Dihydrogen Phosphate Anions Research Articles

Corrosion protection of copper by polypyrrole film studied by electrochemical impedance spectroscopy and the electrochemical quartz microbalance

Polypyrrole (PPy) films were synthesized on copper in solution of sodium di-hydrogen phosphate and phytate for corrosion protection. The protection properties of PPy films were comparatively investigated in NaCl solution. During two months immersion, the PPy film doped with phytate anions, working as a cationic perm-selective membrane, inhibited the dissolution of copper to 1% of bare copper. Differently, the PPy film doped with di-hydrogen phosphate anions, possessing anionic perm-selectivity, was gradually reduced, and inhibited the dissolution to 7.8% of bare copper. Degradation of the PPy films was studied by comparing the electrochemical impedance spectroscopy change at different immersion time and Raman spectra change after immersion.

Melting point depression effect with CO2 in high melting temperature cellulose dissolving ionic liquids. Modeling with group contribution equation of state

Ionic liquids of the alkylmethylimidazolium chloride family are able to solubilize high amount of cellulose and other natural polymers and have very good characteristics for their processing. Nevertheless, they present important disadvantages related to their high melting points and viscosities. Dissolution of carbon dioxide (CO2) can reduce the melting point of these ionic liquids as well as other ones presenting the same problems. In this work, the effect of pressurized carbon dioxide on the melting point depression of some ionic liquids able to dissolve biopolymers was experimentally determined using the first melting point method. Five different ionic liquids were studied in contact with CO2 using a high-pressure visual cell, up to a pressure of 10MPa. The ILs studied were four ionic liquids with chloride anion coupled with the cations: 1-butyl-3-methylimidazolium, [C4mim]+, 1-ethyl-3-methylimidazolium, [C2mim]+, 1-allyl-3-methylimidazolium, [Amim]+ and 1-(2-hydroxyethyl)-3-methylimidazolium, [C2OHmim]+ and one ammonium-based cation choline [C5H14NO]+ combined with dihydrogen phosphate anion, [H2PO4]−. Melting point depression effect observed for these groups of ionic liquids were around 10K for chloride ILs and went as high as 33.2K for choline dihydrogen phosphate. To correlate the melting point depression of imidazolium chloride ILs, parameters for the Group Contribution Equation of State (GC-EoS) of Skjold-Jørgensen for the liquid phase plus a fugacity expression for solid phases was employed. Experimental data used for the parameterization includes literature data of binary vapor–liquid, liquid–liquid and solid–liquid equilibria, and activity coefficients at infinite dilution. Melting point depression was calculated with an average deviation of 1.7K (0.5%) and a maximum deviation of 4.3K (1.3%).

Dihydrogen Phosphate Stabilized Ruthenium(0) Nanoparticles: Efficient Nanocatalyst for The Hydrolysis of Ammonia-Borane at Room Temperature

Intensive efforts have been devoted to the development of new materials for safe and efficient hydrogen storage. Among them, ammonia-borane appears to be a promising candidate due to its high gravimetric hydrogen storage capacity. Ammonia-borane can release hydrogen on hydrolysis in aqueous solution under mild conditions in the presence of a suitable catalyst. Herein, we report the synthesis of ruthenium(0) nanoparticles stabilized by dihydrogenphosphate anions with an average particle size of 2.9 ± 0.9 nm acting as a water-dispersible nanocatalyst in the hydrolysis of ammonia-borane. They provide an initial turnover frequency (TOF) value of 80 min−1 in hydrogen generation from the hydrolysis of ammonia-borane at room temperature. Moreover, the high stability of these ruthenium(0) nanoparticles makes them long-lived and reusable nanocatalysts for the hydrolysis of ammonia-borane. They provide 56,800 total turnovers and retain ~80% of their initial activity even at the fifth catalytic run in the hydrolysis of ammonia-borane at room temperature.

Sensitivity improvement of kukoamine determination by complexation with dihydrogen phosphate anions in capillary zone electrophoresis.

