Iron phosphates are of interest because of rich crystal chemistry and practical applications. New crystalline iron phosphates have been prepared in aqueous or predominantly nonaqueous solvents under mild hydrothermal conditions using organic amines as structure-directing agents. The effects of pH, solvent, and temperature on the reaction products are discussed. FePOs have been prepared with 1-D chain, 2-D layered, and 3-D open framework structures. An FePO containing a chiral amine is also synthesized. This review will summarize some of the results of the work in the area of organically templated iron phosphates.

The development of zeolite-like structures with extra-large pores (>12-membered rings, 12R) has been sporadic and is currently at 30R. In general, templating via molecules leads to crystalline frameworks, whereas the use of organized assemblies that permit much larger pores produces noncrystalline frameworks. Synthetic methods that generate crystallinity from both discrete templates and organized assemblies represent a viable design strategy for developing crystalline porous inorganic frameworks spanning the micro and meso regimes. We show that by integrating templating mechanisms for both zeolites and mesoporous silica in a single system, the channel size for gallium zincophosphites can be systematically tuned from 24R and 28R to 40R, 48R, 56R, 64R, and 72R. Although the materials have low thermal stability and retain their templating agents, single-activator doping of Mn(2+) can create white-light photoluminescence.

A nanoporous zinc gallophosphate framework, NTHU-4, possessing 14-ring channels, disordered rims, and two luminant analogues, NTHU-4Y and NTHU-4W, has been synthesized and characterized; NTHU-4Y is an intrinsic yellow phosphor, while NTHU-4W is a white phosphor. The unique tetrahedral framework can be excited by wavelengths longer than 254 nm to give intense yellow-to-white luminescence. Subtle changes in disorderliness were observed to be related to the distinct photoluminescence property.

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Two novel piperazinium vanadyl(IV) compounds, (C4H12N2)[VO(C2O4)HAsO4] (1) and (C4H12N2)[VO(C2O4)HPO4] (2), have been prepared under mild hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. They adopt a one-dimensional structure in which ladder-like chains are constituted by the three-connected V and three-connected X (X = As for 1 and P for 2) centers. Within the infinite chains the oxalate group coordinates to each of the V centers as a bidentate ligand. They are the first inorganic/organic mixed-anion materials prepared in the vanadium arsenate and vanadium phosphate systems. Crystal data for 1:  orthorhombic, P212121, a = 6.5595(1) Å, b = 12.4689(1) Å, c = 14.6363(1) Å, Z = 4. Crystal data for 2:  as above, except a = 6.4022(4) Å, b = 12.4735(8) Å, c = 14.653(1) Å. Acccording to the results of TG analysis, both compounds are thermally stable to ca. 250 °C. Our magnetic study revealed that exchange coupling occurred between the nearest VO2+ centers along the infinite (-V-O-X-O)2 chains. Good fits of the magnetic susceptibility data were obtained by using the Bonner and Fisher S = 1/2 linear chain model.

The first mixed-valence uranium(IV,V) silicate is synthesized under high-temperature, high-pressure hydrothermal conditions. The structure contains chains of corner-sharing U(IV,V)O(6) octahedra which are interconnected by Si(4)O(12) four-membered rings to form a 3-D framework. XPS and XANES spectra were measured to identify the valence state of uranium.

Two salt-inclusion uranyl silicates, [K(3)Cs(4)F][(UO(2))(3)(Si(2)O(7))(2)] (compound 1) and [NaRb(6)F][(UO(2))(3)(Si(2)O(7))(2)] (compound 2), have been synthesized at high temperature using mixtures of alkali metal fluorides as fluxes and structurally characterized by single-crystal X-ray diffraction. Both compounds contain UO(6) tetragonal bipyramids linked by disilicate groups to form three-dimensional framework structures with identical framework composition but different framework structures and salt inclusions. Both structures contain elliptical 12-ring channels where the K(2)Cs(4)F and Rb(6)F units are located. They are the first examples of salt-inclusion uranium silicates. The frameworks of 1 and 2 are thermally stable up to 850 and 750 degrees C, as indicated from powder X-ray diffraction. The (19)F and (29)Si MAS NMR spectra and the second-harmonic-generation response of 1 are consistent with the crystal structure analysis results. Crystal data: [K(3)Cs(4)F][(UO(2))(3)(Si(2)O(7))(2)], Cmc2(1), a = 7.8095(3) A, b = 22.2819(7) A, c = 14.0861(4) A, and Z = 4; [NaRb(6)F][(UO(2))(3)(Si(2)O(7))(2)], Pnnm, a = 11.1429(2) A, b = 13.5151(3) A, c = 7.8868(1) A, and Z = 2.