Synthesis,structure and characterization of five new organically templated metal sulfates with 2‐aminopyridinium

The chemistry of organically templated metal sulfates has attracted interest from the materials science community and the development of synthetic strategies for the preparation of organic–inorganic hybrid materials with novel structures and special properties is of current interest. Sulfur–oxygen–metal linkages provide the possibility of using sulfate tetrahedra as building units to form new solid‐state materials. A series of novel organically templated metal sulfates of 2‐aminopyridinium (2ap) with aluminium(III), cobalt(II), magnesium(II), nickel(II) and zinc(II) were obtained from the respective aqueous solutions and studied by single‐crystal X‐ray diffraction. The compounds crystallize in centrosymmetric triclinic unit cells in three structure types: type 1 for 2‐aminopyridinium hexaaquaaluminium(III) bis(sulfate) tetrahydrate, (C₅H₇N₂)[Al(H₂O)₆](SO₄)₂·4H₂O, (I); type 2 for bis(2‐aminopyridinium) tris[hexaaquacobalt(II)] tetrakis(sulfate) dihydrate, (C₅H₇N₂)₂[Co(H₂O)₆]₃(SO₄)₄·2H₂O, (II), and bis(2‐aminopyridinium) tris[hexaaquamagnesium(II)] tetrakis(sulfate) dihydrate, (C₅H₇N₂)₂[Mg(H₂O)₆]₃(SO₄)₄·2H₂O, (III); and type 3 for bis(2‐aminopyridinium) hexaaquanickel(II) bis(sulfate), (C₅H₇N₂)₂[Ni(H₂O)₆](SO₄)₂, (IV), and bis(2‐aminopyridinium) hexaaquazinc(II) bis(sulfate), (C₅H₇N₂)₂[Zn(H₂O)₆](SO₄)₂, (V). The templating role of the 2ap cation in all of the reported crystalline substances is governed by the formation of characteristic charge‐assisted hydrogen‐bonded pairs with sulfate anions and the presence of π–π interactions between the cations. Additionally, both coordinated and uncoordinated water molecules are involved in hydrogen‐bond formation. As a consequence, extensive three‐dimensional hydrogen‐bonding patterns are formed in the reported crystal structures.     

Sb6O7(SO4)2: A Promising Ultraviolet Nonlinear Optical Material with an Enhanced Second-Harmonic-Generation Response Activated by SbIII Lone-Pair Stereoactivity

The stereochemical activity of lone pairs (SCALP) in a cation favors the formation of acentric materials and can enhance the second-harmonic-generation (SHG) response and/or the birefringence. By introducing functional Sb^III into sulfates, an anhydrous sulfate of Sb₆O₇(SO₄)₂ ( 1 ) is explored. Sb³⁺ cations are in seesaw configurations and in-phase aligned in a 3D asymmetric dense structure. Compound 1 exhibits an enhanced phase-matching SHG response, a moderate birefringence, a wide transparency window, and considerable environmental stabilities, which result in it being a promising UV nonlinear optical (NLO) material. Theoretical studies reveal that the stereoactive lone pairs on Sb³⁺ cations make the predominant contribution to the SHG effect. This work will attract more interest from scientists for research into SCALP-cation-based NLO materials.     

A fast and efficient method for the preparation of aryl azides using stable aryl diazonium silica sulfates under mild conditions

An efficient, fast, and straightforward procedure for the synthesis of aromatic azides using aryl diazonium silica sulfates and sodium azide at room temperature under mild conditions is described. The use of inexpensive materials, simple and clean work-up, short reaction times and good yields are advantages of this method.     

Determination of Sulfur in Trace Amounts

Abstract

An absolute method for the determination of trace amounts of sulfur in water and organic matrices is described. The method involves decomposition of organic samples in an oxygen bomb or oxidation of water samples with hydrogen peroxide. The resultant sulfates are reduced and distilled as hydrogen sulfide by the action of stannous phosphate in anhydrous phosphoric acid. The evolved hydrogen sulfide is absorbed in zinc acetate solution, converted to methylene blue and measured spectrophotometrically at 665 mm. The range is from 2 to 40 μg of sulfur using 1 cm cells.     

Influence of temperature and solution composition on the formation of calcium sulfates

T Calcium sulfates(anhydrite and hydrates)were synthesized by mixing CaCl2 and Na2SO4 solutions at room temperature followed by aging the resulting slurries at elevated temperatures.The variation of the morphology and structure of the calcium sulfates with aging temperature was investigated.Experimental results indicated that CaSO4.2H2O plates,CaSO4.0.5H2O whiskers and CaSO4 spindles were formed at≤100℃,130-160℃ and ≥170℃,respectively.The formation and conversion of the calcium sulfates were discussed on the basis of characterization of the products and chemical analysis of the solutions.Compared to NaCl solution,pure water favors one-dimensional hydrothermal growth of CaSO4.0.5H2O whiskers owing to lower supersaturation.     

