Phosphonate Oxygen Atoms Research Articles

Syntheses, crystal structures, and fluorescence properties of two new copper phosphonates from hydroxy-functionalized bisphosphonic acid ligand

Exploring metal phosphonates with new crystal structures is of significance for the development of metal-organic frameworks (MOFs). In this work, two new copper phosphonates, [tetraauqa-1,4-phenylenebis(hydroxymethylene))bisphosphonate biscopper(II)] bishydrate [Cu2(H2L)(H2O)4]·2H2O (1) and 1,4-phenylenebis(hydroxymethylene))bisphosphonate-(4,4’-bipy) copper(II) [Cu(H4L)(4,4’-bipy)] (2) (4,4’-bipy = 4,4’-bipyridine), have been synthesized from a hydroxy functionalized bisphosphonate ligand, H6L = (1,4-phenylenebis(hydroxymethylene))bis(phosphonic acid). The introduction of a hydroxy group can regulate the crystal structures. The bisphosphonate ligand in 1 is hexadentate, binding six copper ions with its six phosphonate oxygen atoms and two hydroxy oxygen atoms, forming a three-dimensional framework structure with rectangle channels running along the b-direction. For 2, the bisphosphonate ligands are double deprotonated and chelate or bridge two copper ions, showing a two-dimensional layered crystal structure. These compounds have interesting fluorescence properties with emission maxima (307 and 410 nm) lying in the blue region.

Synthesis and In Situ Monitoring of Mechanochemical Preparation of Highly Proton Conductive Hydrogen-Bonded Metal Phosphonates.

Crystalline porous materials are recognized as promising proton conductors for the proton exchange membrane (PEM) in fuel cell technology owing to their tunable framework structure. However, it is still a challenging bulk synthesis for real-world applications of these materials. Herein, we report the mechanochemical gram-scale synthesis of two isostructural metal hydrogen-bonded organic frameworks (MHOFs) of Co(II) and Ni(II) based on 1-hydroxyethylidenediphosphonic acid (HEDPH4) with 2,2'-bipyridine (2,2'-bipy): Co(HEDPH3)2(2,2'-bipy)·H2O (1) and Ni(HEDPH3)2(2,2'-bipy)·H2O (2). In situ monitoring of the mechanochemical synthesis using different synchrotron-based techniques revealed a one-step mechanism - the starting materials are directly converted to the product. With the existence of extensive hydrogen bonds with amphiprotic uncoordinated phosphonate hydroxyl and oxygen atoms, both frameworks exhibited proton conduction in the range of 10-4 S cm-1 at room temperature under humid conditions. This study demonstrates the potential of green mechanosynthesis for bulk material preparation of framework-based solid-state proton conductors.

A turn-on fluorescence sensor based on Cu2+ modulated DNA-templated silver nanoclusters for glyphosate detection and mechanism investigation

The abuse application of glyphosate can result in a potential hazard for environment and human, however its ultrasensitive detection remains challenging. Herein, a Cu2+ modulated DNA-templated silver nanoclusters (DNA-AgNCs) sensor was constructed to sensitively determine glyphosate based on the turn-on fluorescence strategy. The fluorescence quenching of DNA-AgNCs occurred with the existence of Cu2+. Upon the presence of glyphosate, the functional groups on the surface of glyphosate could chelate with Cu2+, following the fluorescence recovery of DNA-AgNCs. Through the stoichiometric methods, we unveil that Cu2+-trigged fluorescence quenching mode is a combination of static and dynamic quenching with the static mode being predominant. In DNA-AgNCs/Cu2+ system, the carboxylate, amine, and phosphonate groups of glyphosate interact with Cu2+ through chelation, in which the carboxylate oxygen, the phosphonate oxygen atoms, and the monoprotonated secondary amine nitrogen atom and Cu2+ form chelate rings. This fluorescence sensor showed a desired linearity of glyphosate analysis under the optimum conditions, ranging from 15 to 100 μg/L with a low detection down to 5 μg/L. Moreover, the proposed sensor was successfully utilized to measure glyphosate in real samples, indicating a promising application in pesticide residues detection.

