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A.E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Science, Ul. Akad. Arbuzov 8, 420088 Kazan, Russia; Kazan State Technological University, Ul. K. Marx 68, 420015 Kazan, Russia.
New amphiphilic pyrimidinic (AP) compounds with two ammonium head groups and different kinds of counterions, inorganic bromide anions (APB) and hydrophobic tosylate anions (APT) were synthesized. Self-organization in these systems has been studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy. The critical micelle concentrations (cmc's) of bola-type surfactants are only a little lower than those of cetyltrimethylammonium (CTA) analogues. For both pairs APB/CTAB and APT/CTAT the counterion binding is stronger for the conventional cationic surfactants as compared to 'bola' pyrimidinic surfactants. Unlike the CTAT micelles no sharp micellar growth occurs with the APT concentration. The geometry of AP compounds is assumed to be mainly responsible for the above finding. A branched molecular architecture prevents a close packing of the monomers in the bulk solution and at the interface producing a steric hindrance around the head groups.

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A. E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Sciences, 8 Arbuzov Str., Kazan 420088, Russia.
Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties.

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A E Arbuzov Institute of Organic and Physical Chemistry of Kazan Scientific Center of the Russian Academy of Sciences, Kazan, Russia. lucia@iopc.ru
Novel mono- and dicationic pyrimidinic surfactants are synthesized and their aggregation behavior is studied by methods of tensiometry and nuclear magnetic resonance (NMR) self-diffusion. To estimate their potentiality as gene delivery agents, the complexation with oligonucleotides (ONus) is explored by dynamic light scattering (DLS) and zeta-potential titration methods and ethidium bromide exclusion experiments. Bola-type pyrimidinic amphiphile (BPM) demonstrates rather a weak affinity to ONus. Although it induces mixed associations with ONus, only slight charge compensation changes occur at a large excess of bola, with no recharging reached. Similarly, the ethydium bromide exclusion study reveals a slow increase in the binding capacity toward an ONu with an increment in BPM concentration. The monocationic pyrimidinic surfactant (MPM) and its gemini analogue (GPM-1) are ranked as intermediates in both their aggregative activity and complexing properties toward ONus. They both form mixed associates with ONus well below the critical micelle concentrations (cmcs) of 2 and 15 mM respectively. However, GPM-1 has a much lower isoelectric point at the molar ratio surfactant/ONu r~1 compared to r~3 for MPM. This probably indicates a larger electrostatic contribution to the ONu complexation in the case of GPM-1. The most hydrophobic pyrimidinic surfactant (GPM-2), bearing three alkyl tails, demonstrates enhanced aggregative activity and binding capacity toward ONus as compared to former pyrimidinic surfactants. Due to effective aggregative (low cmc of 0.04 mM) plus binding properties (fraction of bound ONu β=0.76 at r=2.5), GPM-2 may be ranked as a promising agent for wider biological applications.
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New amphiphilic pyrimidinic macrocycles (APMs) with two (APM-1) and three (APM-2) decyl tails have been synthesized by quaternization of the bridged N. Complex examination of the APM-based systems with the help of tensiometry, conductometry, dynamic light scattering, and UV and NMR spectroscopy provides evidence for their aggregation. Calculations based on surface tension isotherms and on packing parameter considerations make it possible to assume a lamellar packing of macrocycles when aggregating. Marked differences in the aggregation behavior of APM-1 and APM-2 have been found. The additives of polyethylenimine (PEI) exert little influence on the critical micelle concentration (cmc) of APM-1, while in the APM-2/PEI systems there occurs a pronounced decrease in the cmc and also a ca. 2-fold decrease in the surface area per molecule. The APM-based assemblies are explored as nanoreactors for the hydrolysis of O-alkyl O-p-nitrophenyl (chloromethyl)phosphonates (alkyl = ethyl, hexyl). The kinetic study reveals a minor rate effect of the APM-1-based systems. In the APM-2-based systems an acceleration of the hydrolysis of both phosphonates occurs as compared to the uncatalyzed process. Within the APM-2 --> APM-2/PEI --> APM-2/PEI/La(III) series, due to the cooperative contributions of the supramolecular, polymer, and homogeneous catalysis, an increase in the catalytic effect is observed from 30 times to 3 orders of magnitude as compared to that of the basic hydrolysis of the substrates.
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A.E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Sciences, 8, ul. Akad. Arbuzov, Kazan, 420088, Russia; and Kazan State Technological University, Kazan, 420015, Russia.
