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Dihydrogen Phosphate (dihydrogen + phosphate)

Distribution by Scientific Domains

Chemistry	84%

Kinds of Dihydrogen Phosphate

ammonium dihydrogen phosphate

potassium dihydrogen phosphate

Terms modified by Dihydrogen Phosphate

dihydrogen phosphate anion

Selected Abstracts

Dipyrrolyl-Functionalized Bipyridine-Based Anion Receptors for Emission-Based Selective Detection of Dihydrogen Phosphate

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007
Patrick Plitt Dr.
Abstract New cationic anion receptors, based on the use of pyrrole-substituted bipyridine and coordinated to transition metals, are described. Specifically, polypyridine,ruthenium and ,rhodium cores have been functionalized to generate an anion binding site. The design was chosen to probe the influence of the pyrrole-to-pyrrole separation on anion-binding affinities and selectivities; this distance is greater in the new systems of this report (receptors 1 and 2) relative to that present in related dipyrrolyl quinoxaline based receptors 3 and 4. Solution-phase anion-binding studies, carried out by means of 1H,NMR spectroscopic titrations in [D6]DMSO and isothermal titration calorimetry (ITC) in DMSO, reveal that 1 and 2 bind most simple anions with substantially higher affinity than either 3 or 4. In the case of chloride anion, structural studies, carried out by means of single-crystal X-ray diffraction analyses, are consistent with the solution-phase results and reveal that receptors 1 and 2 are both able to stabilize complexes with this halide anion in the solid state. [source]

Dihydrogen phosphate mediated supramolecular frameworks in 2- and 4-chloroanilinium dihydrogen phosphate salts

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010
P. Balamurugan
The title compounds, 2-chloroanilinium dihydrogen phosphate (2CADHP) and 4-chloroanilinium dihydrogen phosphate (4CADHP), both C6H7NCl+·H2PO4,, form two-dimensional supramolecular organic,inorganic hybrid frameworks. In 2CADHP, the dihydrogen phosphate anions form a double-stranded anionic chain generated parallel to the [010] direction through O,H...O hydrogen bonds, whereas in 4CADHP they form a two-dimensional supramolecular net extending parallel to the crystallographic (001) plane into which the cations are linked through strong N,H...O hydrogen bonds. [source]

Powder second harmonic generation measurement and thermal decomposition mechanisms of a new organometallic compound [(18C6)Li][Cd(SCN)3]

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009
J. J. Zhang
Abstract Single crystals of a novel nonlinear optical organometallic compound CLTC, ([(18C6)Li][Cd(SCN)3]), were grown from aqueous solutions via evaporation technique and characterized by IR spectroscopy, thermal gravimetric analysis and X-ray single-crystal diffraction. By X-ray single-crystal structural analysis it is revealed that the compound crystallized in a noncentrosymmetric space group Cmc21 of orthorhombic system with cell parameter a = 14.767(3) Å, b = 15.454(3) Å, c = 10.644(2) Å, V = 2429.0(8) Å3 and Z = 4. The thermal stability and thermal decomposition of CLTC crystal were investigated by means of thermogravimetry and differential thermal analysis. The second harmonic generation (SHG) efficiency was measured using the Kurtz and Perry powder technique. It was shown that the value of the SHG efficiency of CLCT powder was about 2 times higher than that of potassium dihydrogen phosphate (KDP). (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The combined effects of supersaturation and Ba2+ on the batch cooling crystallization of potassium dihydrogen phosphate

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2008
Guozong Zheng
Abstract The combined effects of supersaturation and Ba2+ on potassium dihydrogen phosphate (KDP) were investigated in batch cooling suspension crystallization. Growth size, morphology, and impurity Ba2+ adsorbed in the KDP crystals were measured with changing Ba2+ concentration and supersaturation. Significant changes in shapes and volume of the grown crystals have been observed. The results further confirmed that the size and shape of crystals were greatly determined by supersaturation. Ba2+ ions significantly modified the growth habit of KDP crystals. The concentration of Ba2+ ions adsorbed in the crystals increases with the increasing Ba2+ ions in the solutions and supersaturation. The foggy phenomena caused by the addition of Ba to the KDP solution were also described. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Enantioselectivity of alcohol-modified polymeric surfactants in micellar electrokinetic chromatography