Structural features of semi-synthetic galactomannan sulfates

The positions of sulfate groups in two specimens of sulfated galactomannan from Cyamopsis tetragonoloba seeds were established by analysis of ¹H and ¹³C NMR spectra. For the degree of substitution of 0.6, the signals of galactopyranose residues sulfated at position O(6) or simultaneously at positions O(2) and O(3) were the most intense. Minor signals were due to O(2)- or O(3)-monosubstituted and 2,3,4-tri-O-substituted galactose residues. The substitution of mannopyranose residues involved positions O(6) > O(2,3) > O(2) > O(3). At higher degree of substitution (1.0), the pattern of distribution of sulfate groups over various positions in the residues did not change, the molar content of 2,3-di-O-substituted galactopyranose residues being higher than the content of 6-O-monosubstituted residues. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1745–1749, August, 2008.     

The synthesis of daidzein sulfates

The first syntheses of the urinary isoflavone metabolites, daidzein 4′-sulfate, daidzein 7-sulfate and daidzein 4′,7-disulfate are described. These syntheses employ a key protecting group strategy, allowing regiospecific sulfation.     

第二结构导向剂诱导形成的二维有机模板稀土硫酸盐

水热条件下合成了具有超大孔道和层状结构的有机模板稀土硫酸盐。超大孔道的稀土硫酸盐（1）的分子式为[（CH₃）₂NH₂]₉[Pr₅（SO₄）₁₂]·2H₂O,它展现出有趣的交叉二十元环孔道结构。层状的稀土硫酸盐的分子式为[H₃O]₃[（CH₃）₂NH₂]₃[Ln₂（SO₄）₆]（Ln=Pr,2;Nd,3）,它可以被看作是由双链和八元环结合而成。这3种化合物的合成揭示了大的有机胺（三聚氰胺）可能用作为第二结构导向剂,阻止形成高维数的无机骨架,从而诱导了二维层状结构稀土硫酸盐晶体的生长。对化合物1和3的磁性进行了研究,测试的温度范围在2~300 K。     

Crystal Structures of Mono-, Di-, and Triaminoguanidinium Sulfate,as Well as Azidoformamidinium Sulfate: Important Precursors for Syntheses of Nitrogen Rich Ionic Compounds

Bis(1-aminoguanidinium) sulfate monohydrate (AG₂SO₄ … H₂O, 1), bis(1,3-diamino-guanidinium sulfate (DAG₂SO₄, 2), bis(1,3,5-triaminoguanidinium) sulfate dihydrate (TAG₂SO₄ … 2 H₂O, 3) and bis(azidoformamidinium) sulfate (AF₂SO₄, 5) were synthesized and characterized by multinuclear NMR, IR, and Raman spectroscopy and elemental analysis. In the synthesis of 3, double protonated triaminoguanidinium sulfate (HTAGSO₄, 4) was obtained as a byproduct. The molecular structures of 1–5 in the crystalline state were determined by low-temperature single crystal X-ray diffraction. 1: orthorhombic, Pnma, a = 6.7222 (8) Å, b = 14.153 (2) Å, c = 11.637 (1) Å, V = 1107.1(2) ų, Z = 4, ρ_calc.= 1.586 g cm^?3 R₁ = 0.0442, wR₂ = 0.1007 (all data). 2: hexagonal, P6₁22, a,b = 6.6907 (1) Å, c = 43.4600 (8) Å, γ= 120°, V = 1684.86 (5) ų, Z = 6, ρ_calc.= 1.634 g cm^?3, R₁ = 0.0321, wR² = 0.0714 (all data). 3: monoclinic, C2/c, a = 9.6174 (8) Å, b = 22.858 (1) Å, c = 6.7746 (5) Å, β= 109.49 (1), V = 1404.0 (4) ų, Z = 4, ρ_calc.= 1.620 g cm_?3, R₁ = 0.0292, wR₂ = 0.0781 (all data). 4: monoclini c, P2₁/c, a = 8.9998 (9), b = 6.3953 (6), c = 13.3148(12) Å, β= 99.679 (8), V = 755.44 (13) ų, Z = 4, ρ_calc.= 1.778 g cm^?3, R₁ = 0.0305, wR₂ = 0.0809 (all data); 5: orthorhombic, Pbca, a = 11.3855 (9), b = 7.1032 (6), c = 12.807 (1) Å, V = 1035.74 (14) ų, Z = 4, ρ_calc.= 1.720 g cm^?3, R₁ = 0.0389, wR₂ = 0.0862 (all data).