Phthalate Ions Research Articles

Indicator displacement-based colorimetric assay for dibutyl phthalate in pharmaceutical products with titanium(IV)-pyridylazo resorcinol (PAR)

Taking advantage of the competitive binding affinity towards Ti(IV) between 4-(2-pyridylazo) resorcinol (PAR) and phthalate, a simple indicator displacement (ID)–based colorimetric assay was designed for indirect determination of a well-known phthalic acid ester, dibutyl phthalate (DBP). The indicator PAR and Ti(IV) formed a purplish-red-colored Ti(IV)-PAR complex (λmax = 540 nm) at a 1:1 ratio. In the presence of pre-hydrolyzed DBP, colorless complex formation of phthalate ion (emerging from alkaline hydrolysis of DBP) with Ti(IV) resulted in a hypsochromic shift in absorbance maximum, accompanying a color change from purplish-red to yellowish-orange (λmax = 390 nm) by the release of PAR from Ti(IV)-PAR system. Based on this mechanism, the linear response range of the system for DBP was found to lie between 0.16 and 0.37 mmol L–1 with an experimental detection limit of 11.6 µmol L–1. The recommended Ti(IV)-PAR system was successfully applied to DBP-containing pharmaceutical products (as real sample) after a simple clean-up process for removing possible water-soluble interferents. The analytical results obtained from the recommended method (by applying the standard addition approach) and the reference liquid chromatography-tandem mass spectrometric (LC–MS/MS) method were statistically compared using DBP-extract of the drug samples. Consequently, a simple and selective colorimetric ID strategy was proposed for the analysis of DBP in pharmaceuticals for the first time.

POTENTIOMETRIC DETERMINATION OF PERO-COMPOUNDS IN MAYONNAISE

I3-sensitive sensor was developed, where the ionic acetate of the neutral red triiodide was used as the electrodoactive substance. The main electroanalytical characteristics of the sensor have been studied. It is established that the operating interval of the pH of the chain is 2–12. The interval of linearity of the electrode function is 9×10–5 – 1×10–1 mol/l, the slope is 51–59 mV/pC. The selectivity of the triiodide sensor by the “individual-solutions” method has been studied. The method of potentiometric titration allows to determine peroxo compounds and peroxide number in mayonnaise in the presence of tartrate, citrate, benzoate, salicylate, oxalate, phthalate ions, glucose, glycine, histidine, aspirin.

High refractive index colorless glasses composed of titanium oxo-oligomers modified with phthalate ions

High refractive index colorless glasses composed of titanium oxo-oligomers modified with phthalate ions

Computational, Spectral and Structural Studies of New Hydrazinium Hydrogen Phthalate Monohydrate Salt

Pure single crystals of Lewis acid-base salt, hydrazinium hydrogen phthalate monohydrate (HHPMH) has been synthesized, crystallized and isolated as a single crystal by slow evaporation method at room temperature (22 ºC). Analysis of analytical, spectral, thermal and structural data confirmed the salt formation in aqueous medium. The analytical data is in favour of the proposed composition HOOC-C6H4COO N2H5·H2O. The compound crystallized in a monoclinic crystal system and P21/C space group with cell parameters, a = 15.409(3) Å, b = 10.292(2) Å and c = 6.7087(12) Å. Though strong intramolecular hydrogen bonding interaction is anticipated between acidic hydrogen of HHPMH and deprotonated carboxylate oxygen surprisingly in the present case it is absent and a weak interaction is observed between acidic hydrogen and water molecule, which is quite evident from the ORTEP diagram. The nature of interactions between hydrazine cation and hydrogen phthalate ion and the crystal packing diagram from various types of intermolecular contacts were determined by Hirshfeld surface analysis. The compound was stable up to 40 ºC and undergoes dehydration from 40-70 ºC with an endotherm at 47 ºC. The experimental and theoretical infrared spectra are also in favour of the formation of ionic crystal. The molecular structure was optimized using B3LYP method by 6-311G (d,p) basis set. The energy gap between HOMO and LUMO is 7.7340 eV. Theoretical calculation based on DFT studies and natural bond orbital analyses has been carried out to evaluate the molecular electrostatic potential. The structure was optimized by DFT and the vibrational frequencies were calculated. Comparison of experimental and optimized structures revealed that there is a good coincidence between the two.

