Novel pH responsive luminescent poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes

The paper reports on the dependence of the absorbance and luminescent intensity from pH of novel poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes. The photophysical data obtained allow some preliminary assumptions about the nature of this phenomenon. Increase in luminescent efficiency is a consequence of enhanced efficiency of energy transfer caused by structural changes in complexes after water deprotonation. Remarkable change has been observed in photophysical properties of the polymer complexes by studying the fluorescent emission and excitation spectra and absorption recorded at various pH both in solution and in the solid state. Some of the complexes derivative of the dibenzoylmethane (DBM) show more than hundred times increase in the luminescence after alkalization. The pH value, at which the maximum luminescent efficiency appears, depends on the type of the fourth ligand. The difference between luminescent efficiency of the complexes in alkaline and neutral environment depends on the β-diketonate ligands and on polymer type as well.      

Intercalation of porphyrin (TMPyP) and copper-porphyrin into γ-zirconium phosphate

Water-soluble ,,,-tetrakis(4-N-methylpyridyl)porphine(TMPyP) was directly intercalated into -zirconium phosphate (-ZrP) with expansion of the interlayer distance from 12.3 to a maximum of 17.2 Å, indicating parallel orientation of porphyrin to the layer of -ZrP. Diffuse reflectance spectra of the intercalate shows that the porphyrin is protonated in the interlayer space. Uptake of Cu²⁺ ions into the porphyrin intercalate takes place with further increase in the interlayer distance. It was observed that TMPyP metalated Cu²⁺ in -ZrP. Copper porphyrin can also be taken up quite easily and an interlayer spacing of 18.6 Å is attained.     

Thermodynamics of the hydrolysis reactions of adenosine 3′,5′-(cyclic)phosphate(aq) and phosphoenolpyruvate(aq); the standard molar formation properties of 3′,5′-(cyclic)phosphate(aq) and phosphoenolpyruvate(aq)

Molar calorimetric enthalpy changes Δ_rH_m(cal) have been measured for the biochemical reactions {cAMP(aq) + H₂O(l)=AMP(aq)} and {PEP(aq) + H₂O(l)=pyruvate(aq) + phosphate(aq)}. The reactions were catalyzed, respectively, by phosphodiesterase 3^′,5^′-cyclic nucleotide and by alkaline phosphatase. The results were analyzed by using a chemical equilibrium model to obtain values of standard molar enthalpies of reaction Δ_rH_m^∘ for the respective reference reactions {cAMP⁻(aq) + H₂O(l)=HAMP⁻(aq)} and {PEP³⁻(aq) + H₂O(l)=pyruvate⁻(aq) + HPO²⁻₄(aq)}. Literature values of the apparent equilibrium constants K^′ for the reactions {ATP(aq)=cAMP(aq) + pyrophosphate(aq)}, {ATP(aq) + pyruvate(aq)=ADP(aq) + PEP(aq)}, and {ATP(aq) + pyruvate(aq) + phosphate(aq)=AMP(aq) + PEP(aq) + pyrophosphate(aq)} were also analyzed by using the chemical equilibrium model. These calculations yielded values of the equilibrium constants K and standard molar Gibbs free energy changes Δ_rG_m^∘ for ionic reference reactions that correspond to the overall biochemical reactions. Combination of the standard molar reaction property values (K, Δ_rH_m^∘, and Δ_rG_m^∘) with the standard molar formation properties of the AMP, ADP, ATP, pyrophosphate, and pyruvate species led to values of the standard molar enthalpy Δ_fH_m^∘ and Gibbs free energy of formation Δ_fG_m^∘ and the standard partial molar entropy S_m^∘ of the cAMP and PEP species. The thermochemical network appears to be reasonably well reinforced and thus lends some confidence to the accuracy of the calculated property values of the variety of species involved in the several reactions considered herein.     

Electrochemical investigation of N,N′-Propylene-bis-(salicylideneiminato) Mn(III) in phosphate buffer solutions

Summary An electrochemical study on N,N-Propylene-bis-(salicylideneiminato) Mn(III) was performed using cyclic voltammetry with convolution-deconvolution and digital simulation in phosphate buffer solutions ofpH values ranging from 5–9.5 at a hanging mercury drop electrode (HMDE). The reduction pathway of the investigated complex shows that a moderately fast transfer of one electron is followed by a very fast chemical reaction (E _q C _irr scheme). The electrochemical parameters have been determined experimentally andvia digital simulation experiments.

