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

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

Ab initio calculation of the 31P NMR shielding tensor for the series POaFb−(2a+b−5), a+b=4 and for HPO42−

Ab initio coupled Hartree-Fock perturbation theory (CHFPT) calculations on PO₄³⁻, PO₃F²⁻, PO₂F₂⁻, PF₃O, PF₄⁺ and HPO₄²⁻ using large polarized Gaussian bases satisfactorily reproduce experimental trends in ³¹P magnetic shielding anisotropies.Accurate evaluation of the shielding tensor for HPO₄²⁻ requires the inclusion of the H atom. Along the series PO_a F_b^{−(2a+b−5)} the calculated isotropic shielding shows a “sagging” pattern, i.e. the shielding is smallest for the intermediate member of the series PO₃F²⁻. The shielding for this species is, however, a strong function of the P-F and P-O distances. PO₃F²⁻ and HPO₄²⁻ are calculated to be similar in both average shielding and shielding anisotropy.     

Hydrothermal synthesis and structural characterization of organically-templated copper vanadium phosphates: the two-dimensional [{Cu2(bisterpy)}V3O5(HPO4)2(PO4)] (1) and the three-dimensional [{Cu2(bisterpy)}V2O5(HPO4)2] (2) (bisterpy=2,2′:4′,4″:2″,2‴-quarterpyridyl, 6′,6″-dipyridine)

The hydrothermal reactions of appropriate vanadium oxides and copper(II) salts with bisterpy in the presence of phosphoric acid or fluorophosphoric acid yield the Cu(II)-bisterpy/oxovanadium phosphate materials [{Cu₂(bisterpy)}V₃O₅(HPO₄)₂(PO₄)] (1) and [{Cu₂(bisterpy)}V₂O₅(HPO₄)₂] (2). Compound 1 is layered material, consisting of inorganic {V₃O₅(HPO₄)₂(PO₄)}_n⁴ⁿ⁻ chains propagating parallel to the crystallographic a-axis, linked in the second dimension through binuclear {Cu₂(bisterpy)}⁴⁺ units. The chain is constructed from corner-sharing {V₄O₁₀(PO₄)₂}⁶⁻ and {V₂O₂(PO₄)₄}⁶⁻ cluster building blocks. There are two distinct vanadium sites: a tetrahedral {V(V)O₄} site and a square pyramidal {V(IV)O₅} center. The Cu(II)-bisterpy subunits are linked to the vanadophosphate chains through phosphate oxygen atoms exclusively. In contrast, the structure of 2 is three-dimensional, exhibiting inorganic {Cu₂V₂O₅(HPO₄)₂}_n networks linked through bisterpy bridges to provide the overall three-dimensional connectivity. The oxovanadium subunit consists of the well-documented {V₂O₇} binuclear unit of corner-sharing tetrahedral.     

Fe6.67(PO4)5.35(HPO4)0.65 and Fe6.23(PO4)4.45(HPO4)1.55: two new mixed‐valence iron phosphates

Two new mixed‐valence iron phosphates, namely heptairon pentaphosphate hydrogen phosphate, Fe_6.67(PO₄)_5.35(HPO₄)_0.65, and heptairon tetraphosphate bis(hydrogen phosphate), Fe_6.23(PO₄)_4.45(HPO₄)_1.55, have been synthesized hydrothermally at 973 K and 0.1 GPa. The structures are similar to that of Fe^II₃Fe^III₄(PO₄)₆ and are characterized by infinite chains of Fe polyhedra parallel to the [101] direction. These chains are formed by the Fe1O₆ and Fe2O₆ octahedra, alternating with the Fe4O₅ distorted pentagonal bipyramids, according to the stacking sequence ...Fe1–Fe1–Fe4–Fe2–Fe2.... The Fe3O₆ octahedra and PO₄ tetrahedra connect the chains together. Fe^II is localized on the Fe3 and Fe4 sites, whereas Fe^III is found in the Fe1 and Fe2 sites, according to bond‐valence calculations. Refined site occupancies indicate the presence of vacancies on the Fe4 site, explained by the substitution mechanism Fe^II + 2(PO₄³⁻) = vacancies + 2(HPO₄²⁻).     

