Phosphonic Systems Research Articles

Hollow Superhelices Based on Chiral Europium Coordination Polymers.

The construction of helical nanotubes based on chiral coordination polymers (CPs) is an intriguing but challenging task, which is important for the development of functional materials that combine macroscopic chirality with tube-related properties. Here, we selected a chiral europium phosphonate system, e.g., Eu(NO3)3/R-,S-pempH2, and carried out a systematic work. By controlling the hydrothermal reaction conditions such as the pH value of the reaction mixture, the molar ratio and concentration of the reactants, we obtained block-like crystals of R/S-1b, rod-like crystals ofR/S-3r, hollow superhelices of R/S-2hh, and solid superhelices of R/S-4sh. In the latter two cases, the chirality has been successfully transferred and amplificated from the molecular level to the macroscopic level. Interestingly, compounds R/S-2hh and R/S-4sh have the same chemical composition of Eu(R/S-pempH)3×2H2O and show identical PXRD patterns, thus can be considered as the same material except for different morphologies. We further investigatedtheir circularly polarized luminescence (CPL) properties and found that the hollow superhelix of R/S-2hh had a larger dissymmetry factor than the solid superhelix of R/S-4sh. This study not only provides the first example of hollow superhelices of chiral CPs, but also offers the possibility of modulating the chiroptical properties of CPs through morphological control.

Charge Separated One-Dimensional Hybrid Cobalt/Nickel Phosphonate Frameworks: A Facile Approach to Design Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions.

Two new organoamine templated one-dimensional transition metal phosphonate compounds are synthesized, and their bifunctional electrocatalytic activities are examined in highly alkaline and acidic media. Compared with state-of-the-art materials, the cobalt phosphonate system is a new fabrication of sustainable and highly efficient catalysts toward electrochemical water splitting systems.

Solvent extraction and separation of light rare earths from chloride media using HDEHP-P350 system

Solvent extraction is the most important method for rare earth extraction and separation. Currently, di(2-ethylhexyl) phosphoric acid (HDEHP) and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH/EHP) are widely used in industrial production, but there are still obvious deficiencies that require further research to resolve. In this paper, the unsaponification extraction of light rare earth ions in a hydrochloric acid medium by di(2-ethylhexyl) phosphoric acid-di(1-methyl-heptyl) methyl phosphonate (HDEHP-P350) system was studied. The results show that the addition of P350 reduces the extraction capacity of HDEHP, and also greatly reduces the concentration of acidity required for the back-extraction. It still has a good separation factor for light rare earths without saponification, and the extractant is not easy to emulsify. With an aqueous phase of pH = 2.85, and HDEHP mole fraction XHDEHP = 0.9 (compared with O/A = 2), the separation effect of light rare earth is the best, resulting in the separation coefficient βCe/La = 3.39, βPr/Ce = 1.67 and βNd/Pr = 1.45, respectively. The loaded light rare earth ions extracted by HDEHP-P350 can be easily stripped when 2 mol/L HCl is used as the stripping agent. Finally, the extraction mechanism is discussed using a slope method, and the final structure of the extracted complex is determined to be RECl[(DEHP)2]2P350(o), based on a combination of infrared spectra and 1H NMR and 31P NMR analyses.

Advances and Challenges in the Creation of Porous Metal Phosphonates.

In the expansive world of porous hybrid materials, a category of materials that has been rather less explored than others and is gaining attention in development is the porous metal phosphonates. They offer promising features towards applications which demand control over the inorganic–organic network and interface, which is critical for adsorption, catalysis and functional devices and technology. The need to establish a rationale for new synthesis approaches to make these materials in a controlled manner is by itself an important motivation for material chemists. In this review, we highlight the various synthetic strategies exploited, discussing various metal phosphonate systems and how they influence the properties of porous metal phosphonates. We discuss porous metal phosphonate systems based on transition metals with an emphasis on addressing challenges with tetravalent metals. Finally, this review provides a brief description of some key areas of application that are ideally suited for porous metal phosphonates.

