Structural features of semi-synthetic galactomannan sulfates

The positions of sulfate groups in two specimens of sulfated galactomannan from Cyamopsis tetragonoloba seeds were established by analysis of ¹H and ¹³C NMR spectra. For the degree of substitution of 0.6, the signals of galactopyranose residues sulfated at position O(6) or simultaneously at positions O(2) and O(3) were the most intense. Minor signals were due to O(2)- or O(3)-monosubstituted and 2,3,4-tri-O-substituted galactose residues. The substitution of mannopyranose residues involved positions O(6) > O(2,3) > O(2) > O(3). At higher degree of substitution (1.0), the pattern of distribution of sulfate groups over various positions in the residues did not change, the molar content of 2,3-di-O-substituted galactopyranose residues being higher than the content of 6-O-monosubstituted residues. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1745–1749, August, 2008.     

Synergistic effects of sulfation and Fe-doping on the photocatalysis of titania

Fe-doped sulfated titania photocatalysts were prepared by one-step thermal hydrolysis of industrial titanyl sulfate and characterized using XRD, FT-IR, UV–Vis DRS, and N₂ adsorption–desorption techniques. The effects of the volume ratio of pre-adding water to TiOSO₄ on the structure of the titania photocatalysts were investigated. The photocatalytic activities of Fe-doped sulfated titania samples were evaluated using the photooxidation of methylene blue in aqueous solutions under UV light irradiation. The results indicate that Fe-doping induces the red shift of the absorption edge to the visible light range. Meanwhile, sulfur species in the form of sulfate are incorporated into the network of Ti–O–Ti and coordinated to titania in bidentate models, which can effectively promote the separation of the photogenerated electrons and holes. Synergistic effects of both are beneficial for improving the photocatalytic activity of the Fe-doped sulfated titania photocatalysts.     

Determination of the positions of the sulfate groups in sulfated polysaccharides

1. The possibility has been shown of using a method proposed by us previously to determine the positions of the sulfate groups in sulfated polysaccharides. 2. The positions of the sulfate groups in the following sulfated polysaccharides have been determined: fucan and pelvecyan fromPelvetia wrightii and sargassan fromSargassum pallidum.     

Polymeric alkenoxy amino acid surfactants: V. Comparison of carboxylate and sulfate head group polymeric surfactants for enantioseparation in MEKC

In this work, six amino acid derived (L-leucinol, L-leucine, L-isoleucinol, L-isoleucine, L-valinol, and L-valine) polymeric chiral surfactants with carboxylate and sulfate head groups that were recently synthesized in our laboratory [30, 33, 35] are compared for the simultaneous enantioseparation of several groups of structurally similar analytes under neutral and basic pH conditions. The physicochemical properties of the monomers and polymers of both classes of sulfated and carboxylated surfactants are compared. In addition, cryogenic high-resolution electron microscopy showed tubular structures with distinct order of the tubes of 50-100 nm width. A Plackett-Burmann experimental design is used to study the factors that influence the chiral resolution and analysis time of ten structurally related phenylethylamines (PEAs). It is observed that increasing the number of hydroxy groups on the benzene ring of the PEAs resulted in deterioration of enantioseparation using any of the six polymeric surfactants. For all three classes of PEAs, polysodium N-undecenoxycarbonyl-L-amino acidate (poly-L-SUCAA)-type surfactants provided enhanced resolution compared to that of polysodium N-undecenoxycarbonyl-L-amino acid sulfates (poly-L-SUCAASS). Several classes of basic and neutral chiral compounds (e.g., beta-blockers benzoin derivatives, PTH-amino acids, and benzodiazepines) also provided improved chiral separations with poly-L-SUCAA. Among the poly-L-SUCAAs, polysodium N-undecenoxycarbonyl-L-isoleucine sulfate (poly--SUCL) exhibited overall the best enantioseparation capability for the investigated basic and neutral compounds, while among the poly-L-SUCAASs, polysodium N-undecenoxycarbonyl-L-isoleucine sulfate (poly-L-SUCILS), and polysodium N-undecenoxycarbonyl-L-valine sulfate (poly-L-SUCVS) proved to be equally effective for enantioseparation. This work clearly demonstrates that variation in the head group of polymeric alkenoxy amino acid surfactants has a significant effect on chiral separations.     

