Tetraphenylborate Anion Research Articles

The Magnesium Dication and Water Synergistically Promote the Protonolysis of Two of the B-C Bonds in the Tetraphenylborate Anion.

Analytes are sampled from both solution phase and gas-phase environments during the ESI process, and thus, the mass spectrum that is measured can reflect both solution and gas-phase conditions. In the gas-phase regime, ion-molecule reactions can influence the types of ions that are observed. Herein, the synergistic effects of a Lewis acid (Mg2+) and background water are shown to lead to protonolysis of two of the B-C bonds of the tetraphenylborate ion in the gas phase, giving rise to different ions at different reaction times in ESI-MS/MS experiments in a linear ion trap mass spectrometer. At short reaction times (1 ms), the expected adduct [Mg(BPh4)]+ is observed. At 10 ms, [(HO)Mg(BPh3)]+ and [(HO)2Mg(BPh2)]+ are observed. At 100 ms, the water adducts [(HO)2Mg(BPh2)(H2O)]+ and [(HO)2Mg(BPh2)(H2O)2]+ appear, and these become the dominant ions at longer reaction times. DFT calculations provide a plausible explanation as to why only [(HO)Mg(BPh3)]+ and [(HO)2Mg(BPh2)]+ but not [(HO)3Mg(BPh)]+ are observed.

Superb enhancement of thermal decomposition of ammonium perchlorate in the presence of methyl viologen salts: A TG-DSC/MS and kinetic study

Different salts of 1,1′-dimethyl-4,4′-bipyridinium which known as methyl viologen compounds (MVX2) (where X= iodide (I‾, MVI2), perchlorate (ClO4‾, MVC2) and tetraphenylborate anion (BPh4‾, MVT2)) were prepared and characterized using 1H NMR, 13C NMR, elemental analysis and mass spectroscopy. The impact of these viologen salts on the thermal decomposition of ammonium perchlorate was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and mass spectroscopy. The obtained results revealed that the high-temperature decomposition (HTD) temperature of MVX2:AP mixtures (5:100 (w/w)) significantly decreases by 121 ◦C, 151 ◦C and 112 ◦C compared to pure AP in MVC2, MCI2 and MVT2, respectively. Moreover, the apparent released heat of AP decomposition in these mixtures grows up from 574.2 J g−1 for the pure AP to 2108, 1965 and 1564 J g−1 for MVC2, MCI2 and MVT2, respectively. Furthermore, the calculation of the kinetic parameters confirms that the activation energy of HTD of AP was significantly decreased from 142.9 to 124.9, 138.9 and 131.2 KJ mol−1, upon mixing with MVC2, MVI2 and MVT2 respectively. The rate constant of AP decomposition at the peak temperatures of these mixtures was higher than that at the peak temperature of pure AP. The evolved gas analysis using mass spectrometry shows that the decomposition of pure AP mainly results in ClO3, ClO2, HClO4, ClO, Cl2, HCl, N2O and O2, while the major gaseous products of the 5:100 (w/w) mixture of MVX2 salts with AP were detected as N2, NO, N2O, O2, Cl2, ClO, ClO2, ClO3, HClO4, HCl and 4, 4′-Bipyridine (Bpy). The amounts of Bpy in decomposition products of AP/MVX2 mixtures follow the order of MVC2>MVI2>MVT2, which surprisingly is in accordance with the catalytic activity of these compounds.

Light Harvesting Nanoprobe for Trace Detection of Hg2+ in Water.

The continuously increasing flow of toxic heavy metals to the environment due to intensive industrial activity and tightening requirements with regard to the content of metal ions in drinking and discharged waters urges the development of affordable and sensitive devices to the field control of pollutants. Here, we report a new thiated Rhodamine-lactam probe for Hg2+ detection and demonstrate how its sensitivity can be increased via the incorporation of the probe molecules into the optically transparent siloxane-acrylate coatings on polymethyl methacrylate and, alternatively, into the water-dispersible light-harvesting FRET nanoparticles (NPs), in which dye cations are separated by fluorinated tetraphenylborate anions. We have shown that the optimization of the FRET NPs composition had allowed it to reach the antenna effect of ~300 and fabricate "off/on" sensor for Hg2+ ion determination in aqueous solutions with the detection limit of ~100 pM, which is far below the maximum permissible concentration (MPC) of mercury in drinking water recommended by the World Health Organization. Although this work is more proof-of-concept than a ready-to-use analytical procedure, the suggested approaches to fabrication of the FRET NPs based on the popular rhodamine-lactam platform can be used as a background for the development of low-cost portable sensing devices for the extra-laboratory determination of hazardous metal ions.