Dysprosium Coordination Polymer Incorporating Dianthracene: Thermo‐induced Phase Transition Accompanied with Magnetic and Optical Changes

AbstractDianthracene ligands obtained through photocycloaddition reaction can undergo de‐dimerization upon heating. Here we report the first examples of lanthanide‐dianthracene coordination polymers with chain structures, namely, [LnL(depma2)]Br ⋅ xH2O [1‐Ln, Ln=Dy (x=5), Gd (x=4); H2L=N1,N3‐bis(salicylideneimino)diethylenetriamine, depma2=photodimerized 9‐diethylphosphonomethylanthracene]. The lanthanide ions possess pseudo‐D5h geometries with five equatorial positions occupied by three N and two O atoms from L2− and two axial positions by the phosphonate oxygen atoms from bridging depma2 ligands. Thermo‐induced structural transformation is observed for both compounds between 120 and 140 °C, which involves de‐dimerization of depma2 and elimination of bromoethane. The structural transformation is accompanied with the switch‐on of photoluminescence and, in the case of 1‐Dy, also changes of magnetic dynamics.

A series of C-Shaped heterometallic Diruthenium(II,III) phosphates: NH4[{M(H2O)5}2Ru2(HPO4)2(PO4)2(H2O)2]·4H2O (M = Mg, Co, Ni and Zn)

A series of heterometallic diruthenium(II,III) phosphates, namely NH4[{M(H2O)5}2Ru2(HPO4)2(PO4)2(H2O)2]·4H2O [M = Mg(1), Co(2), Ni(3) and Zn(4)], were synthesized from reaction of Ru2(PO4)47- and M2+ in aqueous solution. They are composed of ionic crystals with the [{M(H2O)5}2Ru2(HPO4)2(PO4)2(H2O)2]- : NH4+ ratio of 1:1, in which each Ru2 unit is connected in a cis manner to two octahedral environment M(H2O)52+ through phosphonate oxygen (Op) atoms forming a C-shaped ionic structure [{M(H2O)5}2Ru2(HPO4)2(PO4)2(H2O)2]-. The magnetism data fitting with the temperature dependent susceptibility χ(T,D,θ,) and extensional Brillouin function M(H,D,θ) equations convinces that the protonated HPO4 bridges between Ru2(II,III) dimer and M(II) ions mediate ferromagnetic coupling.

Coordination polymers of transition metal diphosphonates: Synthesis, crystal structure and magnetic behaviour

Five new transition metal coordination polymers: [Cu2L(4,4′-bipy)(H2O)0.5] (1), [Cu(H2L)H2O] (2), [Cd2(H2L)2H2O] (3), [Co2L(H2O)2]·0.184H2O (4), [Fe3L2(OH)(H2O)3]·2H2O (5) (H4L = 4-CH3-C6H4CH2N(CH2PO3H2)2), were obtained through hydrothermal reactions. The complexes have been characterized by IR, elemental analysis, TGA and XRD. Crystal structure analysis reveals that all of 2–5 contain 2D inorganic layer structures, constructed by the coordination interactions between metal ions and phosphonate oxygen atoms. 4,4′-bipy molecules in 1 act as a bridging ligand to connect the adjacent 2D layers into a 3D framework. Moreover, magnetic properties of the complexes have been quantificationally investigated by the classical spin approximation and PHI software program, revealing that 2, 4 and 5 exhibit antiferromagnetism, while 1 shows ferromagnetism.

Synthesis, structures, and properties of a series of similar structural coordination polymers with triphosphonate anions as ligands

The hydrothermal reactions of metal precursors with aminotri(methylenephosphonic acid) yielded a series of similar structural coordination polymers of general formula {M[HN(CH2PO3H)3](H2O)3}n [M = Mg(II) (1), Mn(II) (2), Co(II) (3), Zn(II) (4) and Cd(II) (5)]. Compounds 1–5 were characterized by X-ray single crystal diffraction, elemental analyses, and thermogravimetric analyses. Compounds 1–5 all reveal the wave-like 1D chain structures and the structures are constructed by two types of eight-membered, square-like rings linked alternatively via the phosphonate oxygen atoms, generating double-channel systems. The magnetic studies of 2 and 3 reveal that antiferromagnetic interactions are mediated between the metal ions.