Quantifying Ligand Exchange on InP Using an Atomically Precise Cluster Platform

The surface chemistry of a colloidal nanoparticle is intrinsic to both its structure and function. It is therefore necessary to characterize the surfaces of colloidal materials to rationally underpin any synthetic, catalytic, or transformative mechanisms they enable. Here we characterize the surface properties of colloidal InP clusters and quantum dots by examining the binding of traditional stabilizing ligands including carboxylates, phosphonates, and thiolates. By using the In37P20X51 (X = carboxylate) cluster species as an ideally monodisperse and well-defined starting scaffold, we quantify surface-exchange equilibria. Using quantitative 1H and 31P NMR spectroscopy, we show that 1:1 metathesis-type binding models are insufficient to fully describe the surface dynamics. In particular, for the case of the highly reversible carboxylate ligand exchange, a more detailed isotherm approach using a two-site, competitive model is necessary. This model is used to deconvolute L- and X-type binding modalities. We additionally quantify the reversible and irreversible ligand-exchange reactions observed in the thiolateand phosphonate systems.

Systematic Investigation of the in Situ Reduction Process from U(VI) to U(IV) in a Phosphonate System under Mild Solvothermal Conditions.

The oxidation state greatly affects the chemical behavior of uranium in the nuclear fuel cycle and in the environment. Phosphonate ligands, on the other hand, show strong complexation toward uranium at different oxidation states and are widely used in nuclear fuel reprocessing. Therefore, in this work, the reduction behavior of U(VI) with the presence of a phosphonate ligand is investigated under mild solvothermal conditions. By adjusting the reaction time, temperature, and counterion species, a series of uranium diphosphonates including two U(VI), seven U(IV), two mixed-valent U(IV/VI), and one distinct U(IV/V/VI) compounds were obtained. All these compounds were characterized by single crystal X-ray diffraction and UV-vis-NIR absorption and fluorescence spectroscopy. The structural diversity among those compounds not only illustrates the intrinsic structural complexity in this system, but also illuminates the in situ reduction pathways that are affected by the variation of reaction conditions. The UV-vis-NIR absorption spectra of the tetravalent uranium compounds show that the absorption features are closely related to the local coordination environments of the uranium centers as well as the bonding modes of the phosphonate ligand. The fluorescence spectra of mixed-valent uranium compounds show unique emission features of U(VI) luminescence that are partially quenched by the multiple electronic transitions of U(IV) centers in the visible and NIR regions.

Cerium(IV) phenylphosphonates and para-substituted phenylphosphonates: preparation and characterization

Cerium(IV) phenylphosphonates and 4-substituted phenylphosphonates were prepared by reaction of a cerium(IV) salt with corresponding acids (phenylphosphonic, 4-carboxyphenylphosphonic, 4-sulfamoylphenylphosphonic, 1,4-benzenediphosphonic, 1,4-biphenyldiphosphonic and 4-sulfophenylphosphonic acid) and characterized by elemental analysis, energy-dispersive X-ray analysis, TGA, powder X-ray diffraction and infrared spectroscopy. Three different cerium phenylphosphonates can be prepared in dependence on the reaction conditions. On the other hand, only one compound is formed in each 4-substituted phosphonate system regardless the variation of the reaction conditions. All three phenylphosphonates, 4-carboxyphenylphosphonate and 4-sulfamoylphenylphosphonate are layered with the organic parts pointed below and above the plane of the metal phosphonate layers, with the functional groups placed at the end of the organic part. 4-Sulfophenylphosphonate, 1,4-benzenediphosphonate and 4,4′-biphenyldiphosphonate form pillared structures. Cerium 4-carboxyphenylphosphonate is able to intercalate aliphatic amines due to the presence of the free carboxylic groups in its interlayer space.

Phosphonate Based High Nuclearity Magnetic Cages.