Quartz crystal microbalance determination of vapors of volatile organic compounds on carbon nanotubes under batch conditions

Specific features of the sorption of vapors of monoatomic aliphatic alcohols and aromatic compounds on coatings formed from carbon nanotubes of various genesis studied by the method of piezoelectric micro weighing are considered. The morphology of the coatings is considered in dependence on the conditions of synthesis and aftertreatment of carbon nanotubes. A new method of the processing of signals from an array piezoelectric sensors is proposed; it allows an increase in the selectivity of the determination of volatile organic compounds in an equilibrium gas phase by 2–2.5 times. The advantages of the application of carbon nanotubes as sorption coatings in comparison to the standard polymeric sorbents for piezoelectric micro weighing are demonstrated: the detection limit decreases by 4–15 times and the duration of measurement by 5–55 times.     

Oxidative polymerization of aniline on the surface of insoluble solid poly(sulfo acids) as a method for the preparation of efficient biosorbents

Polyaniline coatings of the cation-exchange resin Dowex and a synthetic composite material based on silica gel surface-modified by a sulfated styrene-divinylbenzene copolymer were prepared by precipitative polymerization of aniline on the surface of the supports. The optimal conditions for the preparation of the polyaniline-containing material providing the formation of a thin polymeric coating on the support surface were determined. Aniline is predominantly consumed to the formation of a uniform polymeric coating about 3 nm thick with an increase in the concentration of sulfo groups on the support surface. The efficiency of using the polyaniline-containing sorbents for the preparative isolation of DNA from plant tissue lysates was demonstrated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1123–1130, June, 2007.     

Surface sulfation of crab chitin for anisotropic swelling and nanodispersion

Cellulose - Crab chitin was sulfated under heterogeneous conditions using sulfamic acid in N’N-dimethylformamide to selectively sulfate the microfibril surface. The degree of sulfation...     

Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several <Emphasis Type="Italic">O</Emphasis>-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

A concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO₃Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.     

Determination of the positions of the sulfate groups in sulfated polysaccharides

Summary 1. The possibility has been shown of using a method proposed by us previously to determine the positions of the sulfate groups in sulfated polysaccharides.2. The positions of the sulfate groups in the following sulfated polysaccharides have been determined: fucan and pelvecyan fromPelvetia wrightii and sargassan fromSargassum pallidum.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 573–577, September–October, 1976.     

Photo-and thermochromic spiranes. 24. Novel photochromic spiropyrans from 2,4-dihydroxyisophthalaldehyde

Novel series of photochromic indoline and benzoxazine spiropyrans containing ortho-placed formyl and hydroxyl groups in the benzene ring of the chromene part of the molecule have been prepared. X-ray analysis has shown that, depending on the structure of the heterocyclic component in the spiro cyclization reaction different, nonequivalent formyl groups of 2,4-dihydroxyisophthalaldehyde can participate. The synthesized compounds were used as original analogs of salicylaldehyde. The novel photochromic bispyropyrans prepared contain two different asymmetric spiro carbon atoms. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 919–929, June, 2006.     

Quantification of urinary conjugates of bisphenol A, 2,5-dichlorophenol,and 2-hydroxy-4-methoxybenzophenone in humans by online solid phase extraction–high performance liquid chromatography–tandem mass spectrometry

