Phosphonate Chemistry Research Articles

Recent Synthesis of Nucleoside Phosphonate Analogs Using Olefin Cross-metathesis.

Nucleotide analogs known as acyclic and cyclic nucleoside phosphonates (ANPs and CNPs, respectively) have a variety of biological properties, including antibacterial, antiviral, antiparasitic, antineoplastic, and immunomodulatory. A strong reaction that has emerged in the last several decades has fundamentally changed our knowledge of the chemistry of nucleoside phosphonates. In particular, Olefin cross-metathesis (CM) has been a potent and practical synthesis route to produce functionalized olefins from essential alkene precursors. This review describes recent synthesis examples of ANPs and CNPs analogs using the Ru-catalyzed olefin cross-metathesis reactions. Olefin cross-metathesis reactions are performed in the olefinic parts of nucleoside and phosphonate produced by Grubbs, Hoveyda-Grubbs, and Nolan. This review presents a synthetic overview of a few chosen nucleosides with biological significance. Their biological activity results are briefly discussed.

Reticular chemistry of uranyl phosphonates: synthesis, design, and beyond

The successful design strategy put reticular chemistry in uranyl phosphonate frameworks, which integrate multifunction to corresponding applications.

Chemistry of difluoromethylene phosphonates: history, state of the art, and prospects

Difluoromethylene phosphonates are non-hydrolyzable bioisosteres of phosphates. They have proven their efficiency as inhibitors of the enzymes that specialize in utilizing these essential biogenic molecules. Difluoromethylene phosphonates show a broad spectrum of biological activity and are used as molecular tools to study enzymes and enzyme-substrate interactions. In this review, we briefly summarize the importance of difluoromethylene phosphonates as a distinct class of synthetic phosphonates resulting from multidisciplinary efforts of the organophosphorus, organofluorine, and bioorganic research communities. We outline the development of the synthetic chemistry of difluoromethylene phosphonates from the historical perspective, discuss the most recent trends in the field, and highlight the existing challenges and unsolved questions

Surface NMR using quantum sensors in diamond

NMR is a noninvasive, molecular-level spectroscopic technique widely used for chemical characterization. However, it lacks the sensitivity to probe the small number of spins at surfaces and interfaces. Here, we use nitrogen vacancy (NV) centers in diamond as quantum sensors to optically detect NMR signals from chemically modified thin films. To demonstrate the method's capabilities, aluminum oxide layers, common supports in catalysis and materials science, are prepared by atomic layer deposition and are subsequently functionalized by phosphonate chemistry to form self-assembled monolayers. The surface NV-NMR technique detects spatially resolved NMR signals from the monolayer, indicates chemical binding, and quantifies molecular coverage. In addition, it can monitor in real time the formation kinetics at the solid-liquid interface. With our approach, we show that NV quantum sensors are a surface-sensitive NMR tool with femtomole sensitivity for in situ analysis in catalysis, materials, and biological research.

Melanogenesis inhibition effect of ethanolic Andrographis paniculata leaf extract via suppression of tyrosinase and MITF expression

Synthesis of dialkylaminoaryl phosphonate bioisosteres of tyrosine and tyramine: a novel application of allene phosphonate chemistry for the synthesis of false substrates of tyrosinaseDean Mazzuca, Christo Angelov, Leonard I Wiebe