Transition metal based high nuclearity molecular magnetic cages are a very important class of compounds owing to their potential applications in fabricating new generation molecular magnets such as single molecular magnets, magnetic refrigerants, etc. Most of the reported polynuclear cages contain carboxylates or alkoxides as ligands. However, the binding ability of phosphonates with transition metal ions is stronger than the carboxylates or alkoxides. The presence of three oxygen donor sites enables phosphonates to bridge up to nine metal centers simultaneously. But very few phosphonate based transition metal cages were reported in the literature until recently, mainly because of synthetic difficulties, propensity to result in layered compounds, and also their poor crystalline properties. Accordingly, various synthetic strategies have been followed by several groups in order to overcome such synthetic difficulties. These strategies mainly include use of small preformed metal precursors, proper choice of coligands along with the phosphonate ligands, and use of sterically hindered bulky phosphonate ligands. Currently, the phosphonate system offers a library of high nuclearity transition metal and mixed metal (3d-4f) cages with aesthetically pleasing structures and interesting magnetic properties. This Account is in the form of a research landscape on our efforts to synthesize and characterize new types of phosphonate based high nuclearity paramagnetic transition metal cages. We quite often experienced synthetic difficulties with such versatile systems in assembling high nuclearity metal cages. Few methods have been emphasized for the self-assembly of phosphonate systems with suitable transition metal ions in achieving high nuclearity. We highlighted our journey from 2005 until today for phosphonate based high nuclearity transition metal cages with V(IV/V), Mn(II/III), Fe(III), Co(II), Ni(II), and Cu(II) metal ions and their magnetic properties. We observed that slight changes in stoichiometry, reaction conditions, and presence or absence of coligand played crucial roles in determining the final structure of these complexes. Most of the complexes included are regular in geometry with a dense arrangement of the above-mentioned metal centers in a confined space, and a few of them also resemble regular polygonal solids (Archimedean and Platonic). Since there needs to be a historical approach for a comparative study, significant research output reported by other groups is also compared in brief to ensure the potential of phosphonate ligands in synthesizing high nuclearity magnetic cages.

ChemInform Abstract: Electrocatalytic Fast and Efficient Multicomponent Approach to Medicinally Relevant (2‐Amino‐4H‐chromen‐4‐yl)phosphonate Scaffold.

‘One-pot’ electrocatalytic transformation of salicylaldehydes, malononitrile, and triethyl phosphite in an undivided cell results in the formation of diethyl (2-amino-3-cyano-4H-chromen-4-yl)phosphonates in 88–93% substance yields and 880–930% current efficiency via complex multicomponent process. This novel electrocatalytic chain process opens an effective, fast, and convenient way to cyano-functionalized (2-amino-4H-chromen-4-yl)phosphonate systems which are promising compounds for biomedical applications. This efficient electrocatalytic approach to the (2-amino-4H-chromen-4-yl)phosphonate scaffold represents novel synthetic concept for multicomponent reactions (MCR) strategy and allows to combine the synthetic virtues of conventional MCR with ecological benefits and convenience of facile electrocatalytic procedure.

Electrocatalytic Fast and Efficient Multicomponent Approach to Medicinally Relevant (2‐Amino‐4H‐chromen‐4‐yl) phosphonate Scaffold

ABSTRACT‘One‐pot’ electrocatalytic transformation of salicylaldehydes, malononitrile, and triethyl phosphite in an undivided cell results in the formation of diethyl (2‐amino‐3‐cyano‐4H‐chromen‐4‐yl)phosphonates in 88–93% substance yields and 880–930% current efficiency via complex multicomponent process. This novel electrocatalytic chain process opens an effective, fast, and convenient way to cyano‐functionalized (2‐amino‐4H‐chromen‐4‐yl)phosphonate systems which are promising compounds for biomedical applications. This efficient electrocatalytic approach to the (2‐amino‐4H‐chromen‐4‐yl)phosphonate scaffold represents novel synthetic concept for multicomponent reactions (MCR) strategy and allows to combine the synthetic virtues of conventional MCR with ecological benefits and convenience of facile electrocatalytic procedure.