Urinary concentrations of phenols or their metabolites have been used as biomarkers to assess the prevalence of exposure to these compounds in the general population. Total urinary concentrations, which include both free and conjugated (glucuronide and sulfated) forms of the compounds, are usually reported. From a toxicologic standpoint, the relative concentrations of the free species compared with their conjugated analogs can be important because conjugation may reduce the potential biologic activity of the phenols. In this study, we determined the percentage of glucuronide and sulfate conjugates of three phenolic compounds, bisphenol A (BPA), 2,5-dichlorophenol (2,5-DCP), and 2-hydroxy-4-methoxybenzophenone (benzophenone-3, BP-3) in 30 urine samples collected between 2000 and 2004 from a demographically diverse group of anonymous adult volunteers. We used a sensitive on-line solid phase extraction–isotope dilution–high performance liquid chromatography–tandem mass spectrometry method. These three phenols were detected frequently in the urine samples tested. Only small percentages of the compounds (9.5% for BPA, and 3% for 2,5-DCP and BP-3) were excreted in their free form. The percentage of the sulfate conjugate was about twice that of the free compound. The glucuronide conjugate was the major metabolite, representing 69.5% (BPA), 89% (2,5-DCP), and 84.6% (BP-3) of the total amount excreted in urine. These results are in agreement with those reported before which suggested that BPA-glucuronide was an important BPA urinary metabolite in humans. To our knowledge, this is the first study describing the distribution of urinary conjugates of BP-3 and 2,5-DCP in humans.     

Analysis of priority pesticides and phenols in Portuguese river water by liquid chromatography-mass spectrometry

Summary The determination of selected pesticides and phenols in Portuguese river water samples was carried out from April to September, 1999. The method involved 200 mL samples taken by offline, solid phase extraction by OASIS polymeric cartridges followed by liquid chromatography-atmospheric pressure, chemical ionization-mass spectrometry (LC-APCI-MS). Recoveries of pesticides were 50–96% and 72–120% for the Platform and HP 1100 instruments, respectively. Chlorophenols gave recoveries of 60–91%. Triazines and transformation products like desethylatrazine (DEA) and desisopropylatrazine (DIA) and compounds such as diuron and chlorophenols were positively identified by LC-APCI-MS. The levels detected of the different compounds varied from 0.01–2.61 μg L⁻¹, the most frequently detected compounds being, atrazine, simazine, terbuthylazine, alachlor, metolachlor, Irgarol, diuron, 2,4,6-trichlorophenol, desisopropylatrazine and desethylatrazine.     

Structural analysis of κ-carrageenan sulfated oligosaccharides by positive mode Nano-ESI-FTICR-MS and MS/MS by SORI-CID

Structural analysis of sulfated oligosaccharides from kappa-carrageenan of up to ten residues (MW >2 kDa) was successfully carried out by positive mode nano-ESI-FTICR-MS together with MS/MS using sustained off-resonance irradiation-collision induced dissociation (SORI-CID). Glycosidic bond cleavage reactions via the B- and Y-types of fragmentation were observed and enabled complete sequencing of the oligosaccharide samples. The positions of the labile sulfate substituents were observable using SORI-CID, enabling the determination of the sequence of the sulfated residues.     

Solid-phase condensation of rhodium(III) aqua sulfates

Solid-phase condensation of rhodium(III) aqua sulfates yielding oligomeric rhodium(III) aqua sulfate complexes was revealed. The isothermal dehydration of rhodium(III) aqua sulfates under thermal diffusion conditions in the temperature range 100–130°C was studied, and effective rate constants and activation energies were determined. The solid phases of dehydration products were studied by X-ray powder diffraction and IR spectroscopy, and solutions of polymeric phases were studied by ¹⁰³Rh and ¹⁷O NMR, electronic absorption spectroscopy, chromatography, and electrophoresis.     

Electrosynthesized, non-conducting films of poly(2-naphthol): electrochemical and XPS investigations

Advanced biosensors are frequently based on electrosynthesized polymeric films. In this context, the electrosynthesis mechanism underlying the electrochemical oxidation of 2-naphthol (2-NAP) in phosphate buffer at pH 7 on Pt electrodes has been investigated. The voltammetric behaviour suggested the formation of a non-conducting polymer (poly(2-NAP)) through an irreversible electrochemical process complicated by 2-NAP adsorption and fast electrode passivation. Repeat experiments showed the passive films to be strongly adherent to the Pt surface with thicknesses of approximately 10 nm, as estimated by in-situ electrochemical quartz crystal microbalance (EQCM) measurements and by X-ray photoelectron spectroscopy (XPS). The polymer structure was then investigated by XPS, which gave evidence of the presence of naphthalene rings bonded through poly(oxide) groups (C–O–C) and of quinonoid groups, probably present as the ends of polymeric chains. The polymer repeat unit and terminal groups derived by XPS analysis are in accordance with electrochemical results and with synthesis routes reported for phenol-derived compounds in aqueous solution. XPS also gave evidence of a large excess of oxygen, probably arising from water molecules entrapped by the polymeric chains, as suggested by angle-resolved XPS and thermal treatment of poly(2-NAP)/Pt film under ultra-high vacuum (UHV).     