Novel Scale Inhibitor Extends Treatment Lifetimes in Permian EOR

Background A new extended-release (ER) scale-inhibitor technology showing significantly increased lifetimes has been applied in the Permian Basin. Tomson Technologies and Group 2 Technologies, in partnership with Occidental Petroleum (Oxy), implemented a scale-squeeze program for this carrier system. It allows for fewer squeeze treatments, which results in lower chemical usage, decreased plugging risk, and reduced environmental impact. Squeeze programs are an effective field treatment strategy to prevent scale formation in wells for extended periods of time. However, in some cases, squeeze lifetimes can be short, leading to frequent re-squeezing and production decreases, lowering overall economic recoveries. The ER phosphonate-based chemistry (SI1313) was used in selected wells where incumbent (previous chemical provider) treatment lifetimes were shorter than expected. The incumbent squeeze volumes and additives were used, and the scale-inhibitor (SI) chemistry was replaced with SI1313 to obtain directly comparable results. The wells selected are vertical wells, with predominantly carbonate mineralogy and 14–18% porosity and 9–16 mD permeability. Bottomhole temperature is 105°F (40°C). These wells are under continuous CO2 flooding operations, and the scales of interest are calcium carbonate and calcium sulfate predominantly. The selected wells were targeted to have a good squeeze history for comparison and stable water production. Pre-Job Validation Work Coreflood laboratory experiments were performed to simulate the adsorption and desorption under these specific Oxy Permian conditions. The coreflood showed over 10,000 pore volume (PV) of flow with inhibitor concentration remaining above the minimum effective concentration (MEC) during the entire run. Once greater than two times incumbent performance was reached, the coreflood was stopped, although the return concentration was still above MEC. For reference, corefloods with incumbent phosphonate chemistry under the same conditions usually drop below MEC around approximately 3,000–5,000 PVs. The adsorption of SI1313 to core material was measured during the coreflood experiment and the results show 12.5 mg of inhibitor adsorbed per gram of core material. As a comparison, a typical incumbent phosphonate scale inhibitor adsorbs 1–2 mg of inhibitor per gram of core material. This increase in adsorption is considered a large improvement over traditional chemistry. The carrier platform’s superior adsorption, when combined with controlled desorption, is the basis for extending the lifetimes of scale- inhibitor treatments. The corefloods results validate the ER characteristics expected from SI1313 and allowed for field squeezes to be conducted. Field Application Group 2 Technologies provided SI1313 to be squeezed for Oxy in January 2020, into five vertical conventional wells. The selected wells are in one area where CO2 flooding is in place and there is risk of calcium carbonate (CaCO3) and calcium sulfate (CaSO4) scaling. These wells have had many scale squeezes performed on them, yielding an excellent data set to compare against. The goal of this trial was to show significant lifetime extension compared to previous incumbent squeeze lifetimes.

Front Cover Picture: Recent Advances in Synthesis of Difluoromethylene Phosphonates for Biological Applications (Adv. Synth. Catal. 12/2021)

The front cover picture, designed by Michael Shevchuk, illustrates difluoromethylene phosphonates as bioisosteric, non-hydrolyzable analogs of natural phosphates, reflecting on their prominence as molecular tools to study intricate phosphate biochemistry and beyond. The review comprehensively summarizes the recent synthetic advances in the chemistry of difluoromethylene phosphonates, such as visible light-driven photocatalytic transformations, and highlights compounds that have found significant importance in biochemical research. Details can be found in the Review by Gerd-Volker Röschenthaler, Jianlin Han, and co-workers (M. Shevchuk, Q. Wang, R. Pajkert, J. Xu, H. Mei, G.-V. Röschenthaler, J. Han, Adv. Synth. Catal. 2021, 363, 2912–2968; DOI: 10.1002/adsc.202001464).

External Control of GaN Band Bending Using Phosphonate Self-Assembled Monolayers.

We report on the optoelectronic properties of GaN(0001) and (11̅00) surfaces after their functionalization with phosphonic acid derivatives. To analyze the possible correlation between the acid's electronegativity and the GaN surface band bending, two types of phosphonic acids, n-octylphosphonic acid (OPA) and 1H,1H,2H,2H-perfluorooctanephosphonic acid (PFOPA), are grafted on oxidized GaN(0001) and GaN(11̅00) layers as well as on GaN nanowires. The resulting hybrid inorganic/organic heterostructures are investigated by X-ray photoemission and photoluminescence spectroscopy. The GaN work function is changed significantly by the grafting of phosphonic acids, evidencing the formation of dense self-assembled monolayers. Regardless of the GaN surface orientation, both types of phosphonic acids significantly impact the GaN surface band bending. A dependence on the acids' electronegativity is, however, only observed for the oxidized GaN(11̅00) surface, indicating a relatively low density of surface states and a favorable band alignment between the surface oxide and acids' electronic states. Regarding the optical properties, the covalent bonding of PFOPA and OPA on oxidized GaN layers and nanowires significantly affects their internal quantum efficiency, especially in the nanowire case due to the large surface-to-volume ratio. The variation in the internal quantum efficiency is related to the modification of both the internal electric fields and surface states. These results demonstrate the potential of phosphonate chemistry for the surface functionalization of GaN, which could be exploited for selective sensing applications.