In depth investigation of the synthesis, structural, and spectroscopic characterization of a high pH binary Co(II)–N,N-bis(phosphonomethyl)glycine species. Association with aqueous speciation studies of binary Co(II)–(carboxy)phosphonate systems

Cobalt is an abundant metal ion present in the abiotic and biological world. The chemical reactivity of Co(II) is exemplified through complex interactions with variable molecular mass ligands, including amino acids, peptides, variable nature organic ligands, and/or phospho(nate)-derivatives thereof. Poised to gain insight into the chemical reactivity of Co(II) toward the family of mixed (carboxy)phosphonate-containing ligands, pH-specific aqueous reactions were carried out between Co(II) and N,N-bis(phosphonomethyl)-glycine (NTA2P), leading to a new pH-structural variant species (NH4)3[Co(C4H6O8NP2)(H2O)2]·4H2O (1) at pH 8. Compound 1 was characterized analytically, spectroscopically (FT-IR, UV–Vis, EPR), and magnetically. X-ray crystallography reveals a mononuclear complex of Co(II) in an NO5 octahedral environment. The solid state magnetic and EPR data on 1 suggest the presence of a high-spin Co(II) in a distorted octahedral geometry, with a ground state of an effective spin S=1/2. The solution UV–Vis and EPR data suggest retention of the integrity of 1, consistent with the magnetization measurements. Detailed aqueous speciation studies on binary Co(II)–carboxylate (NTA) and all Co(II)–(carboxy)phosphonate (NTAxP; x=1–3) systems reveal the aqueous distributions of all species involved in the respective systems and project a mononuclear species not unlike that of 1 in the Co(II)–NTA2P system. The structural and chemical attributes of the title complex reflect the (a) pH-dependent chemical reactivity in the binary Co(II)–NTA2P system, and (b) structure–activity correlations in the aqueous media linking both high and low pH-structural variants. To this end, fundamental structural properties influence the reactivity of Co(II) toward phosphonate and mixed carboxyphosphonate ligands and are ultimately exemplified as a function of phosphonate-containing moieties in NTA derivatives. The variably configured species in such binary Co(II)–ligand systems define the pH dependence and nature of interactions between the two reagents, and could serve further as precursors in the design and discovery of new Co(II)–organophosphonate materials of specific structural lattice, spectroscopic, and magnetic properties.

ChemInform Abstract: Phosphonic Systems. Part 2. Functional Group and Skeleton Modifications in Diethyl Esters of 2-Propenyl (and 2-Pentenyl) Phosphonic Acids.

ChemInform Abstract: Phosphonic Systems. Part 2. Functional Group and Skeleton Modifications in Diethyl Esters of 2-Propenyl (and 2-Pentenyl) Phosphonic Acids.

Hydrothermal chemistry of vanadium oxides with aromatic di- and tri-phosphonates in the presence of secondary metal copper(II) cationic complex subunits

The hydrothermal chemistry of the copper-organonitrogen ligand/vanadium oxide/aromatic phosphonate system has been studied. Not only was HF required to induce crystallization, but product composition was highly dependent on the HF/V ratio of the reactions. At relatively low concentrations of HF/V of 6:1, materials of the Cu(II)-ligand/VxOy/organophosphonate type were observed, namely, [{Cu(phen)}2V2O5(O3PC6H4PO3)] (1), [Cu(phen)VO2(HO3PC6H4PO3)] (2), [{Cu(terpy)}2V2O5(O3PC6H4PO3)] (3), [{Cu(phen)(H2O)}VO2(HO3PC6H4PO3)] (6), [{Cu(phen)}VO2(HO3PC6H4PO3)] (7a and 7b), [Cu(C5H4NCO2)2V2O4(HO3PC6H4POH3)] (8), [Cu(bpy)VO2 {(HO3P)3C6H3}]·1.5H2O (12·1.5H2O), [{Cu(bpy)}2V3O7{(O3P)2C6H3PO3H}] (13) and [Cu(phen)V3O6(H2O){(O3P)2C6H3(PO3H)}] (14). When the HF concentration was raised, materials incorporating fluoride anion were observed; that is, compounds of the Cu(II)-ligand/VxOyFz/organophosphonate type: [{Cu(bpa)}2VO2F(H2O)(O3PC6H4PO3)]·H2O (4), [{Cu(bpa)}2V2O4F2(O3PC6H4PO3)] (5), [{Cu(bpy)}2V2O4F2(O3PC6H4PO3)] (9), [{Cu(terpy)}2V3O6F(HO3PC6H4PO3)2] (10), [{Cu(bpa)}2V2O4F2(O3PC6H4PO3)] (11). At HF/V concentrations of 25:1 or greater, vanadium free products, Cu(II) ligand/organophosphonate, were obtained: [Cu(C5H4NCO2)2(H2O3PC6H4PO3H2)]·H2O (15·H2O), [Cu(C5H4NCO2)2(H2O3PC6H4PO3H2)] (16), [Cu(bpy)(H2O){(HO3P)2C6H3(PO3H2)}] (17), [Cu(bpy){(HO3P)2C6H3(PO3H2)}]·H2O (18·H2O), [Cu(phen){(H2O3P)C6H3(PO3H)2}]·2H2O (19·2H2O) and [Cu(bpa){H2O3PC6H3(PO3H)2}]·H2O (20·H2O). The structural chemistry is unusually diverse with the Cu(II) ligand/VxOy/organophosphonate series exhibiting one-, two- and three-dimensional structures with a variety of copper-vanadate and vanadophosphonate substructures. The structural chemistry is discussed in relation to other examples of materials of the Cu(II) ligand/VxOy/organophosphonate and Cu(II) ligand/VxOyFz/organophosphonate families.