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Elektrochemische Untersuchung von N,N-Propylen-bis-(salicylideniminato)-Mn(III) in Phosphatpufferlösungen

Zusammenfassung N,N-Propylen-bis-(salicylideniminato)-Mn(III) wurde in Phosphatpufferlösungen mitpH-Werten im Bereich von 5–9.5 an einer Quecksilbertrofelektrode (HMDE) mittels cyclischer Voltammetrie (Konvolution-Dekonvolution, digitale Simulation) elektrochemisch untersucht. Ein mäßig schneller Transfer eines Elektrons wird von einer sehr schnellen chemischen Reaktion gefolgt (E _q C _irr-Schema). Die elektrochemischen Parameter wurden experimentell und durch Simulations-experimente bestimmt.

     

A Search for Quantitative Acylation of α-Trinositol (1d-myo-Inositol 1,2,6-tris(dihydrogen phosphate) Pentasodium Salt)

Abstract

The acylation of α-trinositol is very sensitive to reaction conditions. Competing condensation reactions may give pyrophosphates and cyclic phosphates. Treatment of a tert-ammonium salt corresponding to α-trinositol with carboxylic acid anhydride and DMAP gives a good yield of the expected esters.     

A new efficient synthesis of oseltamivir phosphate (Tamiflu) from (−)-shikimic acid

New synthesis of oseltamivir phosphate was accomplished in 9 steps with a 27% overall yield from a readily available (?)-shikimic acid. Selective ring opening reaction of ketal and azide Mitsunobu reaction for facile replacement of a hydroxyl group by the N3 group at the C-3 position of (3R,4R,5R)-ethyl 4-hydroxy-5-(methoxymethoxy)-3-(pentan-3-yloxy)cyclohex-1-enecarboxylate 4 and at the C-4 position of (3R,4S,5R)-ethyl 4-acetamido-5-hydroxy-3-(pentan-3-yloxy)cyclohex-1-enecarboxylate 7 successfully served as the key steps.     

Synthesis and characterization of uranium bromide phosphate UBrPO4·2H2O and uranium hydroxide phosphate U(OH)PO4

Uranium chloride phosphate tetrahydrate UClPO₄·4H₂O was obtained by mixing uranium (IV) hydrochloric solution and concentrated phosphoric acid [1]. From crystal structure studies its formula was determined as dihydrate [2]. Using the same method, i.e. starting from uranium (IV) hydrobromic solution and H₃PO₄, two crystal forms of a new compound, uranium bromide phosphate UBrPO₄·2H₂O were synthesized. Their XRD patterns, UV-visible and infrared spectra are presented in this paper. The hydrolysis process of the chloride and bromide phosphates leads to the amorphous uranium hydroxide phosphate U(OH)PO₄·6H₂O.     

Counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) using tris-2-ethyl hexyl phosphate (TEHP)

Evaluation of tris-2-ethyl hexyl phosphate (TEHP) for counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) from nitric acid medium was carried out under wide experimental conditions. Batch extraction studies were carried out to investigate the effect of nitric acid concentration in feed solution, U(VI)/Th(IV) ratio and extractant concentration and the results were compared with established solvent such as tri-n-butyl phosphate (TBP) for separation of U(VI) from nitric acid medium. McCabe–Thiele diagrams for extraction as well as stripping of U(VI) were constructed under simulated conditions. Based on batch experiments, six stage counter-current extraction studies were conducted under various TEHP concentration and it was observed that 0.1 M TEHP/n-paraffin was most suitable for selective recovery of U(VI) from a mixture of U(VI)–Th(IV). An optimized condition, 0.1 M TEHP/n-paraffin, 2 M HNO₃ in feed and six number of stages was evaluated for selective extraction and stripping of U(VI) from a solution containing mixture of U(VI)–Th(IV)–Y(III) in nitric acid medium. The U(VI) in strip solution was precipitated using 30 % H₂O₂ at pH ~3. Average particle size of the final precipitate was found to be ~33 μm.     

Vibrational spectroscopic characterization of the phosphate mineral hureaulite – (Mn,Fe)5(PO4)2(HPO4)2·4(H2O)

