Two- and three-dimensional hybrid zinc phosphites: syntheses, structures and photoluminescence properties

Two zinc-phosphites modified by a rigid amine 3,5-bis(imidazole-1-yl)pyridine (BIP), [Zn2(HPO3)2(BIP)]·H2O (1) and [Zn3(HPO3)3(BIP)(H2O)]·H2O (2), were solvothermally prepared. Compound 1 possesses a zincophosphite layer decorated by BIP moieties via coordinating to intralayer Zn(ii) ions. Compound 2 features a 3D frame with a pillar-layer structure, in which the organic BIP pillars the inorganic zincophosphite layer via coordinating to interlayer Zn(ii) ions. The structural diversity from a 2D layer to a 3D frame was mainly attributable to the different bridging modes of BIP in the process of assembly. Their temperature-dependent photoluminescence properties have also been studied.

New Organic Acidic Cyclohexaphosphate: Synthesis, Crystal Structure, Physicochemical Study, and In Vitro Biochemical Investigation

A novel organic cyclohexaphosphate [o-(OCH3)C6H4NH3]4H2P6O18·4H2O (1) has been synthesised by the slow evaporation method. An X-ray diffraction study on a single crystal was used to identify this compound. It shows that this acidic cyclohexaphosphate crystallizes in the monoclinic space group P21/n with V 2215.1(1) Å3 and Z 2. Its crystal structure is a packing of alternating inorganic and organic layers parallel to the (a, c) planes. Crystal symmetry is confirmed by 31P magic angle spinning-NMR spectroscopy. Furthermore, spectroscopic (IR, UV-visible) and thermal (thermogravimetric/differential thermal analysis and differential scanning calorimetry) characteristics are given. The excitation and emission spectra were recorded showing blue photoluminescence. The alternating current conductivity and dielectric measurements were carried out in the temperature range 333–403 K and the frequency range from 5 Hz to 13 MHz. The impedance data were well fitted to an equivalent electrical circuit. The temperature dependence of the direct current conductivity follows the Arrhenius law and the frequency dependence of σAC(ω,T) follows Jonscher’s universal law. Antioxidant properties of this compound were studied, in vitro, at various concentrations with different tests; 1,1-diphenyl-2-picrylhydrazyl, hydroxyl scavenging ability, ferric reducing power, and ferrous ion chelating ability, using ascorbic acid as control.

A gel aging effect in the synthesis of open-framework gallium phosphates: structure solution and solid-state NMR of a large-pore, open-framework material

The templated zeolite-analogue GaPO-34 (CHA structure type) crystallises from a gel precursor Ga2O3 : 2H3PO4 : 1HF : 1.7SDA : 70H2O (where SDA = structure directing agent), treated hydrothermally for 24 hours at 170 °C using either pyridine or 1-methylimizadole as SDA and one of either poorly crystalline ε-Ga2O3 or γ-Ga2O3 as gallium precursor. If the same gels are stirred for periods shorter than 2 hours but treated under identical hydrothermal conditions, then a second phase crystallises, free of GaPO-34. If β-Ga2O3 is used as a reagent only the second phase is found to crystallise, irrespective of gel aging time. The competing phase, which we denote GaPO-34A, has been structurally characterised using synchrotron powder X-ray diffraction for the pyridine material, GaPO-34A(pyr), and using single-crystal X-ray diffraction for the 1-methylimiazole material, GaPO-34A(mim). The structure of GaPO-34A(pyr), P1[combining macron], a = 10.22682(6) Å, b = 12.09585(7) Å, c = 13.86713(8) Å, α = 104.6531(4)°, β = 100.8111(6)°, γ = 102.5228(6)°, contains 7 unique gallium sites and 6 phosphorus sites, with empirical formula [Ga7P6O24(OH)2F3(H2O)2]·2(C5NH6). GaPO-34A(mim) is isostructural but is modelled as a half volume unit cell, P1[combining macron], a = 5.0991(2) Å, b = 12.0631(6) Å, c = 13.8405(9) Å, α = 104.626(5)°, β = 100.346(5)°, γ = 101.936(4)°, with a gallium and a bridging fluoride partially occupied and two partially occupied SDA sites. Solid-state 31P and 71Ga NMR spectroscopy confirms the structural complexity of GaPO-34A with signals resulting from overlapping lineshapes from multiple Ga and P sites, while 1H and 13C solid-state NMR spectra confirm the presence of the protonated SDA and provide evidence for disorder in the SDA. The protonated SDA is located in 14-ring one-dimensional channels with hydrogen bonding deduced from the SDA nitrogens to framework oxygen distances. Upon thermal treatment to investigate SDA removal, structure collapse occurs, which may be due the large number of bridging hydroxides and fluorides in the as-made material, and the unequal amounts of gallium and phosphorus present.

Syntheses and Characterizations of Three Organically Templated Zinc Phosphites with 12-Ring Channels

Three new zinc phosphites, [Hapy]2[Zn3(HPO3)4] (1; apy = 4-aminopyridine), [H2hepip][Zn3(HPO3)4]·(H2O)0.25 (2; hepip = N-(2-hydroxyethyl)piperazine), and [H2tmdab][Zn3(HPO3)4] (3; tmdab = N,N,N′,N′-tetramethyl-1,3-diaminobutane), have been synthesized and characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and powder and single-crystal X-ray diffraction. The frameworks of 1–3 are constructed from 4-connected ZnO4 tetrahedra and 3-connected HPO3 pseudo pyramids with distinct connection mode driven by different organic amine templates. There are 12-membered ring (12-MR) and 8-MR apertures in the (3,4)-connected three-dimensional architecture of 1–3. It is notable that helical chains are observed in the framework of compound 3.

New discrete iodometallates with in situ generated triimidazole derivatives as countercations (Mn+ = Ag+, Pb2+, Bi3+)

By employing solvothermal in situ N-alkylation of organic bases with alcohols, four new iodometallates were obtained, and their structures are reported.