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Metal phosphates represent an important group of materials with established industrial applications that are still attracting special scientific interest, owing to their outstanding physical and chemical properties. In this review, we account on the different synthetic routes and applications of zirconium and titanium phosphates, with a special focus on their application in the medicinal field. While zirconium phosphate has been extensively studied and explored with several reported industrial and medicinal applications, especially for drug delivery applications, titanium phosphates have not yet attracted the deserved attention regarding their established applications. However, titanium phosphates have been the focus of several structural studies with their different polymorphic forms, varied chemical structures, and morphologies. These variations introduce titanium phosphates as a strong candidate for technological and, particularly, biomedical applications. [ABSTRACT FROM AUTHOR]

A series of layered alkylammonium–chromium phosphates, formulated as [C n H 2 n +1 NH 3 ]Cr(OH)PO 4 ( n =2–6), has been synthesized under hydrothermal conditions. The interlayer spacing, increasing linearly with the increase of alkyl-chain length from 13.61 Å ( n =2) to 21.20 Å ( n =6), is occupied by a double sheet of packed amine molecules with a tilt angle of ca. 51° respect to the inorganic sheet. The powders are constituted by circular plates (diameter=0.5–3 µm, thickness=~50 nm) with central holes when n =4–6, stacked in axial direction showing worm-like morphologies. The presence of holes, and some corrugated and zig-zag fashions observed on the edge of thin circular plates are the most probable ways for the reduction of the steric tensions between organic and inorganic portions in these hybrid materials. The thermal and thermo-oxidative stability of selected compounds have been studied, including the determination of activation energy data for the decomposition processes. [ABSTRACT FROM AUTHOR]

A novel metal-organic framework assembled from Y(III), Li(I), and terephthalate ligand, formulated as [LiY- (BDC)2(H2O).2(H2O)] (1) (H2BDC = terephthalic acid), has been obtained as single phase under hydrothermal conditions. The crystal structure was solved by single-crystal X-ray diffraction and the bulk was characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, and BF-STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). 1 crystallizes in monoclinic space group (P21/c, with a = 11.6415(7) Å, b = 16.0920(4) Å, c = 13.2243(8) Å and β = 132.23(1)°) and possesses a 3D framework with 1D trigonal channels running along the [101] direction containing water molecules. The structure of 1 is made up of unusual four-membered rings formed by edge- and vertex-shared {YO8} and {LiO4} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. HT-XRD reveals that 1 undergoes phase transformation upon the dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetics. Topological studies were also performed revealing that 1 has a new 2-nodal net. [ABSTRACT FROM AUTHOR]

The synthesis of single-atom catalysts and the control of the electronic properties of catalytic sites to arrive at superior catalysts is a major challenge in heterogeneous catalysis. A stable supported single-atom silver catalyst with a controllable electronic state was obtained by anti-Ostwald ripening. An electronic perturbation of the catalytic sites that is induced by a subtle change in the structure of the support has a strong influence on the intrinsic reactivity. The higher depletion of the 4d electronic state of the silver atoms causes stronger electronic metal-support interactions, which leads to easier reducibility and higher catalytic activity. These results may improve our understanding of the nature of electronic metal-support interactions and lead to structure-activity correlations. [ABSTRACT FROM AUTHOR]

Single-phase Cr doped zinc ferrites have been synthesized by hydrothermal method. The crystal structure, microstructure, crystallite size and distribution, composition and magnetic properties of the synthesized nanoparticles were determined using X-ray powder diffraction, electron microscopies and vibrating sample magnetometry. Powders are composed of ultrafine spherical nanoparticles with a highly homogeneous elemental composition. The nanoparticles have partially inversed cubic spinel structure with average crystallite size below 10 nm. Superparamagnetic behavior is observed at high temperature while ferrimagnetic ordering and surface spin canting is reported at 5 K. Substitution of Fe with Cr ions controls both structural and magnetic parameters. [ABSTRACT FROM AUTHOR]

A two-dimensional piperazinium cobalt–zinc phosphate , formulated as (C 4 N 2 H 12 ) 1.5 (Co 0.6 Zn 0.4 ) 2 (HPO 4 ) 2 (PO 4 )·H 2 O (2D) , was synthesized under hydrothermal conditions. The crystal structure was determined using single-crystal X-ray diffraction data (monoclinic P 2 1 /c, a =8.1165(3) Å, b =26.2301(10) Å, c =8.3595(4) Å, and β =110.930(5)°) and the hydrogen atom positions were optimized by DFT calculations. A single-crystal corresponding to one-dimensional metastable phase, (C 4 N 2 H 12 )Co 0.3 Zn 0.7 (HPO 4 ) 2 ·H 2 O (1D) , was also isolated and the crystal structure was determined (monoclinic P 2 1 /c, a =8.9120(6) Å, b =14.0290(1) Å, c =12.2494(5) Å, and β =130.884(6)°). The bulk was characterized by chemical (C–H–N) analysis, powder X-ray diffraction (PXRD), powder X-ray thermodiffractometry (HT-XRD) , transmission electron microscopy (STEM(DF)-EDX and EFTEM), and thermal analysis (TG/SDTA-MS), including activation energy data of its thermal decomposition. The magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. [ABSTRACT FROM AUTHOR]

A novel ethylenediamine-gallium phosphate, formulated as Ga(H2NCH2CH2NH2)2PO4·2H2O, was synthesized under hydrothermal conditions. The crystal structure, including hydrogen positions, was determined using single-crystal X-ray diffraction data (monoclinic, a=9.4886(3)Å, b=6.0374(2)Å, c=10.2874(3)Å, and β=104.226(3)°, space group Pc) and the bulk was characterized by chemical (Ga–P–C–H–N) and thermal analysis (TG–MS and DSC), including activation energy data of its thermo-oxidative degradation, powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (SS-NMR) measurements, and transmission electron microscopy (TEM, SAED/NBD, and STEM BF-EDX). The crystal structure is built up of infinite zig-zag chains running along the c-axis, formed by vertex-shared {PO4} and {GaO2N4} polyhedra. The new compound is characterized by unusual four equatorial Ga–N bonds coming from two nonequivalent ethylenediamine molecules and exhibits strong blue emission at 430nm (λ ex=350nm) in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

The layered piperazinium cobalt-zinc phosphate, (pipH2)1.5 (Co0.6Zn0.4)2(HPO4)2 (PO4)·H2O, is prepared under hydrothermal conditions from a mixture of CoCl2, ZnCl2, H3PO4 (85 wt%), and piperazine (pip) hexahydrate (autoclave, 180 °C, 6 d). [ABSTRACT FROM AUTHOR]