ToF-SIMS study of selective anchoring of Ru(tpy)2 complexes on zirconium-phosphate functionalized oxide surfaces

Polypyridine-based ruthenium complexes are among the most interesting photoactive molecular systems, in virtue of a number of outstanding (photo)physicochemical properties. To exploit such properties in solid-state applications, such as molecular electronics, optoelectronics, and photovoltaics, tailored experimental strategies are needed for the anchoring of such complexes on surfaces. At the same time, these strategies need to be investigated and validated through precise monitoring of the surface composition. In this contribution, the authors report on the application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for studying the anchoring onto transparent (semi)conducting fluorine tin-doped oxide of the polypyridinic photoactive RuDT2. This molecule is characterized by an Ru(tpy)2 core and two free terpyridinic units. The authors’ approach involves the use of a surface priming strategy based on the chemistry of zirconium phosphates and phosphonates (ZP-priming) to provide a platform for direct anchoring of RuDT2 molecules at the oxide surface. Onto patterned ZP-fluorine-doped tin oxide (FTO), the authors report selective anchoring of RuDT2 only onto ZP domains, while no binding occurs onto bare FTO areas. The latter were shown to remain available for further functionalization using functional molecules containing phosphonic moieties, and in the authors’ case, a phosphonic derivative of rhodamine B (RhB-P) was used. ToF-SIMS imaging was intensively used to monitor each reaction step and confirm the successful laterally resolved and selective adsorption of RuDT2 and RhB-P onto ZP and bare FTO domains, respectively.

Reticular Chemistry of Uranyl Phosphonates: Sterically Hindered Phosphonate Ligand Method is Significant for Constructing Zero-Dimensional Secondary Building Units.

Designability is an attractive feature for metal-organic frameworks (MOFs) and essential for reticular chemistry, and many ideas are significantly useful in the carboxylate system. Bi-, tri-, and tetra-topic phosphonate ligands are used to achieve framework structures. However, an efficient method for designing phosphonate MOFs is still on the way, especially for uranyl phosphonates, owing to the complicated coordination modes of the phosphonate group. Uranyl phosphonates prefer layer or pillar-layered structures as the topology extension for uranyl units occurs in the plane perpendicular to the linear uranium-oxo bonds and phosphonate ligands favor the formation of compact structures. Therefore, an approach that can construct three-dimensional (3D) uranyl phosphonate MOFs is desired. In this paper, a sterically hindered phosphonate ligand method (SHPL) is described and is successfully used to achieve 3D framework structures of uranyl phosphonates. Four MOF compounds ([AMIM]2 (UO2 )(TppmH4 )⋅H2 O (UPF-101), [BMMIM]2 (UO2 )3 (TppmH4 )2 ⋅H2 O (UPF-102), [Py14]2 (UO2 )3 (TppmH4 )2 ⋅3 H2 O (UPF-103), and [BMIM](UO2 )3 (TppmH3 )F2 ⋅2 H2 O (UPF-104); [AMIM]=1-allyl-3-methylimidazolium, [BMMIM]=1-butyl-2,3-dimethylimidazolium, [Py14]=N-butyl-N-methylpyrrolidinium, and [BMIM]=1-butyl-3-methylimidazolium) are obtained by ionothermal synthesis, with zero-dimensional nodes of uranyl phosphonates linked by steric tetra-topic ligands, namely tetrakis[4-(dihyroxyphosphoryl)phenyl]methane (TppmH8 ), to give 3D framework structures. Characterization by PXRD, UV/Vis, IR, Raman spectroscopy, and thermogravimetry (TG) were also performed.

