Arrangement Of Sulfur Atoms Research Articles

Systematic Modulation of Thiol Functionalities in Inexpensive Porous Polymers for Effective Mercury Removal.

Through accumulation, mercury contamination in aquatic systems still poses serious health risks despite the strict regulations on drinking water and industrial discharge. One effective strategy against this is adsorptive removal, in which a suitably functionalized porous material is added to water treatment protocols. Thiol (SH) group-grafted structures perform commendably; however, insufficient attention is paid to the cost, scalability, and reusability or how the arrangement of sulfur atoms could affect the HgII binding strength. We used an inexpensive and scalable porous covalent organic polymer (COP-130) to systematically introduce thiol functional groups with precise chain lengths and sulfur content. Thiol-functionalized COP-130 demonstrates enhanced wettability and excellent HgII uptake of up to 936 mg g-1 , with fast kinetics and exceptionally high selectivity. These Hg adsorbents are easily regenerated with HCl and can be used at least six times without loss of capacity even after treatment with strong acid, a rare performance in the domain of Hg-removal research.

Structure of Li5AlS4 and comparison with other lithium-containing metal sulfides

Lithium aluminum sulfide (Li5AlS4) was synthesized by solid state reaction, and its crystal structure was characterized by ab initio structure determination on the basis of powder neutron diffraction (ND) data. Li5AlS4 was found to have monoclinic unit cell (space group, P21/m) with the lattice parameters: a = 6.8583(4)Å, b = 7.8369(4)Å, c = 6.2488(4)Å, and β = 90.333(4)°. This structure is built from a hexagonal close-packed (hcp) arrangement of sulfur atoms with a stacking sequence of …ABAB…. The hcp sulfide lattice consists of two different double-sulfide layers alternately stacked along the c-axis. Between the first pair of sulfur layers all the tetrahedral interstices (T+ and T- sites) are filled with lithium and aluminum atoms. All octahedral interstices between the second pair of sulfur layers are occupied by the remaining lithium atoms. The structure of Li5AlS4 is compared with those of various lithium-containing metal sulfides like Li2FeS2, NaLiMS2 (M = Zn, Cd), Li4GeS4, LiM′S2 (M′ = Al, Ga, In) and γ-Li3PS4. Each sulfide represents a specific distribution of lithium atoms in the lattice depending on how the octahedral and tetrahedral interstitial sites are filled. The low ionic conductivity of Li5AlS4 (9.7 × 10−9Scm−1 at 323K) relative to other sulfides may be due to the highly-ordered distribution of the lithium atoms in the layered structure and the lack of adjacent void spaces that can be used for lithium ion hopping.

ChemInform Abstract: Preparation and Crystal Structure of Na4Cu2S3, a Thiocuprate with Discrete Anions.

Abstract Transparent pale yellow crystals of Na 4 Cu 2 S 3 were obtained from the melt of a corresponding mixture of the binary sulphides. Na 4 Cu 2 S 3 is tetragonal, space group I4 1 /a with a = 9.468(1) A , c=36.64(2) A and Z=16 . The crystal structure was determined from four-circle diffractometer data and refined to a conventional R of 0.021 for 1682 observed reflections with F 0 2 > 3 σ ( F 0 2 ) and 83 variables. An outstanding feature of Na 4 Cu 2 S 3 is the formation of discrete V-shaped thiocuprate anions [SCuSCuS] 4− with copper in an almost linear coordination by sulphur. The bond lengths ( d CuS =2.15 A ) and angles are in good agreement with those of the infinite anionic chains of KCuS. The crystal structure is based on a cubic close-packed arrangement of sulphur atoms with sodium in the centres of the tetrahedral voids, while copper atoms are shifted from the centres towards one of the edges in order to attain a linear co-ordination.

Structure and Phase Transition of Solid Hydrogen Sulphide

By electron diffraction and X-ray diffraction, the following facts are found. 1) A new tetragonal structure ( a =13.5 A and c =4.14 A) exists below a transformation point at about -168°C. 2) This structure changes (at -168°C) to the cubic structure which has already been known, after changing into a transient tetragonal structure ( a '=1/2· a and c '= c ). 3) The cubic structure shows a volume change of about 2% at a higher transformation Point at -147°C. The arrangement of sulphur atoms in the transient tetragonal form is determined from Patterson synthesis and trial and error method on the basis of the data given by electron diffraction. The structure is composed of double zigzag chains of sulphur atoms along the c -axis. The stable tetragonal structure of the lowest temperature phase is considered to be a super-structure of the intermediate form. The relations between these lattice transformations and changes of physical quantities are discussed.

Antibacterial action of a reaction product of cysteine and iron. II. Preparation and properties of the substance.

It has been shown that when low concentrations of cysteine and ferric ammonium citrate or other ferric salts in distilled water, adjusted to faintly acid reaction, are repeatedly autoclaved, an insoluble granular precipitate forms. Chemical analysis of the precipitate indicates that it is sulphur. X-ray photographs of the precipitate and orthorhombic colloidal sulphur, while showing broadly similar patterns, possess significant differences which indicate that the precipitate has a lower symmetry or larger unit cell in its arrangement of sulphur atoms than has orthorhombic sulphur. This precipitate added to Dubos' medium in concentrations of 0.5 to 4 μgm. per ml. inhibits growth of M. tuberculosis. In a concentration of 10 μgm. per ml. growth of all of four other Gram positive species of bacteria and three of five Gram negative species was inhibited. Colloidal sulphur had a similar growth inhibiting property but larger concentrations were required than of the precipitate prepared from cysteine and iron.