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A surface coating made of α-zirconium phosphate (α-ZrP) nanoparticles was synthesized using one-step drop-cast processing. The coating consisted of surface-modified α-ZrP nanoparticles of three dif...

According to the solid-state 13C, 31P NMR study and 13C chemical shift anisotropy (CSA) measurements, aromatic rings in the layered metal(IV) phosphonate materials behave as low-energy rotors at ro...

Nanosized α-zirconium phenylphosphonate particles were successfully prepared by the reaction between different zirconium sources and molten phenylphosphonic acid in the absence of solvent. The resultant nanoplates exhibit particle sizes in the range of 15 to 30 nm. The use of a topotactic anion exchange method starting from α-zirconium phosphate instead resulted in the generation of 15 to 180 nm plates, while also resulting in nanoparticles with a higher degree of crystallinity. The topotactic anion exchange of the phosphate groups by phenylphosphonate groups could be performed to completion when performed in molten phenylphosphonic acid. Characterization of both the final products as well as the individual steps in the anion exchange were performed by powder XRD, fast neutron activation analysis, TGA, FTIR spectroscopy, TEM, solid-state NMR and XPS.

A layered prism is an ideal system for fundamental studies due to its unique structure with uniform-sized sheets. However, there are very limited reports in the last few decades on the preparation of such materials. In this contribution, we report for the first time the preparation of α-ZrP intercalation compound-based hexagonal prisms. Preferential crystal growth perpendicular to the (001) crystal plane of α-ZrP intercalation compounds was achieved by incorporating a complexing agent and a layer growth coordinator into a crystal growth reaction system. With the presence of a layer growth coordinator to coordinate the crystal growth perpendicular to the (001) crystal plane and the presence of a complexing agent to slow down the crystal growth rate, the previously unknown layer growth coordination effect is revealed. After a facile ion exchange treatment, pure α-ZrP hexagonal prisms can also be obtained.

Isotropic and anisotropic motions and molecular states of pyridine-d5, adsorbed on the surface within the pores of a layered Sn(iv) phosphonate-phosphate material (1) have been characterized thermodynamically and kinetically by solid-state NMR. The data obtained provide formulation of macrostructure and shapes of pores in 1.

The advancement of electric vehicles demands lubricants with multifunction and performance. In this research, we investigated amphiphilic ZrP nanoparticles as lubricant additives. Experiments showed that the nanolubricant produced a tribofilm reduced the friction for 40% and wear 90%, while the electrical conductivity remained to be stable during tribotesting. Surface characterization of the tribofilm showed that there was a layered pyrophosphate on the wear track. The in situ impedance study about tribochemical kinetics revealed that the process in formation of a tribofilm involved simultaneous growth and wear. During growth, the coefficient of friction increased with continued formation of such film. During wear, the material removal rate was a function of friction, i.e., the higher the wear-rate, the higher the friction coefficient. The competing mechanisms of film growth and wear resulted in an electrically uniformed surface.

Nanocrystalline (nc) graphite produced from pyrolyzed vegetable oil has properties that deviate from typical graphites, but is similar to the previously reported G raphite from the U niversity of I daho T hermolyzed A sphalt R eaction (GUITAR). These properties include (i) fast heterogeneous electron transfer (HET) at its basal plane and (ii) corrosion resistance beyond graphitic materials. To discover the structural basis for these properties, characterization of this nc-graphite was investigated with Raman and X-ray photoelectron spectroscopies, nano-indentation, density, X-ray diffraction (XRD), thermogravimetric and elemental analyses. The results indicate that this nc-graphite is in Stage-2 of Ferrari's amorphization trajectory between amorphous carbon (a-C) and graphite with a sp2/sp3 carbon ratio of 85/15. The nano-crystallites size of 1.5 nm from XRD is consistent with fast HET rates as this increases the density of electronic states at the Fermi-level. However, d-spacing from XRD is 0.350 nm vs. 0.335 for graphite. This wider distance does not explain its corrosion resistance. Literature trends suggest that increasing sp2 content in a-C's increase both HET and corrosion rates. While nc-graphite's HET rate follows this trend, it exhibits higher than predicted corrosion resistance. In general, this form of nc-graphite matches the best examples of boron-doped diamond in HET and corrosion rates.