Abstract 984: Synthesis of mixed, hypoxia-activated phosphoramidate esters for the inhibition of Enolase in ENO1-deleted glioblastoma

Abstract Background: Precision oncology is currently restricted to activated oncogenes as drug targets, with tumor suppressor deletions remaining largely in-actionable. We developed a novel method that targets tumor suppressor deletions by exploiting vulnerabilities generated by the co-deletion of neighboring metabolic housekeeping genes with critical but normally redundant functions. Proof-of-principle studies were conducted for the glycolytic enzyme Enolase. Cancers harboring the homozygous deletion of 1p36-localized ENO1 remain metabolically active and viable through redundant action of its paralogue, ENO2. Inhibition of ENO2 in cancer cells harboring ENO1-homozygous deletion discriminately kills ENO1-deleted cells. In accordance, our synthetic efforts have focused on phosphonate chemistry to generate clinically-useful substrate mimics of 2-phosphoglycerate, the natural substrate for Enolase. We have generated a phosphonohydroxamate ENO2-inhibitor termed HEX and a pro-drug of which, POMHEX, kills ENO1-homozygously deleted glioma cells in culture with strong specificity. However, the pharmacokinetics of POMHEX are poor, due to the presence of carboxyesterase in extracellular fluids, including plasma. Results: We have synthesized mechanistically different pro-drugs of HEX, utilizing nitro-aromatics as protecting groups. Nitroaromatic groups are bioactivated by nitroreductases intracellularly, in a manner that is inversely related to oxygen concentration. As such, removal of nitroaromatic pro-drug moieties and release of active drug is favored under low oxygen (hypoxic) conditions. We synthesized a series of nitroaromatic pro-drugs of HEX (the structures will be disclosed at AACR presentation, pending patent filings) and demonstrate that 1) these exhibit selective toxicity to ENO1-deleted glioma cells in culture and 2) this killing is dramatically enhanced by lowering oxygen concentrations as compared to POMHEX. We further find that redox potential of the nitroaromatic moiety correlates with the degree of hypoxia activation with the lower redox potential being associated with great oxygen dependence. Importantly, unlike POMHEX, nitroaromatic HEX pro-drugs are stable in human plasma ex-vivo. We have thus successfully synthesized a pro-drug inhibitor of Enolase that is hypoxia-activated. Conclusion and future directions: We are gearing up synthesis for pre-clinical evaluation of nitroaromatic-HEX in intracranial tumor xenograft models. While the primary purpose of Nitroaromatic HEX is for the precision oncology treatment of ENO1-homozygously deleted tumors, it has not escaped our notice that such drugs have wider applicability within the context of targeting treatment-resistant tumors cells hiding in hypoxic niches. Indeed, we have observed that virtually all glioma cell lines can be killed by nitroaromatic HEX under hypoxia. Note: This abstract was not presented at the meeting. Citation Format: Florian Muller, Victoria C. Yan, Elliot S. Ballato, Kristine L. Yang, Dimitra K. Georgiou, Kenisha Arthur, Pakriti Shrestha, Sunada Khadka, Jeffrey Ackroyd. Synthesis of mixed, hypoxia-activated phosphoramidate esters for the inhibition of Enolase in ENO1-deleted glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 984.

Synthesis of Nickel Phosphide Electrocatalysts from Hybrid Metal Phosphonates.