Complex Formation of Copper(II) Ions with Phthalate Ions in Non-Aqueous Solvents

Complex Formation of Copper(II) Ions with Phthalate Ions in Non-Aqueous Solvents

Dimerization of Phthalate Ion in Non-Aqueous Solvents

Dimerization of Phthalate Ion in Non-Aqueous Solvents

Highly-porous uniformly-sized amidoxime-functionalized cellulose beads prepared by microfluidics with N-methylmorpholine N-oxide

Uniformly-sized porous cellulose beads functionalized with amidoxime groups were prepared for the first time using a microfluidic method with N-methylmorpholine N-oxide (NMMO) monohydrate as a cellulose solvent. The molten state cellulose dope in NMMO monohydrate (cell/NMMO dope) as a disperse phase and hot mineral oil as a continuous phase were used in a T-junction microfluidic chip to produce uniformly-sized cell/NMMO droplets. Coagulation of the molten state cell/NMMO droplet at high temperature and amidoxime functionalization could prepare the highly-porous spherical amidoxime-functionalized cellulose beads with a uniform fibrous open internal structure. The prepared amidoxime-functionalized cellulose beads showed excellent metal adsorption properties with a maximum adsorption capacity of ~ 80 mg g−1 in the case of Cu2+/phthalate ions. The newly developed highly-porous cellulose beads can open many new applications with other proper functionalization at the reactive hydroxyl groups of the cellulose.Graphic abstract

Interaction mechanism of organic carboxylate with kaolinite and montmorillonite: A density functional theory study

The covering of aimed minerals by kaolinite and montmorillonite is an important factor leading to poor flotation selectivity. Organic inhibitors with small molecular weights can significantly improve this phenomenon. We selected nine kinds of organic carboxylate inhibitors with small molecules, and the stable adsorption conformations and adsorption energy of nine kinds of carboxylate ions on kaolinite (0 0 1) and montmorillonite Na (0 0 1) surfaces were obtained using DFT calculations. We found that the hydrogen phthalate ion has the strongest interaction with both the kaolinite and montmorillonite surfaces. Finally, a mixed system of acetate-kaolinite (0 0 1) surface and acetate-montmorillonite Na (0 0 1) surface were constructed, and the bond populations between the acetic acid and mineral surface and the atomic Mulliken charges were calculated. The interaction mechanism of small molecular organic carboxylates with kaolinite and montmorillonite were explained directly at the atomic and electronic levels. This work might shed new light on the flotation separation of minerals associated with kaolinite and montmorillonite under the condition of small molecular organic carboxylates as inhibitor. And it provides with a reliable method to select inhibitors before flotation.

Mechanism of phthalic acid collector in flotation separation of fluorite and rare earth

The mechanism of phthalic acid, a dicarboxylic acid collector, in flotation separation of fluorite and rare earth (RE) was studied in this paper. The experimental data of flotation show that phthalic acid, as the collector, can realize highly efficient separation of fluorite and rare earth under weakly acidic conditions. The adsorption mechanism of phthalic acid on the surface of fluorite and bastnaesite was analyzed in this paper by means of the zeta potential measurement, the Fourier transform infrared (FT-IR), the X-ray photoelectron spectroscopy (XPS) and the stability constant measurement of active metal ion and phthalic acid coordination complex. According to the zeta potential testing results, the surfaces of fluorite adsorb the collector phthalate ion with negative charge under weakly acidic conditions which, in turn, increases its electronegativity and results in the motion of its potential. After the reaction between phthalic acid and fluorite ores under weakly acidic conditions, the peak of the fluorite ores is found to have significant changes in the FT-IR results, indicating strong chemical adsorption on the surfaces of phthalic acid and fluorite ores. According to the XPS analysis, the peak of benzene ring of phthalic acid is as high as 2% on the surface of fluorite, while no obvious characteristic peak of benzene ring is found on the surface of bastnaesite. According to the pH potentiometric titration results, the stability constant Ktotal of calcium phthalate complex within the acid range is higher than the stability constant Ktotal' of cerium phthalate complex, indicating that the complex generated between phthalic acid and Ca2+ is more stable than the complex generated between phthalic acid and Ce3+. The possible reason is that Ca2+, with the highest reticular density, plays a prevailing role in the octahedron structure of fluorite amidst the acidic media. As the active point of flotation, Ca2+ works with the carboxyl groups of the collector phthalic acid (–C=O–) to form polycyclic calcium phthalate complex.