Se⋯π Chalcogen Bonding in 1,2,4-Selenodiazolium Tetraphenylborate Complexes

The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where “mutated” anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations.

Use of sodium tetraphenylborate reagent for conductometric titration of Amlodipine Besylate in pure and pharmaceutical forms

Simple, accurate and reliable conductometric method for the quantitative determination of Amlodipine Besylate (AML) in pure form and pharmaceutical formulations using sodium tetraphenylborate (TPB) in aqueous solution at 20°C has been described. The method is based on the formation of ion association complex of cation coming from the cited drug with tetraphenylborate anion and the conductance of the solution is measured as a function of the volume of titrant. Many experimental conditions were evaluated. The described procedure allowed the determination of AML in double distilled water in the range of 0.200-1.000mM. The accuracy of the method is indicated by the excellent recovery 98.60-101.40%, and the precision is supported by the low relative standard deviation < 4.74 %. The method was further applied successively to pharmaceutical formulations with no interference from the excipients, the results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision.

Use of sodium tetraphenylborate reagent for conductometric titration of Amlodipine Besylate in pure and pharmaceutical forms

Simple, accurate and reliable conductometric method for the quantitative determination of Amlodipine Besylate (AML) in pure form and pharmaceutical formulations using sodium tetraphenylborate (TPB) in aqueous solution at 20°C has been described. The method is based on the formation of ion association complex of cation coming from the cited drug with tetraphenylborate anion and the conductance of the solution is measured as a function of the volume of titrant. Many experimental conditions were evaluated. The described procedure allowed the determination of AML in double distilled water in the range of 0.200-1.000mM. The accuracy of the method is indicated by the excellent recovery 98.60-101.40%, and the precision is supported by the low relative standard deviation < 4.74 %. The method was further applied successively to pharmaceutical formulations with no interference from the excipients, the results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision.

Towards Anion Recognition and Precipitation with Water-Soluble 1,2,4-Selenodiazolium Salts: Combined Structural and Theoretical Study

The synthesis and structural characterization of a series of supramolecular complexes of bicyclic cationic pyridine-fused 1,2,4-selenodiazoles with various anions is reported. The binding of trifluoroacetate, tetrachloroaurate, tetraphenylborate, perrhenate, and pertechnetate anions in the solid state is regarded. All the anions interact with selenodiazolium cations exclusively via a pair of “chelating” Se⋯O and H⋯O non-covalent interactions, which make them an attractive, novel, non-classical supramolecular recognition unit or a synthon. Trifluoroacetate salts were conveniently generated via novel oxidation reaction of 2,2′-dipyridyl diselenide with bis(trifluoroacetoxy)iodo)benzene in the presence of corresponding nitriles. Isolation and structural characterization of transient 2-pyridylselenyl trifluoroacetate was achieved. X-ray analysis has demonstrated that the latter forms dimers in the solid state featuring very short and strong Se⋯O and Se⋯N ChB contacts. 1,2,4-Selenodiazolium trifluoroacetates or halides show good solubility in water. In contrast, (AuCl4)−, (ReO4)−, or (TcO4)− derivatives immediately precipitate from aqueous solutions. Structural features of these supramolecular complexes in the solid state are discussed. The nature and energies of the non-covalent interactions in novel assembles were studied by the theoretical methods. To the best of our knowledge, this is the first study that regards perrhenate and pertechnetate as acceptors in ChB interactions. The results presented here will be useful for further developments in anion recognition and precipitation involving cationic 1,2,4-selenodiazoles.

Highly Sensitive Detection of the Antidepressant Fluoxetine With an Extended Gate Field Effect Transistor

Fluoxetine (FL) is one of the selective serotonin reuptake inhibitors, which is used as an anti-depressant, as well as anti-panic drug. In this work, a sensor for label-free recognition of trace amounts of FL is introduced, which is based on an extended gate field-effect transistor (EGFET). This sensor enables the detection and accurate measurement of FL concentrations over wide dynamic range. The sensing part of the device is a Pt electrode covered by a sensitive polyvinyl chloride (PVC) membrane. The functionalized Pt electrode acting as an extended gate of the EGFET, is connected to the internal gate of a MOSFET transducer. The sensing element of the PVC membrane is the insoluble ion-pair of FL cation and tetraphenylborate anion. The sensor performance for detection of FL was characterized in different ionic strengths of the matrix solution. Then, the sensor capability to operate in physiological phosphate-buffered saline (PBS) was assessed, where the sensor indicated two linear dynamic ranges of its response, with different sensitivities in 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−11</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> M and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> M ranges. Also the calculated detection limit for the sensor was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.63\times 10^{-12}$ </tex-math></inline-formula> M. Moreover, the selectivity of the sensor was examined and validated in the presence of Citalopram, which is another anti-depressant drug with a similar structure to FL. We proposed a comprehensive analytical mapping of current sensitivity in all working regimes of the EGFET, providing a guide to the design of optimized sensors in any integrated systems of interest. Finally, the sensor was successfully exploited to assay citalopram in its pharmaceutical formulation.

Paper-Based Potentiometric Sensors for Nicotine Determination in Smokers' Sweat.

Herein, we describe for the first time, the design and fabrication of a novel nicotine paper-based sensor, in which a miniaturized paper reference electrode is integrated for potentiometric measurements. The paper-based sensors were designed using printed wax barriers to define the electrochemical cell and the sample zones. The electrodes were based on the use of the ion association complexes of the nicotinium cation (Nic) with either tetraphenylborate (TPB) or 5-nitrobarbiturate (NB) counter anions as sensing materials for nicotine recognition. A poly (3,4 ethylenedioxythiophene)/poly-(styrene sulfonate) (PEDOT/PSS) conducting polymer was used as an ion-to-electron transducer. The performance characteristics of the proposed sensors were evaluated and it revealed a rapid and stable response with a Nernstian slope of 55.2 ± 0.3 and 51.2 ± 0.6 mV/decade over the linear range of 1.0 × 10–5 to 1.0 × 10–2 M and detection limits of 6.0 and 8.0 μM for [Nic/TPB] and [Nic/NB], respectively. The sensors revealed a constant response over the pH range 3.5–6.5. The designed sensors provided a portable, inexpensive, and disposable way of measuring trace levels of nicotine coming from different cigarettes and in the collected human sweat of heavy smokers. All results were compared favorably with those obtained by the standard gas chromatographic method.

Immobilization of a copper complex based on the tripodal ligand (2‐aminoethyl)bis(2‐pyridylmethyl)amine (uns‐penp)

AbstractA new derivative of the ligand (2‐aminoethyl)bis(2‐pyridylmethyl)amine (uns‐penp), capable for covalent immobilization on silica, was synthesized. Silica powder for column chromatography and mesoporous monoliths served as surface material. Functionalized silica was sufficiently characterized with reflectance UV/Vis and FTIR techniques. Copper(I) was successfully complexed with the immobilized ligand and exhibits reversible reactivity towards dioxygen at low temperatures. Suspending the oxygen species with toluene at low temperatures led to selective oxygenation to benzaldehyde, determined by GC‐MS. Copper(I) complexes with the ligands Me‐PTS‐uns‐penp and Me‐Prop‐uns‐penp were prepared and characterized to model the reaction behavior towards dioxygen in solution. Additionally, solid copper peroxido complexes with these ligands were obtained by precipitation with the sterically demanding anion tetraphenylborate. Furthermore, these complexes could be obtained in a reversible reaction by treating corresponding copper(I) complexes with dioxygen. With all oxygenated copper complexes catalytic oxidation of toluene was observed.

A new solid-state anionic surfactant-selective sensor based on functionalized MWCNT

A new solid-state potentiometric sensor for anionic surfactants (AnS) determination was prepared. The sensor material in the liquid membrane was made of multi-walled carbon nanotubes (MWCNTs) chemically functionalized with a quaternary ammonium group and tetraphenylborate (TPB) anion (MWCNT-N+(CH3)3TPB−).The response of the MWCNT-N+(CH3)3TPB− sensor was Nernstian (59.3 mV/decade of activity) for both AnS investigated (sodium dodecyl sulfate (NaDDS) and sodium dodecylbenzenesulfonate (NaDBS)). The limits of detection were 2.0 ∙ 10−7 and 1.5 ∙ 10−7 for NaDDS and NaDBS, respectively, and the average response time was only 5 s.The new MWCNT-N+(CH3)3TPB− sensor was very selective for NaDDS compared to anions usually contained in commercial products and is not affected by nonionic surfactants that can also be present in these products. It was tested to determine AnS concertation by the potentiometric titration method in a pH range between 3 and 12 and successfully applied for its determination in three-component mixtures and real systems.