α-Zirconium phosphate (α-ZrP), a classical layered compound, has found widespread application. Exfoliation of α-ZrP has been mainly achieved by propylamine (PA) or tetrabutylammonium hydroxide (TBAOH), but the exact mechanism of exfoliation has not been completely elucidated. We examined the feasibility of exfoliation utilizing tetraalkylammonium hydroxide (TXAOH) and investigated the stepwise intercalation/exfoliation mechanism of α-ZrP. All of the TXAOHs examined (carbon number of the branches: 1-4) were able to exfoliate α-ZrP in an aqueous dispersion under ultrasonication. Furthermore, exfoliation of α-ZrP by two different exfoliators (either a mixture of two or sequentially) was also investigated to pinpoint the exfoliation mechanism. Our results indicate that small TXA cations are kinetically preferred to diffuse into the galleries of α-ZrP, while large TXA cations can help open up the galleries and facilitate transport of the already intercalated cations. These findings should help fellow researchers to choose the most suitable exfoliators for their own projects and develop better intercalation/exfoliation systems.

Isotropic and anisotropic motions and molecular states of pyridine-d

The kinetics of ion exchange of Zr/Sn(IV) phosphonate–phosphate hybrid ion exchange materials have been studied with several types of ions of specific interest to nuclear fuel recycling including N...

For the first time, pore spaces in the Zr (IV) phosphonate (1) as a representative of layered metal (IV) phosphonate materials have been investigated by studying mobility of guest molecules, benzene-d6 , and toluene-d8 . Guest molecules located in micropores of 1 have been characterized by solid-state 13 C{1 H} and 2 H NMR spectra in static samples with varying temperatures. At moderately low temperatures, the benzene and toluene molecules experience fast isotropic reorientations and show the motionally averaged liquid-like carbon and deuterium line shapes in the NMR spectra. At lower temperatures, two anisotropic motional modes have been found for benzene molecules by analyzing the 2 H NMR line shapes: the well-known in-plane C6 rotation and composite motions. Interpretation of the variable-temperature 2 H T1 relaxation times identifies the composite motions as 120° flips around the C6 axis perpendicular to the molecular plane and the rotations around the molecular para-C-C axis. The data obtained resulted in the idealized (cylinder-shaped) model of micropores in compound 1 with the diameter of 20-30 A. Furthermore, the activation energy of 20.1 kJ/mol determined for the benzene motions classifies the molecule-surface interactions as weak but enough for absorption.

Multinuclear solid-state NMR and powder X-ray diffraction data collected for phosphonate materials Zr(O3 PC6 H4 PO3 ) · 3.6H2 O and Sn(O3 PC6 H4 PO3 )0.85 (O3 POH)0.30 · 3.09H2 O have resulted in the layered structure, where the phosphonic acids cross-link the layers. The main structural motif (the 111 connectivity in the PO3 group) has been established by determination of chemical shift anisotropy parameters for phosphorus nuclei in the phosphonate groups. An analysis of the variable-temperature 31 P T1 measurements and the shapes of the phosphorus resonances in the 31 P static NMR spectra have resulted in the dipolar mechanism of the phosphorus spin-lattice relaxation, where the rotating phenylene rings reorient dipolar vectors P… H as a driving force of the relaxation process. It has been found that water protons do not affect the 31 P T1 times. The activation energy of the phenylene rotation in both compounds has been determined as low as 12.5 kJ/mol. The interpretation of the phosphorus relaxation data has been independently confirmed by the measurements of 1 H T1 times for protons of the phenylene rings.

Treatment of a pyrazine (pz)-impregnated CuI metal-organic framework (MOF) ([1⊃pz]) with HCl vapor renders an interstitial pyrazinium chloride salt-hybridized MOF ([1⊃pz⋅6 HCl]) that exhibits proton conductivity over 10-2 S cm-1 both in anhydrous and under humid conditions. Framework [1⊃pz⋅6 HCl] features the highest anhydrous proton conductivity among the lesser-known examples of MOF-based materials exhibiting proton conductivity under both anhydrous and humid conditions. Moreover, [1⊃pz] and corresponding pyrazinium sulfate- and pyrazinium phosphate-hybridized MOFs also exhibit superprotonic conductivity over 10-2 S cm-1 under humid conditions. The impregnated pyrazinium ions play a crucial role in protonic conductivity, which occurs through a Grotthuss mechanism.