This research was done on hureaulite samples from the Cigana claim, a lithium bearing pegmatite with triphylite and spodumene. The mine is located in Conselheiro Pena, east of Minas Gerais. Chemical analysis was carried out by Electron Microprobe analysis and indicated a manganese rich phase with partial substitution of iron. The calculated chemical formula of the studied sample is: (Mn_3.23, Fe_1.04, Ca_0.19, Mg_0.13)(PO₄)_2.7(HPO₄)_2.6(OH)_4.78. The Raman spectrum of hureaulite is dominated by an intense sharp band at 959 cm⁻¹ assigned to PO stretching vibrations of HPO₄²⁻ units. The Raman band at 989 cm⁻¹ is assigned to the PO₄³⁻ stretching vibration. Raman bands at 1007, 1024, 1047, and 1083 cm⁻¹ are attributed to both the HOP and PO antisymmetric stretching vibrations of HPO₄²⁻ and PO₄³⁻ units. A set of Raman bands at 531, 543, 564 and 582 cm⁻¹ are assigned to the ν₄ bending modes of the HPO₄²⁻ and PO₄³⁻ units. Raman bands observed at 414, and 455 cm⁻¹ are attributed to the ν₂ HPO₄²⁻ and PO₄³⁻ units. The intense A series of Raman and infrared bands in the OH stretching region are assigned to water stretching vibrations. Based upon the position of these bands hydrogen bond distances are calculated. Hydrogen bond distances are short indicating very strong hydrogen bonding in the hureaulite structure. A combination of Raman and infrared spectroscopy enabled aspects of the molecular structure of the mineral hureaulite to be understood.     

Incorporation of layered tin(Ⅳ) phosphate in graphene framework for high performance lithium-sulfur batteries

To anchor the polysulfide and enhance the conversion kinetics of polysulfide to disulfide/sulfide is critical for improving the performance of lithium-sulfur battery.For this purpose,the graphene-supported tin(Ⅳ) phosphate(Sn(HPO_4)_2·H_2 O,SnP) composites(SnP-G) are employed as the novel sulfur hosts in this work.When compared to the graphene-sulfur and carbon-sulfur composites,the SnP-G-sulfur composites exhibit much better cycling performance at 1.0 C over 800 cycles.Meanwhile,the pouch cell fabricated with the SnP-G-sulfur cathodes also exhibits excellent performance with an initial capacity of1266.6 mAh g^-1(S) and capacity retention of 76.9% after 100 cycles at 0.1 C.The adsorption tests,density functional theory(DFT) calculations in combination with physical cha racterizations and electrochemical measurements provide insights into the mechanism of capture-accelerated conversion mechanism of polysulfide at the surface of SnP.DFT calculations indicate that the Li-O bond formed between Li atom(from Li_2 S_n,n=1,2,4,6,8) and O atom(from PO_3-OH in SnP) is the main reason for the strong interactions between Li_2 S_n and SnP.As a result,SnP can effectively restrain the shuttle effect and improving the cycling performance of Li-S cell.In addition,by employing the climbing-image nudged elastic band(ciNEB) methods,the energy barrier for lithium sulfide decomposition(charging reaction) on SnP is proved to decrease significantly compared to that on graphene.It can be concluded that SnP is an effective sulfur hosts acting as dual-functional accelerators for the conversion reactions of polysulfude to sulfide(discharging reaction) as well as polysulfide to sulfur(charging reaction).     

Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (α-FeOOH) nanoparticles

Typically, a significant fraction of phosphorus in soils is composed of organic phosphates, and this fraction thus plays an important role in the global phosphorus cycle. Here we have studied adsorption of monomethyl phosphate (MMP) to goethite (α-FeOOH) as a model system in order to better understand the mechanisms behind adsorption of organic phosphates to soil minerals, and how adsorption affects the stability of these molecules. The adsorption reactions and stability of MMP on goethite were studied at room temperature as a function of pH, time and total concentration of MMP by means of quantitative batch experiments, potentiometry and infrared spectroscopy. MMP was found to be stable at the water-goethite interface within the pH region 3-9 and over extended periods of time, as well as in solution. The infrared spectra indicated that MMP formed three predominating pH-dependent surface complexes on goethite, and that these interacted monodentately with surface Fe. The complexes differed in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The presented surface complexation model was based on the collective spectroscopic and macroscopic results, using the Basic Stern approach to describe the interfacial region. The model consisted of three monodentate inner sphere surface complexes where the MMP complexes were stabilized by hydrogen bonding to a neighboring surface site. The three complexes, which had equal proton content and thus could be defined as surface isomers, were distinguished by the distribution of charge over the 0-plane and β-plane. In the high pH-range, MMP acted as a hydrogen bond acceptor whereas it was a hydrogen bond donor at low pH.     