Synthesis and physicochemical properties of calcium hydroxylapatite/multi-walled carbon nanotubes nanocomposites

Calcium hydroxylapatite/carbon nanotubes (HA/CNT) composites with various CNT contents have been synthesized by coprecipitation from aqueous solutions in the CaCl₂-(NH₄)₂HPO₄-NH₃-CNT-H₂O system (25°C) under conditions modeling the interaction between HA (Ca₁₀(PO₄)₆(OH)₂), which is an inorganic component of osseous tissue, and multi-walled CNTs. The empirical formula of the composites is Ca₁₀(PO₄)₆(OH)₂ · nCNT · 6H₂O, where n = 0.2?C5.0. The synthesis products have been identified by the solubility (Tananaev??s residual concentration) method, pH measurements, chemical analysis, X-ray diffraction, IR spectroscopy, electron spectroscopy for chemical analysis, and scanning and transmission electron microscopy. The effect of the CNT concentration in aqueous solution on the composition of the HA/CNT composites and on the crystallographic and morphological characteristics of HA nanocrystals in HA/CNT has been investigated.     

Hydrothermal synthesis and structural characterization of two new reduced phosphomolybdates based on an organoamine template and copper ion

Two new compounds, (H₂en)₃(H₂enMe)₄(H₃O){Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}?·?6H₂O (1) and (H₂enMe)₄{Cu^ICu^II[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}?·?3H₂O (2), were hydrothermally synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction analysis. Crystallographic analysis reveals that 1 is constructed from cluster anions {Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}^15?, protonated organic amines, and water molecules. Each cluster is bridged through hydrogen bonds to form a 3-D supermolecular structure. For 2, {Cu^I[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}^11? are connected by Cu^II cations to form an infinite chain. The formation of 1 and 2 reveals that organoamines influence the structures of the crystals.     

K6[Fe8.27(HPO3)12]: a new mixed‐valence iron phosphite

The title compound, hexapotassium octairon(II,III) dodecaphosphonate, exhibiting a two‐dimensional structure, is a new mixed alkali/3d metal phosphite. It crystallizes in the space group Rm, with two crystallographically independent Fe atoms occupying sites of m (Fe1) and 3m (Fe2) symmetry. The Fe2 site is fully occupied, whereas the Fe1 site presents an occupancy factor of 0.757 (3). The three independent O atoms, one of which is disordered, are situated on a mirror and all other atoms are located on special positions with 3m symmetry. Layers of formula [Fe₃(HPO₃)₄]²⁻ are observed in the structure, formed by linear Fe₃O₁₂ trimer units, which contain face‐sharing FeO₆ octahedra interconnected by (HPO₃)²⁻ phosphite oxoanions. The partial occupancy of the Fe1 site might be described by the formation of two [Fe(HPO₃)₂]⁻ layers derived from the [Fe₃(HPO₃)₄]²⁻ layer when the Fe1 atom is absent. Fe²⁺ is localized at the Fe1 and Fe2 sites of the [Fe₃(HPO₃)₄]²⁻ sheets, whereas Fe³⁺ is found at the Fe2 sites of the [Fe(HPO₃)₂]⁻ sheets, according to bond‐valence calculations. The K⁺ cations are located in the interlayer spaces, between the [Fe₃(HPO₃)₄]²⁻ layers, and between the [Fe₃(HPO₃)₄]²⁻ and [Fe(HPO₃)₂]⁻ layers.     