Dichromate method for the determination of chemical oxygen demand

The oxidizability of organic substances of different classes was studied under the conditions of an official procedure for the determination of chemical oxygen demand (COD) with and without using Ag₂SO₄ as a catalyst. Organic substances can be divided into three groups: easily oxidizable compounds that are oxidized by 80–100% without a catalyst; medium-oxidizable compounds that are oxidized by 40–80% in the absence of a catalyst; and hardly oxidizable compounds that are oxidized by less than 40% without a catalyst. It was shown that, in the presence of a catalyst, not all organic substances are completely oxidized; therefore, the verification of the results of the determination of COD using easily oxidizable potassium hydrophthalate and glucose cannot be reliable in the presence of more hardly oxidizable substances. A standard mixture containing ethylene glycol, acetic acid, dimethylformamide, and nitrobenzene was proposed to verify the results of determining COD in waters of any type. The error in COD values found in a standard mixture varied in the range from 15 to 840 mg O/L. A modified procedure for the determination of COD in pure waters was proposed.     

Synthesis, spectral, electrochemical, and anion binding properties of 3,5-bis(dipyrromethanyl) boron-dipyrromethenes

Four new boron-dipyrromethenes (BODIPYs) containing dipyrromethanyl substituents at 3,5-positions, bis(3,5-dipyrromethanyl) BODIPYs 5-8, were synthesized by treating their corresponding 3,5-diformyl BODIPYs 1-4 with excess pyrrole under mild acid catalyzed reaction conditions. The compounds 5-8 are stable and freely soluble in common organic solvents. One-dimensional, two-dimensional NMR, high resolution mass spectrometry (HRMS), absorption, fluorescence, and electrochemical techniques were used to characterize the compounds. The spectral and electrochemical studies indicated that dipyrromethanyl groups at 3,5-positions of BODIPY are less electron deficient compared to formyl groups at the same positions. The anion binding studies indicated that bis(3,5-dipyrromethanyl) BODIPY compounds containing four pyrrole NH groups showed preferential binding with F(-) ion over other anions, as confirmed by using NMR, fluorescence, and electrochemical studies.     

Peculiar features of sorption of positional isomers of formyl-, acetyl-, and aminopyridines in capillary gas-liquid chromatography

The GLC retention parameters of α-, β-, and γ-isomers of formyl-, acetyl-, and aminopyridines were determined on two columns with stationary phases of different polarities. The contributions of formyl, acetyl, methyl, and amino groups located in the α-, β-, and γ-positions of the ring to the retention indices were calculated. The contributions of these groups to the retention were found to depend on their positions with respect to the N atom of the ring and are the smallest for α-substituents. The difference between pyridines containing electron-withdrawing substituents and those containing electron-donating substituents is manifested as different orders of elution of α-, β-, and γ-derivatives. The distinctions between the GLC behaviors of pyridines, benzenes, and furans with the same substituents were identified. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 91–94, January, 1997.     

Syntheses based on β-phenylethylamines VI. Synthesis and mass-spectrometric properties of bis-β-phenylethylbenzylamines and the products of their methylation

Fourteen previously undescribed bases of the bis-β-phenylethylbenzylamine series with a central diphenyl ether group differing by the relative positions of the oxygen bridge and the β-phenylethylbenzylamine substituent have been synthesized. The main directions of the fragmentationof these compounds under electron impact are competing single or successive processes of cleavage of the benzyl bonds, accompanied by the structuredependent transfer of hydrogen atoms. Institute of the Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii. No. 6, pp. 839–853, November–December, 1993.     

Specific Interaction Between Negative Atmospheric Ions and Organic Compounds in Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry

The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O₂^–, HCO₃^–, COO^–(COOH), NO₂^–, NO₃^–, and NO₃^–(HNO₃) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion.