Observations on the swelling characteristics of the zwitterionic hydrogel of poly(1-3-sulfopropyl)-2-vinyl-pyridinium-betaine hydrogel

Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA). The densities of the resultant xerogels increased regularly with the content of MBA. Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis. The water contents increased with decreasing content of MBA, the value of 92.7 wt% at the lowest MBA content being higher than that for other zwitterionic hydrogels. Enhanced swelling occurred in 1 M aq. KSCN at each MBA content, the total swelling being 98.1 wt% at the lowest crosslinker content. Swelling increased with increasing temperature. An approximate procedure to formulating swelling equilibrium in term of the volume fraction of water in hydrogel, in conjunction with the van’t Hoff equation, yields a small positive value for the enthalpy of swelling. This is compared with values derived similarly for other hydrogels.     

Steroid polyols from the Far-Eastern starfish Henricia sanguinolenta

A new polyhydroxylated steroid (20R,24S)-5-cholestane-3,6,15,24-tetraol and a known glycoside, laeviuscoloside G, was isolated from the Far-Eastern starfish Henricia sanguinolenta, collected in the sea of Okhotsk, and characterized.     

Charge equilibria and pK values of 5-carboxypyranomalvidin-3-glucoside (vitisin A) by electrophoresis and absorption spectroscopy

Apparent pK values of the wine pigment, 5-carboxypyranomalvidin-3-glucoside (vitisin A), were determined using UV-vis spectroscopy, viz. pK_a1=0.98 (±0.10), pK_H1=4.51 (±0.03) and pK_H2=7.57 (±0.02). An additional ionisation constant at high pH (pK_a4=8.84±0.06) was established by high-voltage paper electrophoresis. These data in conjunction with previously published pK_a values determined by high-voltage electrophoresis suggest that in wine (pH 3.2-3.8), 5-carboxypyranomalvidin-3-glucoside exists as a complex mixture of hydrated and non-hydrated, partially ionised species with the predominant species being the quinonoidal base (λ_max 498 nm).     

Online photocatalytic device for highly selective pre-column fluorescence derivatization of 5-hydroxyindoles with benzylamine

A fluorimetric liquid chromatographic method for the determination of 5-hydroxyindoles based on the benzylamine derivatization process mediated through an online photocatalytic oxidation has been developed. In this study, we used a photocatalytic column comprising tefzel tubing packed with TiO₂-coated glass beads, as a pre-column derivatization reactor. The fluorescence derivatization of 5-hydroxyindoles using benzylamine proceeded during their passage through the reaction column under near-UV irradiation. The 5-hydroxyindole derivatives were separated continuously on a reversed-phase liquid chromatography within 50 min, using 100 mM acetate buffer (pH 4.6)-acetonitrile (72:28, v/v; isocratic elution) containing 3 mM sodium octanesulfonate; the samples were detected fluorimetrically at 465 nm upon excitation at 350 nm. The detection limits (signal-to-noise ratio = 3) of the 5-hydroxyindoles were in the range from 160 to 360 fmol per 5 μL injection. We have applied this method, which requires minimal sample pre-treatment, to the determination of 5-hydroxyindole-3-acetic acid in human urine.     

Trends in the CNDO/2 molecular orbital study of electronic structure in some neurotransmitter drugs

An investigation of electronic structure in some neurotransmitter drugs has been made using the CNDO/2 semi-empirical molecular orbital method.The electronic structure has been conveniently characterized by the electronic parameters nett atomic population (NAP) and bond index (BI). A variation of these electronic parameters with respect to conformation has been studied and has been found unlikely to exceed 0.1 e in most. cases. Further, the useful extent to which the electronic parameters of some commonly occurring functional groups may be regarded as conformationally invariant has been demonstrated. Also presented are (i) a discussion on the intramolecular close-approach of functional groups — the interaction between terminal —COO^? and ?NH₃⁺ groups of α-ω anaino acids is explicitly considered; (ii) an enquiry into the extension of ‘standard’ (idealized) geometry models in the elucidation of electronic structure.The implication of the results and observations presented here are briefly discussed with reference to classical and quantum structure-activity studies of drug molecules.     

Transformed steroids

A preparative method for 9a-hydroxylation of ⁵-3-hydroxysteroids using the fungi ofCircinella sp. 10Kh-1220 not capable of modifying theA ring has been developed. It is established that the yields of the main and the side products greatly depend on the transformation conditions, mycelium age, and the structure of the steroid substrate. Under the optimal transformation conditions novel 9-hydroxysubstituted derivatives of androstenolone, pregnenolone, 16-dehydro-16,17-epoxy-, and-16-methoxypregnenolone have been obtained in 36–80 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 1994.     

Synthesis of bis(alk-3-en-1-ynyl)benzene with either E- or Z-configuration via a one-pot three-component coupling reaction and its optical properties

A convenient, efficient and stereoselective synthesis of a range of bis(alk-3-en-1-ynyl)benzenes with E- and Z-configuration is described. The protocol involves Cu-mediated cross-coupling reaction of (E)- and (Z)-alk-1-enyldisiamylboranes with (trimethylsilyl)ethynyl bromide and Pd/Cu-catalyzed cross-coupling reaction with diiodobenzene. The sequential cross-coupling reaction proceeds readily under extremely mild conditions in a one-pot manner to afford bis(alk-3-en-1-ynyl)benzenes in good to excellent yields. The optical properties of the products are also described.     

Deoxypegan-1-one derivatives. synthesis and borohydride reduction of 3-[(E)-arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolin-1(2H)-ones

3-[(E)-Arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolin-1(2H)-ones were prepared by reaction of quinazolyl-2-propionic acid hydrochloride with aromatic aldehydes in acetic anhydride in the presence of Et₃N. 3-[(E)-Arylmethylidene]-1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-1-ols were formed by reduction of the 3-arylidene derivatives with sodium borohydride in methanol, readily lost water when heated with acids, and were converted into 3-[(E)-arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolines. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 463–467, September–October, 2006.     

Reaction of 1,2-Diamino-4,5-diphenylimidazole with 1,3-Diarylpropenones and Their Dibromo Derivatives

The reaction of 1,2-diamino-4,5-diphenylimidazole with 1,3-diarylpropenones and 1,3-diaryl-2,3-dibromopropenones gives dihydro- and heteroaromatic derivatives of 6-hydroxyimidazopyrimidines and also imidazopyrimidines which do not contain the 6-hydroxy group. It was found that the structure of the products depended on the conditions for carrying it the reaction.     

Crystal and molecular structure of nitraminotetrazole and nitramino-1,2,4-triazole. IV. 5-nitraminotetrazole sodium salt sesquihydrate

The structure of 5-nitraminotetrazole sodium salt sesquihydrate was determined by X-ray diffraction. The crystals are monoclinic, space group P2₁/c;a = 3.551(1) Å, b = 21.834(4) Å, c = 9.075(2) Å; = 110.68(3)°; V = 658.3(2) ų; Z = 4; _calc = 1.807 g/cm³. The anion is planar and has an intramolecular hydrogen bond. The negative charge of the anion is localized on one of the oxygens of the nitro group. The sodium cation (c.n.6) is coordinated by three oxygen atoms of different anions and three oxygens of crystallization water. One of the crystallization water molecules is disordered in the unit cell. The anions are hydrogen-bonded with each other and with crystallization water molecules.Original Russian Text Copyright © 2004 by A. M. Astakhov, A. D. Vasiliev, M. S. Molokeev, L. A. Kruglyakova, A. M. Sirotinin, and R. S. StepanovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 562–565, May–June 2004.