The hydrogenphosphate complex of (1,5-cyclooctadiene)iridium(I), {[Bu4N][(1,5-COD)Ir · HPO4]}n: synthesis, spectroscopic characterization, and ES-MS of a new, preferred precursor to HPO4 and Bu4N stabilized Ir(0)n nanoclusters

The synthesis and characterization of a previously unknown, rare organometallic-phosphate complex, {[Bu₄N][(1,5-COD)Ir · HPO₄]}_n (1), is described. Characterization of 1 was accomplished by elemental analysis, electrospray mass spectrometry (ES-MS), and ¹H and ¹³C NMR which established the symmetry of the product as at least C₂ or C_s. The ES-MS reveals an interesting, Ir(I) to Ir(III) oxidative process with intense peaks displaying the ¹⁹¹Ir/¹⁹³Ir isotopic distribution patterns expected for the fragments [(1,5-COD)Ir^III(HPO₄)₂]⁻, [(C₈H₁₁)₂(Ir^III)₂(PO₄)(HPO₄)(H₂O)]⁻, and [(C₈H₁₁)₂(Ir^III)₂(PO₄)(HPO₄)(H₂O)₂]⁻. These fragments, in turn, provide evidence for a structure with two HPO₄²⁻ groups attached to a single Ir, for example ring structures (of at least such C₂ or C_s symmetry) such as {[Bu₄N][(1,5-COD)Ir · HPO₄]}₂. Complex 1 is significant since it is known to be the preferred, compositionally precise precursor to the prototype example of a recently discovered class of novel, HPO₄²⁻ and Bu₄N⁺ stabilized nanoclusters, (Bu₄N)_2n²ⁿ⁺[Ir(0)_n · (HPO₄)_n]²ⁿ⁻. Such nanoclusters are being extended, via their analogous hydrogenphosphate-organometallic precursors (1,5-COD)M^{+ or 2+}/HPO₄²⁻ (M=Rh(I), Ru(II), Pt(II)) to their corresponding, catalytically active [M(0)_n · (HPO₄)_n]²ⁿ⁻ nanoclusters.     

The Standard Chemical-Thermodynamic Properties of Phosphorus and Some of its Key Compounds and Aqueous Species: An Evaluation of Differences between the Previous Recommendations of NBS/NIST and CODATA

The aqueous chemistry of phosphorus is dominated by P(V), which under typical environmental conditions (and depending on pH and concentration) can be present as the orthophosphate species H₃PO ₄ ⁰ (aq),H₂PO ₄ ^? (aq),HPO ₄ ^2? (aq) or PO ₄ ^3? (aq). Many divalent, trivalent and tetravalent metal ions form sparingly soluble orthophosphate phases that, depending on the solution pH and concentrations of phosphate and metal ions, can be solubility limiting phases. Geochemical and chemical engineering modeling of solubilities and speciation require comprehensive thermodynamic databases that include the standard thermodynamic properties for the aqueous species and solid compounds. The most widely used sources for standard thermodynamic properties are the NBS (now NIST) Tables (from 1982 and earlier, with a 1989 erratum) and the final CODATA evaluation (1989). However, a comparison of the reported enthalpies of formation and Gibbs energies of formation for key phosphate compounds and aqueous species, especially H₂PO ₄ ^? (aq) and HPO ₄ ^2? (aq), shows a systematic and nearly constant difference of 6.3 to 6.9 kJ?mol^?1 per phosphorus atom between these two evaluations. The existing literature contains numerous studies (including major data summaries) that are based on one or the other of these evaluations. In this report we examine and identify the origin of this difference and conclude that the CODATA evaluation is more reliable. Values of the standard entropies of the H₂PO ₄ ^? (aq) and HPO ₄ ^2? (aq) ions at 298.15 K and p?° =1 bar were re-examined in the light of more recent information and data not considered in the CODATA review, and a slightly different value of S _m ^o (H₂PO ₄ ^? , aq, 298.15 K) = (90.6±1.5) J?K^?1?mol^?1 was obtained.     

Hydrothermal synthesis and structural determination of a three-dimensional microporous iron(III)phosphate: [H3N(CH2)4NH3]3[Fe8(HPO4)12(PO4)2(H2O)6]

A new microporous iron (III) phosphate, [H₃N(CH₂)₄NH₃]₃[Fe₈(HPO₄)₁₂(PO₄)₂(H₂O)₆], has been prepared using low temperature hydrothermal methods and characterized by single-crystal X-ray diffraction, EDAX, infrared spectroscopy, thermogravimetric analysis and bond valence sums. The title compound crystallizes as light pink hexagonal-shaped tabs in the centrosymmetric hexagonal space group 3¯ (No.147) with a = b = 13.495(2) Å, c = 9.396(2) Å, V = 1481.9(4) ų and Z = 4 with R/R_w = 0.044/0.048. The compound exhibits a complicated three-dimensional microporous structure with quaternary ammonium ions acting as a template for the framework. It is similar to previously reported [HN(CH₂CH₂)₃NH]₃[Fe₈(HPO₄)₁₂(PO₄)₂(H₂O)₆].     