Surface modification of doxorubicin (DOX) intercalated zirconium phosphate (ZrP) nanoparticles (DOX@ZrP) is proposed to improve the potential of this drug delivery system for cancer therapy. The surface of DOX@ZrP nanoparticles was modified with an amorphous layer of Zr(IV) followed by modification with monomethyl-poly(ethylene glycol)-monophosphate (m-PEG-PO3) as a feature to increase the DOX@ZrP biocompatibility. 31P{1H}MAS NMR data shows a new peak at −26 ppm corresponding to the PO43− groups coordinated with Zr(IV) on the surface. Initial MTS cell viability assay reveals that m-PEG-PO3/Zr(IV)/DOX@ZrP exhibits ∼20% higher cytotoxicity than free DOX and the other ZrP materials when human prostate cancer PC3 cells are exposed for 48 h. m-PEG-PO3 polymer coating of DOX@ZrP nanoparticles promise to have a strong impact on the targeting, distribution and degradation of the nanoparticles under physiological environment that should result in a more efficient chemotherapy agent than free doxorubicin.

The careful study of MAS effects on the spin–lattice and spin–spin phosphorus NMR relaxation in two layered zirconium phosphate materials, α-ZrP and m-PEG-PO3/Zr(IV)/DOX/ZrP, has clearly shown that the fast spin-diffusion and limited spin-diffusion mechanisms are completely negligible in spite of the presence of paramagnetic centers detected in these materials by EPR. The 31P T1 relaxation is always nonexponential in static and spinning samples as well. The 31P T1 relaxation in α-ZrP follows a stretched exponential law to show the presence of a 31P T1 distribution. The 31P T1 time remarkably depends on spinning rates only in a 7 mm NMR probe head due to the frictional heating effects in 7 mm rotors but not due to the spin-diffusion mechanism. In accord, the 31P T1 and T2 times are independent of MAS rates in the experiments performed with 2.5 mm rotors. All the 31P T1 and T2 relaxation data support well the interpretation of the 31P T1 times in the zirconium phosphate network by dipolar proton–phosphorus ...

Three heterometallic aggregates, [(CoII)2(GdIII)2(tBuPO3)2(O2CtBu)2(HO2CtBu)2(NO3)4]·NEt3 (1), [(CoII)2(CoIII)2(GdIII)3(μ3-OH)2(tBuPO3)2(O2CtBu)9(deaH)2(H2O)2] (2), and (CoIII)2(GdIII)5(μ2-OH)(μ3-OH)2(tBuPO3)2(O2CtBu)10(HO2CtBu)(deaH)2]·MeOH (3), were successfully isolated in reactions of [Co2(μ-OH2)(O2CtBu)4]·(HO2CtBu)4, Gd(NO3)3·6H2O, tBu-PO3H2, and diethanolamine (deaH3) by varying the stoichiometry of the reactants and/or changing the solvent. The structures of the final products were profoundly affected by these minor changes in stoichiometry or a change in solvent. The metal–oxo core of these complexes displays a hemicubane or a defective dicubane-like view. Bond valence sum calculations and bond lengths indicate the presence of CoII centers in compound 1, mixed valent Co centers (CoII/CoIII) in compound 2, and only CoIII centers in compound 3 as required for the charge balances and supported by the magnetic measurements. Magnetic studies reveal significant magnetic entropy changes for complexes 1–3...

Internal rotations in HPO4– groups and proton transfer between them have been characterized in static α-zirconium phosphate by variable-temperature measurements of 31P T1 and 1H T1ρ times. The 1H T1ρ times have been obtained by the kinetic of phosphorus–proton cross-polarization treated with the I-I*-S model. The calculations of the temperature T1 relaxation dependences have resulted in the rotational activation energy of 2.6 kcal/mol (or 3.9 kcal/mol in account for the τC distribution) and the proton transfer activation energy of 5.5 kcal/mol. Thus, two types of motions have been found in α-zirconium phosphate: the low-frequency proton transfer with the correlation time τc of 1.5 × 10–5 s at 295 K and the high-frequency rotation in P–OH groups with the correlation time τc of 2.2 × 10–8 s at 295 K.