Tetra-arylborate lipophilic anions as targeting groups.

Tetraphenylborate (TPB) anions traverse membranes but are excluded from mitochondria by the membrane potential (Δψ). TPB-conjugates also distributed across membranes in response to Δψ, but surprisingly, they rapidly entered cells. They accumulated within lysosomes following endocystosis. This pH-independent targeting of lysosomes makes possible new classes of probe and bioactive molecules.

Dehydroberberine Analogue Nanoassemblies for Inducing and Self-Reporting Mitochondrial Dysfunction in Tumor Cells.

Mitochondria-targeting probes that allow us to induce and report mitochondrial dysfunction have become promising theranostic agents for cancer; however, the lack of selectivity toward tumor cells over normal tissue cells has impeded the treatment outcome. Herein, we develop 10 fluorescent dehydroberberine derivatives (B1-B10) capable of lighting up mitochondria and exerting moderate cytotoxicity against tumor cells. To enable the selectivity toward tumor cells over normal tissue cells, we introduced a lipophilic anion tetraphenylborate (TPB-) into the most potent compound B3+Cl- to drive molecular self-assembly into monodisperse organic nanoassemblies (B3NPs) in aqueous solution, which efficiently enhance the delivery of B3+ into HeLa cells assisted by an electrostatic interaction-driven anion-exchange process. Fluorescence imaging reveals that B3+ can initially accumulate in the mitochondria after entering HeLa cells, followed by inducing mitochondrial dysfunction and then migrating into the nucleus. Strong B3+ fluorescence translocating from mitochondria to nucleus can be monitored in real-time, allowing for self-reporting of mitochondrial dysfunction in HeLa cells. Moreover, we demonstrate that B3NPs exert significantly higher cytotoxicity against seven different tumor cells (e.g., U87MG, HeLa, MDA-MB-468, MDA-MB-435, MDA-MB-231, MCF-7, and HCT116 cells) compared to human normal tissue cells (e.g., HUVEC, HEK293). This work highlights the utility of the self-assembly approach to improve the cytotoxicity and selectivity of mitochondria-targeting agents against tumor cells.

Electrolytic conductivity of ionic polymers in a nonpolar solvent.

The electrolytic conductivity of two electrolytes as solutions in the nonpolar solvent, n -dodecane, as a function of concentration has been studied. One was a small molecule electrolyte (tetraalkyl cation and a highly fluorinated tetraphenylborate anion), and the other was a macromolecular electrolyte (cation-containing poly(alkyl methacrylate) chain with the same anion). Two series of the macromolecular cation were prepared: one with entirely cation-containing molecules and the other with a small proportion (10%) cation-containing and the rest nonionic. The conductivity data were qualitatively similar for all systems, which formed both single ions and triple ions. The data from the two series of macromolecular electrolytes were particularly informative to understand some recent and counterintuitive electrokinetic data for particles that were stabilized by these polymers. Reducing the proportion of cationic chains in the stabilizer of the particles was found to increase their electrophoretic mobility. In the conductivity data in this study, reducing the proportion of cationic chains in solution was found to increase the magnitude of the single-ion equilibrium constant and suppress the formation of triple ions. These data should support the development of models to understand these electrokinetic results.

Improvement of performance of anti-cancer (dacarbazine) drug sensor utilizing tetraphenylborate anion

A sensor for dacarbazine, an anticancer drug denoted DAC, is presented. A dacarbazine-modified carbon paste electrode was fabricated and improved by incorporation of sodium tetraphenylborate as an additive. Dacarbazine–phosphotungstate, a salt of dacarbazine abbreviated DAC-PT, was used in a carbon paste electrode as an ion-pair. Incorporation of sodium tetraphenylborate abbreviated STPB as an additive distinctly improved the slope from 43.7±0.3 to 55.6±0.3 mV per decade of DAC‏ ion. The present electrode exhibits linearly over a wide concentration range from 1.80 × 10-6 to 1.0 × 10-2 M with a notably small detection limit of 8.9 × 10-7 M in a significantly fast response time (~ 5 s). These measurements are independent of the pH of the test solution in the pH range 3.2 to 9.5. The present sensor has distinct selectivity toward the drug ion over other common inorganic ions, sugars, amino acids, and drugs. This sensor was satisfactorily used as an indicator in potentiometric titrations and determination of dacarbazine in pharmaceutical preparations and urine samples.