Hydrothermal synthesis and characterization of a new layered gallophosphate JGP-L1 with a Ga/P ratio of non-unity

A new compound, Ga₆(OH)₄(HPO₄)₂(PO₄)₅·C₈H₂₈N₅·3H₂O (denoted JGP-L1), with a gallophosphate layer and a Ga/P ratio of 6/7 has been synthesized hydrothermally by using tetraethylenepentamine as template. It is characterized by powder X-ray diffraction (XRD), elemental analysis, inductively coupled plasma, and TGA analysis and structurally determined by single-crystal XRD analysis. JGP-L1 crystallizes in the orthorhombic, space group Pna2₁ (no. 33), with a=16.422(3), b=11.898(2), c=18.730(4) Å, V=3659.6(13) Å³ and Z=4. The structure of JGP-L1 is built up by alternating of Ga(OH)₂O₄ octahedra, Ga(OH)O₄ trigonal bipyramids and PO₄ (or HPO₄) tetrahedra to form inorganic sheets. It is noteworthy that JGP-L1 was synthesized with extremely low reactant concentration, where the reaction mixture exhibits a H₂O:Ga₂O₃ molar ratio of 2220:1.     

Magnetic and catalytic properties of the 2D copper(II) functionalized VPO hybrid system [{Cu(bpy)}2(VO)3(PO4)2(HPO4)2]·2H2O

The hybrid 2D compound [{Cu(bpy)}₂(VO)₃(PO₄)₂(HPO₄)₂]·2H₂O (1), has been investigated due to its interesting magnetic and catalytic properties. Compound (1) acts as an efficient catalyst in the epoxidation of cyclohexene and styrene. The chemoselectivity towards the epoxidation of cyclohexene is notoriously higher than the one observed towards styrene. The bulk antiferromagnetic behaviour of [{Cu(bpy)}₂(VO)₃(PO₄)₂(HPO₄)₂]·2H₂O (1) can be well described with a pentanuclear model, using five J values. Both antiferromagnetic and ferromagnetic interactions mediated by phosphate bridges are found to be present in this hybrid copper(II)–vanadium(IV) material.     

New Gallium Phosphate Frameworks Containing 1,4-Diaminobutane and 1,5-Diaminopentane: [NH3(CH2)xNH3][Ga4(PO4)4(HPO4)] and [NH3(CH2)xNH3][Ga(PO4)(HPO4)] (x=4 and 5)

Two new gallium phosphates, [NH₃(CH₂)₄NH₃][Ga₄(PO₄)₄ (HPO₄)] (I) and [NH₃(CH₂)₄NH₃][Ga(PO₄)(HPO₄)] (II), have been synthesized under solvothermal conditions in the presence of 1,4-diaminobutane and their structures determined using room-temperature single-crystal X-ray diffraction data. Compound (I) (M_r=844.90, triclinic, space group P-1, a=9.3619(3), b=10.1158(3) and c=12.6456(5) Å, α=98.485(1), β=107.018(2) and γ=105.424(1)°; V=1070.39 ų, Z=2, R=3.68% and R_w=4.40% for 2918 observed data [I>3(σ(I))]) consists of GaO₄ and PO₄ tetrahedra and GaO₅ trigonal bipyramids linked to generate an open three-dimensional framework containing 4-, 6-, 8-, and 12-membered rings of alternating Ga- and P-based polyhedra. 1,4-Diaminobutane dications are located in channels bounded by the 12-membered rings in the two-dimensional pore network and are held to the framework by hydrogen bonding. Compound (II) (M_r=350.84, monoclinic, space group P2₁/c, a=4.8922(1), b=18.3638(6) and c=13.7468(5) Å, β=94.581(1)°; V=1227.76 ų, Z=4, R=2.95% and R_w=3.37% for 2050 observed data [I>3(σ(I))]) contains chains of edge-sharing 4-membered rings of alternating GaO₄ and PO₄ tetrahedra constituting a backbone from which hang ‘pendant’ PO₃(OH) groups. Hydrogen bonding between the GaPO framework and the diamine dications holds the structure together. A previously reported phase, [NH₃(CH₂)₄NH₃][Ga₄(PO₄)₄(HPO₄)] (V), structurally related but distinct from its stoichiometric equivalent, (I), has been prepared as a pure phase by this method. Two further materials, [NH₃(CH₂)₅NH₃][Ga₄(PO₄)₄(HPO₄)] (III) (tricli- nic, lattice parameters from PXD: a=9.3565(4), b=5.0156(2) and c=12.7065(4) Å, α=96.612(3), β=102.747(4) and γ=105.277(3)°) and [NH₃(CH₂)₅NH₃][Ga(PO₄)(HPO₄)] (IV) (M_r=364.86, monoclinic, space group P2₁/n, a=4.9239(2), b=13.2843(4) and c=19.5339(7) Å, β=96.858(1)°; V=1268.58 ų, Z=4, R=3.74% and R_w=4.44% for 2224 observed room-temperature data [I>3(σ(I))]), were also prepared under similar conditions in the presence of 1,5-diaminopentane. (III) and (IV) are structurally related to, yet distinct from (I) and (II) respectively.     

Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-phenylalanine L-phenylalaninium malonate

The mineral crandallite CaAl₃(PO₄)₂(OH)₅·(H₂O) has been identified in deposits found in the Jenolan Caves, New South Wales, Australia by using a combination of X-ray diffraction and Raman spectroscopic techniques. A comparison is made between the vibrational spectra of crandallite found in the Jenolan Caves and a standard crandallite. Raman and infrared bands are assigned to PO₄³⁻ and HPO₄²⁻ stretching and bending modes. The predominant features are the internal vibrations of the PO₄³⁻ and HPO₄²⁻ groups. A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated.     

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O, CsHfF₂PO₄ · 0.5H₂O, CsHf₂F₆PO₄ · 4H₂O and X-ray amorphous Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O, Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O) was determined. The weight ratios Cs⁺/Hf and PO ₄ ^3? /ZrHf in CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O were confirmed by identifying the calcination production CsHf₂(PO₄)₃ (～1000°C). A new crystalline compound CsHf₂F(HPO₄)(PO₄)₂ was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf₂(PO₄)₃, which was different from the already known one, was proposed. It was ascertained that CsHf₂(PO₄)₃ possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.     

Synthesis,structure and NMR characterization of a new monomeric aluminophosphate [dl-Co(en)3]2[Al(HPO4)2(H1.5PO4)2(H2PO4)2](H3PO4)4 containing four different types of monophosphates

A new zero-dimensional (0D) aluminophosphate monomer [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄ (designated AlPO-CJ38) with Al/P ratio of 1/6 has been solvothermally prepared by using racemic cobalt complex dl-Co(en)₃Cl₃ as the template. The Al atom is octahedrally linked to six P atoms via bridging oxygen atoms, forming a unique [Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂]^6? monomer. Notably, there exists intramolecular symmetrical O?H?O bonds, which results in pseudo-4-rings stabilized by the strong H-bonding interactions. The structure is also featured by the existence of four different types of monophosphates that have been confirmed by ³¹P NMR and ¹H NMR spectra. The crystal data are as follows: AlPO-CJ38, [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄, M = 1476.33, monoclinic, C2/c (No. 15), a = 36.028(7) Å, b = 8.9877(18) Å, c = 16.006(3) Å, β = 100.68(3)°, U = 5093.2(18) Å³_, Z = 4, R₁ = 0.0509 (I > 2σ(I)) and wR₂ = 0.1074 (all data). CCDC number 689491.     

