Methylphosphonic Acid Research Articles

Environmental remediation of Pb–Cd contaminated soil with organic phosphonic acids-saponin: Conditions, effectiveness, ecological risk and recovery

Soil washing is a rapid and efficient method for heavy metals removal. In this study, a kind of novel environmentally friendly eluent is proposed, consisting of ethylenediamine tetra methylene phosphonic acid and saponin (E-S). In a response surface optimization design (RSOD), the operating parameters were optimized and ecological effects were investigated. Additionally, soil microbial diversity and composition were discussed. Finally, an optimal method for chelator recovery was presented. The single-factor and RSOD results showed that E-S had higher remediation efficiency for Pb–Cd contaminated soil with the best parameters of duration 240 min, temperature 40 °C, E/S ratio 1:1. Under these operating conditions, the removal rates of Pb and Cd were (72.2 ± 0.5)% and (61.2 ± 0.4)% for the artificially contaminated soil and (69.2 ± 0.1)% and (65.2 ± 0.2)% for in situ contaminated soil, respectively. The contents of Pb and Cd decreased from 562.36 mg/kg to 180.41 mg/kg and 80.96 mg/kg to 27.2 mg/kg respectively, and the soil ecological risk indexes reduced from 32% to 24% for Pb and 36%–27% for Cd. Owing to the efficient enrichment of Stenotrophomonas in soil, E-S has a potential of simultaneous removal effect on organic pollutants as well. Furthermore, the results revealed that E-S can be effectively recovered (>95%) by sodium sulfide precipitation.

Fluorescent-Tagged Antiscalants-The New Materials for Scale Inhibition Mechanism Studies, Antiscalant Traceability and Antiscaling Efficacy Optimization during CaCO3 and CaSO4·2H2O Scale Formation.

Equipment scaling leads to reduced production efficiency in a wide range of industrial applications worldwide. Various antiscaling agents are currently commonly used to mitigate this problem. However, irrespective of their long and successful application in water treatment technologies, little is known about the mechanisms of scale inhibition, particularly the localization of scale inhibitors on scale deposits. The lack of such knowledge is a limiting factor in the development of applications for antiscalants. Meanwhile, fluorescent fragments integrated into scale inhibitor molecules have provided a successful solution to the problem. The focus of this study is, therefore, on the synthesis and investigation of a novel fluorescent antiscalant: (2-(6-morpholino-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)yl)ethylazanediyl)bis(methylenephosphonic acid) (ADMP-F) which is an analog of the commercial antiscalant: aminotris(methylenephosphonic acid) (ATMP). ADMP-F has been found to effectively control the precipitation of CaCO3 and CaSO4 in solution and is a promising tracer for organophosphonate scale inhibitors. ADMP-F was compared with two other fluorescent antiscalants-polyacrylate (PAA-F1) and bisphosphonate (HEDP-F)-and was found to be highly effective: PAA-F1 > ADMP-F >> HEDP-F (CaCO3) and PAA-F1 > ADMP-F > HEDP-F (CaSO4·2H2O). The visualization of the antiscalants on the deposits provides unique information on their location and reveals differences in the "antiscalant-deposit" interactions for scale inhibitors of different natures. For these reasons, a number of important refinements to the mechanisms of scale inhibition are proposed.

Interaction between [(η6-p-cym)M(H2O)3]2+ (MII = Ru, Os) or [(η5-Cp*)M(H2O)3]2+ (MIII = Rh, Ir) and Phosphonate Derivatives of Iminodiacetic Acid: A Solution Equilibrium and DFT Study.

The pH-dependent binding strengths and modes of the organometallic [(η6-p-cym)M(H2O)3]2+ (MII = Ru, Os; p-cym = 1-methyl-4-isopropylbenzene) or [(η5-Cp*)M(H2O)3]2+ (MIII = Rh, Ir; Cp* = pentamethylcyclopentadienyl anion) cations towards iminodiacetic acid (H2Ida) and its biorelevant mono- and diphosphonate derivatives N-(phosphonomethyl)-glycine (H3IdaP) and iminodi(methylphosphonic acid) (H4Ida2P) was studied in an aqueous solution. The results showed that all three of the ligands form 1:1 complexes via the tridentate (O,N,O) donor set, for which the binding mode was further corroborated by the DFT method. Although with IdaP3- and Ida2P4- in mono- and bis-protonated species, where H+ might also be located at the non-coordinating N atom, the theoretical calculations revealed the protonation of the phosphonate group(s) and the tridentate coordination of the phosphonate ligands. The replacement of one carboxylate in Ida2- by a phosphonate group (IdaP3-) resulted in a significant increase in the stability of the metal complexes; however, this increase vanished with Ida2P4-, which was most likely due to some steric hindrance upon the coordination of the second large phosphonate group to form (5 + 5) joined chelates. In the phosphonate-containing systems, the neutral 1:1 complexes are the major species at pH 7.4 in the millimolar concentration range that is supported by both NMR and ESI-TOF-MS.