A novel complexation between kukoamines and dihydrogen phosphate ions (DPI) during CZE was discovered to improve the UV signal of kukoamine by around 30-fold. This complexation formed by electric current was attributed to the hydrogen bonding of hydroxyl and amino (or amide) groups between the analyte and electrolyte anions. The established CZE method is low-cost, easy to operate, and eco-friendly, and it was shown to be superior to HPLC in terms of separation capability, efficiency, specificity, and sensitivity. We believe that our CZE method can be applied as an alternative to HPLC for kukoamine assay. The approach described here can be also extended for analyzing other compounds with similar functional groups.

Anion Coordination of Bis‐bisurea Ligands: Aggregation of Dihydrogen Phosphate Anion into Oligomers and Infinite Chains

AbstractA series of alkanediyl‐spaced bis‐bisurea ligands (L2–L4) were synthesized and their anion coordination behavior studied. These ligands form interesting complexes with polymeric and oligomeric dihydrogen phosphate aggregates in the solid state. The ligands L2 and L3 coordinate with H2PO4– anions to form a unique molecular “necklace” with an infinite (H2PO4–)n chain and surrounding ligand molecules. Meanwhile, two different dihydrogen phosphate‐water oligomers, (H2PO4)6·(H2O)4 and (H2PO4)4·(H2O)2, were observed in the complexes with the ligands L3 and L4. In addition, solution anion binding properties of the ligands were studied by 1H NMR and UV/Vis spectroscopy.

A dihydrogen phosphate anionic network as a host lattice for cations in 1-methylpiperazine-1,4-diium bis(dihydrogen phosphate) and 2-(pyridin-2-yl)pyridinium dihydrogen phosphate-orthophosphoric acid (1/1).

In the salt 1-methylpiperazine-1,4-diium bis(dihydrogen phosphate), C5H13N2(2+)·2H2PO4(-), (I), and the solvated salt 2-(pyridin-2-yl)pyridinium dihydrogen phosphate-orthophosphoric acid (1/1), C10H9N2(+)·H2PO4(-)·H3PO4, (II), the formation of O-H...O and N-H...O hydrogen bonds between the dihydrogen phosphate (H2PO4(-)) anions and the cations constructs a three- and two-dimensional anionic-cationic network, respectively. In (I), the self-assembly of H2PO4(-) anions forms a two-dimensional pseudo-honeycomb-like supramolecular architecture along the (010) plane. 1-Methylpiperazine-1,4-diium cations are trapped between the (010) anionic layers through three N-H...O hydrogen bonds. In solvated salt (II), the self-assembly of H2PO4(-) anions forms a two-dimensional supramolecular architecture with open channels projecting along the [001] direction. The 2-(pyridin-2-yl)pyridinium cations are trapped between the open channels by N-H...O and C-H...O hydrogen bonds. From a study of previously reported structures, dihydrogen phosphate anions show a supramolecular flexibility depending on the nature of the cations. The dihydrogen phosphate anion may be suitable for the design of the host lattice for host-guest supramolecular systems.

A dihydrogen phosphate selective anion receptor based on acylhydrazone and pyrazole

A novel chromogenic anion receptor 1 based on acylhydrazone and pyrazole has been designed and synthesized. Receptor 1 forms stable 1 : 1 complexes with dihydrogen phosphate and other halide anions in DMSO solution.

Dithieno[3,2-a:2′,3′-c]phenazine-based chemical probe for anions: a spectroscopic study of binding

The synthesis and binding studies of N,N′-(2,5-bis(4-(tert-butyl)phenyl)dithieno[3,2-a:2′,3′-c]phenazine-9,10-diyl)bis(4-methylbenzenesulfonamide) (1) are reported.