Effective nanoreactors based on polyethyleneimines (PEIs) for the hydrolytic cleavage of O-alkyl O-p-nitrophenyl chloromethylphosphonates (alkyl = ethyl, hexyl) and di(p-nitrophenyl)phosphate were developed in conformity with the idea of modeling the polyfunctional catalytic mechanism of enzymes. A step-by-step modification of the single PEI solution by additives with their own catalytic activities (sodium dodecyl sulfate and lanthanum salt) gave rise to a marked improvement in the reaction efficiency. A 104-106-fold acceleration of the reaction compared to the aqueous basic hydrolysis of the substrates was achieved in the sodium dodecyl sulfate-polyethyleneimine-La(III) ternary system. This system can be considered to be metallomicelles immobilized on a hydrophilic polymer matrix. When the PEI immobilized on silica gel was used as a catalyst, the full completion of the reaction was achieved for 100 min under mild conditions, while the half-life of the reaction in a comparable homogeneous regime exceeds 100 h.
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Institute of Organic and Physical Chemistry, Arbuzov Str. 8, Kazan, 420088, Russian Federation, Kazan State University, Kazan, 420008, Russian Federation, and University of Connecticut, 55 North Eagleville Road, 4-60, Storrs, Connecticut 06269-3060.
Protonation (alkylation) sites of several thiopyrimidine derivatives were directly determined by 1H-15N (1H-13C) heteronuclear single quantum coherence/heteronuclear multiple bond correlation methods, and it was found that in all compounds, protonation (methylation) occurred at the N1 nitrogen. GIAO DFT chemical shifts were in full agreement with the determined tautomeric structures. According to ab initio calculations, the stability of the different protonated forms and methylated derivatives was favored due to thermodynamic control and not kinetic control.
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A.E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Sciences, 8, ul. Akad. Arbuzov, Kazan 420088, Russia. lucia@iopc.knc.ru
Surface tension measurements and the kinetic study of the basic hydrolysis of ethyl p-nitrophenyl chloromethyl phosphonate were used to examine the structural behavior and catalytic activity of the cethyltrimethylammonium bromide (CTAB)-polyoxyethylene (10) oleyl ether, C(18)H(35)(OCH(2)CH(2))(10)OH (Brij 97)-water mixed micellar system. Application of the regular solution model to the experimental data yields the value of the interaction parameter beta as -4.6, which indicates an attractive interaction of the surfactants in the mixed micelle and reflects synergistic solution behavior of the mixture. The mixed micellar composition is found to be enriched in the surfactant with the lower critical micelle concentration (cmc). In the kinetic study a nonmonotonic change in the pseudo-first-order rate constant of basic hydrolysis of the substrate is observed with increasing mole fraction of nonionic surfactant. The pseudophase micellar model reveals that the concentration factor mainly contributes to the catalytic effect, while the microenvironmental factor plays a negative role.
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AE Arbuzov Institute of Organic and Physical Chemistry, Kazan, Russia. asiyamust@mail.ru
The luminescent colloids have been synthesized through the layer-by-layer assembly of poly(sodium 4-styrenesulfonate)(PSS) and polyethyleneimine (PEI) onto the luminescent core. The latter has been obtained by the reprecipitation of complex Eu[(TTA)(3)1](where TTA(-) and 1 are thenoyltrifluoroacetonate and 2-(5-chlorophenyl-2-hydroxy)-2-phenylethenyl-bis-(2-methoxyphenyl)phosphine oxide, respectively) from organic solvent to aqueous solution. The variation of Eu(III) complexes indicates the role of the complex core in the development of such core-shell colloids. Complex Eu[(TTA)(3)1] is most convenient precursor of Eu-doped luminescent nanocomposites. The fluorometric measurements at each step of the layer-by-layer polyelectrolyte assembly onto Eu[(TTA)(3)1] core, at various pHs and additives reveal the quenching of Eu-centered luminescence as a result of the interfacial interaction of the core and the dye. The AFM images and electrochemical behavior of PSS-(PEI-PSS)(n)-Eu[(TTA)(3)1] colloids deposited on the surface indicate the stability of the polyelectrolyte multilayer in the dried state.
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A.E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, Arbuzov Street, 8, 420088 Kazan, Russia.
Aggregation and cloud point (CP) behavior, as well as CP extraction of lanthanide ions have been studied for novel non-ionic cyclophanic surfactants with the varied length of polyoxyethylene and hydrophobic moieties (CnEm) based on calix[4]arene platform in their mixtures with Triton X100 (TX100). The dynamic light scattering data reveal the contribution of the large size lamellar or stack like mixed aggregates in CnEm-TX100 solutions. Aggregation and CP behavior of TX100-CnEm mixed solutions are quite different from those of conventional non-ionic surfactants. The effect of the hydrophobic substituents and polyoxyethylene chains length of CnEm on the CP extraction of La(III), Gd(III) and Lu(III) in the mixed TX100-CnEm micellar solutions is discussed in the correlation with their aggregation and cloud point behavior. The obtained data elucidate the cyclophanic structure of CnEm as the key reason of the formation of large lamellar-like aggregates with TX100, exhibiting the unusual CP behavior and CPE efficiency.
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Full equilibrium phase diagrams are presented for two ternary systems composed of the cationic surfactant dodecyltrimethylammonium bromide (DTAB), water (D2O) and a cyclodextrin, either β-cyclodextrin (β-CD) or (2-hydroypropyl)-β-cyclodextrin (2HPβCD). 2H-NMR, SAXS, WAXS and visual examination were used to determine the phase boundaries and characterize the nature of the phases formed. Additionally, diffusion 1H-NMR was used to investigate parts of the diagrams. The water solubility of 2HPβCD is 80%(w/w), whereas it is only 1.85%(w/w) for β-CD. Solubility increases for both species upon complexation with DTAB; while the increase is minute for 2HPβCD, it is dramatic for β-CD. Both systems displayed an isotropic liquid solution (L1) one-phase region, the extension of which differs extensively between the two systems. Additionally, the DTAB:2HPβCD:water system also comprised a normal hexagonal (H1) area, which was not found for the DTAB:β-CD:water system. In the DTAB:β-CD:water system, on the other hand, we found co-crystallization of DTAB and β-CD. From this work we conclude that DTAB and CD molecules form 1:1 inclusion complexes with high affinities. Moreover, we observed indications of an association of 2HPβCD to DTAB micelles in the isotropic solution phase, which was not the case for β-CD and DTAB micelles. This is, to our knowledge, the first complete phase diagrams of surfactant-CD mixtures; as a novel feature it includes the observation of co-crystallization at high concentrations.
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A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, 8, Arbuzov str., 420088, Kazan, Russian Federation.
Electrocatalytic generation of nickel catalysts in low oxidation states by reduction of nickel complexes with various ligands (2,2'-bipyridine, 2,2':6',2''-terpyridine,(S,S)-2,6-bis(4-phenyl-2-oxazolin-2-yl)-pyridine) in the presence of olefinic substrates and fluoroalkyl halides leads to new organic products derived from addition-dimerization processes. Due to the presence of two stereocenters in the dimerization products two diastereomers were characterized by a variety of analytical techniques including multi-dimensional NMR methods and X-ray single crystal diffraction. The formation of dimers was prevented by the inclusion of the hydrogen atom donor tributyltin hydride. The cyclic voltammetry study of selected nickel complexes along with fluoroalkyl halides demonstrated that Ni(I)L is the active form of the catalyst.
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Institute of Gene Biology, Russian Academy of Sciences, Vavilov Str. 34/5, Moscow 119334, Russia. korsanna@mail.ru
Avian schistosome Trichobilharzia szidati is a member of the largest genus within the family Schistosomatidae (Trematoda). Population genetic structure of Trichobilharzia spp. schistosomes, causative agents of cercarial dermatitis in humans, has not been studied yet. The knowledge of the genetic structure of trichobilharzian populations is essential for understanding the host-parasite coevolutionary dynamics and epidemiology strategies. Here we examined genetic diversity in three geographically isolated local populations of T. szidati cercariae inhabiting Russia based on nuclear (randomly amplified polymorphic DNA, RAPD) and mt (cox1) markers. We analyzed T. szidati cercariae shed from seven naturally infected snails of Lymnaea stagnalis. Using three random primers, we demonstrated genetic variation among populations, thus posing genetic structure across geographic sites. Moreover, T. szidati cercariae have been genetically structured among hosts (infrapopulations). Molecular variance analysis was performed to test the significance of genetic differentiation within and between local populations. Of total parasitic diversity, 18.8% was partitioned between populations, whereas the higher contribution (48.9%) corresponds to the differences among individual cercariae within infrapopulations. In contrast to RAPD markers, a 1,125-bp fragment of cox1 mt gene failed to provide any significant within-species structure. The lack of geographic structuring was detected using unique haplotypes which were determined in the current work for Moscow and Western Siberian local populations as well as obtained previously for European isolates (Czech Republic and Germany). All T. szidati/Trichobilharzia ocellata haplotypes were found to be mixed across their geographical origin.
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2012-05-24 07:27:35 © BioInfoBank Institute