ELECTROPHORESIS, Issue 15 2003
Jepkoech Tarus
Abstract A novel method of modifying sodium undecanoyl- L -leucinate (SUL) micelles employed in chiral separation of analytes in micellar electrokinetic chromatography (MEKC) to enhance selectivity toward specific analytes is discussed. The current study aimed at modifying the SUL micelles by introducing different alcohols into the mono-SUL micelles. The micellar solutions were then polymerized in the presence of alcohols followed by postpolymerization extraction of the alcohols to yield alcohol-free polymeric surfactants (poly- L -SUL). The effects of hexanol (C6OH) and undecylenyl alcohol (C11OH) on micellar properties of this surfactant were investigated by use of surface tensiometry, fluorescence spectroscopy, pulsed field gradient-nuclear magnetic resonance (PFG-NMR), and MEKC. The surface tension and PFG-NMR studies indicated an increase in the critical micelle concentration (cmc) and micellar size upon increasing the alcohol concentration. Fluorescence measurements suggested that alcohols induce closely packed micellar structures. Coumarinic and benzoin derivatives, as well as (±)-1, 1'-binaphthyl-2,2'-dihydrogen phosphate (BNP) were used as test analytes for MEKC experiments. Examination of MEKC data showed remarkable resolutions and capacity factors of coumarinic derivatives obtained with modified poly- L -SUL as compared to the unmodified poly- L -SUL. Evaluation of fluorescence, PFG-NMR, and MEKC data suggest a strong correlation between the polarity and hydrodynamic radii of alcohol-modified micelles and the resolution of the test analytes. [source]

Enhancement of crystalline perfection by organic dopants in ZTS, ADP and KHP crystals as investigated by high-resolution XRD and SEM

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2006
S. Parthiban
To reveal the influence of complexing agents on crystalline perfection, tristhiourea zinc(II) sulfate (ZTS), ammonium dihydrogen phosphate (ADP) and potassium hydrogen phthalate (KHP) crystals grown by slow-evaporation solution growth technique using low concentrations (5 × 10,3M) of dopants like ethylenediamminetetraacetic acid (EDTA) and 1,10-phenanthroline (phen) were characterized by high-resolution X-ray diffractometry (XRD) and scanning electron microscopy (SEM). High-resolution diffraction curves (DCs) recorded for ZTS and ADP crystals doped with EDTA show that the specimen contains an epilayer, as observed by the additional peak in the DC, whereas undoped specimens do not have such additional peaks. On etching the surface layer, the additional peak due to the epilayer disappears and a very sharp DC is obtained, with full width at half-maximum (FWHM) of less than 10,arcsec, as expected from the plane wave dynamical theory of X-ray diffraction for an ideally perfect crystal. SEM micrographs also confirm the existence of an epilayer in doped specimens. The ZTS specimen has a layer with a rough surface morphology, having randomly oriented needles, whereas the ADP specimen contains a layer with dendric structure. In contrast to ADP and ZTS crystals, the DC of phen-doped KHP shows no additional peak, but it is quite broad (FWHM = 28,arcsec) with a high value of integrated intensity, , (area under the DC). The broadness of the DC and the high value of , indicate the formation of a mosaic layer on the surface of the crystal. However, similar to ADP and ZTS, the DC recorded after etching the surface layer of the KHP specimen shows a very sharp peak with an FWHM of 8 arcsec. An SEM photograph of phen-doped KHP shows deep cracks on the surface, confirming the mosaicity. After removing the surface layer, the SEM pictures reveal a smooth surface. A similar trend is observed with other complexing agents, like oxalic acid, bipy and picolinic acid. However, only typical examples are described in the present article where the effects were observed prominently. The investigations on ZTS, ADP and KHP crystals, employing high-resolution XRD and SEM studies, revealed that some organic dopants added to the solution during the growth lead to the formation of a surface layer, due to complexation of these dopants with the trace metal ion impurities present in the solution, which prevents the entry of impurities, including the solvent, into the crystal, thereby assisting crystal growth with high crystalline perfection. The influence of organic dopants on the second harmonic generation efficiency is also investigated. [source]

Synthesis of 2-(5Z,8Z,11Z,14Z)-Icosa-5,8,11,14-tetraenamidoethyl-d4 dihydrogen phosphate, tetra-deuterated pAEA,

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 12 2008
Kejun Cheng
Abstract A labile intermediate phospho-anandamide (2-(5Z,8Z,11Z,14Z)-icosa-5,8,11,14-tetraenamidoethyl dihydrogen phosphate, pAEA) has been identified in mouse brain and macrophages, but its precise quantitation was difficult because of its low concentration and chemical instability. We report the synthesis of tetra-deuterated pAEA from 2-aminoethyl dihydrogen phosphate-1,1,2,2-d4 and (5Z,8Z,11Z,14Z)-2,5-dioxopyrrolidin-1-yl icosa-5,8,11,14-tetraenoate. The compound will be used to quantitate the pAEA necessary for a novel biosynthetic pathway. Published in 2008 by John Wiley & Sons, Ltd. [source]

HPLC for stress-free screening of potential prostate cancer marker catechol estrogens in urine using a diamond-electrode electrochemical and a fluorescence detector

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2007
Masatoki Katayama
Abstract Improvement of the sensitivity and specificity of a simultaneous stress-free screening method for catechol estrogens as a potential prostate cancer marker in urine has been accomplished by HPLC with a diamond-electrode electrochemical detector and a fluorescence detector. Since taking urine samples generates less stress (or pain) than the drawing of blood, the method can readily be applied to almost any patient, and will also assist in improving the sensitivity and specificity of the prostatic specific antigen test. Catechol estrogens (2-hydroxyestrone, 4-hydroxyestrone, 2-methoxyestrone, 2-hydroxyestradiol, 4-hydroxyestradiol, 2-methoxyestradiol, and 2-hydroxyestriol) and estrogens (estrone, estradiol, estriol) were separated on an Inertsil ODS-II column with acetonitrile,potassium dihydrogen phosphate (pH 3.0). The diamond-electrode electrochemical detector used had the great advantage of being a maintenance-free system, and could sequentially analyze hundreds of samples. Fluorescence detection improved the sensitivity 10,500 times (e. g., the LOD of 2-hydroxyestriol was improved 250 times) compared to previous electrochemical detection reports, and dual detection improved peak identification in the urine samples. The proposed method was applied to the simultaneous determination of catechol estrogens in spiked urine in a preliminary study on estrogens and PSA values in biopsy and prostate cancer patients. [source]

Development and validation of a stereoselective HPLC method for the determination of the in vitro transport of nateglinide enantiomers in rat intestine

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2007
Srinivas Maddi
Abstract A simple stereoselective high performance liquid chromatographic method was developed for the determination of the in vitro transport of the enantiomers of nateglinide (N -(trans -4-isopropylcyclohexyl-carbonyl)-phenylalanine) in the rat intestine using a Chiralcel OJ-RH column (150×4.0 mm, 5 ,m). The effects of the mobile phase composition, pH, the flow rate, and the temperature on the chromatographic separation were investigated. The enantioseparation was achieved at 33°C using a mobile phase containing 100 mM potassium dihydrogen phosphate, pH 2.5, and ACN (32:68 v/v) delivered at a flow rate of 1 mL/min. The analytes were monitored at 210 nm and linearity (r >0.99) was obtained for a concentration range of 0.5,50 ,g/mL. The LOD and LOQ were 0.2 and 0.5 ,g/mL for the R -enantiomer and 0.2 and 0.8 ,g/mL for the S -enantiomer, respectively. Both, the intra- and interday accuracy and precision of the calibration curves were determined. The method was successfully applied to estimate the in vitro passage of the enantiomers and the racemate of nateglinide in duodenum, jejunum, and ileum of rats. Generally, higher concentrations of nateglinide and the S -enantiomer were observed when the racemate was administered compared to administration of the individual enantiomers of nateglinide. [source]

Separation and determination of enkephalin-related peptides using capillary electrophoresis

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2005
Ying Huang
Abstract CZE with UV-absorption detection has been used for the separation and determination of enkephalin-related peptides. The experimental conditions, such as pH and concentration of running buffer, applied voltage, injection method, and time, were investigated in detail. Excellent separation efficiency could be obtained for ten enkephalin-related peptides with a 50 ,m (ID)×58 cm capillary using sodium dihydrogen phosphate as the running buffer (pH 3.11) when 20 kV of applied voltage was used. The concentration detection limits were found to be in the range of 0.31,1.94 ,g/mL (defined as S/N = 3). The proposed method has been applied to analyze the spiked cerebrospinal fluid (CSF) sample, and the results showed that CZE is a powerful technique for separation and detection of the above biological peptides. [source]