Synthetic, structural and solution speciation studies on binary Al(III)–(carboxy)phosphonate systems. Relevance to the neurotoxic potential of Al(III)

Efforts to delineate the interactions of neurotoxic Al(III) with low molecular mass substrates relevant to neurodegenerative processes, led to the investigation of the pH-specific synthetic chemistry of the binary Al(III)-[N-(phosphonomethyl) iminodiacetic acid] (Al-NTAP), Al(III)-[nitrilo-tris(methylene-phosphonic acid)] (Al-NTA3P), and Al(III)-[1-hydroxy ethylidene-1,1-diphosphonic acid] (Al-HEDP) systems, in correlation with solution speciation studies. Reaction of Al(NO(3))(3).9H(2)O with NTAP at pH 7.0 and 4.0 afforded the new species (CH(6)N(3))(4)[Al(2)(C(5)H(6)NPO(7))(2)(OH)(2)].8H(2)O (1) and (NH(4))(2)[Al(2)(C(5)H(6)NPO(7))(2)(H(2)O)(2)].4H(2)O (2), while reaction of Al(NO(3))(3).9H(2)O with NTA3P led to K(8)[Al(2)(C(3)H(6)NP(3)O(9))(2)(OH)(2)].20H(2)O (3). Complexes 1-3 were characterized by elemental analysis, FT-IR, (13)C, (31)P, (1)H NMR (for 1-2 solid state and solution NMR where feasible), and X-ray crystallography. The structures of 1-3 reveal the presence of uniquely defined dinuclear complexes of octahedral Al(III) bound to fully deprotonated phosphonate ligands, water and hydroxo moieties. The aqueous solution speciation studies on the aforementioned binary systems project a clear picture of the binary Al(III)-(carboxy)phosphonate interactions and species under variable pH-conditions and specific Al(III):ligand stoichiometry. The concurrent solid state and solution work (a) exemplifies essential structural and chemical attributes of soluble aqueous species, reflecting well-defined interactions of Al(III) with phosphosubstrates and (b) strengthens the potential linkage of neurotoxic Al(III) chemical reactivity toward O,N-containing (carboxy)phosphate-rich cellular targets.

PH-Specific synthetic chemistry, and spectroscopic, structural, electrochemical and magnetic susceptibility studies in binary Ni(II)-(carboxy)phosphonate systems