Enhanced Photosensitive Schottky Diode Behavior of Pyrazine over 2-Aminopyrimidine Ligand in Copper(II)-Phthalate MOFs: Experimental and Theoretical Rationalization.

Two novel Cu(II)-based metal–organic frameworks [C40H34Cu2N6O18 (1) and C20H18CuN2O10 (2)] have been synthesized using 2-aminopyrimidine or pyrazine ligands and phthalate ion and characterized spectroscopically and by X-ray single-crystal diffraction. Both 1 and 2 show electrical conductivity and photosensitivity, evidencing their potentiality in optoelectronic device applications. Experimental and theoretical investigations revealed that the electrical conductivity under irradiation of visible light increases compared to that under dark condition (photosensitive Schottky barrier diode behavior), especially in complex 2. Both 1 and 2 have been successfully applied in technologically challenging thin-film active devices.

Comparison study between corrosion protection of polypyrrole synthesized on stainless steel from phthalate and saccharinate aqueous medium

Polypyrrole (PPy) was deposited on 304 stainless steel (SS) surfaces from aqueous solutions of sodium phthalate and sodium saccharinate, by electrochemical methods including cyclic voltammetry, chronopotentiometry and chronoamperometry. The anticorrosive properties of PPy coating doped with phthalate ions were studied by various techniques of analysis such as (XPS, SEM, SIE and OCP), and compared to those of PPy doped by saccharinate. The coating doped with phthalate ions showed the same structural characteristics obtained in the case of films synthesized in a saccharinate medium. In addition, these coatings have shown good protection against corrosion of stainless steel in saline medium (3% NaCl). The polypyrrole film has a dual behavior as an energy barrier against the penetration of aggressive ions (Cl−) and as an oxygen reduction catalyst.

Ion sensitivity of large-area epitaxial graphene film on SiC substrate

We investigated the intrinsic ion sensitivity of graphene field-effect transistors (FETs) fabricated by a resist-free stencil mask lithography process from a large-scale graphene film epitaxially grown on a SiC substrate. A pH-adjusted phosphate-buffered solution was used for the measurement to eliminate the interference of other ions on the graphene FET's ion sensitivity. The charge neutrality point shifted negligibly with changing pH for the pH-adjusted phosphate-buffered solution, whereas for the mixed buffer solution, it shifted toward the negative gate voltage owing to the decrease in the concentration of phthalate ions. This phenomenon is contrary to that observed in previous reports. Overall, our results indicate that the graphene film is intrinsically insensitive to ions except for those with functional groups that interact with the graphene surface.

Modeling the adsorption of hydrogen, sodium, chloride and phthalate on goethite using a strict charge-neutral ion-exchange theory.

Simultaneous adsorption modeling of four ions was predicted with a strict net charge-neutral ion-exchange theory and its corresponding equilibrium and mass balance equations. An important key to the success of this approach was the proper collection of all the data, particularly the proton adsorption data, and the inclusion of variable concentrations of conjugate ions from the experimental pH adjustments. Using IExFit software, the ion-exchange model used here predicted the competitive retention of several ions on goethite by assuming that the co-adsorption or desorption of all ions occurred in the correct stoichiometries needed to maintain electroneutrality. This approach also revealed that the retention strength of Cl− ions on goethite increases in the presence of phthalate ions. That is, an anion-anion enhancement effect was observed. The retention of Cl− ions was much weaker than phthalate ions, and this also resulted in a higher sensitivity of the Cl− ions toward minor variations in the surface reactivity. The proposed model uses four goethite surface sites. The drop in retention of phthalate ions at low pH was fully described here as resulting from competitive Cl− reactions, which were introduced in increasing concentrations into the matrix as the conjugate base to the acid added to lower the pH.

