| 1. |
- Ahmed, Mukhtiar, et al.
(författare)
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Aromatic Heterocyclic Anion Based Ionic Liquids and Electrolytes
- 2023
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 25:4, s. 3502-3512
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Tidskriftsartikel (refereegranskat)abstract
- Five new ionic materials comprising fluorine-free aromatic heterocyclic anions based on pyridine and pyrazine combined with a common n-tetrabutylphosphonium cation, (P4444)+, result in two room temperature ionic liquids (RTILs), one semi-solid, and two organic ionic plastic crystals (OIPCs) with melting points >20 °C. The OIPCs showed a plastic crystalline phase, multiple solid–solid transitions, and plastic crystalline and melt phases. For both the neat RTILs and the Li+ conducting electrolytes, the nature and strength of the ion–ion interactions mainly depend on the position of the nitrogen atom with respect to the carboxylate group in the anions. Furthermore, for the RTILs the ionic conductivity is effected by the electronic structure and flexibility of the ions and the anions diffuse faster than the (P4444)+ cation, but are slowed down in the electrolytes due to the strong electrostatic interactions between the carboxylate group of the anions and the Li+, as shown both experimentally and computationally. Overall, this study describes the effect of structural tuning of aromatic anions on the ion–ion interactions and introduces new ionic materials with promising properties to be used as solid and liquid electrolytes in energy storage devices.
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| 2. |
- Ahmed, Mukhtiar, et al.
(författare)
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Ionic Liquids and Electrolytes with Flexible Aromatic Anions
- 2023
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 29:41
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Tidskriftsartikel (refereegranskat)abstract
- Five new n-tetrabutylphosphonium (P4444)+ cation based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 ºC), phase behaviour (Tg < -55 ºC) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.
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| 3. |
- Ahmed, Mukhtiar, et al.
(författare)
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Pyrrolidium- and Imidazolium-Based Ionic Liquids and Electrolytes with Flexible Oligoether Anions
- 2024
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Ingår i: ChemPhysChem. - : John Wiley & Sons. - 1439-7641 .- 1439-4235. ; 25:9
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Tidskriftsartikel (refereegranskat)abstract
- A new class of fluorine-free ionic liquids (ILs) and electrolytes based on aliphatic flexible oligoether anions, 2-(2-methoxyethoxy)acetate (MEA) and 2-[2-(2-methoxyethoxy)ethoxy]acetate (MEEA), coupled with pyrrolidinium and imidazolium cations is introduced. For the ILs with MEEA anions, Li+ conducting electrolytes are created by doping the ILs with 30 mol % of LiMEEA. The structural flexibility of the oligoether functionality in the anion results in glass transition temperatures (Tg) as low as −60 °C for the neat ILs and the electrolytes. The imidazolium-based ILs and electrolytes reveal better thermal stabilities but higher Tg and lower electrochemical stabilities than the corresponding pyrrolidinium-based analogues. All neat ILs show comparable transport properties for the cations and these decrease by the addition of lithium salt – the pyrrolidinium-based electrolyte being affected the most.
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| 4. |
- Antzutkin, Oleg, et al.
(författare)
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Exploring solid-state 17O NMR to distinguish secondary structures in Alzheimer's Aβ fibrils
- 2009
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Ingår i: Euromar 2009. ; , s. 107-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It has been shown by a large number of studies that Alzheimer's disease (AD) amyloid-β-peptide (Aβ) deposits contribute directly to the disease's progressive neurodegeneration. Aggregation cascade for Aβ peptides, its relevance to neurotoxicity in the course of AD, various factors modulating Aβ aggregation kinetics and experimental methods useful for these studies were recently discussed [1]. Results of Tycko and co-workers point at neurotoxicity in vitro of the two different types of Alzheimer's amyloid fibrils dispersed by ultrasonication into small fragments [2]. The high toxicity of Aβ oligomers in vitro has been discussed by Stege et. al who have found that the molecular chaperone αB-crystallin prevents Aβ from forming amyloid fibrils but nevertheless enhances Aβ toxicity [3]. Glabe and co-workes successfully prepared antibodies for Aβ oligomers and small spherical aggregates using nanogold technology [4]. They also have shown that these antibodies decrease toxicity of Aβ for SH-SY5Y human neuroblastoma cell cultures in vitro [4]. In this concern both structure of Aβ-oligomers/fibrils and the specific interaction (aggregation/fusion) of Aβ peptides with nerve cell membranes is of a particular importance [5].We explore Solid-State 17O NMR on selectively 17O,13C,15N-labeled Aβ(1-40), Aβ(11-25) and Ac-Aβ(16-22)-NH2 peptides to distinguish a parallel and anti-parallel β-sheet secondary structures in β-NH2 peptides to distinguish a parallel and anti-parallel β-sheet secondary structures in amyloid fibrils. Aβ(1-40) fibrils form in-registry parallel β-sheets [6], while Aβ(11-25) [7] and Ac-Aβ(16-22)-NH2 [8] form different anti-parallel β-sheet structures, which were previously identified β-NH2 [8] form different anti-parallel β-sheet structures, which were previously identified by 13C multiple-quantum and 13C{15N} REDOR solid-state NMR. In our unpublished work presented here it was found that 17O NMR chemical shifts are sensitive to the type of the secondary structure, i. e. a parallel vs. an anti-parallel β-sheet structures, while the quadrupolar parameters of 17O nuclei unexpectedly do not vary beyond the error limits in the simulated lineshapes of both fibrillized and unfibrillized peptide systems. Results of more advanced solidstate NMR techniques to measure heteronuclear distances, 15N{17O}-REAPDOR, 15N{17O}-TRAPDOR and 17O{15N}-REDOR on selectively 17O-Val18 and 15N-Phe20 labeled Ac-Aβ(16-22)-NH2 fibrils will be also discussed. These novel solid-state NMR experiments will provide additional tools for measuring hydrogen bonding in different secondary structures of peptides in amyloid fibrils.[1.] O.N.Antzutkin, Magn. Reson. Chem. 42 (2004) 231-246; [2.] A.Petkova et al. Science 307 (2005) 262-265; [3.] G.J.J.Stege, et al. Biochem. Biophys. Res. Comm., 262 (1999) 152-156;[4.] R.Kayed et al. Science, 300 (2003) 486-489; [5.] M.Bokvist, et al. J. Mol. Biol. 335 (2004) 1039-1049; [6.] O.N. Antzutkin, et al. Proc. Nat. Acad. Sci, U.S.A., 97 (2000) 13045-13050;[7.] A.T. Petkova, et al. J. Mol. Biol., 335 (2004) 247-260;[8.] J.J. Balbach, Y. (2000) 13045-13050; [9] A.T. Petkova, (2004) 247-260; [10] J.J. Balbach, Y.Ishii, O.N. Antzutkin, et al. Biochemistry 39 (2000) 13748-13759.
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| 5. |
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| 6. |
- Antzutkin, Oleg, et al.
(författare)
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Hydrogen bonding in Alzheimer’s amyloid-β fibrils probed by 15N{17O} REAPDOR solid-state NMR spectroscopy
- 2012
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Ingår i: Angewandte Chemie. - : Wiley. - 0044-8249. ; 124:41, s. 10435-10438
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Tidskriftsartikel (refereegranskat)abstract
- Nach selektiver Markierung mit 17O und 15N wurden mithilfe von 15N{17O}-REAPDOR-NMR-Spektroskopie intermolekulare C17O⋅⋅⋅H15N-Wasserstoffbrücken in Ac-Aβ(16–22)-NH2- (siehe Schema) und Aβ(11–25)-Amyloidfibrillen untersucht, die mit der Alzheimer-Krankheit in Verbindung gebracht werden. Die Methode, die eine Bestätigung für die Struktur dieser Fibrillen lieferte, könnte auch im Zusammenhang mit anderen biologischen Proben nützlich sein.
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| 7. |
- Antzutkin, Oleg, et al.
(författare)
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Hydrogen bonding in Alzheimer’s amyloid-β fibrils probed by 15N{17O} REAPDOR solid-state NMR spectroscopy
- 2012
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 51:41, s. 10289-10292
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Tidskriftsartikel (refereegranskat)abstract
- An exclusive label: 15N{17O} REAPDOR NMR was used to validate intermolecular C17O⋅⋅⋅H15N hydrogen bonding in Ac-Aβ(16–22)-NH2 (see scheme) and Aβ(11–25) amyloid fibrils, which are associated with Alzheimer’s disease, by selectively labeling them with 17O and 15N. This method was effective for confirming the structure of these fibrils, and could be useful for a number of other biological samples.
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| 8. |
- Arkhipov, Victor, et al.
(författare)
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Micelle structure and molecular self-diffusion in isononylphenol ethoxylate–water systems
- 2013
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Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 51:7, s. 424-430
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Tidskriftsartikel (refereegranskat)abstract
- The structure and dynamic properties of micellar solutions of nonionic surfactants of a series of isononylphenol ethoxylates, C9H19C6H4O(C2H4O)nH (where n = 6,8,9,10, and 12), were studied by NMR diffusometry, dynamic light scattering, and viscosimetry. The sizes of the micelles were determined for different surfactants and at different surfactant concentrations. The numbers of water molecules bound by a micelle and by one oxyethylene group of the surfactant were estimated
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| 9. |
- Arkhipov, Victor P., et al.
(författare)
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Abnormal diffusion behavior and aggregation of oxyethylated alkylphenols in aqueous solutions near their cloud point
- 2022
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 358
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated solutions of oxyethylated alkylphenols (neonols) in a mixture of ordinary and heavy water with equal densities of the neonols and the aqueous mixture. The equal densities allow exclusion of sedimentation effects and study of the evolution of micelles and neonol aggregates in the range from room temperature to above the cloud point. The self-diffusion coefficients of neonols were measured by NMR and the effective hydrodynamic radii of micelles and neonol aggregates were calculated using the Stokes-Einstein relation. An abnormal decrease in neonols diffusion coefficients occurred when the system approached the cloud point, while an abnormal increase in the diffusion coefficients occurred at temperatures above the cloud point. We explained the abnormal temperature behavior of the diffusion coefficients of neonols by changes in the size of the diffusing objects from the spherical and spherocylindrical micelles to dehydrated aggregates and the destruction of micelles by thermal motion and by formation of aggregates with sizes of the order 102 nm at temperatures above the cloud point. Conclusions about the increase in the hydrodynamic radii of the micelles with increasing temperature up to the cloud point and about the formation of dehydrated aggregates above the cloud point are confirmed by the results of DLS studies.
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| 10. |
- Arkhipov, Victor P., et al.
(författare)
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Aggregation Properties of Triton X-100 in a Mixture of Ordinary and Heavy Water
- 2023
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Ingår i: Applied Magnetic Resonance. - : Springer Nature. - 0937-9347 .- 1613-7507. ; 54:3, s. 415-425
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic and aggregation properties of Triton X-100 in a mixture of ordinary and heavy water in a wide temperature range from room temperature to the cloud point and above were studied. The ratio of ordinary and heavy water was calculated in such a way as to ensure equal densities of Triton X-100 and the water mixture. This made it possible to exclude the effects of sedimentation and study the evolution of Triton X-100 micelles and aggregates, without complication by the effects of spatial phase separation above the cloud point. Self-diffusion coefficients of Triton X-100 molecules were measured by NMR, and the effective hydrodynamic radii of micelles and aggregates were calculated using the Stokes-Einstein relation. The anomalous temperature behavior of the diffusion coefficient of Triton X-100 molecules is explained by changes in the sizes of diffusing objects during their evolution from micelles to dehydrated aggregates below the cloud point and by changes in the sizes of aggregates above the cloud point. The results of the NMR studies are confirmed by data obtained by dynamic light scattering.
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| 11. |
- Arkhipov, Victor P., et al.
(författare)
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Dynamic and molecular association in premicellar aqueous solutions of dicarboxylate amino acid-based surfactant as studied by 1H NMR
- 2022
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Ingår i: Magnetic Resonance in Chemistry. - : John Wiley & Sons. - 0749-1581 .- 1097-458X. ; 60:3, s. 359-368
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Tidskriftsartikel (refereegranskat)abstract
- We examined a series of amino acid-based surfactants with two carboxylic groups separated by a spacer of one, two, or three carbon atoms with sodium and calcium counterions in the premicellar concentration region near the CMC. 1H NMR spectroscopy and NMR diffusometry techniques were used to study the local environment, association and translational dynamics of the surfactant’s molecules. We measured the self-diffusion coefficients of the micelles, calculated the effective hydrodynamic radii, and determined the temperature region in which the premicelles exist. With an increase in temperature from 295 to 335 K, the premicellar state of the surfactant is replaced by the monomeric state.
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| 12. |
- Arkhipov, Viktor P., et al.
(författare)
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Dynamic and structural properties, cloud point of mixed micelles of oxyethylated isononylphenols
- 2021
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Ingår i: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 42:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- We measured the self-diffusion coefficients of mixed micelles formed in binary mixtures of oxyethylated isononylphenols (neonols) AF9-2,3,4,6,8,9,10,12 by NMR diffusometry in aqueous 1 wt% solutions. The effective hydrodynamic radii of the micelles were calculated using the Stokes-Einstein relation. Cloud points of these solutions were determined visually and the relation between the cloud point and the composition of the mixture was suggested. Extraction of phenol from the solutions at their cloud points was also studied.
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| 13. |
- Arkhipov, Victor P., et al.
(författare)
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Dynamic and structural properties of oxyethylated isononylphenols
- 2016
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Ingår i: Mendeleev communications (Print). - : Elsevier BV. - 0959-9436 .- 1364-551X. ; 26:4, s. 355-357
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion coefficients, dielectric relaxation times and refraction coefficients were measured, and activation energies of translational and rotational mobilities were determined for a series of oxyethylated phenols (neonols AF9-n) p-C9H19C6H4-O(CH2CH2O)nH, n = 4, 6, 8, 9, 10, 12, at different temperatures. The results demonstrated the existence of contraction and transition phenomena that changed the structure of neonol molecules at n ∼ 9 from a zigzag to a meander form.
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| 14. |
- Arkhipov, Victor P., et al.
(författare)
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Micellar and solubilizing properties of rhamnolipids
- 2023
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Ingår i: Magnetic Resonance in Chemistry. - : John Wiley & Sons. - 0749-1581 .- 1097-458X. ; 61:6, s. 345-355
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Tidskriftsartikel (refereegranskat)abstract
- We studied the micellar and solubilizing properties of aqueous solutions of unfractionated rhamnolipids produced by Pseudomonas aeruginosa. We used nuclear magnetic resonance (NMR) diffusometry, dynamic light scattering, and conductometry to measure the critical micelle concentration (CMC) of rhamnolipid solutions and determined the effective hydrodynamic radii of rhamnolipid monomers and micelles. Based on selective measurements of the self-diffusion coefficients of molecules, performed by NMR diffusometry, the solubilizing properties of rhamnolipids were studied depending on their concentration in solution; aromatic hydrocarbons, benzene, toluene, ethylbenzene, and para-xylene were taken as solubilizates. On the basis of the measurement results, we estimated the distribution coefficient of the solubilizate between the micellar (solubilized) and free (in the aqueous phase) states and the solubilizing capacity of rhamnolipid micelles.
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| 15. |
- Arkhipov, Victor P., et al.
(författare)
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Micelles and aggregates of oxyethylated isononylphenols and their extraction properties near cloud point
- 2014
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 118:20, s. 5480-5487
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Tidskriftsartikel (refereegranskat)abstract
- We used nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS) techniques to study the structural and dynamic properties of micellar solutions of nonionic surfactants of a homologous series of oxyethylated isononylphenols - C9H19C6H 4O(C2H4O)nH, where n = 6, 8, 9, 10, or 12 - in a wide range of temperatures, including cloud points. The radii of the micelles and aggregates, as well as their compositions at different concentrations of surfactant, were determined. Using aqueous phenol solutions as a model, we studied the process of cloud point extraction with oxyethylated isononylphenols
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| 16. |
- Arkhipov, Victor P., et al.
(författare)
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Micelles of Oxyethylated Isononylphenols in Aqueous Solutions and Hydrophilic–Lipophilic Balance
- 2020
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:43, s. 28224-28232
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the self-diffusion coefficients and calculated the effective hydrodynamic radii of micelles of ethoxylated isononylphenols in aqueous solutions in the presence of sodium chloride, as well as in their binary mutual mixtures, when approaching cloudy conditions. These cloudy conditions were created by an increase in temperature, a change in the concentration of an electrolyte in the solution, or a mutual ratio of neonols in their binary mixtures. The results are discussed within the concept of the hydrophilic–lipophilic balance.
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| 17. |
- Arkhipov, Victor P., et al.
(författare)
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Molecular self-diffusion and micellar structure in the aqueous solutions of AF9-10 ethoxylated isononylphenol near a cloud point
- 2014
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Ingår i: Mendeleev communications (Print). - : Elsevier BV. - 0959-9436 .- 1364-551X. ; 24:5, s. 266-268
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Tidskriftsartikel (refereegranskat)abstract
- Sizes of micelles and compositions of aggregates in the aqueous solutions of the nonionic surfactant oxyethylated monoalkyl phenol (neonol AF9-10) were determined by NMR spectroscopy, NMR diffusometry and dynamic light scattering in a wide range of tem- peratures near the cloud point. The cloud point extraction of phenol from aqueous solutions by the surfactant AF9-10 was performed.
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| 18. |
- Arkhipov, Victor P., et al.
(författare)
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Oxyethylated Isononylphenols in Carbon Tetrachloride
- 2019
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Ingår i: Applied Magnetic Resonance. - : Springer Nature. - 0937-9347 .- 1613-7507. ; 50:12, s. 1381-1389
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Tidskriftsartikel (refereegranskat)abstract
- Translational diffusion coefficients of ethoxylated isononylphenol molecules C9H19C6H4O(C2H4O)nH in carbon tetrachloride were measured by nuclear magnetic resonance diffusometry. The hydrodynamic radii of the molecules were determined within the framework of the Stokes–Einstein relation. We showed that ethoxylated isononylphenols in carbon tetrachloride do not form micelles, and the dependence of the diffusion coefficients and, accordingly, the hydrodynamic radii of the nonionic surfactants on the number of oxyethylene groups have a kink in the region n = 6–8.
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| 19. |
- Arkhipov, Victor P., et al.
(författare)
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Rhamnolipid Biosurfactant: Use for the Removal of Phenol from Aqueous Solutions by Micellar Solubilization
- 2023
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Ingår i: ACS Omega. - : American Chemical Society. - 2470-1343. ; 8:33, s. 30646-30654
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Tidskriftsartikel (refereegranskat)abstract
- Selective measurements of the self-diffusion coefficients of molecules of the biological surfactant rhamnolipid (RL) in individual aqueous solutions and in solutions with phenol as a solubilizate were carried out by nuclear magnetic resonance (NMR) diffusometry. Based on the obtained results, the solubilization characteristics of RLs were calculated. They are the fraction of solubilized phenol molecules, the phenol micelle-water distribution coefficient, the molar solubilization coefficient, the hydrodynamic radii of RL monomers and micelles, the aggregation numbers of micelles, and the solubilization capacity of micelles. Fraction of the solubilized phenol molecules increases and approaches 80-90% with increasing RL concentration. The solubilization capacity of the micelles increases from several units to 102 with an increase in both the concentration of RLs and the concentration of phenol in solution.
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| 20. |
- Arkhipov, Victor P., et al.
(författare)
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Self-Diffusion Coefficients, Aggregation Numbers and the Range of Existence of Spherical Micelles of Oxyethylated Alkylphenols
- 2021
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Ingår i: Applied Magnetic Resonance. - : Springer. - 0937-9347 .- 1613-7507. ; 52:5, s. 607-617
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation numbers were calculated based on measurements of the self-diffusion coefficients, the effective hydrodynamic radii of micelles and aggregates of oxyethylated alkylphenols in aqueous solutions. On the assumption that the radii of spherical micelles are equal to the lengths of fully extended neonol molecules, the limiting values of aggregation numbers corresponding to spherically shaped neonol micelles were calculated. The concentration and temperature ranges under which spherical micelles of neonols are formed were determined.
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| 21. |
- Arkhipov, Victor P., et al.
(författare)
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Study of the premicellar state in aqueous solutions of sodium dodecyl sulfate by nuclear magnetic resonance diffusion
- 2021
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Ingår i: Magnetic Resonance in Chemistry. - : John Wiley & Sons. - 0749-1581 .- 1097-458X. ; 59:11, s. 1126-1133
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Tidskriftsartikel (refereegranskat)abstract
- Self‐diffusion coefficients of sodium dodecyl sulfate (SDS) were measured in aqueous solutions in the premicellar range of the SDS concentrations 7‐34.7 mM and temperatures 30‐900C. Average effective hydrodynamic radii and aggregation numbers of SDS in the premicellar region were determined. At C < CMC at all temperatures, the SDS solution is the solution of monomers. At C > CMC the increase of temperature leads to decrease in the effective hydrodynamic radii and the average aggregation numbers. At C >> CMC, it is impossible to reach the monomeric state by increasing the temperature.
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| 22. |
- Arkhipov, Victor P., et al.
(författare)
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The cloud point of aqueous solutions of ethoxylated monoalkylphenols in the individual state and in the presence of electrolytes
- 2018
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Ingår i: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 39:10, s. 1442-1446
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Tidskriftsartikel (refereegranskat)abstract
- The cloud points tcp of aqueous solutions of ethoxylated monoalkylphenols, AF9-n (n = 8,9,10,12), were measured in the concentration (C) range of 0.25-40 wt.%. tcp increased as C decreased at C < 1 wt.%. At 1 < С < 10 wt.%, tcp changed insignificantly; Δtcp/tcp did not exceed 5%. Solutions transformed into the gel state at С > 10-20 wt.% and tcp sharply increased. The dependence of tcp on the length of the oxyethylene chains of ethoxylated nonylphenols at C = 1 wt.% can be described by the equation tcp = b·ln(n-n0), where n0 = 6. The cloud points of aqueous solutions (C = 1 wt.%) of the ethoxylated nonylphenols were measured at different concentrations of NaI, NaCl, NaF, Na2CO3, and Na2SO4 salts. For all of these solutions, tcp decreased in the presence of NaCl, NaF, Na2CO3, Na2SO4 and increased in the presence of NaI. To describe the dependence of tcp on the salt concentration, the equation was suggested, where and tcp are the cloud points of a neat aqueous solution of ethoxylated nonylphenols and of the solution in the presence of electrolytes, respectively.
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| 23. |
- Arkhipov, Victor P., et al.
(författare)
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The efficiency of micellar solubilization of naphthalene from aqueous solutions using rhamnolipid as a biological surfactant according to NMR diffusometry
- 2024
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Ingår i: Magnetic Resonance in Chemistry. - : John Wiley & Sons. - 0749-1581 .- 1097-458X. ; 62:10, s. 712-717
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Tidskriftsartikel (refereegranskat)abstract
- The micellar solubilization of naphthalene from its saturated aqueous solutions using the biosurfactant rhamnolipid was studied. Using the NMR diffusion method, selective measurements of the self-diffusion coefficients of molecules of all components of the solution—naphthalene, rhamnolipid, and water—were carried out at various rhamnolipid concentrations from 0.06 to 100 g/L. Based on the results of diffusometry, the distribution of naphthalene molecules between the states free in solution and states bound by micelles was found. With an increase in the concentration of rhamnolipids, the proportion of bound naphthalene molecules increases from 50% at CRL = 2 g/L to 100% at CRL ≥ 50 g/L. The micelle-water partition coefficient Km and the molar solubilization ratio MSR were calculated.
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| 24. |
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| 25. |
- Bhattacharyya, Shubhankar, et al.
(författare)
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High CO2 absorption capacity by chemisorption at cations and anions in choline-based ionic liquids
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:46, s. 31216-31226
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Tidskriftsartikel (refereegranskat)abstract
- The effect of CO2 absorption on the aromaticity and hydrogen bonding in ionic liquids is investigated. Five different ionic liquids with choline based cations and aprotic N-heterocyclic anions were synthesized. Purity and structures of the synthesized ionic liquids were characterized by 1H and 13C NMR spectroscopy. CO2 capture performance was studied at 20 °C and 40 °C under three different pressures (1, 3, 6 bar). The IL [N1,1,6,2OH][4-Triz] showed the highest CO2 capture capacity (28.6 wt%, 1.57 mol of CO2 per mol of the IL, 6.48 mol of CO2 per kg of the ionic liquid) at 20 °C and 1 bar. The high CO2 capture capacity of the [N1,1,6,2OH][4-Triz] IL is due to the formation of carbonic acid (–OCO2H) together with carbamate by participation of the –OH group of the [N1,1,6,2OH]+ cation in the CO2 capture process. The structure of the adduct formed by CO2 reaction with the IL [N1,1,6,2OH][4-Triz] was probed by using IR, 13C NMR and 1H–13C HMBC NMR experiments utilizing 13C labeled CO2 gas. 1H and 13C PFG NMR studies were performed before and after CO2 absorption to explore the effect of cation–anion structures on the microscopic ion dynamics in ILs. The ionic mobility was significantly increased after CO2 reaction due to lowering of aromaticity in the case of ILs with aromatic N-heterocyclic anions.
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| 26. |
- Bhattacharyya, Shubhankar, et al.
(författare)
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Insights into the Effect of CO2 Absorption on the Ionic Mobility of Ionic Liquids
- 2016
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 18:41, s. 28617-28625
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a comparative effect of CO2 absorption on the ionic mobility of two choline based ionic liquids comprising two different anions such as threonine and imidazole. The synthesized ionic liquids were characterized using 1H and 13C NMR and other spectroscopic techniques. By keeping a common cation and changing the anion from threonine to imidazole both the viscosity and density reduced drastically. We found that [N1,1,6,2OH][Imi] exhibits the highest CO2 capture capacity at 20 °C of 5.27 mol of CO2 per kg of ionic liquid (1.27 mol of CO2 per mol of ionic liquid, 23.26 wt% of CO2) whereas [N1,1,6,2OH][Threo] exhibits 3.6 mol of CO2 per kg of ionic liquid (1.05 mol of CO2 per mol of ionic liquid, 15.87 wt% of CO2). The activation energy for diffusion is calculated using the Vogel-Fulcher-Tamman (VFT) equation in the form of diffusivity. It was found that the activation energy for the diffusion of [N1,1,6,2OH][Threo] is ∼10 times higher than that of [N1,1,6,2OH][Imi]. 1H diffusion NMR data revealed that the diffusivity of [N1,1,6,2OH][Imi] is increased after CO2 absorption whereas a decrease in diffusivity was observed in the case of [N1,1,6,2OH][Threo]. This anomalous behavior of [N1,1,6,2OH][Imi] was further explained by using DFT calculations.
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| 27. |
- Bhowmick, Sourav, et al.
(författare)
-
Ambient temperature liquid salt electrolytes
- 2023
-
Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 59:18, s. 2620-2623
-
Tidskriftsartikel (refereegranskat)abstract
- Alkali metal salts usually have high melting points due to strong electrostatic interactions and solvents are needed to create ambient temperature liquid electrolytes. Here, we report on six phosphate-anion-based alkali metal salts, Li/Na/K, all of which are liquids at room temperature, with glass transition temperatures ranging from −61 to −29 °C, and are thermally stable up to at least 225 °C. While the focus herein is on various physico-chemical properties, these salts also exhibit high anodic stabilities, up to 6 V vs. M/M+ (M = Li/Na/K), and deliver some battery performance - at elevated temperatures as there are severe viscosity limitations at room-temperature. While the battery performance arguably is sub-par, solvent-free electrolytes based on alkali metal salts such as these should pave the way for conceptually different Li/Na/K-batteries, either by refined anion design or by using several salts to create eutectic mixtures.
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| 28. |
- Bhowmick, Sourav, et al.
(författare)
-
Physical and electrochemical properties of new structurally flexible imidazolium phosphate ionic liquids
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:38, s. 23289-23300
-
Tidskriftsartikel (refereegranskat)abstract
- New structurally flexible 1-methyl- and 1,2-dimethyl-imidazolium phosphate ionic liquids (ILs) bearing oligoethers have been synthesized and thoroughly characterized. These novel ILs revealed high thermal stabilities, low glass transitions, high conductivity and wide electrochemical stability windows up to 6 V. Both anions and cations of 1-methyl-imidazolium ILs diffuse faster than the ions of 1,2-dimethyl-imidazolium ILs, as determined by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The 1-methyl-imidazolium phosphate ILs showed relatively higher ionic conductivities and ion diffusivity as compare with the 1,2-dimethyl-imidazolium phosphate ILs. As expected, the diffusivity of all the anions and cations increases with an increase in the temperature. The 1-methyl-imidazolium phosphate ILs formed hydrogen bonding with the phosphate anions, the strength of which is decreased with increasing temperature, as confirmed by variable temperature 1H and 31P NMR spectroscopy. One of the representative IL, [EmDMIm][DEEP], presented a promising performance at elevated temperatures as an electrolyte in a supercapacitor composed of multiwall carbon nanotubes and activated charcoal (MWCNTs/AC) composite electrodes.
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| 29. |
- Bhowmick, Sourav, et al.
(författare)
-
Structurally Flexible Pyrrolidinium- and Morpholinium-based Ionic Liquid Electrolytes
- 2023
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 25:29, s. 19815-19823
-
Tidskriftsartikel (refereegranskat)abstract
- Ion transport measures and details as well as physico-chemical and electrochemical properties are presented for a small set of structurally flexible pyrrolidinium (Pyrr) and morpholinium (Morph) cation-based ionic liquids (ILs), all with oligoether phosphate-based anions. All have high thermal stabilities, low glass transition temperatures, and wide electrochemical stability windows, but rather moderate ionic conductivities, whereas both the anions and the cations of the Pyrr-based ILs diffuse faster than those of the Morph-based ILs. Overall the former ILs have significantly more promise as high-temperature supercapacitor electrolytes, rendering a specific capacitance of 164 F g−1 at 1 mV s−1, a power density of 241 W kg−1 and a specific energy density of 30 Wh kg−1 at 90 °C in a symmetric graphite supercapacitor.
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| 30. |
- Blochin, Dimri S., et al.
(författare)
-
Spatial structure of heptapeptide Glu-Ile-Leu-Asn-His-Met-Lys, a fragment of the HIV enhancer prostatic acid phosphatase, in aqueous and SDS micelle solutions
- 2013
-
Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1033, s. 59-66
-
Tidskriftsartikel (refereegranskat)abstract
- Prostatic acid phosphatase (PAP) is a protein abundantly present in human seminal fluid. PAP plays important role in fertilization. Its 39-amino-acid fragment, PAP(248-286), is effective in enhancing infectivity of HIV virus. In this work, we determined the spatial structure in aqueous solution of a heptapeptide within the PAP fragment, containing amino acid residues 266-272 (Glu-Ile-Leu-Asn-His-Met-Lys). We also report the structure of the complex formed by this heptapeptide with sodium dodecyl sulfate micelles, a model of a biological membrane, as determined by 1H NMR spectroscopy and 2D NMR (TOCSY, HSQC-HECADE, NOESY) spectroscopy. Complex formation was confirmed by chemical shift alterations in the 1H NMR spectra of the heptapeptide, as well as by the signs and values of NOE effects. We also present a comparison of the spatial structure of Glu-Ile-Leu-Asn-His-Met-Lys in water and in complex with sodium dodecyl sulfate
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| 31. |
- Blokhin, Dimitry S., et al.
(författare)
-
Spatial structure of fibrinopeptide B in water solution with DPC micelles by NMR spectroscopy
- 2015
-
Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1102, s. 91-94
-
Tidskriftsartikel (refereegranskat)abstract
- Fibrinopeptide B (GluFib) is one of the factors of thrombosis. Normal blood protein soluble, fibrinogen (fibrinopeptide A and fibrinopeptide B), is transformed into the insoluble, fibrin, which in the form of filaments adheres to the vessel wall at the site of injury, forming a grid. However, the spatial structure of this peptide has not been established till now. In this article, GluFib peptide is investigated together with dodecylphosphocholine (DPC) micelles which were used for mimicking the environment of peptide in blood vessels. The spatial structure was obtained by applying 1D and 2D 1H-1H NMR spectroscopy (TOCSY, NOESY). It was shown that the fibrinopeptide B does not have a secondary structure but we can distinguish the fragment Gly 9 – Arg 14 with a good convergence (the backbone RMSD for the Gly9 – Arg14 is 0.18 ± 0.08 Å).
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| 32. |
- Blokhin, Dimitry S., et al.
(författare)
-
Spatial structure of oligopeptide PAP(248-261), the N-terminal fragment of the HIV enhancer prostatic acid phosphatase peptide PAP(248-286), in aqueous and SDS micelle solutions
- 2014
-
Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1070, s. 38-42
-
Tidskriftsartikel (refereegranskat)abstract
- Prostatic acid phosphatase (PAP) is an enzyme that facilitates infection of cells by HIV. Its peptide fragment PAP(248-286) forms amyloid fibrils known as SEVI, which enhance attachment of the virus by viral adhesion to the host cell prior to receptor-specific binding via reducing the electrostatic repulsion between the membranes of the virus and the target cell. The secondary structure of PAP(248-286) in aqueous and SDS solutions can be divided into an N-terminal disordered region, an -helical central part and an /310-helical C-terminal region (R.P.R. Nanga et al., JACS, 2009, 131, 17972). In this work, we used NMR spectroscopy to study the spatial structure of the isolated N-terminal fragment of PAP(248-286), PAP(248-261) (GIHKQKEKSRLQGG), in aqueous and SDS micelle solutions. Formation of a PAP(248-261)-SDS complex was confirmed by chemical shift alterations in the 1H NMR spectra of the peptide, as well as by the signs and values of Nuclear Overhauser Effect (NOE). In addition, the PAP(248-261) peptide does not form any specified secondary structure in either aqueous or SDS solutions.
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| 33. |
- Blokhin, D.S., et al.
(författare)
-
Spatial structure of the decapeptide Val-Ile-Lys-Lys-Ser-Thr-Ala-Leu-Leu-Gly in water and in a complex with sodium dodecyl sulfate micelles
- 2011
-
Ingår i: Applied Magnetic Resonance. - : Springer Science and Business Media LLC. - 0937-9347 .- 1613-7507. ; 41:2-4, s. 267-282
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the spatial structure of the decapeptide Val-Ile-Lys-Lys-Ser-Thr-Ala-Leu-Leu-Gly in aqueous solution and in a complex with sodium dodecyl sulfate (SDS) micelles by 1H nuclear magnetic resonance (NMR) spectroscopy and two-dimensional (2-D) NMR spectroscopy (total correlation spectroscopy and nuclear Overhauser effect spectroscopy (NOESY)). The approach used to determine the decapeptide spatial structure was based on analysis of the 1H–13C residual dipolar couplings in the molecules partially aligned in lyotropic liquid crystalline media. Analysis of the interproton distances obtained from the 2-D NOESY NMR spectrum was used to reveal the spatial structure of the decapeptide in a complex with SDS micelles. Complex formation was confirmed by analysis of 1H chemical shifts in the NMR spectrum of the decapeptide and analysis of the signs and values of NOEs in a solution with SDS micelles.
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| 34. |
- Blokhin, Dimitry S., et al.
(författare)
-
Spatial Structures of PAP(262–270) and PAP(274–284), Two Selected Fragments of PAP(248–286), an Enhancer of HIV Infectivity
- 2015
-
Ingår i: Applied Magnetic Resonance. - : Springer Science and Business Media LLC. - 0937-9347 .- 1613-7507. ; 46:7, s. 757-769
-
Tidskriftsartikel (refereegranskat)abstract
- Prostatic acid phosphatase (PAP) assembles into amyloid fibrils that facilitate infection by HIV. Its peptide fragments PAP(248–286) and PAP(85–120) also enhance attachment of the virus by viral adhesion to the host cell prior to receptor-specific binding via reducing the electrostatic repulsion between the membranes of the virus and the target cell. The secondary structure of monomeric PAP(248–286) in a biomembrane-mimicking environment can be separated into an N-terminal unordered region, an α-helical central domain, and an α/310-helical C-terminal section (Nanga et al., J. Am. Chem. Soc., 131:17972–17979, 2009). In this work, we used two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy techniques to study spatial structures of isolated central [PAP(262–270)] and C-terminal [PAP(274–284)] fragments of PAP(248–286) in SDS micelle solutions. NMR studies revealed the formation of complexes of both peptides with SDS micelles, with attraction to the micelle membranes occurring mainly through nonpolar and uncharged residues of the peptides. We demonstrate that, when interacting with SDS micelles, PAP(262–270) and PAP(274–284) form α-helical and 310-helical secondary structures, respectively, similar to that found previously for the 39-residue PAP(248–286).
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| 35. |
- Butakov, Anatoly, et al.
(författare)
-
Peculiarities of NMR relaxation in micellar gels of Pluronic F-127
- 2019
-
Ingår i: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 40:3, s. 403-407
-
Tidskriftsartikel (refereegranskat)abstract
- Based on the 1H relaxation of transverse nuclear magnetization of triblock-copolymer Pluronic F-127 in D2O, we proposed a model of the associated pluronic structure in which the polyethylene oxide of molecules in neighboring micelles are intertwined in regions of overlapping micellar coronas, while the polypropylene oxide cores of the micelles play a role of nodes in the 3D network.
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| 36. |
- Dvoyashkin, Dvoyashkin, et al.
(författare)
-
Diffusivity of crude oils contained in macroporous medium : 1H NMR study
- 2018
-
Ingår i: Mendeleev communications (Print). - : Elsevier. - 0959-9436 .- 1364-551X. ; 28:2, s. 222-224
-
Tidskriftsartikel (refereegranskat)abstract
- Diffusivity of crude oils confined in pores of sand decreased with raising the fraction of oil at ordinary temperatures. This behaviour is suggested to be caused by adsorption of the high-molecular fractions of oils at the solid–liquid interface.
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| 37. |
- Filippov, Andrei, et al.
(författare)
-
31P NMR Studies of Phospholipids
- 2015
-
Ingår i: Annual Reports on NMR Spectroscopy. - : Elsevier. - 0066-4103 .- 2163-6052. ; 85, s. 27-92
-
Tidskriftsartikel (refereegranskat)abstract
- 31P nuclear magnetic resonance (NMR) can provide information on the composition of phospholipid (PL) membranes, lipid headgroup orientation relative to the bilayers normal, and the phase state of PL systems. Interaction of the membrane with ions, drugs, other small molecules and peptides may lead to lipid phase change and lamellar phase disturbances, which can also be revealed in 31P NMR spectra. Traditional 31P NMR spectroscopy has been used for years, mainly to study lipid phase state. In the last few years, however, its utility has been extended by a number of solid-state methods in field-cycling spectroscopy. Membrane mimicking systems have been complemented with bicelles, which are more convenient for studying peptide structure in lipid–peptide interactions. Another challenge is the study of ordered membrane domains (rafts) induced in the presence of cholesterol or certain proteins. As a result, recent work has refined the structure of PL headgroups and elucidated membrane responses to interactions with peptides and other molecules. Selected examples of such fascinating investigations are presented here.