Impact of acids on the structure and composition of Linde Type A zeolites for use in reverse osmosis membranes for recovery of urine-containing wastewaters

On the International Space Station (ISS) there are low pH, urine containing wastewaters that need to be recycled. We evaluated the effects of synthetic ISS wastewater on Linde Type A (LTA) zeolites to assess their applicability in membrane separations to produce potable water. Specifically, we studied the impact of the four acid-producing components found in the wastewater: chromium(VI) oxide, potassium phosphate monobasic, sodium phosphate monobasic dihydrate and sulfuric acid. We characterized effects of the acids on crystal structure, bonding, surface morphology and solid phase composition of the LTA zeolites. After 24h of exposure to synthetic wastewater brine (pH 1.94), the zeolites sustained some damage with extensive structural degradation occurring after 128h. The crystal structure of the LTA particles completely degraded in all acid-type solutions with a pH below 1 and in phosphate solutions with a pH below 5. The structural degradation resulted from the removal of aluminum from the zeolite framework. Additionally, we observed that phosphate caused changes in bonding of the zeolite, through removal of silicon from the framework and formation of aluminum phosphate precipitates. Ultimately, we found that the presence of acidic anions (specifically dihydrogen phosphate anions that catalyzed aluminum and silicon removal), rather than pH, was the most significant factor causing degradation of LTA in dihydrogen phosphate-containing solutions. Our results indicate that Linde Type A zeolites are inappropriate for use with low-pH, dihydrogen phosphate containing solutions.

Accuracy of density functionals in the description of dispersion interactions and IR spectra of phosphates and phosphorylated compounds.

The performances of quantum chemistry methods (i.e., DFT and ab initio) in calculating the structural and vibrational properties of phosphates and phosphorylated compounds have been evaluated. Diethyl-phosphate, phosphonic acid, dihydrogen phosphate anion, phosphoric acid dimer and protonated glycylphosphotyrosine dipeptide were selected for our study. Geometry and harmonic frequency deviations were investigated, pointing out the contribution of dispersion interactions on diethyl-phosphate, [Gly-pTyr+H](+) and the phosphoric acid dimer. The B3LYP-D functional, followed by CC2 and MP2 methods, revealed significant accuracy for frequency calculations of the majority of the phosphorylated compounds in comparison with available experimental data. These investigations provide a guide to the accurate computation of phosphorylated biological compounds.

Crystal structure of 4-sulfamoylanilinium di-hydrogen phosphate.

In the crystal structure of the title mol­ecular salt, C6H9N2O2S+·H2PO4 −, the sulfomylalinium cations and the di­hydrogen phosphate anions form independent [100] chains through Ns—H⋯O (s = sulfamo­yl) and O—H⋯O hydrogen bonds, respectively. The chains are cross-linked by Na—H⋯O (a = amine) hydrogen bonds, generating (010) sheets. Two C—H⋯O hydrogen bonds involving diametrically opposite C atoms in the benzene ring of the cation as donors form chains parallel to [202] in which P=O and P—OH groups are acceptors. Together, these inter­actions lead to a three-dimensional network.

A reversible fluorescent chemosensor for Fe3+ and H2PO4 − with “on-off-on” switching in aqueous media

To realize highly selective relay recognition of Fe3+ and H2PO4 − ions, a simple benzimidazole-based fluorescent chemosensor (L) was designed and synthesized. Sensor L displays rapid, highly selective, and sensitive recognition to Fe3+ in H2O/DMSO (1:1, v/v) solutions. The in situ-generated L-Fe3+ complex solution exhibits a fast response and high selectivity toward dihydrogen phosphate anion via the Fe3+ displacement approach. The detection limits of sensor L to Fe3+ and L-Fe3+complex to H2PO4 − anion were estimated to be 1.0 × 10−9 mol/L. Notably, the sensor was retrievable to indicate dihydrogen phosphate anions with Fe3+, and H2PO4 −, in turn, increased. This successive recognition feature of sensor L makes it a potential utility for Fe3+ and H2PO4 − anion detection in aqueous media.

Cationic Tripodal Receptor Assisted Formation of Anion and Anion–Water Clusters: Structural Interpretation of Dihydrogen Phosphate Cluster and Sulfate–Water Tetramer [(SO4)2–(H2O)2]4–

Well-defined anion and anion–water clusters based on tetrahedral oxyanions are reported herein. Self-assembled infinite dihydrogen phosphate anion clusters of 10 H2PO4– ions consist of a hexameric cluster linked to tetrameric and trimeric clusters. Octahedrally arranged discrete anionic [Na(ClO4)6]5– cluster is found to stabilize by self-complementary H-bonding and electrostatic interactions in noncapsular complexes. Our findings also indicate the presence of discrete sulfate–hydrogen sulfate anion trimers [SO4—(HSO4)2]4– and sulfate–water tetramers [(SO4)2—(H2O)2]4– in the bimolecular capsular complexes of the tripodal receptor. All complexes were well characterized by FT-IR and NMR spectroscopies, TGA, DSC, and XRD.