There is little systematic understanding of pore surfaces in layered microporous metal(IV) phosphate–phosphonate materials and their interactions with guest molecules. In this paper, we show how to probe the mobility of guest molecules in such poorly crystalline systems using multinuclear solid-state NMR and relaxation time measurements. Anisotropic motions of benzene-d6 molecules absorbed on the pore walls of material Sn(O3PC6H4PO3)0.85(O3POH)0.33 (1) have been recognized as the fast in-plane C6 rotation due to metal−π interactions with pore walls. The benzene-d6 absorption enthalpy due to Sn···π interactions has been determined as –ΔH = 5.9 kcal/mol. Specific interactions between pyridine and the pore walls of 1 have been observed as immobile pyridine, the population of which grows strongly at low temperatures to show thermodynamic parameters −ΔH of 5.0 kcal/mol and ΔS of −11.0 e.u. It has been suggested that these parameters characterize N···H–OP hydrogen bonding as a driving force for accumulation of ...

Layered double hydroxide (LDH) single-layer nanosheets were synthesized through a single-step process in the presence of formamide. This one-step process is simple, fast, and efficient and thus is potentially viable for large-scale production. Two key factors for the growth of LDH single-layer nanosheets, formamide concentration and LDH layer charge, were investigated thoroughly. A higher formamide concentration and a higher LDH layer charge are favorable for the growth of LDH single-layer nanosheets. The LDH single-layer nanosheets obtained at the premium formamide concentration and LDH layer charge were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force micrscopy (AFM). Poly(vinyl alcohol) (PVA)/LDH nanocomposite coatings were also prepared. The coated polyethylene terephthalate (PET) and poly(lactic acid) (PLA) films exhibited significantly improved oxygen gas barrier properties thanks to the well-dispersed and -aligned LDH single-layer nanosheets in the coating.

There is little systematic understanding of the motions of phosphate groups in layered zirconium phosphate (α-ZrP) materials applied in chemistry, industry, and nanomedicine for drug delivery. In this paper, we show how to quantitatively characterize correlation times of motions in the zirconium phosphate network on the basis of NMR 31P relaxation time measurements. By studies of α-ZrP phosphates and their intercalated and decorated derivatives, we have established that room-temperature 31P relaxation is governed by rotations of HPO4– groups with correlation times of (1.1–4.7) × 10–8 s restricted by H-bonding with water molecules in ordered and locally disordered areas. The disordered areas have been found by the 1H spin-lock proton–phosphorus cross-polarization 31P{1H} MAS NMR experiments.

We report a rare example of the preparation of HKUST-1 metal-organic framework nanoplatelets through a step-by-step seeding procedure. Sodium ion exchanged zirconium phosphate, NaZrP, nanoplatelets were judiciously selected as support for layer-by-layer (LBL) assembly of Cu(II) and benzene-1,3,5-tricarboxylic acid (H3BTC) linkers. The first layer of Cu(II) is attached to the surface of zirconium phosphate through covalent interaction. The successive LBL growth of HKUST-1 film is then realized by soaking the NaZrP nanoplatelets in ethanolic solutions of cupric acetate and H3BTC, respectively. The amount of assembled HKUST-1 can be readily controlled by varying the number of growth cycles, which was characterized by powder X-ray diffraction and gas adsorption analyses. The successful construction of HKUST-1 on NaZrP was also supported by its catalytic performance for the oxidation of cyclohexene.

In the recent past an enormous number of Metal-Organic Framework type compounds (MOFs) have been synthesized. The novelty resides in their extremely high surface area and the ability to include additional features to their structure either during synthesis or as additives to the MOF. This versatility allows for MOFs to be designed for specific applications. However, the question arises as to whether a particular MOF can withstand the stress that may be encountered in fulfillment of the designated application. In this study we describe the behavior of two flexible MOFs under pressure and several others under temperature increase. The pressure study includes both experimental and theoretical calculations. In the thermal processes evidence for colossal negative thermal expansion were encountered.

The structural characteristics of two-dimensional (2-D) materials result in unique physical, electronic, chemical, and optical properties, making them potentially useful in a wide range of applications. These unique properties can be fine-tuned and enhanced via intercalation, expanding the applications of various 2-D intercalation compounds to a much wider scope. This article aims to provide an overview of innovations in the field of intercalation chemistry of 2-D intercalation materials, as well as to highlight their leading applications. A brief perspective on the intercalation of 2-D layered compounds is provided, focusing on mechanisms, approaches, and influential factors involving intercalation. Insights into the potential applications, challenges, and future opportunities of 2-D intercalated materials are discussed.