3D Framework and Supramolecular Structures Assembly from a Carboxyphosphonic Acid and Transition Metals: Sensing of Nitro Compounds and Surface Photovoltage Properties

AbstractThree new metal carboxyphosphonates with 3D framework and supramolecular structures, namely, [Zn(H4L)2] (1), [Cu2(HL)(H2O)2] (2) and [NH(CH2)4NH]0.5[Cu(H3L)] (3) (H5L=4‐HOOC‐C6H4‐CH2N‐(CH2PO3H2)2), have been synthesized under hydrothermal conditions. For compound 1, {ZnO6} and {CPO3} polyhedra are interconnected into a 2D layer via corner‐sharing, which is further assembled into a 3D supramolecular structure through π‐π stacking interactions. Compound 2 exhibits a 3D framework structure. The interconnection of {CuO4N}, {CuO5} polyhedra and {CPO3} tetrahedra via corner‐sharing forms a 2D inorganic layer. These inorganic layers are further linked via the organic backbone {−C6H4CH2N(CH2)2−} of the carboxyphosphonate ligands, generating a 3D framework structure. In compound 3, two {CuO4N} polyhedra and four {CPO3} tetrahedra are interconnected into a unit, and then these units are further connected into a 1D infinite chain via corner‐sharing. Neighboring chains are assembled into a 2D layered structure through hydrogen bond interactions between the nitrogen atoms from piperazine and uncoordinated phosphonate oxygen atoms. Then, such layers are further assembled into a 3D supramolecular network via interlayer hydrogen bonds. Compound 1 has been realized for the sensitive sensing of 4‐nitrophenol (4‐NP) by luminescence quenching method in the liquid phase. Surface photovoltage properties of compounds 2 and 3 have been investigated.

Two new supramolecular metal diphosphonates: Synthesis, characterization, crystal structure and inhibiting effects on metallic corrosion

Two new divalent metal(II) aminodiphosphonates with layered structure, namely, Cu(H3L1)2·2H2O (1), [H4L1=methyl-N(CH2PO3H2)2] and Cd2(H2L2)4(2), [H4L2=n-propyl-N(CH2PO3H2)2] were synthesized and characterized. The Cu(II) ions in complex 1 are octahedrally coordinated by four oxygen atoms from two chelating ligands and two phosphonate oxygen atoms from two neighboring Cu(H3L1)2 units. The Cu(H3L1)2 units are interconnected by bridging phosphonate groups, forming a 2-D metal phosphonate layer. The structure of complex 2 contains two unique Cd(II) ions octahedrally-coordinated by six phosphonate oxygen atoms from four H2L2 diphosphonate anions. Corrosion inhibition performances of 1 and 2 were also compared with each other in order to study the effect of combinations of externally added Cd/H4L2 and Cu/H4L1 (1:1 ratio) on corrosion rates of carbon steel. It was found that at pH 3.0, Cd/H4L2 or Cu/H4L1 combinations do not have noticeable corrosion inhibition efficiency for carbon steel. In contrast, at pH 7.0, higher corrosion inhibition efficiency was achieved for Cd/H4L2. Physical characterizations such as scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were applied to study the corrosion specimens and film material.

Synthesis, structure, and properties of nitrilo-tris(methylenephosphonato)-triaquairon(II) {Fe[µ-NH(CH2PO3H)3](H2O)3}, as an ingredient of anticorrosive protective coatings on the steel surface

A new non-electrolyte complex of iron(II), {Fe[μ-NH(CH2PO3H)3](H2O)3}, has been synthesized and investigated. The crystallographic characteristics of the complex are as follows: sp. gr. P21/c , Z = 4, a = 9.2619(3) A, b = 16.0548(3) A, c = 9.7570(3) A, and β = 115.685(4)°. The iron atom is octahedrally coordinated by the three phosphonate oxygen atoms and three water molecules in the meridional configuration. The complex has a coordination polymer structure; each Fe atom closes the eight-membered chelating cycle Fe–O–P–C–N–C–P–O, and one of the phosphorus atoms of this cycle is bound with an iron atom of a neighboring structural unit.