Transition-metal phosphides (TMPs) have recently emerged as efficient and inexpensive electrocatalysts for electrochemical water splitting. The synthesis of nanostructured phosphides often involves highly reactive and hazardous phosphorous-containing compounds. Herein, we report the synthesis of nickel phosphides through thermal treatment under H2(5%)/Ar of layered nickel phenylphosphonate (NiPh) or methylphosphonate (NiMe) that act as single-source precursors. Ni12P5, Ni12P5-Ni2P, and Ni2P nanoparticles (NPs) with sizes of ca. 15-45 nm coated with a thin shell of carbonaceous material were produced. Thermogravimetric analysis coupled with mass spectrometry (TG-MS) showed that H2, H2O, P2, and -C6H5 are the main compounds formed during the transformation of the precursor under argon and no hazard phosphorous-containing compounds are created, making this a simple and relatively safe route for fabricating nanostructured TMPs. The H2 most likely reacts with the -PO3 groups of the precursor to form H2O and P2, and the latter subsequently reacts with the metal to produce the phosphide. The Ni12P5-Ni2P and Ni2P NPs efficiently catalyze the hydrogen evolution reaction (HER), with Ni2P showing the best performance and generating a current density of 10 mA cm-2 at an overpotential of 87 mV and exhibiting long-term stability. Co2P and CoP NPs were also synthesized following this method. This approach may be utilized to explore the rich metal phosphonate chemistry for fabricating phosphide-based materials for electrochemical energy conversion and storage applications.

ChemInform Abstract: Magnetic Materials Based on 3D Metal Phosphonates

AbstractReview: 162 refs.

Amino-Functionalized Layered Crystalline Zirconium Phosphonates: Synthesis, Crystal Structure, and Spectroscopic Characterization.

Two new layered zirconium phosphonates functionalized with amino groups were synthesized starting from aminomethylphosphonic acid in the presence of different mineralizers, and their structures were solved from powder X-ray diffraction data. Their topologies are unprecedented in zirconium phosphonate chemistry: the first, of formula ZrH[F3(O3PCH2NH2)], prepared in the presence of hydrofluoric acid, features uncommon ZrO2F4 units and a remarkable thermal stability; the second, of formula Zr2H2[(C2O4)3(O3PCH2NH2)2]·2H2O, prepared in the presence of oxalic acid, is based on ZrO7 units with oxalate anions coordinated to the metal atom, which were never observed before in any zirconium phosphonate. In addition, the structure of another compound based on (2-aminoethyl)phosphonic acid is reported, which was the object of a previously published study. This compound has layered α-type structure with -NH3(+) groups located in the interlayer space. All of the reported compounds were further characterized by means of vibrational spectroscopy, which provided important information on fine structural details that cannot be deduced from the powder X-ray diffraction data.

Functionalized phosphonates as building units for multi-dimensional homo- and heterometallic 3d-4f inorganic-organic hybrid-materials.

Using the multifunctional ligand H4L (2,2'-bipyridinyl-5,5'-diphosphonic acid), a new family of inorganic-organic hybrid-materials was prepared. The ligand shows a very high flexibility regarding the coordination mode, leading to a large structural diversity. The compounds 1a, 1b ([M(H2L)(H2O)4]·2.5H2O; M = Co(2+) (a), Ni(2+) (b)), 2 ([Gd2(H2H'L)2(H2H'2L)(H2O)6]Cl4·14H2O), 3a, 3b, 3c ([MCo(iii)(H2L)3(H2O)2]·6.5H2O; M = Gd(3+) (a), Dy(3+) (b) and Tb(3+) (c)), and 4 ([GdNi(ii)(H2L)3(H2O)3]NaCl·6H2O) were isolated and characterized with single crystal X-ray diffraction. Depending on the used metal ions and on the stoichiometry, either discrete entities (0D), extended 2D layers or 3D frameworks were obtained. In contrast to the general approach in phosphonate chemistry, the compounds were prepared without hydrothermal synthesis, but under ambient pressure. Variable temperature magnetic measurements were carried out to determine the magnetic properties.

Synthesis of dialkylaminoaryl phosphonate bioisosteres of tyrosine and tyramine: a novel application of allene phosphonate chemistry for the synthesis of false substrates of tyrosinase

Tyrosinase is the rate-limiting oxidase in the synthesis of melanin, making it an obvious target for the treatment of melanotic melanomas. Tyrosine and tyramine are its natural substrates, but many of their derivatives are inhibitors or false substrates, and are therefore prime candidates for melanoma chemotherapy. A series of dialkylphosphonate derivatives of tyramine have now been synthesized in order to extend the chemical diversity of tyrosinase substrates. The known reactivity between alkenephosphonates and nucleophiles was exploited by the addition of 4-(2-aminoethyl)phenol (tyramine) across the 2,3-double bond of dialkyl 1,2-alkadiene phosphonates, to obtain the desired bisphosphonate derivatives. These reactions were highly chemoselective and regioselective but not stereoselective. Five of the reported novel dialkylphosphonate aminophenols were substrates for mushroom tyrosinase in vitro: dimethyl 2-[2(4-hydroxyphenyl)ethylamino]-3-methyl-1-butene phosphonate (3); diethyl 2-[2(4-hydroxyphenyl)ethylamino]-3-methyl-1-butene phosphonate (4); dimethyl 2-[2-(4-hydroxyphenyl)ethylamino]-2-cyclohexyl-1-ethene phosphonate (5); diethyl 2-[2-(4-hydroxyphenyl)ethylamino]-2-cyclohexyl-1-ethene phosphonate (6); diethyl 2-[2-(4-hydroxyphenyl)ethylamino]ethane phosphonate (7). Compound 3 blocked the pigmentation of anagen hair in vivo in a murine animal model, a further demonstration that these compounds are able to enter and disrupt the melanogenic pathway.

Exploiting phosphonate chemistry to present biomolecules at the orthopaedic implant interface

s / International Journal of Surgery 12 (2014) S13eS117 S65 treated with surgical debridement followed by antibiotics, with removal of implants on 3 occasions. Conclusions: Propionibacterium Acnes is a normal skin commensal with a high incidence of infection in elective upper limb surgery. Decolonisation of the surgical field prior to surgery may reduce deep infection rates. Chlorhexidine (2%) is known to be effective against Propionibacterium Acnes. Recommendation has included routine surgical field preparation using 2% chlorhexidine scrub. Further studies have been planned to identify the most effective method of decolonisation. Re-audit will be performed in 12 months time. 1183: EXPLOITING PHOSPHONATE CHEMISTRY TO PRESENT BIOMOLECULES AT THE ORTHOPAEDIC IMPLANT INTERFACE Nathan M. Campbell , Mark Birch, Lee Higham. Newcastle University,

Mechanistic Aspects for the Formation of Copper Dimer Bridged by Phosphonic Acid and Extending Its Dimensionality by Organic and Inorganic Linkers: Synthesis, Structural Characterization, Magnetic Properties, and Theoretical Studies

Six new copper metal complexes with formulas [Cu(H2O)(2,2′-bpy)(H2L)]2·H4L·4H2O (1), [{Cu(H2O)(2,2′-bpy)(H3L)}2(H2L)]·2H2O (2), [Cu(H2O)(1,10-phen)(H2L)]2·6H2O (3), [Cu(2,2′-bpy)(H2L)]n·nH2O (4), [Cu(1,10-phen)(H2L)]n·3nH2O (5), and [{Cu(2,2′-bpy)(MoO3)}2(L)]n·2nH2O (6) have been synthesized starting from p-xylylenediphosphonic acid (H4L) and 2,2′-bipyridine (2,2′-bpy) or 1,10-phenanthroline (1,10-phen) as secondary linkers and characterized by single crystal X-ray diffraction analysis, IR spectroscopy, and thermogravimetric (TG) analysis. All the complexes were synthesized by hydrothermal methods. A dinuclear motif (Cu-dimer) bridged by phosphonic acid represents a new class of simple building unit (SBU) in the construction of coordination architectures in metal phosphonate chemistry. The initial pH of the reaction mixture induced by the secondary linker plays an important role in the formation of the molecular phosphonates 1, 2, and 3. Temperature dependent hydrothermal synthesis of the compounds 1, 2, and 3 reveals the mechanism of the self-assembly of the compounds based on the solubility of the phosphonic acid H4L. Two-dimensional coordination polymers 4, 5, and 6, which are formed by increasing the pH of the reaction mixture, comprise Cu-dimers as nodes, organic (H2L) and inorganic (Mo4O12) ligands as linkers. The void space-areas, created by the (4,4) connected nets in compounds 4 and 5, are occupied by lattice water molecules. Thus compounds 4 and 5 have the potential to accommodate guest species/molecules. Variable temperature magnetic studies of the compounds 3, 4, 5, and 6 reveal the antiferromagnetic interactions between the two Cu(II) ions in the eight-membered ring, observed in their crystal structures. A density functional theory (DFT) calculation correlates the conformation of the Cu-dimer ring with the magnitude of the exchange parameter based on the torsion angle of the conformation.

Multifunctional Luminescent and Proton-Conducting Lanthanide Carboxyphosphonate Open-Framework Hybrids Exhibiting Crystalline-to-Amorphous-to-Crystalline Transformations

The chemistry of metal phosphonates has been progressing fast with the addition of new materials that possess novel structural features and new properties, occasionally in a cooperative manner. In this paper, we report a new family of functional lanthanide-carboxyphosphonate materials. Specifically, the lanthanide is La, Ce, Pr, Sm, Eu, Gd, Tb, or Dy and the carboxyphosphonate ligand is 2-hydroxyphosphonoacetic acid (H3HPA). All reported LnHPA compounds, Ln3(H0.75O3PCHOHCOO)4·xH2O (x = 15–16), crystallize in the orthorhombic system. Two types of structures were isolated: series I and II polymorphs. For both series, the three-dimensional (3D) open frameworks result from the linkage of similar organo-inorganic layers, in the ac-plane, by central lanthanide cations, which yield trimeric units also found in other metal-HPA hybrids. Large oval-shaped 1D channels are formed by the spatial separation of the layers along the b-axis and filled with lattice water molecules. LnHPA materials undergo remarkable crystalline-to-amorphous-to crystalline transformations upon dehydration and rehydration cycles, as confirmed by thermodiffraction and NMR spectroscopy. The highest proton conductivity was observed for GdHPA (series II), 3.2 × 10–4 S cm–1 at 98% RH and T = 21 °C. The dehydration–rehydration chemistry was also followed by photoluminescence spectroscopy. It was shown that loss and reuptake of water molecules are accompanied by clear changes in the photoluminescence spectra and lifetimes of the Eu analog (series II). Our present results reveal a wide family of well-characterized, multifunctional lanthanide-based phosphonate 3D-structured metal–organic frameworks (MOFs) that show reversible crystalline-to-amorphous-to-crystalline transformations and, at the same time, exhibit high proton conductivity.

Red vs. Green Scale Inhibitors for Extending Squeeze life—A Case Study From the North Sea, Norwegian Sector—Part II

SummaryOver the years, environmental legislation has forced changes in the types of scale-inhibitor molecule that can be deployed in certain regions of the world. These regulations have resulted in changes from phosphonate scale inhibitor to polymer-based chemistry, particularly in the Norwegian and UK continental shelf where phosphonates have been either on the substitution list or phased out for many applications. Over the past 10 years, significant improvements in inhibitor properties of the so-called "green" scale inhibitors have been made. However, for one particular operator, the squeeze application of this green scale inhibitor resulted in poorer than expected treatment lifetimes and significant operating cost because of the frequency of retreatment. To overcome the increasing operating cost, an evaluation was made of the current treatment chemicals vs. the older, more-established phosphonate scale inhibitors. The results for the laboratory evaluation suggested that the older chemistry would extend treatment life and reduce operating cost. A case was made to the legislative authority, who approved the use of the phosphonate scale inhibitor, and field applications started. The squeeze lifetimes for the red phosphonate chemistry were shown to be significantly better than the existing yellow/green inhibitors. During the following months, other scale inhibitors with improved environmental characteristics were developed and evaluated. One such molecule was shown to have similar coreflood retention to that of the applied red phosphonate and presented no formation damage. This paper presents the laboratory evaluation of the new scale inhibitor, and illustrates the improvement observed with this new inhibitor through field squeeze-treatment results from a well treated with both the red and new yellow environmental profile inhibitor chemicals.This paper outlines the challenges with environmental legislation and how it has been possible to develop technical solutions (in terms of environmental vs. safety issues and with new inhibitor chemicals) to meet the challenges of offshore scale control.