Layer by layer metal-organic framework (MOF) supported on zirconium phosphate (ZrP) was synthesized at very mild conditions and used for the liquid phase oxidation of cyclohexene in solvent free condition in the presence of molecular oxygen. The MOF-ZrP was characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), thermal gravimetric analyzer (TGA), Fourier-transform infrared spectrometer (FT-IR) and Brunauer-Emmett-Teller (BET) surface area analyzer. The characterization shows a smooth morphology of MOF-ZrP with good stability under 200 &deg, C having surface area 285 m2/g. The catalytic activity of the MOF-ZrP revealed that increase of layers of MOF on ZrP enhances conversion, as well as selectivity of oxidation of cyclohexene. DFT studies were used to explore the structure and electron properties of HKUST-1 (Hong Kong University of Science and Technology), which is a clue for the catalytic behavior of the catalyst.

Grease plays important roles in reducing frictional loss and providing protection of rubbing surfaces. In this research, we investigated the effects of α-zirconium phosphate nanoparticles as additives in grease on the galling behavior of a pair of steels (4130 against P530). The results showed that the addition of 0.5 wt% of nanoparticles in petroleum jelly could reduce the friction for 10% and the area being galled for 80%. In terms of particle sizes, the 1 μm sized particles have profound influence in galling reduction. This is due to the increased contribution of van der Waals forces in the stacked layers of those particles. Under shear, those particles are exfoliated, resulting in low friction and more surface coverage to protect surfaces from galling.

For the first time, pore spaces in the Zr (IV) phosphonate (1) as a representative of layered metal (IV) phosphonate materials have been investigated by studying mobility of guest molecules, benzene-d

In this study, a solid acid was prepared by the sulfonation of surface modified α-zirconium phosphate (ZrP) single-layer nanosheets (SO3H@ZrP), and the prepared solid acid was investigated for the esterification of oleic acid with methanol to produce biodiesel. For comparison, liquid H2SO4 and commercial Amberlyst® 15 catalyst were also evaluated for the same reaction under the same conditions. The experimental results showed that the SO3H@ZrP solid acid catalyst has a superior catalytic efficiency for the esterification reaction, as well as excellent recyclability. The SO3H@ZrP single-layer solid acid catalyst can be uniformly dispersed in the reaction media, but remains heterogeneous and thus can be easily separated and recycled.

Molybdocene dichloride (Cp2MoCl2), a metallocene dichloride currently being evaluated as potential anti-cancer drug, has been intercalated into zirconium phosphate, an inorganic layered nanomaterial. Hydrolysis of the chloride ligands appears to occur, leading to the formation of the monocation species ([Cp2Mo(H2O)(OH)]+), which intercalates into the ZrP layers by ion exchange. IR spectroscopy, X-ray powder diffraction (XRPD), UV–Vis spectrophotometry, scanning electron microscopy with energy dispersive X-ray spectroscopy, NMR spectroscopy, and thermogravimetric analysis were used to confirm the presence of the metallocene between the layers of zirconium phosphate. The XRPD data indicates that a new intercalated phase with an expanded interlayer distance of 11.0 A was obtained; thermogravimetric analysis indicates up to 64% loading in the context of molar ratio (0.64 mol per ZrP formula unit) or 32% exchange capacity. Further evidence for intercalation was obtained from 31P MAS NMR experiments. IR spectroscopy confirms the presence of the cyclopentadienyl bearing metallocene in the layers.

Layered double hydroxide (LDH) single-layer nanosheets were traditionally prepared through a multi-step exfoliation process which is very time-consuming and of low efficiency. Herein we report the preparation of LDH single-layer nanosheets through a facile direct synthesis method. By introducing a layer growth inhibitor, one can directly synthesize LDH single-layer nanosheets instead of LDH layered compounds. The inhibitor weakens the interactions between neighboring layers, thus preventing the interlayer growth. This investigation on blocking interlayer growth by weakening interlayer interactions to obtain inorganic single-layer nanosheets opens a new route for the synthesis of 2-dimensional materials.

Multinuclear solid-state NMR and powder X-ray diffraction data collected for phosphonate materials Zr(O

Treatment of a pyrazine (pz)-impregnated Cu

The structures of Zr(IV) phosphonate-phosphate based, unconventional metal organic framework materials have been determined using atomic pair distribution function analysis of high energy, X-ray total scattering diffraction data. They are found to form as nanocrystalline layers of Zr phosphate, similar to the bulk, but with a high degree of interlayer disorder and intermediate intralayer order extending around 5 nm. These materials are of interest for their high selectivity for 3+ lanthanide ions. To investigate the mechanism of the selectivity, we utilize difference pair distribution function analysis to extract the local structural environment of Tb3+ ions loaded into the framework. The ions are found to sit between the layers in a manner resembling the local environment of Tb in Scheelite-type terbium phosphate. By mapping this local structure onto that of the refined structure for zirconium-phenyl-phosphonate, we show how dangling oxygens from the phosphate groups, acting like nose hairs, are able to ...

Three heterometallic aggregates, [(Co

Immobilized catalysts can be obtained by using a linker to bind a homogeneous catalyst to a solid support. Ideally, immobilized catalysts combine the advantages of homogeneous and heterogeneous catalysts. Porous supports such as silica result in optimal recyclability, however, the catalytic reactions are slowed down by pore diffusion. Here, non-porous zirconium phosphate nanoplatelets (ZrP) are used as support material to bridge the gap between homogeneous and immobilized catalysts. ZrP nanoplatelets provide sufficient outside surface area, while still being easily separable from the reaction mixtures. First, a phosphine linker containing an ethoxysilyl group, (EtO) 3 Si(CH 2 ) 3 PPh 2 ( 1 ), is reacted with ZrP to give the phosphine-modified 1i . Addition of Wilkinson's catalyst ClRh(PPh 3 ) 3 to 1i gives, via ligand exchange, the immobilized catalyst 1i – Rh . In the absence of pore diffusion the catalytic hydrogenation of 1-dodecene using 1i – Rh proceeds with unprecedented speed and the catalyst can be recovered and recycled 15 times. In the course of the catalytic reaction the mononuclear species forms catalytically active Rh nanoparticles on the surface. Finally it is demonstrated that ClRh(PPh 3 ) 3 can be bound to ZrP directly without linker. However, the catalytic activity of the resulting material ZrP–Rh does not quite match the favorable characteristics of 1i – Rh .

Through the systematic investigation of zinc alkylbisphosphonates, four new structural families have been obtained. These families are named zinc alkyl-tunnel, -gate, -cation, and -sheet (ZAT, ZAG, ZAC, and ZAS) for convenience and have been synthesized and further extended through isoreticular design utilizing alkylbis(phosphonic acid) ligands of the formula H2O3PCnH2nPO3H2 (n = 3–6) (H4Ln). Both even- and odd-length chains were utilized to help determine the effect of chain conformation on structure formation. The investigation lead to two known compounds (ZAG-4, and ZAS-3) and nine new compounds, two of which contain large 1-D channels. The crystal structures of all compounds were determined by single-crystal X-ray diffraction. Of the nine new compounds, only seven of them fall into the new families. In three of the four families, the structure is controlled by alkyl-chain length and conformation (i.e., odd vs even), and in the fourth, a conformational distortion allows both odd and even lengths to for...

Surface-functionalized zirconium phosphate (ZrP) nanoparticles were synthesized using a combination of ion exchange and self-assembly techniques. The surface of ZrP was used as a platform to deposit tetravalent metal ions by direct ion exchange with the protons of the surface phosphate groups. Subsequently, phosphonic acids were attached to the metal ion layer, effectively functionalizing the ZrP nanoparticles. Use of axially oriented bisphosphonic acids led to the ability to build layer-by-layer assemblies from the nanoparticle surface. Varying the metal ion and ligand used allowed designable architectures to be synthesized on the nanoparticle surface. X-ray powder diffraction, XPS, electron microprobe, solid-state NMR, FTIR, and TGA were used to characterize the synthesized materials.