Hydrothermal synthesis, crystal structure and properties of a novel chain coordination polymer constructed by tetrafunctional phosphonate anions and cobalt ions

A novel cobalt phosphonate, [Co(HL)(H2O)3]n (1) (L=N(CH2PO3H)33−) has been synthesized by hydrothermal reaction at 150°C and structurally characterized by X-ray diffraction, infrared spectroscopy, elemental and thermogravimetric analysis. Complex 1 features a 1D chain structure with double-channel built from CoO6 octahedra bridged together by the phosphonate groups. Each cobalt ion is octahedrally coordinated by three phosphonate oxygen atoms and three water molecules. The coordinated water molecules can form the hydrogen bonds with the phosphonate oxygen atoms to link the 1D chains, building a 2D layered structure, further resulting in a 3D network. The luminescence spectrum indicates an emission maximum at 435nm. The magnetic susceptibility curve exhibits a dominant antiferromagnetic behavior with a weakly ferromagnetic component at low temperatures.

Hydrothermal synthesis and structural characterization of ammonium ion-templated lanthanide(III) carboxylate-phosphonates.

Using N-(phosphonomethyl) iminodiacetic acid (H4PMIDA), as a complexing agent, two new complexes, (NH4)La(PMIDA)(H2O)•H2O, 1 and (NH4)Yb(PMIDA), 2 have been synthesized hydrothermally. In both compounds, the metal ions are trapped by a three five-membered chelate rings by the chelating PMIDA anions giving a tricapped trigonal prismatic LaO8N and monocapped trigonal prismatic YbO6N geometries for 1 and 2, respectively. The structure of 1 consists of La(PMIDA)(H2O) chelating units, linked together by the phosphonate oxygen atoms O1 and O3 to form a chain along the c-axis. The chains are then connected together by the bridging phosphonate oxygen O2 to form a 2D layered structure with alternating 4- and 8-membered apertures. The structure of 2 consists Yb(PMIDA) chelating units, which are connected by alternating bridging carboxylate and phosphonate groups along the [010] direction forming chains with a corrugated pattern. The third phosphonate oxygen bridges the chains together along the [001] direction to build the two-dimensional layer with 4- and 6-membered apertures in the bc-plane. Under excitation of 330 nm, compound 2 shows a broad emission band at λmax = 460 nm. This emission is essentially in the blue luminescent region, which corresponds to ligand centered fluorescence.

M2(pbtcH)(phen)2(H2O)2 [M(II)=Co, Ni]: Mixed-ligated metal phosphonates based on 5-phosphonatophenyl-1,2,4-tricarboxylic acid showing double chain structures

Two new mixed-ligated metal phosphonates, M2(pbtcH)(phen)2(H2O)2 [M(II) = Co (1), Ni (2)] (pbtcH5 = 5-phosphonatophenyl-1,2,4-tricarboxylic acid, phen = 1,10-phenanthroline), have been synthesized and characterized. Both show one-dimensional double chain structures, where the M(phen)(H2O) moieties are chelated and bridged by pbtcH4− through the carboxylate and phosphonate oxygen atoms. The chains are connected by hydrogen bonding interactions and π–π stacking, forming a three-dimensional supramolecular structure. The IR and magnetic properties of the two compounds are also investigated.

Syntheses, structures, thermal stabilities and magnetic properties of two-layered metal diphosphonates

Hydrothermal reactions of CuII or NiII with risedronic acid (H4Ris) in the presence of organic amine afforded two-layered metal phosphonates with different types of structures, namely [Cu2(HRis)]·(H2O)·0.5(NH2CH2CH2NH2) (1) and [Ni(HRis)2]2{Ni(H2O)2}2]·H2O (2). In compound 1, the adjacent equivalent [Cu1O5] square pyramids are linked by two μ2-O atoms into an edge-sharing {Cu2(μ2-O)2} dimer. These dimers are linked together by four {PCO3} tetrahedra, leading to an inorganic chain. The adjacent chains are further connected by Cu atoms through the phosphonate oxygen atoms from one chain and one pyridyl nitrogen atom (N1) from the other chain to give an organic–inorganic layer. In compound 2, the Ni is connected by O–P–O units into a chain structure, which is further connected by {NiO6} octahedra into a double-chain structure. Neighboring double chains are linked by HRis3− ligands into a layered structure. Magnetic susceptibility measurements indicate that antiferromagnetic interactions dominate in both complexes.