High-performance liquid chromatographic resolution of 1-(1,4-benzodioxane-2-formyl)- piperazine enantiomers after chiral derivatization

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005
Zhiqiong Chen
Abstract Chiral separation of racemic mixtures is of the greatest importance to the pharmaceutical industry, as the isomers of a given racemate may exhibit substantially different pharmacological effects, not to mention possibly differing toxicity behaviour. A novel chiral separation method is developed for the determination of 1-(1,4-benzodioxane-2-formyl)piperazine (BFP) enantiomers. The indirect resolution is performed by applying precolumn derivatization with the chiral reagent 2,3,4,6-tetra- O -acetyl-,-D-glucopyranosyl isothiocyanate (GITC). The resulting diastereoisomers are separated on a reversed-phase ODS column with methanol-potassium dihydrogen phosphate (0.02mol/L, 50:50) as mobile phase. UV detection is at 250 nm. The effect of mobile phase composition upon resolution and analysis time is investigated. Two diastereoisomers show nearly base-line separation under optimal chromatographic conditions. The presented study provides a simple and accurate method for the enantiomeric quality control and the optical purity assay of BFP. [source]

4-(3,5-Dimethyl-1H -pyrazol-4-ylmethyl)-3,5-dimethyl-1H -pyrazol-2-ium dihydrogen phosphate: a combined X-ray and DFT study

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010
Dipak K. Hazra
The molecular structure of the title salt, C11H17N4+·H2PO4,, has been determined from single-crystal X-ray analysis and compared with the structure calculated by density functional theory (DFT) at the BLYP level. The crystal packing in the title compound is stabilized primarily by intermolecular N,H...O, O,H...N and O,H...O hydrogen bonds and ,,, stacking interactions, and thus a three-dimensional supramolecular honeycomb network consisting of R42(10), R44(14) and R44(24) ring motifs is established. The HOMO,LUMO energy gap (1.338,eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) indicates a high chemical reactivity for the title compound. [source]

Dihydrogen phosphate mediated supramolecular frameworks in 2- and 4-chloroanilinium dihydrogen phosphate salts

Hydrogen-bonded network in the trichloroacetate salts of 2-amino-5-chloropyridinium and 2-methyl-5-nitroanilinium monohydrate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009
Jan Janczak
In the crystal structures of 2-amino-5-chloropyridinium trichloroacetate, C5H6ClN2+·C2Cl3O2,, (I), and 2-methyl-5-nitroanilinium trichloroacetate monohydrate, C7H9N2O2+·C2Cl3O2,·H2O, (II), the protonated planar 2-amino-5-chloropyridinium [in (I)] and 2-methyl-5-nitroanilinium [in (II)] cations interact with the oppositely charged trichloroacetate anions to form hydrogen-bonded one-dimensional chains in (I) and, together with water molecules, a three-dimensional network in (II). The crystals of (I) exhibit nonlinear optical properties. The second harmonic generation efficiency in relation to potassium dihydrogen phosphate is 0.77. This work demonstrates the usefulness of trichloroacetic acid in crystal engineering for obtaining new materials for nonlinear optics. [source]

Cloning, expression, purification and crystallization of a transcriptional regulatory protein (Rv3291c) from Mycobacterium tuberculosis H37Rv

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2004
Tripti Shrivastava
Rv3291c, the translational product of the Mycobacterium tuberculosisRv3291c gene, is an 18,kDa protein. It is a putative transcriptional regulatory protein belonging to the leucine-responsive regulatory protein/asparagine synthase C (Lrp/AsnC) family, which are proteins that have been identified in archaea and bacteria. Rv3291c probably plays a significant role during the persistent/latent phase of M. tuberculosis, as supported by its up-regulation several-fold during this stage. Orthorhombic crystals of recombinant Rv3291c have been grown from trisodium citrate dihydrate-buffered solutions containing monoammonium dihydrogen phosphate. Diffraction data extending to 2.7,Å have been collected from a single crystal with unit-cell parameters a = 99.6, b = 100.7, c = 100.6,Å. Assuming an octamer in the asymmetric unit results in a Matthews coefficient (VM) of 1.75,Å3,Da,1, corresponding to a solvent content of about 30%. [source]

Cloning, purification, crystallization and preliminary crystallographic studies of Bradyrhizobium fucosyltransferase NodZ

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004
Krzysztof Brzezinski
The ,-1,6-fucosyltransferase NodZ from Bradyrhizobium sp. WM9 (Lupinus), composed of 325 amino acids with a molecular weight of 37,kDa, has been cloned, expressed and purified. Protein crystals suitable for X-ray diffraction were obtained under optimized crystallization conditions using ammonium dihydrogen phosphate as a precipitant. The crystals are hexagonal and belong to space group P6122 or P6522, with unit-cell parameters a = 125.5, c = 95.6,Å, and contain 56.8% solvent and a single protein molecule in the asymmetric unit. Native data were collected to 2.85,Å using synchrotron radiation and cryogenic conditions. The native crystals were soaked in a mother-liquor solution containing 2.5,mM [Ta6Br12]2+ cluster for derivatization and SAD data were collected to 3.4,Å at the tantalum LIII absorption peak. [source]

Crystallization and preliminary X-ray analysis of flap endonuclease 1 (FEN1) from Desulfurococcus amylolyticus

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2009
Tomoko Mase
Flap endonuclease 1 (FEN1) is a structure-specific nuclease that removes 5,-overhanging flaps in DNA repair and removes the RNA/DNA primer during maturation of the Okazaki fragment in lagging-strand DNA replication. FEN1 from the hyperthermophilic archaeon Desulfurococcus amylolyticus was expressed in Escherichia coli, purified and crystallized using the sitting-drop vapour-diffusion method with monoammonium dihydrogen phosphate as the precipitant at pH 8.3. X-ray diffraction data were collected to 2.00,Å resolution. The space group of the crystal was determined as the primitive hexagonal space group P321, with unit-cell parameters a = b = 103.76, c = 84.58,Å. The crystal contained one molecule in the asymmetric unit. [source]

HPLC-fluorescence assay for measuring mosapride in small volumes of rat plasma

BIOMEDICAL CHROMATOGRAPHY, Issue 3 2010
Ching-Ling Cheng
Abstract A simple and sensitive HPLC-fluorescence assay was developed for the determination of a gastroprokinetic agent mosapride in small volumes of rat plasma. Samples (50 ,L) were treated with 200 ,L of the internal standard solution (cisapride, 0.1 ,g/mL in acetonitrile). Chromatographic separation was achieved on a C18 column by gradient elution with the mobile phase of acetonitrile-water containing 20 mM potassium dihydrogen phosphate, at a flow rate of 1 mL/min. Fluorescence was measured with excitation and emission set at 315 and 354 nm, respectively. The retention time was about 16 min for cisapride and 20 min for mosapride. No endogenous substances were found to interfere. The calibration curve was linear from 0.015 to 10 ,g/mL. The lower limit of quantification was 0.015 ,g/mL. The intra- and inter-day precision expressed as relative standard deviation did not exceed 7.7%, and the accuracy was within 4.7% deviation of the nominal concentration. The method was used successfully to investigate the disposition kinetics of mosapride in rats. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Determination of a novel diarylheptanoid (Juglanin B) from green walnut husks (Juglans regia L.) in rat plasma by high-performance liquid chromatography

BIOMEDICAL CHROMATOGRAPHY, Issue 3 2010
Xin-Yi Huang
Abstract A simple and reliable analytical method based on high-performance liquid chromatography (HPLC) coupled with a diode array detector (DAD) was developed for the determination of a novel diarylheptanoid (Juglanin B) from green walnut husks (Juglans regia L.) in rat plasma using rhoiptelol as an internal standard. Chromatographic separation was carried out on a Sinochrom ODS-AP C18 column (250 × 4.6 ,m i.d., 5 mm) with acetonitrile,10 mM postassium dihydrogen phosphate (pH = 3; 55:45, v/v) as mobile phase, and the detection wavelength was set at 214 nm. The plasma samples were prepared using methanol as protein precipitator. The extraction recovery of Juglanin B ranged from 70.26 to 78.59%, and the calibration curve had a good linearity in the range 0.08,50 ,g/mL (r2 = 0.9932). The RSDs of intra- and inter-day precision ranged from 1.19 to 4.92% and 4.35 to 4.54%, respectively. The HPLC-DAD method described is a simple, rapid and reliable method for the determination of Juglanin B level and for use in studies involving pharmacokinetics. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Crystallization and preliminary crystallographic analysis of a chitinase from Clonostachys rosea

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2009
Zhongwei Gan
CrChi1 is a chitinase from the nematophagous fungus Clonostachys rosea that plays a role in the infection of nematodes. In order to resolve the crystal structure of CrChi1 and to gain a better understanding of its biological functions, recombinant CrChi1 was crystallized at 291,K using PEG 3350 and ammonium dihydrogen phosphate as precipitant and a 1.8,Å resolution X-ray data set was collected from a single flash-cooled crystal (100,K). The crystals belonged to space group P21, with unit-cell parameters a = 44.1, b = 71.7, c = 59.1,Å, , = , = 90, , = 91.3°. Assuming the presence of one molecule per asymmetric unit, the Matthews coefficient and solvent content were calculated to be 2.45,Å3,Da,1 and 40%, respectively. To our knowledge, this is the first structure determination study of a chitinase from a nematophagous fungus. [source]

Expression, purification and crystallization of the ecto-enzymatic domain of rat E-NTPDase1 CD39

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 11 2008
Xiaotian Zhong
CD39 is a prototype member of the ecto-nucleoside triphosphate diphosphohydrolase family that hydrolyzes extracellular nucleoside diphosphates and triphosphates in the presence of divalent cations. Here, the expression, purification and crystallization of the ecto-enzymatic domain of rat CD39, sCD39, are described. The 67,kDa secreted soluble glycoprotein was recombinantly overexpressed in a glycosylation mutant CHO line, Lec.3.2.8.1, and purified from conditioned media. Diffraction-quality crystals of sCD39 were produced by the vapor-diffusion method using PEG 3350 and ammonium dihydrogen phosphate as precipitants. The enzyme crystallized in a primitive trigonal form in space group P32, with unit-cell parameters a = b = 118.1, c = 81.6,Å and with two sCD39 copies in the asymmetric unit. Several low- to medium-resolution diffraction data sets were collected using an in-house X-ray source. Analysis of the intensity statistics showed that the crystals were invariably merohedrally twinned with a high twin fraction. For initial phasing, a molecular-replacement search was performed against the complete 3.2,Å data set using a maximum-likelihood molecular-replacement method as implemented in Phaser. The initial model of the two sCD39 monomers was placed into the P32 lattice and rigid-body refined and position-minimized with PHENIX. [source]

Expanding Sapphyrin: Towards Selective Phosphate Binding

CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2008
Evgeny
Abstract The anion-templated syntheses and binding properties of novel macrocyclic oligopyrrole receptors in which pyrrole rings are linked through amide or imine bonds are described. The efficient synthesis was accomplished by anion-templated [1+1] Schiff-base condensation and acylation macrocyclization reactions. Free receptors and their host,guest complexes with hydrochloric acid, acetic acid, tetrabutylammonium chloride, and hydrogen sulfate were analyzed by single-crystal X-ray diffraction analysis. Stability constants with different tetrabutylammonium salts of inorganic acids were determined by standard 1H,NMR and UV/Vis titration techniques in [D6]DMSO/0.5,% water solution. According to the titration data, receptors containing three pyrrole rings (10 and 12) exhibit high affinity (log,Ka=5,7) for bifluoride, acetate, and dihydrogen phosphate, and interact weakly with chloride and hydrogen sulfate. The amido-bipyrrole receptors 11 and 13 with four pyrrole rings exhibit 104 - and 102 -fold selectivity for dihydrogen phosphate, respectively, as inferred from competitive titrations in the presence of tetrabutylammonium acetate. [source]

Cyanide Sensing with Organic Dyes: Studies in Solution and on Nanostructured Al2O3 Surfaces

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008
Nélida Gimeno
Abstract The synthesis of two new azo phenyl thiourea compounds and their optical response to different anions is reported herein. Solution studies in methanol indicate that cyanide induces a colour change in these dyes (whereas no changes are observed in the presence of other anions, such as F,, Cl,, Br,, CH3COO,, H2PO4,, HSO4,). Interestingly, in DMSO these dyes are responsive not only to cyanide, but also to fluoride, acetate and dihydrogen phosphate. Each of these anions induces a different colour change. In the second part of the paper, we report the attachment of one of these dyes onto nanostructured TiO2 and Al2O3 films. The stability of these sensitised films to pH was studied and we concluded that the sensitised Al2O3 films are more robust, and hence, better than the TiO2 for anion sensing. The dye-sensitised Al2O3 films were immersed in solutions of different anions and their response studied. The films can detect cyanide down to 3,ppm in aqueous solution with relatively good selectivity over other anions. [source]