Impact of the Chelate Complex of Nitrilotris(methylenephosphonic Acid) with Copper on the Corrosion-Electrochemical Behavior of Carbon Steel in an Aqueous Medium

Impact of the Chelate Complex of Nitrilotris(methylenephosphonic Acid) with Copper on the Corrosion-Electrochemical Behavior of Carbon Steel in an Aqueous Medium

Investigating the potential of hydroxyethylamino-di(methylene phosphonic acid) in inhibiting gypsum crystallization

HEMPA has the potential to mitigate gypsum scaling through chelation with Ca2+ in solution and adsorption onto and incorporation into the crystals.

Enhanced Carbonate Scale Inhibition in the North Sea via Synergistic Inhibitor Molecule Blends

_ Controlling inorganic sulphate and carbonate scales with polymer, phosphonate, and phosphate ester scale inhibitors is commonplace in the oilfield services industry. It is well understood in what environments induvial inhibitor types work best; for example, sulphonates are very effective for sulphate scale control in low temperatures (SPE 80229) whereas phosphonates are much less effective under these same conditions but improve at higher temperatures (SPE 179889). Less well understood is the potential for scale inhibitors utilizing synergistic interactions with blends of polymers, phosphonates, and phosphate esters to reduce chemical cost, treatment rates, and transport logistics, resulting in a more effective scale management program with a reduced operational footprint. To evaluate performance of a selected range of blended inhibitors, ChampionX performed a trial on a North Sea produced water system, which was applying monoethanolamine (MEA) phosphonate-type scale inhibitor as well as novel cleaning programs to counter a high carbonate saturation ratio in the heater (SPE 204365). The objective was to find an improved scale inhibitor formulation that would outperform MEA phosphonate to control the high calcite saturation ratio brine. In this application, produced fluids pass through a heater with a skin temperature between 90°C and 105°C. Identifying the Scale Challenge Studies of synergistic properties of phosphonates and polymer scale inhibitors show there is potential to create blends of existing chemicals to make a formulation that shows a performance greater than either inhibitor component on its own. Four generic scale inhibitors that could effectively prevent scale at 105°C were considered. 1. A poly aspartate acid, generally found to be thermally stable to 120°C 2. The incumbent MEA phosphonate chemical, which is widely used for this type of scale inhibition at elevated temperature 3. A phosphate ester, found to be thermally stable at temperatures of 90°C 4. Phosphonate-functionalized biopolymer, which showed good carbonate inhibition properties and excellent environmental properties The goal was to develop a synergistic blend that would mitigate the legislative (cost of REACH registration) and economic (cost of new raw material product set up within the supply chain system) issues associated with the development of new classes of scale inhibitor for a relatively small market. There are two primary methods of scale inhibition in produced water. The first is crystal nucleation inhibition, which prevents the onset of scale formation itself by keeping the ions in solution. This mechanism of inhibition is best evaluated via dynamic scale loop (DSL) tests. The polymer-type scale inhibitors (such as carboxylic acid functionated homo and copolymers, for example VS-Co) work well within this test, as they prevent deposition at low treatment rate. The other principal inhibition mechanism is crystal-growth inhibition. This prevents the continued growth of microscale crystals as the inhibitor interacts with the scale crystal surface to prevent further addition of sulphate/barium ions. This is best evaluated via static bottle tests. Phosphonate-type scale inhibitors, for example, diethylenetriamine penta (methylene phosphonic acid), work well within this type of test.

Расчёт фармакокинетических и дозиметрических характеристик Lu-177-ЭДТМФ – потенциального препарата для радионуклидной терапии костных метастазов

Phosphonic acids labeled with beta-emitting radionuclides are promising radiopharmaceutical drugs for palliative therapy of bone metastases. Currently, the possibility of using a new osteotropic compound N,N,N’,N’-ethylenediaminetetrakis (methylene phosphonic acid) with lutetium-177 (177Lu-EDTMP) is being studied. The aim of the work is to develop a compartment mathematical model of the kinetics of 177Lu labeled osteotropic radiopharmaceutical drugs in the body of laboratory animals and calculate their pharmacokinetic and dosimetric characteristics based on it. To assess the stability of 177Lu-EDTMP in vivo, the characteristics of the distribution of free lutetium in the form of 177LuCl3 were also studied. To identify the model parameters and calculate the characteristics of radiopharmaceutical drugs, quantitative data on the bio-distribution of 177Lu-EDTMP and 177LuCl3 in the body of intact Wistar rats were used. A compartment model of kinetics has been developed and two approaches to the identification of its transport constants have been proposed – through the residual functional and using approximation by monoexponential functions. According to pharmacokinetic modeling, it was found that 177Lu-EDTMP is deposited in bone tissues (up to 55% of the administered dose). The calculated value of the apparent volume of distribution of 177Lu-EDTMP is approximately 200 times greater than the volume of blood plasma, the values of biological half-lives from bone tissues are 10-20 times higher than from internal organs. The excretion of 177Lu-EDTMP from the body occurs mainly through renal clearance. Comparative modeling with 177LuCl3 revealed high resistance of 177Lu-EDTMP in vivo. The highest values of absorbed doses are formed in the skeleton and kidneys with minimal radiation load on other internal organs and blood. The results obtained indicate the prospects for further studies of 177Lu-EDTMP and the possibility of its clinical application for the treatment of skeletal metastases.

Quantum Label of Organic Acid Ligands-Determined CsPbBr3 Perovskite Magic-Sized Clusters

A strategy for synthesizing stable, pure, and excellent luminescent perovskite magic-sized clusters (PMSCs) by optimizing ligands is proposed. The optimal ligand pair was selected from methylphosphonic acid (MPA), valeric acid (VA), and butanesulfonic acid (BA) ligands in conjunction with ethylenediamine (EDA), respectively. Through ligand-assisted reprecipitation (LAPR) method, MPA–EDA CsPbBr3 PMSCs with high photoluminescence quantum yield (PLQY) of up to [Formula: see text]72% and excellent stability were optimized. By the density of states (DOS) analysis, the differences in luminescence properties were explored to originate from Pb(6s)–Br(4p) hybridization, and the hypothesis of constructing quantum maps of functional materials based on valence electron orbital hybridization was proposed. The above results provide a reliable experimental and theoretical direction for the future application of quantum label PMSCs in the field of optoelectronic devices.

Toxic effects and bioaccumulation of pinacolyl methylphosphonate acid in zebrafish following soman exposure to a water environment.

Soman has been shown to be highly neurotoxic and can be easily degraded to produce pinacolyl methylphosphonate acid (PMPA). Thus, the perniciousness of PMPA deserved serious attention after soman was exposed to the environment. However, the toxicity of PMPA was not clearly elucidated to date. In this regard, the objective of this study was to determine if PMPA could pose an environmental risk after soman exposure to a water environment. In this study, the toxicity and bioaccumulation assessments of PMPA were carried out on zebrafish. Histological examination was used to assess the toxicity of PMPA in zebrafish and revealed that PMPA has chronic toxicity in view of tissue injury. The contents of PMPA in whole zebrafish and tissues were determined after soman exposure. The result showed that PMPA bioaccumulated in the whole zebrafish and tissue, especially the liver and intestinal tissues. This is the first report showing that the hydrolyzate of a G-series chemical nerve agent could accumulate in organisms. This study offers novel insights into the environmental risk assessments associated with soman exposure to a water environment.

PH and Salt-Assisted Macroscopic Chirality Inversion of Gadolinium Coordination Polymer.

The precise adjustment of handedness of helical architectures is important to regulate their functions. Macroscopic chirality inversion has been achieved in organic supramolecular systems by pH, metal ions, solvents, chiral and non-chiral additives, temperature, and light, but rarely in coordination polymers (CPs). In particular, salt-assisted macroscopic chirality inversion has not been reported. In this work, we carried out a systematic investigation on the role of pH and salt in regulating the morphology of CPs based on Gd(NO3)3 and R-(1-phenylethylamino)methylphosphonic acid (R-pempH2). Without extra NO3-, the chirality inversion from the left-handed superhelix R-M to the right-handed superhelix R-P can be achieved by pH modulation from 3.2 to 3.8. The addition of NaNO3 (2.0 eq) at pH 3.8 results in an inversion of chiral sense from R-P to R-M as a pure phase. To our knowledge, this is the first example of salt-assisted macroscopic helical inversion in artificial systems.

Experimental Study of the Adsorption and Decomposition of Sarin on Dry Copper(II) Oxide.

Organophosphonates were originally developed as insecticides but were quickly identified as highly toxic acetylcholinesterase inhibitors, leading to their exploitation as chemical warfare agents (CWA). To develop next generation filtration technologies, there must be a fundamental understanding of the molecular interactions occurring with toxic chemicals, such as CWAs. In this paper, we investigate the interaction between dry CuO nanoparticles and sarin (GB), using infrared (IR) spectroscopy in an effort to build an atomic understanding. We show sarin strongly interacts with CuO and then quickly degrades, primarily through the cleavage of the P-F bond, creating a bridging species on the CuO surface with the assistance of lattice oxygen. Upon heating, the decomposition product isopropyl methyl phosphonic acid (IMPA) does not continue to decompose but desorbs from the surface. These observations are further elaborated through theoretical models of sarin on dry CuO (111).

Benzyl trichloroacetimidates as derivatizing agents for phosphonic acids related to nerve agents by EI-GC-MS during OPCW proficiency test scenarios.

The use of benzyl trichloroacetimidates for the benzylation of phosphonic acid nerve agent markers under neutral, basic, and slightly acidic conditions is presented. The benzyl-derived phosphonic acids were detected and analyzed by Electron Ionization Gas Chromatography-Mass Spectrometry (EI-GC-MS). The phosphonic acids used in this work included ethyl-, cyclohexyl- and pinacolyl methylphosphonic acid, first pass hydrolysis products from the nerve agents ethylN-2-diisopropylaminoethyl methylphosphonothiolate (VX), cyclosarin (GF) and soman (GD) respectively. Optimization of reaction parameters for the benzylation included reaction time and solvent, temperature and the effect of the absence or presence of catalytic acid. The optimized conditions for the derivatization of the phosphonic acids specifically for their benzylation, included neutral as well as catalytic acid (< 5mol%) and benzyl 2,2,2-trichloroacetimidate in excess coupled to heating the mixture to 60°C in acetonitrile for 4h. While the neutral conditions for the method proved to be efficient for the preparation of the p-methoxybenzyl esters of the phosphonic acids, the acid-catalyzed process appeared to provide much lower yields of the products relative to its benzyl counterpart. The method's efficiency was tested in the successful derivatization and identification of pinacolyl methylphosphonic acid (PMPA) as its benzyl ester when present at a concentration of ~ 5μg/g in a soil matrix featured in the Organisation for the Prohibition of Chemical Weapons (OPCW) 44th proficiency test (PT). Additionally, the protocol was used in the detection and identification of PMPA when spiked at ~ 10μg/mL concentration in a fatty acid-rich liquid matrix featured during the 38th OPCW-PT. The benzyl derivative of PMPA was partially corroborated with the instrument's internal NIST spectral library and the OPCW central analytical database (OCAD v.21_2019) but unambiguously identified through comparison with a synthesized authentic standard. The method's MDL (LOD) values for the benzyl and the p-methoxybenzyl pinacolyl methylphosphonic acids were determined to be 35 and 63ng/mL respectively, while the method's Limit of Quantitation (LOQ) was determined to be 104 and 189ng/mL respectively in the OPCW-PT soil matrix evaluated.

Dual-technique assay for the analysis of organophosphorus compounds for environmental and chemical defense applications

Forensic and environmental sciences often rely on chromatographic separations coupled to mass spectrometry to detect contaminants in complex matrices. However, these methods require lengthy analysis times and sample preparation that is not suitable for analysis in the field. In this work, two analytical methods were combined that are known for their potential for portable analysis. The ambient ionization technique, paper spray mass spectrometry (paper spray-MS) was coupled to paper-based surface enhanced Raman spectroscopy (pSERS) to detect toxic organophosphorus molecules from the same substrate, with a total analysis time of less than five minutes. The coupling of these techniques presents a potential for portable Raman screening followed by MS confirmation in a field-forward laboratory. A cartridge insert was designed and 3D printed to facilitate the sample collection and analysis for PS-MS and pSERS. Three chemical warfare agent simulants: dimethyl methylphosphonate (DMMP), diethyl phosphoramidate (DEPA), and diisopropyl methylphosphonate (DIMP) were included in the method due to having similar chemistries to G- and V-series chemical warfare agents (CWAs). Organophosphorus pesticides, malathion and dichlorvos, with similar mechanisms of action to the CWAs, were also included in the method. Because CWAs quickly degrade in the environment, the CWA hydrolysis products, ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PinMPA), methylphosphonic acid (MPA), 2-Diethylaminoethanethiol (EDA), and 2-Diisopropylaminoethanethiol (IDA) were also studied. A mixture of the analytes was used to create calibration curves using the dual-polarity, PS-MS method with sub-ng to low ng limits of detection. A dilution series, spanning 3 orders of magnitude, was made using pSERS, also with low ng limits of detection. These experiments show the potential and feasibility for PS-MS coupled to pSERS to be used to rapidly, screen and confirm the presence of organophosphorus molecules, in complex matrices, with portable instrumentation.

Porous Proton Exchange Membrane with High Stability and Low Hydrogen Permeability Realized by Dense Double Skin Layers Constructed with Amino tris (methylene phosphonic acid)

AbstractPorous proton exchange membranes (PEMs) with abundant porous structures show enhanced phosphoric acid (PA) doping levels and proton transport capability. However, the high PA loss rate and serious hydrogen cross‐over lead to poor membrane stability. Enhancing the stability of PA‐doped porous PEMs is therefore crucial for obtaining high‐performance proton exchange membrane fuel cells. Herein, a porous polybenzimidazole membrane with dense double skin layers is reported using amino tris (methylene phosphonic acid) (ATMP) constructed. This membrane effectively alleviates hydrogen permeation and PA loss in a water/anhydrous environment and exhibits enhanced stability. Surprisingly, as an organic proton conductor, ATMP has strong hydrogen bonding with PA, leading to the formation of more continuous proton transport channels. Due to the dense double skin layers protection and the synergistic mass transfer of ATMP and PA, the porous membrane shows excellent proton conductivity (0.112 S cm−1) and a H2‐O2 fuel cell peak power density of 0.98 W cm−2 at 160 °C. Moreover, it presents excellent fuel cell stability, with a voltage decay rate of only 5.46 µV h−1. In addition, the porous membrane surpasses the traditional working temperature range, operating in the range of 80–220 °C. This study provides new insight into developing high‐performance porous PEMs.

Reactive Flame-Retardant Cotton Fabric Coating: Combustion Behavior, Durability, and Enhanced Retardant Mechanism with Ion Transfer.

In recent years, we have witnessed numerous indoor fires caused by the flammable properties of cotton. Flame-retardant cotton deserves our attention. A novel boric acid and diethylenetriaminepenta (methylene-phosphonic acid) (DTPMPA) ammonium salt-based chelating coordination flame retardant (BDA) was successfully prepared for cotton fabrics, and a related retardant mechanism with ion transfer was investigated. BDA can form a stable chemical and coordination bond on the surface of cotton fibers by a simple three-curing finishing process. The limiting oxygen index (LOI) value of BDA-90 increased to 36.1%, and the LOI value of cotton fabric became 30.3% after 50 laundering cycles (LCs) and exhibited excellent durable flame retardancy. Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) methods were used to observe the bonding mode and morphology of BDA on cotton fibers. A synergistic flame-retardant mechanism of condensed and gas phases was concluded from thermogravimetry (TG), cone calorimeter tests, and TG-FTIR. The test results of whiteness and tensile strength showed that the physical properties of BDA-treated cotton fabric were well maintained.

Low-Temperature Thermal Formation of the Cyclic Methylphosphonic Acid Trimer [c-(CH3 PO2 )3

We report the formation of the cyclic methylphosphonic acid trimer [c-(CH3 PO2 )3 ] through condensation reactions during thermal processing of low-temperature methylphosphonic acid samples exploiting photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) along with electronic structure calculations. Cyclic methylphosphonic acid trimers are formed in the solid state and detected together with its protonated species in the gas phase upon single photon ionization. Our studies provide an understanding of the preparation of phosphorus-bearing potentially prebiotic molecules and the fundamental knowledge of low-temperature phosphorus chemistry in extraterrestrial environments.

Experimental study of the low salinity water injection process in the presence of scale inhibitor and various nanoparticles

In this work, the process of low salinity water injection (LSWI) into reservoirs at various salt concentrations was simulated in order to study the change in the oil recovery factor during oil production. The simulation results of the recovery factor were compared with the experimental data. The results demonstrated that the simulation data were in good agreement with the experimental results. In addition, the formation damage (rock permeability reduction) in carbonate core samples was evaluated through coreflood experiments during LSWI in the range of salt concentration and temperature of 1500–4000 ppm and 25–100 °C, respectively. In the worst scenario of LSWI, the rock permeability has reached about 83% of the initial value. Our previous correlation was used to predict the formation damage in LSWI. In this case, the R-squared value between predicted and experimental data of rock permeability ratios was more than 0.97. Furthermore, the recovery factor during LSWI was analyzed with and without the use of DTPMP scale inhibitor (diethylenetriamine penta (methylene phosphonic acid)), and various nanoparticles (TiO2, SiO2, Al2O3). The results of the coreflood experiments showed that the use of scale inhibitor provides an increase in the recovery factor by more than 8%. In addition, the highest recovery factor was observed in the presence of SiO2 nanoparticles at 0.05 wt.%. The oil displacement during LSWI in the porous media with SiO2 particles was better than TiO2 and Al2O3. The recovery factor in the presence of SiO2, TiO2, and Al2O3 with DTPMP was 72.2, 62.4, and 59.8%, respectively. Among the studied nanoparticles, the lowest values of the oil viscosity and interfacial tension (IFT) between oil and water were observed when using SiO2. Moreover, the contact angle was increased by increasing the brine concentration. The contact angle with the use of SiO2, TiO2, and Al2O3 at 0.05 wt.% was reduced by 11.2, 10.6, and 9.9%, respectively.

Monitoring of hydrolysis products of organophosphorus nerve agents in plant material and soil by liquid chromatography-tandem mass spectrometry

Nerve agents are organophosphorus compounds of the highest toxicity and danger. The production, transportation and use of these substances are prohibited by the Organization for the Prohibition of Chemical Weapons. Any fact of alleged use of nerve agents is a crime against humanity and must be investigated in detail by the world community. For this purpose, such analysis objects as biological fluids (urine, blood) and environmental objects (water, soil) are well studied. The current study demonstrates the possibility of using plants as a convenient material for retrospective analysis. Methyl phosphonic acid and some of its alkyl esters (ethyl, isopropyl, isobutyl, cyclohexyl, pinacolyl) were chosen as nerve agent metabolites. Hedera Helix growing in soil was used as a carrier of the markers. The selected markers were injected once in the soil and their content in the plant and soil was monitored for 4 weeks. A fast and simple way of sample homogenization with liquid nitrogen followed by ultrasonic liquid extraction was applied. The developed HPLC-MS/MS approach with the use of deuterated internal standards for quantitative analysis was validated. The research discovered that all the studied nerve agent markers could be detected and determined both in the soil and the plant for at least one month. The results indicate the promising use of plants as additional objects of analysis in investigation of incidents involving the use of chemical warfare agents.

DOTP versus DOTA as Ligands for Lanthanide Cations: Novel Structurally Characterized CeIV and CeIII Cyclen-Based Complexes and Clusters in Aqueous Solutions.

The coordination and redox chemistry of aqueous CeIV/III macrocyclic compounds were studied by using the ligands DOTA and DOTP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid), respectively). The hydrolysis tendency of the tetravalent cation in the presence of DOTA is shown to result in the formation of a highly ordered, fluorite-like [CeIV 6 (O)4 (OH)4 (H2 O)8 (DOTAH)4 ] oxo-hydroxo structure both in solution and in the solid state. The lifetime of the analogous species formed in the presence of DOTP was found to be much shorter. Spectroscopic measurements of the latter suggest its similarity to the former. Its gradual decomposition in solution leads to the accumulation of the in-cage complexes [CeIV DOTP] and [CeIII DOTP(H2 O)], which were crystallographically characterized in this study. The redox energetics and spectroscopic characteristics for the transition between these two in-cage complexes in aqueous solutions were studied as well. Together with the crystallographic structures of the above-mentioned species, the in-cage [CeIV DOTA(H2 O)] complex structure is presented herein for the first time. An elaborative analysis of the X-ray crystallographic structural data obtained for the in-cage complexes studied herein and similar structures published previously suggests that hard-bonding cyclen-derived ligands are, counter-intuitively, better suited for encapsulating, and perhaps kinetically stabilize softer cations than harder ones with DOTP, marked as a possible adequate chelator for the study of the aqueous properties of LnII and AcIII cations.

Methylphosphonic Acid Detection using DNA Aptamer-Citrate Capped Gold Nanoparticles Enhanced by Digital Image Analysis

Methylphosphonic Acid Detection using DNA Aptamer-Citrate Capped Gold Nanoparticles Enhanced by Digital Image Analysis