On the Crystal Structure of a Previously Unknown Anhydrous Zinc Hydroxide Sulfate

Anhydrous zinc hydroxide sulfates are promising precursors for the preparation of pigments and ZnO nanomaterials. The crystal structure of one such compound 5[Zn(OH)₂] · 2[ZnSO₄] was determined from high resolution laboratory X‐ray powder diffraction data by use of a combination of charge flipping, 18 simulated annealing, 26 and difference Fourier analysis. The material crystallizes in the space group P$\bar{1}$ with the lattice parameters of a = 5.4559(2) Å, b = 8.0528(3) Å, c = 8.9275(3) Å, α = 112.697(2)°, β = 85.219(3)°, γ = 95.441(3)°, and a volume of V = 359.76(2) ų. The basic crystal structure consists of brucite type Zn(OH)₂ layers where every sixth octahedral site is vacant. Tetrahedrally coordinated zinc ions are located above and below these vacancies and consecutive layers are bridged by sulfate molecules. The composition of this layered structure can be written as [Zn₅^VI□(OH)₄ · Zn₂^IV(OH)₆ · (SO₄)₂]. Its thermal decomposition was studied by X‐ray powder diffraction and thermal analysis.     

Synthesis of a 2'-Se-uridine phosphoramidite and its incorporation into oligonucleotides for structural study

[chemical reaction: see text]. We report here the synthesis of the 5'-[benzhydryloxybis(trimethylsilyloxy)]silyl-2'-methylseleno-2'-deoxyuridine phosphoramidite and its incorporation into oligonucleotides by solid-phase synthesis. The coupling yield of this phosphoramidite into oligonucleotides is higher than 99%. We also demonstrate that this 2'-methylselenophosphoramidite is compatible with the 5'-silyl-2'-ACE chemistry, for longer Se-RNA solid-phase synthesis. Our preliminary NMR study on the synthesized 2'-Se-DNA has revealed a U(Se)-A base pair and a duplex structure formation when its complementary strand was present.