistent with the data obtained from 29Si solid-state NMR spectra. The main feature of the VPI-8 structure is a novel “pinwheel” framework building unit that has not been observed before in microporous materials and that seems well-suited for forming extra-large pore molecular sieves. Hypothetical framework models of extra-large pore molecular sieves containing one-dimensional 14MR (2), 16MR (3), 18MR (4), and 20MR (5) channel systems based on this new building unit are presented and discussed.

Electrochemical synthesis of a pseudo-two-dimensional polytelluride containing Te2−12 anions: structure of [(C2H5)4N]2Te12

An unusual pseudo-two-dimensional polytelluride built up from Te2−12 anions was synthesized electrochemically from the cathodic dissolution reaction of an SbTe10 alloy electrode in an ethylenediamine solution of tetraethylammonium iodide, and represents the largest homoatomic polychacogenide anion characterized to date. The compound [(C2H5)4N]2Te12 crystallizes in the acentric monoclinic space group Pn (No. 7) with lattice constants of a = 7.934(1), b = 17.453(8) and c = 13.514(1) Å, β = 104.671(10)° and V = 1810.4(7) Å3, with Z = 2 and R(Rw) = 0.036(0.047). The structure consists of puckered Te122− chains, with internal Te-Te distances of 2.713(2)–2.881(2) Å, loosely bound into infinite two-dimensional sheets via many Te-Te interactions in the range of 3.144(2)–3.504(2) Å. These distances are somewhat shorter than the comparable interchain (2.835(2) Å) and intrachain (3.495(3) Å) Te-Te distances in elemental Te. The complete structure consists of these tellurium layers separated in the crystallographic b direction by layers of tetraethylammonium cations.

Modulation of organic cation transport and lipid fluidity by benzyl alcohol in rat renal brush-border membranes.

Organic cations are actively transported in renal brush-border membranes (BBM) by the H+/organic cation antiport system. In the present study, we investigated the relationship between membrane fluidity and organic cation transport in the BBM. The effects of benzyl alcohol, a membrane fluidizing agent, on the organic cation tetraethylammonium (TEA) uptake were studied using renal BBM vesicles isolated from rat kidney. BBM fluidity was assessed by fluorescence polarization technique. H+ gradient-dependent uptake of TEA in BBM vesicles was inhibited by benzyl alcohol in a dose-dependent manner, with an apparent half inhibitory concentration of 18mM. The decrease in fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in BBM, which represents the increase in membrane fluidity, was correlated with the decrease in TEA transport activity. The dissipation rate of H+ gradient, a driving force for organic cation transport in BBM, was increased by benzyl alcohol. In addition, H+ gradient-independent TEA-TEA exchange was also inhibited by benzyl alcohol. These findings indicate that benzyl alcohol inhibits the uptake of TEA by affecting the intrinsic activity of the organic cation transporter and the H+ gradient dissipation rate. The membrane fluidity should be an important determinant for organic cation transport in renal BBM.

A non‐selective cation current activated via the multifunctional Ca(2+)‐calmodulin‐dependent protein kinase in human epithelial cells.

1. Activation of macroscopic membrane currents by intracellular calcium ([Ca2+]i) signalling pathways was examined in human T84 epithelial cells, a model secretory cell line. 2. Elevation of [Ca2+]i by either the calcium ionophore A23187 (1 microM) or the cholinergic agonist carbachol, led to the transient activation of both a chloride and cation current in single voltage clamped cells. The channels underlying the cation conductance were found to be equally permeable to external Na+, K+ and Cs+, but impermeable to the large organic cations tetraethylammonium and N-methyl-D-glucamine (NMDG). These observations indicate that the cation channels are non-selective with respect to monovalent cations. 3. Persistent activation of both the chloride and non-selective cation currents by [Ca2+]i was observed following inhibition of cellular phosphatase activity by the phosphatase inhibitor microcystin LR or the ATP analogue ATP gamma S. This finding strongly suggests the presence of a phosphorylation event in the calcium-dependent activation pathway for both currents. 4. Intracellular dialysis with peptide inhibitors of the multifunctional Ca(2+)-calmodulin-dependent protein kinase (CaM kinase) blocked the activation of both the chloride and cation conductances by elevated [Ca2+]i. Dialysis with an inactive control peptide had no effect on the activation of either current. CaM kinase thus appears to be critically involved in the calcium-dependent activation of both the chloride and cation currents in these cells. 5. Associated with the whole-cell cation conductance were macroscopic tail currents observed at the chloride reversal potential. The distinct kinetic properties of these tail currents were used as a biophysical 'signature' of the whole-cell conductance. 6. In excised, inside-out membrane patches, [Ca2+]i activated single cation channel activity. These channels had a mean conductance of 20 pS, were impermeable to NMDG, and their mean open probability increased at positive membrane potentials. The properties of these single channel events thus closely resemble those reported previously for calcium-activated cation channels in epithelia. 7. Using a novel 'tail current' voltage clamp protocol in excised membrane patches, we observed that ensemble averages of single cation channel events reproduced the behaviour and kinetic properties of the macroscopic tail currents of the calcium-activated cation conductance. This finding provides evidence that the observed single channel events probably underlie the macroscopic cation current recorded from intact cells. 8. The results from this study demonstrate that CaM kinase mediates the calcium-dependent activation of both a chloride and a non-selective cation current in human T84 epithelial cells. Using single channel recordings, we believe we have identified the corresponding whole-cell current for the 20-40 pS calcium-activated cation channel activity reported previously in epithelia and other cell preparations. Physiologically, a calcium-activated inward cation current would allow sodium influx in association with calcium-dependent electrolyte and protein secretion. Thus CaM kinase-dependent activation of cation channels may serve as a co-ordinated influx pathway to balance the efflux and influx of osmotically active solutes as part of an overall cell volume regulatory mechanism.

A Strongly Luminescent Organic-Solvent-Soluble Salt of the Tris(dipicolinato)europium(III) Trianion

The tetraethylammonium salt of the [Eu(dipic) 3 ] 3- (dipic = 2,6-pyridinedicarboxylate) complex anion, tris(tetraethylammonium) tris(2,6-pyridinedicarboxylato-N,O,O)europium(III) tetrahydrate, (C 8 H 20 N) 3 [Eu(C 7 H 3 NO 4 ) 3 ].4H 2 O, forms monoclinic crystals. The lattice contains alternating columns of the Δ and Λ enantiomeric forms of the trianion, with the water molecules hydrogen bonded to the uncoordinated O atoms of the carboxylate groups and the tetraethylammonium cations forming columns, presumably to optimize electrostatic attractions.

Crystal structure and investigation of phase transitions in di(tetraethylammonium)-pentachloroantimonate (III) [N(C 2H 5) 4] 2SbCl 5

The investigation of phase transitions in [N(C 2H 5) 4] 2SbCl 5 was carried out in the temperature range 100–400 K by the DSC method and by temperature dependencies of lattice parameters. The presence of two phase transitions at 218 K from monoclinic to orthorhombic, of second order, and at 347 K from orthorhombic to tetragonal, of first order, was revealed. The crystal structures of [N(C 2H 5) 4] 2SbCl 5 at 298 K. and at 353 K were determined. At 298 K [N(C 2H 5) 4] 2SbCl 5 crystallizes in an orthorhombic Pcnn space group with a = 14.271 (4), b = 14.173 (4), c = 12.745 (2) A ̊ , V = 2578 A ̊ 3 , Z =4, The anionic sublattice consists of isolated SbCl 5 2− units. The antimony atom has square pyramidal co-ordination with stereochemically active lone pairs of electrons. It has 4 Sb-Cl contacts in the 2.598–2.605 Å range and one is equal to 2.346 Å. One of two crystallographically inequivalent tetraethylammonium cations is disordered. The disorder is realized by presence of two positions for all methylene carbon atoms (CH 2) with the occupancy factor equal to 0.5. The transition at 347 K to P4/mnc space group ( a = 10.138(3), c = 12.816(3) A ̊ , V = 1317 A ̊ 3 , Z = 2) was attributed to triggering of overall rotation of the second tetraethylammonium cation.

Effect of quinidine on kidney biochemistry and function in male sprague-dawley rats

Accumulation of the organic anion p-amino hippurate (PAH) and the organic cation tetraethyl ammonium (TEA) was decreased in renal cortical slices incubated with medium containing quinidine. Renal cortical slice oxygen consumption was also decreased. Quinidine reduced respiratory control index (RCI) and ADP/O ratio in isolated kidney cortex mitochondria. The in vitro data suggest that quinidine can alter renal transport and mitochondrial functions. Intraperitoneal administration of quinidine at 75 mg/kg twice a day for four days inhibited PAH and TEA transport in renal cortical slices. Renal cortical slice oxygen consumption was significantly decreased. Mitochondria showed a significant reduction in ADP/O ratio but no effect on RCI. Serum biochemical measurements indicated significantly elevated blood urea nitrogen. The data suggest that quinidine produces adverse renal effects in vitro and at high doses it produces nephrotoxic effects in vivo.

On the mechanisms underlying hypoxia-induced membrane depolarization in striatal neurons.

Clinical and experimental evidence has shown that the striatal neurons are particularly vulnerable to hypoxia and ischaemia. An excessive excitatory action of glutamate, released by the corticostriatal terminals, has been implicated in this peculiar vulnerability of striatal neurons. We have studied the effects of hypoxia on the membrane properties of striatal neurons intracellularly recorded from a corticostriatal slice preparation. Brief (2-10 min) periods of hypoxia produced reversible membrane depolarizations. During the initial phase of the hypoxia-induced depolarization the frequency of action potential discharge was transiently increased; 2-3 min after the onset of hypoxia the firing activity was fully abolished. Brief periods of hypoxia also caused a reversible reduction of the amplitude of the excitatory postsynaptic potentials (EPSPs) evoked by cortical stimulation. Longer period of hypoxia (12-20 min) produced irreversible membrane depolarizations. In voltage-clamp experiments hypoxia caused an inward current coupled with an increased membrane conductance. Tetrodotoxin (TTX) or low calcium (Ca2+)-high magnesium containing solutions blocked synaptic transmission, but they did not reduce the hypoxia-induced electrical changes. Antagonists of excitatory amino acid receptors failed to affect the electrical effects caused by oxygen deprivation. Hypoxia-induced inward currents were reduced either by the potassium (K+) channel blockers, barium and tetraethyl ammonium (TEA) cations, or by lowering external sodium (Na+) concentration. Blockade of ATP-dependent Na(+)-K+ pump by both ouabain and strophanthidin enhanced hypoxia-induced membrane depolarization/inward current. Our findings indicate that the release of excitatory amino acids does not seem to be required for the acute hypoxia-induced electrical changes in striatal neurons. Moreover, TTX-resistant Na+ influx and K+ currents seem to play an important role in the generation of hypoxia-induced electrical changes. These data also suggest that the selective vulnerability of striatal neurons to oxygen deprivation may be caused by their peculiar sensitivity to energy metabolism failure.