Synthesis of Cyclic Phosphates in Hot,Concentrated Phosphoric Acid

The synthesis of transition metal phosphates in hot, concentrated phosphoric acid medium leads to highly crystalline materials and to increased condensation of the phosphate at higher temperatures. Aluminum extraction from the porcelain crucible is also observed in some circumstances. Two new compounds were produced: (Al_3.28Cr_0.72)(P₄O₁₂)₃ a = 13.512(8) Å, cubic, I-43d, V = 2470(3) ų, Z = 6, density = 2.887 mg/m³, R = 0.055, GOF = 1.29 for 254 data points, was prepared at 748 K whereas (Al_1.97Cr_1.03)P₉O₂₇ a = b = 11.170(6), c = 9.412(9) Å, trigonal P – 3c1, V = 1017(1) ų, Z = 2, density = 2.669 mg/m³, R = 0.0581, GOF = 0.87 for 676 data points, was produced at 798 K from the heating of Cr₂O₃ in H₃PO₄ in a porcelain crucible. Crystal structures of both materials show mixed metal sites containing Al and Cr.     

Structural,Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method: Effect of Precursor Concentration

Transparent zinc oxide(ZnO) thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations(0.3-1.2 M) using zinc acetate dehydrate [Zn(CH_3COO)_2·2H_2O] as precursor and isopropanol and monoethanolamine(MEA) as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.     

Synthesis,antioxidant and anticholinesterase activities of novel quinoline-aminophosphonate derivatives

A series of 20 novel α-aminophosphonate derivatives bearing quinoline or quinolone moiety was designed and synthesized via Kabachnik-Fields reaction in the presence of triethylammonium acetate as a solvent and catalyst under ultrasound irradiation. This procedure affords products in high yields and short reaction times. Molecular structures of the synthesized compounds 4a-g and 5a-m were confirmed using various spectroscopic methods. The antioxidant activity of these compounds was evaluated by eight complementary in vitro tests. The anticholinesterase activity (AChE, BChE) of these compounds were also evaluated. In addition, theoretical calculations of all compounds were investigated as corrosion inhibitors using density functional theory (DFT). The results revealed that 16 of these compounds exhibited high levels of antioxidant activities depending on the assay and that most compounds showed more potent inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).     

Index Abstracts

Abstract List

Index Abstracts     

Identification of a new family of diphosphate compounds, AI2BII3(P2O7)2: Structures of Ag2Co3(P2O7)2, Ag2Mn3(P2O7)2, and Na2Cd3(P2O7)2

Syntheses and single-crystal X-ray structural results are reported for three new mixed diphosphates of the family A^I ₂B^II ₃(P₂O₇)₂; Ag₂Co₃(P₂O₇)₂ (I), Ag₂Mn₃(P₂O₇)₂ (II), and Na₂Cd₃(P₂O₇)₂ (III). All crystallize in the triclinic system, space group P1 bar: (I) a = 5.351(4), b = 6.375(4), c = 16.532(4) Å, = 80.83(6) = 81.45(4), = 72.87(5)°, V = 528.9(6) ų, Z = 2, D _calc = 4.649 mg/m³, R/Rw = 0.0428/0.0548 for 3949 obs. reflns; (II) a = 5.432(7), b = 6.619(6), c = 16.51(3) Å, = 80.78(8) = 82.43(9), = 72.82(7)°, V = 557.7(13) ų, Z = 2, D _calc = 4.338 mg/m³, R/Rw = 0.0679/0.1303 for 2100 obs. reflns and (III) a = 5.67(3), b = 7.08(4), c = 7.90(4) Å, = 77.0(2), = 82.5(2), = 67.8(2)°, V = 286(3) ų, Z = 2, D _calc = 4.249 mg/m³, R/Rw = 0.0307/0.0342 for 1945 obs. reflns. (I) and (II) are isostructural but (III) is of a different type. All three structures are characterized by layers of P₂O₇ groups alternating with layers of mixed metal atoms. Differences are seen in the conglomerate bonding patterns of B atoms and in the irregular geometry of Ag in (I) and (II) compared to the octahedral bonding seen for Na in (III). The differences in structure may be understood in terms of the ratios of the ionic radii of A and B atoms.     

On a Weak Law of Large Numbers with Regularly Varying Normalizing Sequences

Journal of Theoretical Probability - The Kolmogorov–Feller weak law of large numbers for i.i.d. random variables has been extended by Gut (J. Theoret. Probab. 17,  769–779,...