A Series of Imidazolyl-Containing Bisphosphonates with Abundant Hydrogen-Bonding Interactions: Syntheses, Structures, and Bone-Binding Affinity

A series of novel bisphosphonates (BPs) were designed and synthesised as longer-chain analogues of the clinically widely used BP–zoledronate (ZL). They were characterised by mass spectrometry, infrared spectroscopy, NMR spectroscopy, and single-crystal X-ray diffraction. All the crystals are zwitterions with one of the phosphonate oxygen atoms deprotonated and the hydrogen atom transferred to the nitrogen of the imidazole ring. A lot of strong hydrogen bonds are observed among the phosphonate oxygens, hydroxy groups, and protonated nitrogen atoms. An accurate, precise, and robust method was developed to determine the bone binding affinities of BPs based on high performance liquid chromatography. The results show that these five BPs have a strong affinity for hydroxyapatite and the binding capacity decreases when the substituted alkyl groups increase in size.

Supported monocationic copper(II) complexes obtained by coordination with dialkylphosphonate groups on styrene–divinylbenzene copolymer as catalysts for oxidation of organic compounds

New catalysts were synthesized by immobilization of neutral and monocationic copper complexes Cu(hfac)2 (hfac−=hexafluoroacetylacetonato ligand) and [Cu(acac)(tmen)]NO3 (acac−=acetylacetonato ligand, tmen=N,N,N′,N′-tetramethyl-ethylendiamine) on styrene–divinylbenzene copolymer functionalized with four different dialkyl phosphonate moieties typified by PPO(OR)2 (with R=CH3, C2H5, iC3H7, and nC4H9). The formation of P(O)(OR)2 phosphonates groups has been confirmed by the FT-IR spectra. Thermogravimetric analysis results reveal that the thermal stability of polymer support depend on the functional group attached. The complexes were anchored by coordination interaction between the copper(II) ion and the phosphonate oxygen atom on each of the four functionalized supports and the strength of the PO⋯Cun+ coordination interaction was influenced by the nature of the R group. The effect of functionalized supports on the structure and catalytic activity of Cu(hfac)2 and [Cu(acac)(tmen)]+ mononuclear species was determined in oxidation of several organic compounds (anisole, cyclohexene, toluene, styrene, phenol) with hydrogen peroxide. The catalytic activity results show that the activity and selectivity of Cu(II) complexes depends on the equilibrium between steric factor and inductive electron-releasing effect. The best selectivity was obtained in oxidation of anisole, phenol and styrene for all the catalysts. The main products were for 2-methoxyphenol, catechol and benzaldehyde, respectively.

Divalent metal phosphonate coordination polymers constructed from a dipiperidine-based bisphosphonate ligand

The ligand 4,4'-dipiperidine-N,N'-bis(methylenephosphonic acid), H(4)L, has been reacted with divalent metal salts under solvothermal conditions to yield seven new metal phosphonate coordination polymers. The compounds have been characterized by elemental analyses and their structures determined by single-crystal X-ray diffraction. Zn(2)(L)(H(2)O)(2) and Co(2)(L)(H(2)O)(2) have (different) layered structures, while Mn(2)(L)(H(2)O)(3) has a chain motif. In these compounds, the N atoms of the ligand bind to the metal ions. α-Co(2)Cl(2)(H(2)L), formed from CoCl(2)·6H(2)O and H(4)L in ethanol, is also layered but the N atoms of the ligand are protonated. The Co atoms are tetrahedral, coordinated by three phosphonate oxygen atoms and a chloride ion. A polymorph of this compound, β-Co(2)Cl(2)(H(2)L), was obtained from a mixed ionic liquid under microwave irradiation. The primary difference between the polymorphs is the orientation of the phosphonate group relative to the dipiperidine. When reacted hydrothermally with Sn(II)C(2)O(4), H(4)L partially decomposes, producing phosphate ions which are incorporated into the structure of Sn(6)O(2)(H(2)L)(PO(4))(2)·4H(2)O. In this compound, the N atoms of the ligand are protonated, and two oxide anions are incorporated for charge balance. A second phase is obtained from the same reaction, which was determined to be Sn(7)O(L)(3). This compound has a layered structure which contains relatively large voids within the inorganic portion of the layer. These structures are discussed, as well as factors influencing the state of protonation in the final compounds. The choice of solvent and temperature were found to have a significant influence on the type of structure obtained.

Metal complexes as templates: syntheses, structures, and luminescent properties of two zinc phosphonocarboxylates with ABW-zeolite topology

Two novel zinc phosphonocarboxylates, Zn(3)(pbc)(2)(bpy)(H(2)O)·H(2)O (1) and Zn(2)(pbc)(2)·Zn(bpy)(H(2)O)(4)·2H(2)O (2) (pbc = 4-phosphono-benzoic acid, bpy = 2,2'-bipyridine), were hydrothermally synthesized and structurally characterized. Both of them exhibit zeolitic ABW topology in which double-zigzag inorganic chains are cross-linked by the organic parts. It is notable that the metal complex Zn(bpy)(H(2)O)(x) plays different roles in the two compounds. In 1, the Zn(bpy)(H(2)O) units coordinate with the phosphonate and carboxylate oxygen atoms and participate in the construction of the three-dimensional framework. In 2, the in situ generated [Zn(bpy)(H(2)O)(4)](2+) cation acts as a template, which directs the ABW-type open-framework by strong hydrogen bonds. It is the first example where a metal complex is used as a template in the synthesis of metal phosphonates. The luminescent properties of 1 and 2 are also investigated.

Synthesis, characterization, and crystal structure of a 2-D metal diphosphonate: Cu3(H2O)2[HO3PCH2N(CH3)CH2PO3]2 · 2H2O

Hydrothermal reaction of N-methyl-iminobis(methylenephosphonic acid), CH3N(CH2PO3H2)2, (H4L) with copper(II) acetate afforded a new layered Cu(II) amino diphosphonate, Cu3(H2O)2(HL)2 · 2H2O (1). Compound 1 was studied by IR spectroscopy, TGA/DTA data, and X-ray diffraction (XRD) techniques. The XRD patterns are the same for the hydrated and the dehydrated complexes. A single-crystal X-ray crystallographic determination reveals copper in two different coordination environments. Cu1 has a distorted elongated tetragonal octahedral geometry, whereas Cu2 has a square-pyramidal distorted geometry. The HL trianion is a pentadentate ligand with a deprotonated nitrogen atom and two oxygen atoms of each phosphonate binding to copper. Hydrogen bonds between lattice water molecules in interlayer spaces and the non-coordinated phosphonate oxygen atoms as well as water ligands leads to a 3-D supramolecular network structure.

Pillared and open-framework uranyl diphosphonates

The hydrothermal reactions of uranium trioxide, uranyl acetate, or uranyl nitrate with 1,4-benzenebisphosphonic acid in the presence of very small amount of HF at 200 °C results in the formation of three different uranyl diphosphonate compounds, [H 3O] 2{(UO 2) 6[C 6H 4(PO 3)(PO 2OH)] 2[C 6H 4(PO 2OH) 2] 2[C 6H 4(PO 3) 2]}(H 2O) 2 ( Ubbp-1), [H 3O] 4{(UO 2) 4[C 6H 4(PO 3) 2] 2F 4}·H 2O ( Ubbp-2), and {(UO 2)[C 6H 2F 2(PO 2OH) 2(H 2O)} 2·H 2O ( Ubbp-3). The crystal structures of these compounds were determined by single crystal X-ray diffraction experiments. Ubbp-1 consists of UO 7 pentagonal bipyramids that are bridged by the phosphonate moieties to form a three-dimensional pillared structure. Ubbp-2 is composed of UO 5F 2 pentagonal bipyramids that are bridged through the phosphonate oxygen atoms into one-dimensional chains that are cross-linked by the phenyl spacers into a pillared structure. The structure of Ubbp-3 is a three-dimensional open-framework with large channels containing water molecules with internal dimensions of approximately 10.9×10.9 Å. Ubbp-1 and Ubbp-2 fluoresce at room temperature.