The intercalation of inorganic layered materials has resulted in a wide range of applicability. In such cases the applicability of the material is largely dependent upon the species intercalated within the layer, and the layered material acts largely as a host. Recently, the surface modification of inorganic layered materials has been investigated and it has been shown that the exterior layers can be exclusively functionalized. The advent of surface chemistry allows for the synthesis of particles with both a controlled interlayer and surface. This approach can be used to tailor nanoparticles for specific applications. Herein we review the surface chemistry of α-zirconium bis(monohydrogen orthophosphate) monohydrate (Zr(HPO4)2·H2O, α-ZrP) along with some applications of recent interest. Not only can these reactions be applied to α-ZrP, but similar chemistry can also be expanded to other layered materials and systems.

A single step one-pot in situ synthesis method was developed to directly grow layered intercalation compounds. This methodology is expected to be applicable to a wide range of layered materials.

A one-step hydrothermal synthesis with small amines and 1,3,5-benzenetriphosphonic acid was used to prepare single crystals of isostructural anionic metal–organic frameworks (MOF): Zn2.5(H)0.4–0.5(C6H3O9P3)(H2O)1.9–2(NH4)0.5–0.6 and Zn2.5(H)0.75(C6H3O9P3)(H2O)2(CH3NH3)0.25. The ammonium ions are exchangeable with lithium ions. The MOF exhibits reversible dehydration, and the process was studied by two complementary methods: solid state NMR and in situ X-ray diffraction. These experiments revealed three different phases. The crystal structures of all phases have been determined, showing loss in volume of the structure due to a phase change. The ammonium ions remain in the structure and are forced to occupy the larger pores due to a reduction in free volume. The change in positions of the guest molecules in the framework has an effect on the potential conductivity properties of the materials. Changes in framework and guest molecules due to negative expansion have an effect on other physical and chemical pro...

Organically surface-modified α-zirconium phosphate was obtained by reacting the surface P–O–H groups of α-zirconium phosphate nanoparticles (α-ZrP) with octadecyltrichlorosilane (OTS). Surface functionalization of α-ZrP with OTS was accomplished using a one-step synthesis producing highly hydrophobic nanoparticles. The formation of P–O–Si bonds arising from nucleophilic attack of POH to the silane was confirmed by solid-state NMR experiments. The surface coverage of the organic modifier was characterized by TGA, AFM, and FTIR. In addition, we show the applicability of this system with a photoinduced electron-transfer reaction in a nonpolar solvent. Using an organically surface-modified α-ZrP previously loaded with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+), the quenching of the luminescence of Ru(bpy)32+ in the presence of p-benzoquinone was monitored; a static quenching constant (Ks) value of 8.82 × 102 M–1 and a dynamic quenching constant (KD) value of 6.99 × 102 M–1 were obtained.

The structural change and resilience of a single crystal of a metal-organic framework (MOF), Zn(HO(3)PC(4)H(8)PO(3)H)·2H(2)O (ZAG-4), was investigated under high pressures (0-9.9 GPa) using in situ single crystal X-ray diffraction. Although the unit cell volume decreases over 27%, the quality of the single crystal is retained and the unit cell parameters revert to their original values after pressure has been removed. This framework is considerably compressible with a bulk modulus calculated at ∼11.7 GPa. The b-axis also exhibits both positive and negative linear compressibility. Within the applied pressures investigated, there was no discernible failure or amorphization point for this compound. The alkyl chains in the structure provide a spring-like cushion to stabilize the compression of the system allowing for large distortions in the metal coordination environment, without destruction of the material. This intriguing observation only adds to the current speculation as to whether or not MOFs may find a role as a new class of piezofunctional solid-state materials for application as highly sensitive pressure sensors, shock absorbing materials, pressure switches, or smart body armor.

Several layered zirconium phosphates treated with Zr(IV) ions, modified by monomethoxy-polyethyleneglycol-monophosphate and intercalated with doxorubicin hydrochloride have been studied by solid-state MAS NMR techniques. The organic components of the phosphates have been characterized by the

Two heterometallic Co(III)-Gd(III) nanomagnets (Co2Gd6 and Co2Gd9) with defective dicubane-like cores were isolated from the same set of reactants by varying the reaction conditions. These are the first examples of cobalt(III)-gadolinium(III) phosphonate compounds and a rare class of compounds with large 4f ratio among the reported 3d-4f complexes. Magnetic studies reveal large magnetic entropy changes for both complexes (-ΔSm = 27.81 and 33.07 J kg(-1) K(-1), respectively at 3 K and 7 T).