Determination of terbutaline with ferrocene-gold colloid-1,4-benzenedimethanethiol layer-by-layer self-assembled gold electrode

Aminylferrocene is successfully immobilized on nanosized gold colloid particles associated with a 1,4-benzenedimethanethiol monolayer on a gold electrode surface and characterized by cyclic voltammograms and electrochemical impedance spectroscopy. In a pH 7.0 phosphate buffer solution, the formal potential (E ⁰’) of Fc is 0.432 V (SCE), and the apparent surface electron-transfer rate constant is 0.89 s⁻. The immobilized Fc gives an excellent electrocatalytic response to the terbutaline oxidation. The catalytic-current response of differential pulse voltammograms increases linearly with the terbutaline concentration from 1.75 × 10⁻⁷ to 5.62 × 10⁻⁴ mol/l. The detection limit is 2.30 × 10⁻⁸ mol/l. The determination of terbutaline in a tablet dosage is satisfactory. The method is simple, quick, and sensitive. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 8, pp. 969–974. The text was submitted by the authors in English.     

Enhanced chromatographic resolution of amine enantiomers as carbobenzyloxy derivatives in high-performance liquid chromatography and supercritical fluid chromatography

The carbobenzyloxy (cbz) protecting group is evaluated for it's potential to enhance the resolution of chiral amine enantiomers using high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). A series of cbz derivatives of commercially available racemates was prepared and analyzed by enantioselective chromatography using a variety of mobile phases and polysaccharide and Pirkle-type chiral stationary phases (CSPs). The cbz-derivatized product consistently demonstrated enhanced chiral resolution under HPLC and SFC conditions. Improved selectivity and resolution combined with an automated preparative HPLC or SFC system can lead to the rapid generation of highly purified enantiomers of desirable starting materials, intermediates or final products.     

Synthesis of Some Allyl-β-Cyclodextrin Derivatives and their Properties as Capillary GC Stationary Phases

Summary Three -Cyclodextrin derivatives (-CDs) were synthesized by substituting the 2,6-OH groups of -CD with allyl groups and the 3-OH groups with three different acyl groups (valeryl, heptanonyl, octanoyl). The chromatographic properties of these -CDs as stationary phases for capillary gas chromatography (CGC) were studied. The test results showed that the three -CDs possessed good coating properties and that the capillary columns coated with them exhibited high column efficiency. These -CDs can separate not only the disubstituted benzene isomers but also some racemic compounds.     

Synthesis and Inclusion Properties of the Host Compound 1,3-Dihydro-1,1,3,3-tetraphenylisobenzofuran. X-Ray Crystal Structures of the Free Host and of an Inclusion Compound with 1,4-Dioxane

A novel host molecule, 1, suitable for crystalline lattice-type inclusion, has been synthesized, and its cocrystal formation ability has been investigated. Host 1 proved to be of potential use for organic solvent separation and retrieval, and a promising auxiliary for solidification of certain odorous substances. The crystal structures of the solvent-free host 1, and its complex with 1,4-dioxane (1 : 1), have been determined by single crystal X-ray diffraction. The structure of 1 (guest-free) is triclinic, P , with a = 9.452(2), b = 10.359(3), c = 13.116(3) Å, = 101.80(2), = 106.53(1) and = 104.32(1)°. The spacious, propeller-like molecules are held together by weak van der Waals' forces. The dioxane inclusion compound is monoclinic, P21/a, with a = 15.050(1), b = 8.641(1) and c = 20.658(1) Å, and = 94.56(1)°, and contains two crystallographically independent guest molecules, both located around symmetry centres. The molecular packing seems to be governed by C—H···O type bonds (C···O = 3.31 and 3.48 Å) from the host to the dioxane oxygens.     

Photochemical properties and structures ofN-amino andN-azomethine derivatives of 2,4,6-triphenylpyridinium perchlorates

The molecular structures of the initial compounds and the products of photocyclization involving amino and azomethine groups in perchlorates ofN-amino (1) andN-azomethine (2) derivatives of 2,4,6-triphenylpyridinium cations were studied. Cations1 and2 have an essentially non-coplanar arrangement of the -Ph rings, and the product of photocyclization of2, cation3, is characterized by a flattened structure. It was found that the orientation of the lone electron pair of the N atom with respect to one of the planes of the -Ph rings in molecule1 is more favorable for monocyclization involving the amino group. The structure of molecule2 allows two routes of the photoreaction,viz., O N proton transfer and monocyclization with an -Ph ring. However, the structural features of molecule2 are more favorable for photocyclization.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 296–301, February, 1995.     

Resolution of enantiomers by HPLC on cellulose derivatives

Summary Various polysaccharide derivatives, particularly cellulose derivatives, were synthesized and used as chiral stationary phases for optical resolution by HPLC after being adsorbed on macroporous silica gel. Cellulose triacetate (CTA-II), which was synthesized under homogeneous conditions, showed a chiral recognition ability for many racemates. Other cellulose derivatives such as cellulose tribenzoate (OB), cellulose-trisphenylcarbamate (OC), cellulose tribenzyl ether (OE), and cellulose tricinnamate (OK) also showed unique chiral recognition. Among other polysaccharide derivatives, curdlan triacetate was also exhibited an effective chiral recognition. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

2-Quinazolylguanidines in Heterocyclization Reactions. 2. Condensation with α,β-Unsaturated Carbonyl Compounds

4,6,6-Trimethyl-1,4-dihydropyrimidines have been synthesized by condensation of 2-quinazolylguanidines with mesityl oxide. The analogous reaction with benzalacetone leads to unstable 4-methyl-6-phenyl-1,4-dihydropyrimidines, which are oxidized to the corresponding 4-methyl-6-phenylpyrimidines.     

Reductive coupling of polyfunctionalized organobismuth and organolead arylating reagents in the synthesis of benzopyran derivatives

Benzopyran derivatives were synthesized in good yields by the reactions of tris[2-(chloromethyl)phenyl]bismuth diacetate and 2-(halomethyl)aryllead triacetates with phenols and naturally occurring 4-hydroxycoumarins in the presence of bases according to a three-step one-pot procedure. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2520–2529, November, 2005.     

2-（2＇-羟基-3’-甲氧基苯基）-5，6-二硝基苯并咪唑的阴离子识别

设计并合成了2-（2’-羟基-3’-甲氧基苯基）-5，6-二硝基苯并咪唑化合物（1），通过X射线单晶衍射研究了该化合物的固态结构．利用紫外-可见光谱技术研究了其对阴离子的识别，发现化合物1能够在DMSO中对AcO^-，H2PO4^-，OH^-的3种离子进行有效识别，同时溶液由原来的黄色变成红色，实现裸眼检测．