Polymorphs of 1-(5-Methylthiazol-2-yl)-3-phenylthiourea and Various Anion-Assisted Assemblies of Two Positional Isomers

Orientations of the phenyl group and the intramolecular hydrogen bond play prime roles in the packing patterns of three conformational polymorphs of an unsymmetrical thiourea derivative, 1-(5-methylthiazol-2-yl)-3-phenylthiourea (PTH1). Self-assembly of each polymorph is composed of hydrogen-bonded dimeric motifs held together in head-to-tail arrangement but packed in different manners. Each has an intramolecular N–H···N hydrogen bond between an amide N–H and the nitrogen atom of the 5-methylthiazole unit. The packing pattern of 1-(4-methylthiazol-2-yl)-3-phenylthiourea (PTH2) is composed of dimeric assemblies of PTH2 in head-to-tail fashion. PTH2 is monomorphic as there are intermolecular C–H···S interactions between a C–H bond of the phenyl ring of each molecule and the sulfur atom of the thiocarbonyl group of a neighboring molecule. Such interactions lock the orientation of phenyl group in the solid state. The syn–anti conformation across the thiourea group, originally present in the positional isomers PTH1 and PTH2, is invariably transformed to syn–syn conformation in their salts. The extent of hydration of anions in the salts of PTH1 or PTH2 is dependent on the cation as well as the anion. The chloride salt of PTH1 has a large difference in packing patterns in comparison with the corresponding chloride salt of PTH2; they also differ in the numbers of symmetry-nonequivalent molecules in their respective unit cells. The anhydrous salt of PTH1 with hydrogen bromide having a 1:1 ratio of cation and anion is formed, whereas the bromide salt of PTH2 is a hydrate of composition (HPTH2)2(Br)2·6H2O. This salt has bromide–water clusters in its crystal lattice. Nitric acid reacts with PTH1 under different conditions to form hydrated or anhydrous salts. The hydrated salt (HPTH1)2(NO3)2·H2O has anions bridged by water molecules. The anhydrous nitrate salts of PTH1 and PTH2 are structurally similar in having nitrate···nitrate interactions. The deprotonation of polyacids by PTH1 and PTH2 is selective. The ability to abstract a proton from sulfuric acid to form crystalline salts by PTH1 and PTH2 differs. The sulfate salt (HPTH1)2(SO4) is formed by reaction of sulfuric acid with PTH1, but PTH2 forms the bisulfate salt (HPTH2)HSO4·H2O. PTH1 forms the corresponding dihydrogen phosphate salt upon reaction with orthophosphoric acid; the dihydrogen phosphate anions are held together in the form of cyclic hydrogen-bonded hexameric assemblies in the lattice. Water loss from the assemblies of hydrated salt was determined by thermogravimetry and differential scanning calorimetry and showed that dehydration from anion-assisted assemblies was guided by the cationic host and the type of assembly.

Probing the specific ion effects of biocompatible hydrated choline ionic liquids on lactate oxidase biofunctionality in sensor applications

This paper presents an extended study on the ion effects of a series of biocompatible hydrated choline based ionic liquids (ILs) on lactate oxidase (LOx), an important enzyme in biosensing technology for the in vitro detection of lactic acid. Secondary structural analysis revealed changes in the protein conformation in hydrated ILs, while thermal unfolding/aggregation dynamics showed different profiles in the presence or absence of ILs. Moreover, LOx thermally denaturised at 90 °C showed residual activity in the presence of chloride and dihydrogen phosphate anions. Kinetic and lifetime studies were also performed, providing a better understanding of the ion effects of ILs on the biocatalytic activity of the enzyme.

New insights into dihydrogenphosphate recognition with dirhenium(i) tricarbonyl complexes bridged by a thiourea moiety

Three thiourea ligands and their dirhenium(i) complexes are reported that show an unusual cooperative binding to two dihydrogenphosphate anions; this could explain the high selectivity for phosphate in many reported anion receptors.

Large amplitude motion in cold monohydrated dihydrogen phosphate anions H2PO4−(H2O): infrared photodissociation spectroscopy combined with ab initio molecular dynamics simulations

The vibrational spectroscopy of monohydrated dihydrogen phosphate anions, H2PO4(-)(H2O), is studied in the O-H stretching (2700-3900 cm(-1)) and the fingerprint regions (600-1800 cm(-1)). Assignment of the experimental infrared multiple photon photodissociation spectra based on the predicted harmonic spectra of energetically low-lying 0 K structures is not conclusive. Ab initio molecular dynamics simulations reveal that the water molecule undergoes large amplitude motion, even at low internal temperatures, and that the dipole time correlation function qualitatively captures the anharmonic effects of the low-barrier isomerization reaction on the infrared intensities.

Synthesis and evaluation of simple naked-eye colorimetric chemosensors for anions based on azo dye-thiosemicarbazones

A series of novel, highly selective azo dye-thiosemicarbazones based anion sensors (3e–f) have been synthesized from the condensation reaction between thiosemicarbazide and six different azo salicylaldehydes. The structure of the sensors was confirmed by spectroscopic methods. The selectivity and sensitivity in the recognition for acetate anion over other anions such as fluoride, chloride, iodide and dihydrogenphosphate anions were determined by naked-eyes and UV–vis spectra. The color of the solution containing sensor had an obvious change from light yellow to orange only after the addition of acetate anion in aqueous solution (water/dimethylsulfoxide, 7:3, v/v) while other anions did not cause obvious color change. The anion recognition property of the receptor via proton-transfer is monitored by UV–vis titration and 1H NMR spectroscopy. Under condition in aqueous solution of sensor 3e (water/dimethylsulfoxide, 7:3, v/v), linearity range for the quantification of acetate anion was 1–22μM and limit of detection (LOD) of acetate anion was 0.71μM.

Synthesis and anion binding properties of m-diethynylbenzene expanded calix[4]pyrrole

A new expanded calix[4]pyrrole, calix[2]diethynylbenzene[4]pyrrole (3), was synthesized from a bispyrrole intermediate (1,3-bis(3-methyl-3-(1H-pyrrol-2-yl)but-1-ynyl)benzene). The anion binding properties of calixpyrrole 3 were also investigated. Calixpyrrole 3 was found to bind dihydrogen phosphate (H2PO4-) anions better than others. The structure of 3H2PO4- was optimized using semiempirical PM3 calculations. The optimized structure indicates that the weak anion binding properties of calixpyrrole 3 could be attributed to the presence of dimethylmethylene (meso position) and rigid ethynyl groups that block the facile approach of other parts of hydrogen-bonding motifs.

Proton conductive composite electrolytes in the KH2PO4–H3PW12O40 system for H2/O2 fuel cell operation

Potassium dihydrogen phosphate (KH2PO4, PDP) and phosphotungstic acid (H3PW12O40, PTA) were mechanochemically milled in dry nitrogen atmosphere to synthesize highly proton conductive composite electrolytes in the PDP–PTA system. Proton conductivity of these composites significantly depends on the molar ratio of PDP and PTA in the temperature range of room temperature (RT) to 180°C under both anhydrous and hydrous conditions, and the composites exhibited proton conductivities more than 2 orders of magnitude higher than those of the raw substances. Furthermore, when the binders-free PDP–PTA composites in pellet form were used as an electrolyte in H2/O2 fuel cell systems, higher open circuit potential than 0.9V and a maximum power density of 20mWcm−2 were achieved during the single cell test. The structural studies and solid-state proton-magic angle spinning-nuclear magnetic resonance (1H MAS-NMR) results showed new chemical interaction between dihydrogen phosphate anion and K-substituted PTA via ion-exchange and hydrogen bonds, which manifested the essential role of a newly developed hydrogen-bonding network to the improvement of protic conduction behavior, leading to the increase in the electrochemical performances of these composites.