Structural diversity of manganese(II) complexes containing 2,2′-dipyridylamine and benzenedicarboxylates. Conformational analysis of tere-, iso- and phthalate ions: An experimental and quantum chemical approach

Four novel manganese(II) complexes with 2,2′-dipyridylamine (dipya) and various benzenedicarboxylate, BDC, ligands as anions of phthalic (pht), isophthalic (ipht) and terephthalic (tpht) acids were hydrothermally synthesized, namely, [Mn(dipya)(pht)(H2O)]2 (1), [Mn(dipya)(ipht)]n (2), [Mn(dipya)2(tpht)]n (3), and [Mn(dipya)(H2O)4](tpht) (4). All complexes were characterized by single-crystal X-ray diffraction, TG/DSC analysis and IR spectroscopy. The obtained complexes display a plenty of different structural features, including geometry of central metal atoms, BDC coordination modes and crystal packing. The coordination numbers of Mn(II) are different: 5 (in 2), 6 (in 3 and 4) and 7 (in 1). 3D networks in 1–4 are determined by strong non-covalent interactions. A survey of the Cambridge Structural Database for BDC complexes was performed in order to analyze orientation of COO groups. The energies of various BDC conformers were calculated by the second order Møller–Plesset perturbation theory and three hybrid HF/DFT methods with 6-311G∗∗ basis set. To explain different behavior, BDC ions were also examined by Localized Molecular Orbital Energy Decomposition and Natural Bond Orbital analyses. Experimental and calculated geometries are in agreement, showing that tpht and ipht anions prefer the planar conformation, while in pht anions COO groups are inclined and make complementary angles relative to the aromatic rings.

The Stoichiometry of Proton, Chloride, and Phthalate Adsorption on Goethite

The adsorption of ions on solid surfaces can be measured in the absence of competing reactions if the background electrolytes are inert or indifferent. The background electrolytes are not necessarily inert or indifferent, particularly if their concentrations are high, which can result from pH adjustments. Therefore, an understanding of the adsorption of ions on solid surfaces should include the potential role of each of the other ions in the system. This study investigated the adsorption of phthalate, an environmentally common ligand, on goethite with concurrent measurements of other ions present in the matrix. Measuring the stoichiometry of all adsorbing ions will identify any coadsorption process present, if any, and also elucidate the net change in surface charge characteristics. The stoichiometry of protons and Cl− ions adsorbing onto the surface of goethite and the stoichiometry of protons and phthalate ions adsorbing onto the same surface with NaCl as the background electrolyte were measured. Proton adsorption data were obtained using the backtitration technique, while Cl− and phthalate adsorption data were obtained by mass balance as a function of pH. The proton/Cl− adsorption stoichiometry is 1:1 and the proton/phthalate adsorption stoichiometry is 2:1. Such stoichiometries imply that the net charge on the surface is neutral. The Cl− and phthalate anions were found to exhibit a competitive reaction with the surface. The surface showed a preference for phthalate at pH values >2.5. The adsorption reactions of cations and anions are tightly intertwined and occur concurrently, and quantifying both of these reactions is needed to fully understand the adsorption processes involved. Accordingly, the adsorption study of specific ions should also include an adsorption study of all the other competitive or coadsorbing ions present.

The Potassium Channel Interacting Protein 3 (DREAM/KChIP3) Heterodimerizes with and Regulates Calmodulin Function

Downstream regulatory element antagonistic modulator (DREAM/KChIP3), a neuronal EF-hand protein, modulates pain, potassium channel activity, and binds presenilin 1. Using affinity capture of neuronal proteins by immobilized DREAM/KChIP3 in the presence and absence of calcium (Ca(2+)) followed by mass spectroscopic identification of interacting proteins, we demonstrate that in the presence of Ca(2+), DREAM/KChIP3 interacts with the EF-hand protein, calmodulin (CaM). The interaction of DREAM/KChIP3 with CaM does not occur in the absence of Ca(2+). In the absence of Ca(2+), DREAM/KChIP3 binds the EF-hand protein, calcineurin subunit-B. Ca(2+)-bound DREAM/KChIP3 binds CaM with a dissociation constant of ∼3 μM as assessed by changes in DREAM/KChIP3 intrinsic protein fluorescence in the presence of CaM. Two-dimensional (1)H,(15)N heteronuclear single quantum coherence spectra reveal changes in chemical shifts and line broadening upon the addition of CaM to (15)N DREAM/KChIP3. The amino-terminal portion of DREAM/KChIP3 is required for its binding to CaM because a construct of DREAM/KChIP3 lacking the first 94 amino-terminal residues fails to bind CaM as assessed by fluorescence spectroscopy. The addition of Ca(2+)-bound DREAM/KChIP3 increases the activation of calcineurin (CN) by calcium CaM. A DREAM/KChIP3 mutant incapable of binding Ca(2+) also stimulates calmodulin-dependent CN activity. The shortened form of DREAM/KChIP3 lacking the NH(2)-terminal amino acids fails to activate CN in the presence of calcium CaM. Our data demonstrate the interaction of DREAM/KChIP3 with the important EF-hand protein, CaM, and show that the interaction alters CN activity.

Isotope-induced desymmetrization can mimic isotopic perturbation of equilibria. On the symmetry of bromonium ions and hydrogen bonds.

The desymmetrizing effect of isotopic substitution on the geometry of otherwise symmetrical structures can be surprisingly large when there is anharmonic coupling between a desymmetrizing mode and modes whose zero-point energies are strongly isotope-dependent. This phenomenon is found to account for experimental observations that had been previously interpreted as implying asymmetry in bromonium ions and in hydrogen phthalate ions in aprotic solvents. The unlabeled structures are concluded to have the higher symmetry found in computed structures. Great care must be taken in applying isotopic perturbation as a test of asymmetry.

Synthesis, structures and biological properties of nickel(II) phthalates with imidazole and its derivatives

Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)] 6(Pht)·H 2O ( 1), [Ni(Pht)(Im) 3(H 2O) 2]·H 2O ( 2) and [Ni(Pht)(2-MeIm) 3(H 2O) 3]·H 2O ( 3), and coordination polymer [Ni(Pht)(4-MeIm) 2(H 2O)] n ( 4) (where Pht = dianion of o-phthalic acid, Im = imidazole, 2-MeIm = 2-methylimidazole, 4-MeIm = 4-methylimidazole) have been synthesized. The complexes 1– 4 were characterised by elemental analysis, IR data, thermogravimetric, and X-ray diffraction analyses. X-ray analysis shows that the asymmetric unit of 1 consists of [Ni(Im)] 6 2+ cation, Pht 2− anion and solvate H 2O molecule. The phthalate dianion does not take part in coordination to metal ion. The cations, anions and water molecules are linked via N–H ⋯ O and O–H ⋯ O interactions forming 2D hydrogen-bonded networks. The structures of 2 and 3 are similar to other mononuclear Ni(II) phthalate complexes where Pht 2− anions act as monodentate ligands and uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonded double-chains. The structure of 4 consists of [Ni(4-MeIm) 2(H 2O)] building units connected by phthalate ions to form helical chains. The complexes 1– 4 were tested for their ability to increase the biosynthesis of enzymes.

N—H...O and O—H...O hydrogen-bonded supramolecular networks in 4-chloroanilinium, 2-hydroxyanilinium and 3-hydroxyanilinium hydrogen phthalates

The title salts, 4-chloroanilinium hydrogen phthalate (PCAHP), C6H7ClN+.C8H5O4-, 2-hydroxyanilinium hydrogen phthalate (2HAHP), C6H8NO+.C8H5O4-, and 3-hydroxyanilinium hydrogen phthalate (3HAHP), C6H8NO+.C8H5O4-, all crystallize in the space group P2(1)/c. The asymmetric unit of 2HAHP contains two independent ion pairs. The hydrogen phthalate ions of 2HAHP and 3HAHP show a short intramolecular O-H...O hydrogen bond, with O...O distances ranging from 2.3832 (15) to 2.3860 (14) A. N-H...O and O-H...O hydrogen bonds, together with short C-H...O contacts in PCAHP and 3HAHP, generate extended hydrogen-bond networks. PCAHP forms a two-dimensional supramolecular sheet extending in the (100) plane, whereas 2HAHP has a supramolecular chain running parallel to the [100] direction and 3HAHP has a two-dimensional network extending parallel to the (001) plane.

Triaqua(benzene-1,2-dicarboxylato-κO)(1,10-phenanthroline-κ2N,N′)zinc(II) monohydrate

The structure of the title compound, [Zn(C8H4O4)(C12H8N2)(H2O)3]·H2O, displays a distorted octa­hedral coordination geometry, with two N atoms from the bidentate phenanthroline ligand, three O atoms from three meridional H2O mol­ecules and one O atom from the monodentate phthalate ion.