Acidity constants of adenosine-5′-mono- and diphosphate in various water-organic solvent mixtures

Summary The acidity constants of adenosine-5-mono- and diphosphate (AMP andADP) were determined at 25.00±0.1°C by potentiometric titration in pure water and different solvent mixtures (methanol, ethanol, N,N-dimethylformamide, dimethylsulfoxide, acetone, and dioxane). The ionization ofAMP andADP depends on both the proportion and the nature of the organic solvent used. ThepK _a1 values for bothAMP andADP are slightly influenced as the solvent is enriched in ethanol and methanol and remains practically constant in presence of different amounts ofDMF andDMSO. A pronounced change in thepK _a1 values is observed as the solvent is enriched in acetone or dioxane. It is concluded that the electrostatic effect has only a relatively small influence on the dissociation equilibrium, whereas other solvent effects such as solvent basicity, hydrogen bonding and protonsolvent interactions play an important role.

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Aciditätskonstanten von Adenosin-5-mono- und -diphosphat in verschiedenen organisch-wäßrigen Lösungsmittelgemischen

Zusammenfassung Die Aciditätskonstanten von Adenosin-5-mono- und -diphosphat wurden bei 25.0±0.1°C in reinem Wasser und in verschiedenen Lösungsmittelgemischen (Methanol, Ethanol, N,N-Dimethylformamid, Dimethylsulfoxid, Aceton und Dioxan) potentiometrisch bestimmt. Der Ionisierungsgrad vonAMP undADP hängt sowohl von der Menge als auch von der Art des organischen Lösungsmittels ab. DiepK _a1-Werte vonAMP undADP werden durch Zugabe von Methanol und Ethanol nur wenig, durch verschiedene Mengen vonDMF undDMSO gar nicht, durch Aceton und Dioxan jedoch deutlich beeinflußt. Offensichtlich haben elektrostatische Effekte nur geringe Auswirkungen auf das Dissoziationsgleichgewicht, wogegen andere Faktoren wie Basizität des Lösungsmittels, Wasserstoffbrückenbindungen und Lösungsmittel-Proton-Wechselwirkungen eine bedeutende Rolle spielen.

     

Is capillary electrophoresis on microchip devices able to genotype uridine diphosphate glucuronosyltransferase 1A1 TATA‐box polymorphisms?

In this commentary, we focused our attention on capillary electrophoresis. It achieves the efficient separation of molecular species by the application of high voltages to samples in solution. Actually, capillary electrophoresis can be performed on microchip devices, based on an automated and miniaturized electrophoresis system, based on lab‐on‐a‐chip technology. By this technology it is possible to separate nucleic acid fragments (DNA or RNA) with respect to sizing accuracy and sizing resolution. Currently, two automated capillary electrophoresis on microchips devices are available: the Agilent 2100 Bioanalyzer and the Experion? Automated Electrophoresis System. In this study, we evaluated if the CE is able to distinguish the three uridine diphosphate glucuronosyltransferase 1A1 TATA‐box genotypes.     

Detection of cyanide via extended π-conjugation-induced fluorescence enhancement of a metal organic framework composed of terbium(III), bipyridyl and adenosine diphosphate

A metal-organic framework (MOF) was designed and prepared from luminescent Tb(III), adenosine diphosphate (ADP) and bipyridyl (Bipy). Its green fluorescence at 545 nm is shown to enable the fluorometric detection of cyanide ion based on the principle of π-conjugation-induced fluorescence enhancement. The fluorescence of the probe is strongly increased by cyanide due to extended π-conjugation between probe MOF and cyanide which sensitizes the fluorescence of Tb(III). This effect can be used to quantify cyanide at levels as low as 30 nM in aqueous solution. The method was applied to the determination of cyanide in saliva samples. The lack of interference by acetate and fluoride is a specific feature of this method. The method based on the principle of π-conjugation-induced fluorescence enhancement provides a new sensing way for widely used fluorescence assays.

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Graphical abstract A cyanide-selective Tb-ADP-Bipy MOF was designed and synthesized for the detection of cyanide based on the principle of π-conjugation-induced fluorescence enhancement.

     

Synthesis and crystal structure of the hydrated magnesium diphosphate Mg2P2O7·3.5H2O and its high temperature variant Mg2P2O7·H2O

The synthesis and crystal structure of a novel hydrated magnesium diphosphate and its high temperature variant are described. Both structures were solved from powder X-ray diffraction data. The room temperature variant with composition Mg₂P₂O₇·3.5H₂O crystallises in the monoclinic space group P2₁/c (No. 14) with a=10.9317(1), b=8.05578(9), c=9.2774(1) Å, β=90.201(1)°, V=816.99(2) ų and Z=4. The structure consists of sheets stacked along [100] which are linked through MgO₂(H₂O)₄ pillars into a three-dimensional framework with cavities containing water molecules. Within the sheets there are infinite edge-sharing chains of Mg octahedra along [010] which are cross linked by P₂O₇⁴⁻ groups. A high temperature variant exists around 200°C. The crystal structure of this compound with composition Mg₂P₂O₇·H₂O was solved and refined in the monoclinic space group C2/c (No. 15) with a=18.6596(4), b=7.9769(1), c=8.9757(2) Å, β=107.378(1)°, V=1275.01(4) ų, Z=8. The transformation to Mg₂P₂O₇·H₂O involves removal of the water molecules in the cavities and the water molecules of the Mg octahedral pillars in Mg₂P₂O₇·3.5H₂O. The sheets in Mg₂P₂O₇·3.5H₂O however remain unchanged during the transformation as the water molecule coordinating Mg here is retained. These sheets are linked through tetrahedral MgO₄ pillars into a three-dimensional structure containing infinite 10-membered ring channels along [001]. Both compounds have been further characterised by ³¹P MAS NMR spectroscopy, thermogravimetric analysis and high temperature powder X-ray diffraction.     

Synthesis and Crystal Structure of 18-Tungstotetranickel(II) diphosphate Na_(10){(PW_9O_(34))_2Ni_4(H_2O)_2}·26H_2O

1 INTRODUCTIONThe inorganic chemistry concentrating on polyoxometallates, is in a position to connect elementary building blocks and their derivatives in different ways, enabling people to synthesize a large variety of remarkable substances, especially those in the "nanoworld". Of particular importance is the anionic-type which has {MOx}-type building-block units, where M stands for the d block elements in high oxidation states.[1] In 1973 Weakley, Evans and Showell isolated[2] K10P2W1…     

Characterization and crystal structure of a new layered cadmium diphosphate: KCdHP<Subscript>2</Subscript>O<Subscript>7</Subscript>∙2H<Subscript>2</Subscript>O

A new potassium cadmium hydrogen diphosphate dihydrate, KCdHP₂O₇?2H₂O (1), has been synthesized by slow evaporation at room temperature and characterized by FT-IR, Raman, TG-DTA, and single crystal X-ray diffraction. Compound (1) crystallizes in the orthorhombic Pcmn space group with the unit cell parameters a = 6.5814(8) Å, b = 7.9428(9) Å, c = 15.961(6) Å, V = 834.4(3) Å3 and Z = 4. Its structure consists of polyhedral layers parallel to the ab plane where each CdO₆ octahedron (m position) shares four edges with three different diphosphate groups. In the Cd octahedron, two oxygen atoms residing in (m) special positions belong to coordinated water molecules. These layers are joint by K⁺ cations (4c Wyckoff position) and hydrogen bonds, leading thus to a two-dimensional framework. The structural model is supported by the bond-valence-sum validation tool as calculated valences are close to the formal oxidation numbers.     

Voltammetric detection of uridin diphosphate glucuronosyl transferase 1A9 (UGT1A9) gene corresponding oligonucleotide covering promoter region from −268 to −280 including (A/T) polymorphism at position −275 and optimization of the detection factors

In this study, we developed a new peptide nucleic acid (PNA) biosensor for detection of a single nucleotide polymorphism (SNP) in the UGT1A9 gene promoter region via electrochemical assay. The sensor relies on the immobilization of a 13-mer single stranded PNA probe related to the UGT1A9 gene on the Au electrode (AuE). The hybridization between the probe and its complementary sequence (DcUG275) as the target was studied by differential pulse voltammetry (DPV) of methylene blue (MB) signal. In this approach the extent of hybridization is evaluated on the basis of the difference between DPV signals of MB accumulated on the probe-AuE and MB accumulated on the probe-target-AuE. Some experimental variables affecting the performance of the biosensor including oxygen interference during the assay, probe immobilization time, probe concentration and MB accumulation time were investigated. The PNA probe modified AuE in its optimum condition was shown to be an effective sensor for the detection of hybridization and point mutations. The obtained detection limit of the utilized biosensor has been calculated as 22 nm.     

Synthesis, structure and spectroscopic characterization of a new organic cation diphosphate: [2,6-(C2H5)2C6H3NH3]2H2P2O7?·?2H2O

The chemical preparation, crystal structure and spectroscopic characterization of [2,6-(C₂H₅)₂C₆H₃NH₃]₂H₂P₂O₇ · 2H₂O have been reported. The compound crystallizes in the monoclinic system in space group P2₁/c and cell parameters a = 14.323(2), b = 11.158(3), c = 16.387(2) ? and β = 96.34(3)°; V = 2602.8(9) ?³ and Z = 4. Crystal structure has been determined and refined to R = 0.044, using 3528 independent reflections. The atomic arrangement of the title compound shows anionic layer of formulae [H₂P₂O₇(H₂O)₂] _n ²ⁿ⁻ stacked along the c-axis. The 2,6-diethylanilinium cations establish on both sides of these inorganic layer hydrogen bonds so as to contribute to the intralayer cohesion in the network. The different building species are held together by means of O–H···O and N–H···O intermolecular hydrogen bonds in addition to electrostatic and van der Waals interactions.