Improvement of performance of anti-cancer (dacarbazine) drug sensor utilizing tetraphenylborate anion

Improvement of performance of anti-cancer (dacarbazine) drug sensor utilizing tetraphenylborate anion

Multiresponsive Spin Crossover Driven by Rotation of Tetraphenylborate Anion in an Iron(III) Complex

Dynamic molecular materials, which involve mechanical motions in crystals, usually exhibit tunable properties related to conformational polymorphs. Herein, we describe a solvent-free molecular crys...

СТРУКТУРНІ ТА СПЕКТРАЛЬНІ ДОСЛІДЖЕННЯ РІЗНОЛІГАНДНОГО КАТІОННОГО КОМПЛЕКСУ ЛАНТАНУ [Lа(L)2bipy2]BPh4 ІЗ ЛІГАНДОМ КАРБАЦИЛАМІДОФОСФАТНОГО (КАФ) ТИПУ ТА α,α'-ДИПІРИДИЛОМ

A new cationic mixed-ligand complex [Lа(L)2bipy2]BPh4 (where L-= bis(N,N'-diethylamide)(N'-trichloroacetyl)-triamidophosphate anion, bipy = 2,2'-bipyridine) has been synthesized and studied by the means of IR, 1H NMR spectroscopy, thermogravimetric and X-ray structural analyses. Low-frequency shifts of the absorption bands of the carbonyl and phosphoryl groups of phosphorylated ligand in the IR spectra of the complex compared with similar absorption bands in the spectrum of "free" CAPh ligand are Δν(C = O) = 117 cm–1 and Δν(P = O) = 137 cm–1. The analysis of integral signal intensity in the investigated NMR spectra of coordination compounds [Lа(L)2bipy2]BPh4 indicates the molar ratio of ligand : bipyridine : tetraphenylborate anion as a 2:2:1, which corresponds to the proposed structure of the complexes. The compound has been obtained in monocrystalline form. The structure of the complex has been determined by X-ray structural analysis, its ionic structure was proved, and the coordination of two CAPh ligands through the oxygen atoms of the carbonyl and phosphoryl groups was confirmed. Based on the structural data, it was determined that the La3+ ion is octocoordinated (surrounded by four oxygen atoms from two chelated phosphoryl ligands and four nitrogen atoms from two 2,2'-bipyridine molecules). The coordination polyhedron of central ion is interpreted as a square antiprism. Complex cations and tetraphenylborate anions are connected both by electrostatic interaction and by weak intermolecular C – H ∙∙∙ π-contacts between phenyl substituents of BPh4- and molecules of 2,2'-bipyridine. It was established by thermogravimetric analysis that the complex [Lа(L)2bipy2]BPh4 obtained is thermally stable up to a temperature of 150 °C. Significant decomposition of the complex begins at a temperature of 150 °C, occurs in one stage and most intensively continues up to 300 °C. The total weight loss is 78 %.

Electrochemiluminescence analysis of tryptophan in aqueous solutions based on its reaction with tetraphenylborate anions.

The emission of electrogenerated chemiluminescence (ECL) is observed upon the oxidation of fluorescent aromatic amino acid tryptophan in aqueous solutions at a glassy carbon electrode in the presence of a sodium tetraphenylborate co-reactant in a broad pH range. The emission is particularly strong when potential pulses are applied to the electrode. The ECL intensity is proportional to the concentration of amino acid and allows its determination in the concentration range of 0.3 μM-0.3 mM with high selectivity in the presence of other amino acids. The results of studies suggest that the indole ring of tryptophan is responsible for the observed ECL emission.

Synthesis, characterization and modeling of self-assembled porphyrin nanorods

Porphyrin nanorods were prepared by ion-association between free-base meso 5,10,15,20-tetrakis-(4-[Formula: see text]-methylpyridinium)porphyrin cations and tetraphenylborate anions. The nanorods have variable lengths (up to a few micrometers long) and diameters ([Formula: see text]50–500 nm). Their structure at the molecular level was elucidated by combining multinuclear solid state NMR spectroscopy, synchrotron X-ray powder diffraction and DFT calculations.