Internet Information Resources for Analytical Chemistry

The Web collection of electronic materials on Internet information resources for analytical chemistry (http://www.geokhi.ru/rusanalytchem/Resources/ default.htm) is reviewed. Data on the most informative sites maintained by institutions of various countries are systematized.     

Electrophilic reactions of 3-hydroxyisonicotinic acid

Conclusions The aminomethylation, azo-coupling, and nitration of 3-hydroxyisonicotinic acid and its ester are directed to the 2 position, whereas their iodination proceeds with the formation of the 2-iodo and 2,6-diiodo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–454, February, 1977.     

Hexamolybdoaluminates and Hexamolybdochromates of Some Trivalent Lanthanides and Americium

The reactions of some rare-earth elements (La, Ce, Sm, Lu, Gd) and Am(III) with heteropolymolybdate anions are studied. The complexation rate constants of Am(III) in a solution with Al(OH)₆Mo₆O₁₈ ^3- and Cr(OH)₆MoO₁₈ ^3- ₆ (₁ = 18 ± 6 and 25 ± 5, respectively) are determined by spectral methods. The Ln[Al(OH)₆Mo₆O₁₈] · nH₂O, Eu[Cr(OH)₆Mo₆O₁₈] · nH₂O, and Am[Al(OH)₆Mo₆O₁₈] · nH₂O isostructural compounds are synthesized. The crystal structure of the Sm[Al(OH)₆Mo₆O₁₈] · 11H₂O complex was determined by the X-ray diffraction analysis. The results of spectroscopic and thermogravimetric studies of the obtained compounds are presented.     

Silver-carboxymethyl chitin nanocomposites

Nanocomposite macromolecular systems consisting of silver nanoparticles immobilized in a carboxymethyl chitin matrix are obtained. The method of ultrasonic treatment of a heterophase system (isooctane-water) in the presence of antioxidants of plant origin is used to transfer silver nanoparticles from their micellar solution in isooctane to an aqueous polymer solution. The formation of hydrogen bonds between the functional groups of carboxymethyl chitin and hydroxyl groups of antioxidants is confirmed by Fourier transform infrared spectroscopy. This interaction can provide additional stabilization of metal nanoparticles in the macromolecular system. The transmission electron microscopy data shows that the size of silver nanoparticles increases in a series of antioxidants (gallic acid, dihydroquercetin, and syringic acid). The increase is presumably caused by significant differences in the structures of these antioxidants and their interaction with the polymer matrix.     

Structure and Properties of Carboxymethyl Chitin in the Salt,Acid, and Mixed Forms

Russian Journal of Applied Chemistry - Different forms of 6-О-carboxymethyl chitin were prepared, namely, the salt form containing, the carboxy group in the –COONa form, the acid form...     

Crystal structure of hexakis(N,N-dimethylacetamide)ytterbium(III) dodecawolframophosphate [Yb(DMAA)6]PW12O40

An X-ray diffraction study of the [Yb(DMAA)₆]PW₁₂O₄₀ complex (DMAA is N,N-dimethylacetamide) is performed. The structure contains isolated cationic complexes [Yb(DMAA)₆]³⁺ and heteropolyanions PW₁₂O ₄₀ ^3? . The cationic complexes and the heteropolyanions occupy centrosymmetric positions. The coordination polyhedron of the Yb atom is a slightly distorted octahedron. Unlike the Nd complex of the same composition, which was studied earlier, O atoms of the heteropolyanion are not included in the Yb coordination. All the O atoms of the heteropolyanion are disordered. Analysis of the disordering reveals that the heteropolyanion has a Keggin structure (α isomer), and its disordering results from the centrosymmetric position.