Syntheses,crystal structures and optical properties of two one‐dimensional germanophosphates: HRb3Ge2(HPO4)6 and CsGe(HPO4)2(OH)

Germanophosphates, as a young class of metal phosphates, have been less reported but might possess more diverse structural types and potential applications. Here, two one‐dimensional (1D) alkali‐metal germanophosphates (GePOs), namely, hydrogen hexakis(μ‐hydrogen phosphato)digermaniumtrirubidium, HRb₃Ge₂(HPO₄)₆ ( 1 ), and caesium bis(μ‐hydrogen phosphato)(μ‐hydroxido)germanium, CsGe(HPO₄)₂(OH) ( 2 ), have been prepared by the solvothermal method. Compound 1 shows 1D [Ge(HPO₄)₆]_∞ chains along the c axis formed by GeO₆ octahedra and PO₄ tetrahedra, with Rb⁺ cations dissociated between the chains. Compound 2 also exhibits 1D [Ge(HPO₄)₄(OH)₂]_∞ chains constructed from adjacent Ge(HPO₄)₄(OH)₂ octahedra, with Cs⁺ cations dissociated between the chains. XRD, TGA, IR and UV–Vis–NIR absorption spectra are presented and discussed for both compounds.     

Assembly of two novel inorganic–organic hybrid solids based on 3-(aminomethyl)pyridine ligand

Two new inorganic–organic hybrids, (Hampy)Zn₂(PO₄) (HPO₃) (1) and (ampy)Zn₂(HPO₃)₂ (2), where ampy = 3-(aminomethyl)pyridine, have been solvothermally prepared and structurally characterized. Compound 1 exhibits an unusual two-dimensional layer structure, which possesses a central 4.8² zincophosphate sheet wrapped by infinite zincophosphite chains. Left- and right-handed helical chains participate in the formation of the zincophosphate layer. Compound 2 features a three-dimensional pillared-layer structure, in which two-dimensional Zn^II(HPO₃) inorganic sheets were cross-linked by ampy ligands. The simultaneous occurrence of zinc-amine helical chains in 2 is unique and, to the best of our knowledge, firstly encountered in phosphite/phosphate hybrid materials. Different coordination modes and roles of the same ampy ligand were observed in the formation of the hybrid structures.     

A mechanistic investigation on the formation of molybdophosphate complexes in aqueous solution by the use of laser Raman spectroscopy

Two distinct reaction rates were found in the formation of 12-molybdophosphate complex. These differences in the formation processes were understood by the use of laser Raman spectroscopy. The reaction of isopolymolybdate (MoO₄)²⁻(MoO₃)₁₁ with phosphate PO₄^⋯- proceeds slowly via formation of 11- molybdophosphate then to produce 12-molybdophosphate taken for 8 min. This reaction mechanism is considered to undergo first the replacement between MoO₄²⁻ and PO₄³⁻ then the transformation reaction from 11-molybdophosphate into 12-molybdophosphate. On the other hand, the acidification of the mixed solution of molybdate and phosphate rapidly produces 80% of 12-molybdophosphate within 30 s.     

(C6H17N3)[Zn4(PO4)2(HPO3)2]: a new layered zinc phosphate-phosphite templated by 1-(2-Aminoethyl) piperazine

Employing 1-(2-Aminoethyl) piperazine as a template, a new organically templated layered zinc phosphate-phosphite (C₆H₁₇N₃)[Zn₄(PO₄)₂(HPO₃)₂] has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group Cc with a=5.3272(11) Å, b=17.146(3) Å, c=22.071(4) Å, β=94.58(3)°, V=2009.5(7) Å³, Z=4, R₁=0.0201 (I>2σ(I)) and wR₂=0.0812 (all data). The inorganic network is based on strictly alternating ZnO₄ tetrahedral units and P-centered units including PO₄ tetrahedra and HPO₃ pseudo-pyramids forming a double layered structure that contains columns of double six-membered rings. The diprotonated 1-(2-Aminoethyl) piperazine molecules reside in the interlayer region and interact with the inorganic network through H-bonds.