Nickel can play numerous roles in biological systems and in advanced abiotic materials. Supporting the diverse roles of Ni(II) in biological media are, among others, metal ion binding amino acids, their variably phosphorylated forms and/or exogenously administered organophosphonate drug substrates. In an effort to comprehend the aqueous chemistry of interactions between Ni(II) and organophosphonate substrates, research efforts were launched involving the ligands imino bis(methylenephosphonic acid) (H 4IDA2P), H 2O 3P–CH 2– NH 2 + –CH 2–PO 3H −, and N-(phosphonomethyl)glycine (glyphosate–H 3IDAP), HOOC–CH 2– NH 2 + –CH 2–PO 3H −. pH-Specific reactions of Ni(II) with H 4IDA2P and H 3IDAP led to the isolation of [Ni(C 2H 8O 6NP 2) 2(H 2O) 2] ( 1) and [Ni(OOC–CH 2–NH–CH 2–PO 3H) 2]·[Ni(H 2O) 6]·3.3H 2O ( 2), respectively. Compound 1 was characterized by analytical, spectroscopic techniques (UV–Vis, FT-IR), cyclic voltammetry, magnetic susceptibility measurements and X-ray crystallography. Compound 2 was characterized by elemental analysis, FT-IR spectroscopy, and X-ray crystallography. The structures of 1 and 2 reveal mononuclear octahedral Ni(II) assemblies bound by H 3IDA2P − and water ( 1), and glyphosate (HIDAP 2−) and water molecules ( 2), respectively. Magnetic susceptibility studies on 1 support the presence of high-spin octahedral Ni(II) in an oxygen environment, consistent with X-ray crystallography. The collective physicochemical features of the discrete Ni(II) assemblies in both species (a) shed light on aqueous binary Ni(II)–phosphoderivative interactions potentially influencing cellular physiology or toxicity, and (b) define the fundamental properties essential for the employment of such species in advanced materials synthesis and applications.

Diels-Alder chemistry of 2-diethoxyphosphinylcyclohex-2-enones. A new approach to complex phosphonates and synthetic applications of the beta-keto phosphonate system.

Enone phosphonates 1 and 2 were found to be excellent dienophiles for the Diels-Alder reaction, giving phosphonate-containing polycycles, and the phosphonate group of the resulting adducts facilitated both the installation of an angular alkyl group via a reductive alkylation process and the regioselective generation of a ring junction double bond via an intramolecular Wadsworth-Horner-Emmons reaction.

Photo-Arbuzov rearrangements of cyclic phosphite systems

The direct UV irradiation of cyclic phosphites 1– 4 was carried out in argon-saturated solvents. In all cases examined, the rearranged, ring-contracted Photo-Arbuzov phosphonate was the major product formed with isolated yields ranging from 40 to 50%. These phosphonate photoproducts, 5– 8, represent novel, bicyclic, aromatic phosphonate systems never before described in the literature of heterocyclic phosphorus chemistry. These compounds are of interest based on their potential application as ring-constrained, non-hydrolyzable mimics of phosphorylated tyrosine.

Synthesis and Crystal Structure of the Linear Chain Zirconium Organophosphonate (NH4)Zr[F2][H3{O3PCH2NH(CH2CO2)2}2]·3H2O·NH4Cl

The new zirconium phosphonate compound (NH4)Zr[F2][H3{O3PCH2NH(CH2CO2)2}2]·3H2O·NH4Cl was obtained from the reaction of zirconyl chloride with N-(phosphonomethyl)iminodiacetic acid in the presence of HF. It crystallizes in the triclinic space group P1 (No. 2) with a = 10.743(2) A, b = 11.483(2) A, c = 5.330(1) A, α = 90.63(2)°, β = 96.65(2)°, γ = 97.68(2)°, and Z = 1. The structure consists of linear chains of zirconium atoms linked together by phosphonate oxygens. The zirconium atom is six-coordinated by four phosphonate oxygens and two fluoride ions. The compound represents the first example of a linear chain structure in the zirconium phosphate or phosphonate systems. The formation of such linear chains as opposed to the layered structure normally observed for zirconium phosphonates is attributed to the bulkinesss of the phosphonic acid.

ChemInform Abstract: Phosphonic Systems. Part 14. Reactions of Cyclohexenylphosphonates with Aldehydes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Phosphonic systems. Part 15. Addition of diethyl prop‐2‐enylphosphonate to aldehydes: Fragmentation vs. isomerization of kinetic products

AbstractLithiated diethyl prop‐2‐enylphosphonate adds to an aliphatic or an aromatic aldehyde, yielding a diastereomeric mixture of the kinetically controlled α‐adduct. Upon warming, these adducts decompose back to starting materials to give finally the thermodynamically controlled γ‐adducts, or undergo fragmentation to diethyl phosphate and (E) dienes. The distribution of the first product between these two pathways is a function of the aldehyde (aromatic vs. aliphatic) and of steric interactions operating within the two diastereomers of the adduct.