Synthesis of oligo(α-D-glycosyl phosphate) derivatives by a phosphoramidite method via boranophosphate intermediates

An efficient method for the synthesis of short oligo(α-D-glycosyl boranophosphate) derivatives by using an α-D-glycosyl phosphoramidite as a monomer unit was developed. The synthesis of oligomers was carried out by repeating a cycle consisting of the condensation of the monomer unit with a terminal hydroxy group of carbohydrates, boronation of the resultant phosphite intermediates, and terminal deprotection. The phosphoramidite monomer unit was synthesized from the corresponding glycosyl iodide and methyl N,N-diisopropylphosphonamidate in a highly α-selective manner. Di- and tri(α-D-glycosyl boranophosphate) derivatives obtained by the synthetic cycle were converted into the corresponding H-phosphonate diester derivatives, which were then used to synthesize di- and tri(α-D-glycosyl phosphate) derivatives including a fragment of Leishmania glycocalyx lipophosphoglycans.     

Quantitative extraction of uranium(VI) in aqueous solutions with n-alkylamine intercalates of γ-titanium phosphate

The intercalation compounds Ti(C₃H₇NH₂)(HPO₄)₂·H₂O (18.4 Å) (-TiP/n-Pr) and Ti(C₄H₉NH₂)(HPO₄)₂·H₂O (20.5 Å) (-TiP/n-Bu) have been prepared using -titanium phosphate, Ti(HPO₄)₂·2H₂O (11.6 Å), as precursor. The retention of UO ₂ ²⁺ , in aqueous solutions by -TiP is very low being only a superficial adsorption phenomenon. When the intercalated materials are used, the retention is quantitative until 95% of the cation exchange capacity in the -TiP/n-Pr case (c.e.c.=6.30 mequiv./g), and over 80% for the -TiP/n-Bu compound (c.e.c.=6.04 mequiv./g).     

Kinetic study of decomposition for Co(II)- and Ni(II)-1,10-phenanthroline complexes intercalated in γ-zirconium phosphate

The thermal behaviour of the complexes formed in situ between the aromatic diamine 1,10-phenanthroline and the Co(II) and Ni(II) ions intercalated between the layers of γ-zirconium phosphate was studied by simultaneous TG/DSC techniques. The obtained materials show similar thermal behaviour: after a multi-step dehydration process they showed an oxidative decomposition in only one step. The kinetic study of the decomposition process was performed using both the model-free methods of Ozawa-Flynn-Wall and Kissinger. The former method provides a negligible dependence of activation energy on the degree of reaction α for both materials. Activation energies derived by the Kissinger method show a good agreement with the mean values derived by the Ozawa-Flynn-Wall method. The Arrhenius rate constants determined using also the pre-exponential factor values demonstrate that their thermal stability can be considered comparable, within the experimental uncertainty. Finally, a reliable method was applied to determine the model function from the best fit between the numerical dependence of the integral function g(α) vs. α and several theoretical model dependencies reported in literature for the most commonly used models. A Mampel first-order reaction model was selected to describe the thermal decomposition in both the materials studied.     

Self-assembly of porous two-dimensional copper(II) α, β-unsaturated carboxylate complexes with trimethyl phosphate

A new type of two-dimensional network was found in the hydrogen-bonded molecular assemblies of copper(II) α,β-unsaturated carboxylate complexes with TMP [OP(OMe)₃], {Cu₂A₄(H₂O)₂[OP(OMe)₃]} _n [(1) A = CH₂=CHCO₂ ⁻; (2) A = CH₂=C(Me)CO₂ ⁻]. The crystal structure of (1) has been determined by single-crystal X-ray diffraction. Both complexes are unique in terms of a sheet structure brought about by O—H ⋯ O hydrogen-bonded interactions both between neighbouring Cu₂A₄(H₂O)₂ units and between Cu₂A₄(H₂O)₂ and OP(OMe)₃ molecules. The electronic reflectance spectra in the solid state suggest a square pyramidal coordination environment around the copper(II) atom. Room temperature X-band e.s.r. spectra of powered samples and variable-temperature magnetic susceptibility studies indicate the presence of strong antiferromagnetic exchange interactions between two copper(II) atoms, with 2J = −310 cm⁻¹ for (1) and 2J = −304 cm⁻¹ for (2) respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and phase formation in M 0.5(1+x) 2+ FexTi2−x (PO4)3 phosphate series

New complex phosphates of titanium, iron, and alkaline-earth metals have been synthesized. X-ray powder diffraction, differential thermal analysis (DTA), and IR spectroscopy are used to study phase formation in the series of M_0.5(1+x)Fe_xTi_2?x (PO₄)₃ (M = Mg, Ca, Sr, Ba) phosphates. Individual compounds and solid solutions are found to crystallize in the NaZr₂(PO₄)₃ and K₂Mg₂(SO₄)₃ structure types. Their crystal parameters are calculated. CaFeTi(PO₄)₃ is studied using Mössbauer spectroscopy. Its structure is refined by the Rietveld method: space group $R\bar 3$ c, Z = 6, a = 8.5172(1), Å, c = 21.7739(4) Å, V = 1367.91(4) ų.     

Vibrational spectroscopic characterization of the phosphate mineral series eosphorite–childrenite–(Mn,Fe)Al(PO4)(OH)2·(H2O)

The phosphate mineral series eosphorite–childrenite–(Mn,Fe)Al(PO₄)(OH)₂·(H₂O) has been studied using a combination of electron probe analysis and vibrational spectroscopy. Eosphorite is the manganese rich mineral with lower iron content in comparison with the childrenite which has higher iron and lower manganese content. The determined formulae of the two studied minerals are: (Mn_0.72,Fe_0.13,Ca_0.01)(Al)_1.04(PO₄, OHPO₃)_1.07(OH_1.89,F_0.02)·0.94(H₂O) for SAA-090 and (Fe_0.49,Mn_0.35,Mg_0.06,Ca_0.04)(Al)_1.03(PO₄, OHPO₃)_1.05(OH)_1.90·0.95(H₂O) for SAA-072. Raman spectroscopy enabled the observation of bands at 970 cm⁻¹ and 1011 cm⁻¹ assigned to monohydrogen phosphate, phosphate and dihydrogen phosphate units. Differences are observed in the area of the peaks between the two eosphorite minerals. Raman bands at 562 cm⁻¹, 595 cm⁻¹, and 608 cm⁻¹ are assigned to the ν₄ bending modes of the PO₄, HPO₄ and H₂PO₄ units; Raman bands at 405 cm⁻¹, 427 cm⁻¹ and 466 cm⁻¹ are attributed to the ν₂ modes of these units. Raman bands of the hydroxyl and water stretching modes are observed. Vibrational spectroscopy enabled details of the molecular structure of the eosphorite mineral series to be determined.     

Thermal decomposition characteristics of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide-tri n-butyl phosphate–nitric acid systems

Thermal stability of neat octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (OΦD[IB]CMPO) and TRUEX solvent composition (0.2M OΦD[IB]CMPO-1.2M tri n-butyl phosphate-in n-dodecane) in the presence and absence of nitric acid has been studied in ambient air in a closed vessel, employing an adiabatic calorimeter. Enthalpies and kinetic parameters for the decomposition reaction were derived wherever possible and are reported for the first time. Neat OΦD[IB]CMPO was found to be thermally stable up to 633 K and exhibited an exothermic decomposition later. It decomposed at lower temperatures (376–386 K) depending on the nitric acid concentration. The exothermic rise in temperature and pressure increased exponentially, while activation energies exhibited exponential decrease for the decomposition reactions with increase in nitric acid content. TRUEX solvent was found to be stable up to 661 K in the absence of nitric acid while in the presence of 8 and 4M HNO₃, it decomposed between 387 and 413 K. All these samples on decomposition formed incompressible gases and viscous black liquids. The results also indicate that the neat OΦD[IB]CMPO and the TRUEX solvent are thermally more stable than neat tri n-butyl phosphate (TBP), PUREX solvent (1.1M TBP/n-DD), neat diamyl amyl phosphonate (DAAP) and 1.1M DAAP/n-DD, triisoamyl phosphate (TiAP) and 1.1M TiAP/n-DD.     

Gas–condensed phase flame-retardant mechanisms of tris(3-nitrophenyl) phosphine/triphenyl phosphate/ABS

Journal of Thermal Analysis and Calorimetry - Tris(3-nitrophenyl) phosphine (NPPh3), a flame retardant containing phosphorus and nitro group, is synthesized. And a novel flame retardant loading...     

Interaction of metal ions with poly(1,3-propylene phosphate) — a synthetic analogue of natural teichoic acids

The binding of metal ions to poly(1,3-propylene phosphate), (PPP), which can be considered as a synthetic analogue of natural teichoic acids, was examined. Infrared spectra of PPP in different ionic forms and of different degrees of polymerization were analyzed and some information on metal ion binding modes in M(I)-PPP and M(II)-PPP complexes, both in the condensed state as well as in aqueous solution, was obtained. It is concluded that the binding modes of sodium, potassium, cesium, calcium, and magnesium ions to phosphate groups of PPP are the same or similar and/or complexes of the same or similar structure are formed. In aqueous solution the analyzed metal ions are bound to poly(alkylene phosphate) chains mainly in the form of outer sphere complexes.