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| 38. |
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| 39. |
- Filippov, Andrei, et al.
(författare)
-
Aggregation of amyloid Aβ(1-40) peptide in perdeuterated 2,2,2-trifluoroethanol caused by ultrasound sonication
- 2010
-
Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 48:6, s. 427-434
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrasound sonication of protein and peptide solutions is routinely used in biochemical, biophysical, pharmaceutical and medical sciences to facilitate and accelerate dissolution of macromolecules in both aqueous and organic solvents. However, the impact of ultrasound waves on folding/unfolding of treated proteins, in particular, on aggregation kinetics of amyloidogenic peptides and proteins is not understood. In this work, effects of ultrasound sonication on the misfolding and aggregation behavior of the Alzheimer's Aβ(1–40)-peptide is studied by pulsed-field gradient (PFG) spin–echo diffusion NMR and UV circular dichroism (CD) spectroscopy. Upon simple dissolution of Aβ(1–40) in perdeuterated trifluoroethanol, CF3-CD2-OD (TFE-d3), the peptide is present in the solution as a stable monomer adopting α-helical secondary structural motifs. The self-diffusion coefficient of Aβ(1–40) monomers in TFE-d3 was measured as 1.35 × 10−10 m2 s−1, reflecting its monomeric character. However, upon ultrasonic sonication for less than 5 min, considerable populations of Aβ molecules (ca 40%) form large aggregates as reflected in diffusion coefficients smaller than 4.0 × 10−13 m2 s−1. Sonication for longer times (up to 40 min in total) effectively reduces the fraction of these aggregates in 1H PFG NMR spectra to ca 25%. Additionally, absorption below 230 nm increased significantly upon sonication treatment, an observation, which also clearly confirms the ongoing aggregation process of Aβ(1–40) in TFE-d3. Surprisingly, upon ultrasound sonication only small changes in the peptide secondary structure were detected by CD: the peptide molecules mainly adopt α-helical motifs in both monomers and aggregates formed upon sonication.
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| 40. |
- Filippov, Andrei, et al.
(författare)
-
Aggregation on an amyloid peptide as studied by NMR diffusometry and 2D NMR noesy spectroscopy
- 2009
-
Ingår i: Protein folds in infectious and neurodegenerative diseases. - : Centre National de la Recherche Scientifique, CNRS. ; , s. 91-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Alzheimer's disease is a progressive neurodegenerative disorder affecting millions of people world-wide. Alzheimer's amyloid-b peptide forms amorphous aggregates or amyloid fibrils. However, recent studies indicate that soluble oligomers instead of fibrils may form probably most neurotoxic species. These oligomeric aggregates are difficult to study by traditional structural experimental techniques. NMR diffusometry offer useful additional possibilities. In freshly-prepared solutions (without any pre-aggregates of the peptide) diffusion of the peptide can often be described by an unique diffusion kinetics, which corresponds to the calculated diffusion coefficient of the amyloid- b peptide monomers with the Stokes-Einstein hard-sphere approximation (typically D ~10-10 m2/s). In a quasi-equilibrium or in pulse-induced conditions, new larger aggregates of Ab with diffusion coefficients down to <1×10-13 m2/s were detected. 2D 1H NMR NOESY provides both an additional evidence of aggregation and also reveals most probable sites of the side chain interactions in the aggregates. "Pulse-like" treatment of the sample involves: (i) changing of the solution composition; (ii) freezing-thawing; and (iii) sonication of the sample in the course of its incubation. Putative aggregation mechanisms and structures of monomers and oligomers in solutions at different conditions are discussed.1. Filippov A., Sulejmanova A., Antzutkin O. and Gröbner G. (2005) Diffusion and aggregation of Alzheimer's Abeta(1-40)-peptide in aqueous-TFE solutions as studied by pulsed field gradient NMR. Applied Magnetic Resonance. 29. 439 - 449.2. Filippov A., Sulejmanova A., Gröbner G. and Antzutkin O. (2008) Effect of freezing on amyloid peptide aggregation and self-diffusion in an aqueous solution. Colloid J. 70. 501-506.3. Filippov A., Gröbner G. and Antzutkin O. Effect of ultrasonication on amyloid peptide aggregation in trifluoroethanol solution. (in preparation).
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| 41. |
- Filippov, Andrei, et al.
(författare)
-
Alzheimer's Ab(1-40)-peptide aggregation in TFE caused by ultrasonication
- 2009
-
Ingår i: International Bunsen Discussion Meeting on "Structure of Amyloid Fibrils and Mechanism of Amyloid Formation", 8-11 February 2009, Halle an der Saale (Germany). ; , s. 15-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The translational diffusion of Alzheimer's Aβ(1-40)-peptide in sonicated trifluoroethanol (TFE) solutions was studied by the 1H NMR-diffusomery technique. Sonication was performed at the ultrasound frequency of 50 kHz and with the output of 80 W. In freshly-prepared solutions (without any preaggregates of the peptide) diffusion of Aβ(1-40) can be described by an unique diffusion coefficient (~1×10-10 m2/s), which corresponds to the calculated diffusion coefficient of Aβ(1-40) monomers using the Stokes-Einstein hard-sphere approximation. For untreated samples both the diffusion coefficient and the NMR signal amplitude were not changing with time that suggests no aggregation of the peptide in TFE. In contrary, the diffusion decay of the stimulated spin-echo in sonicated samples was more complex suggesting a presence of a few components with different diffusion coefficients. The diffusion decay was separated into spectral components using the CORE method for global analysis of correlated spectral data. This analysis revealed a new diffusion component, which is characterized by a very small diffusion coefficient (<1×10-13 m2/s), which may be attributed to large oligomers of Aβ(1-40) formed upon sonication. A fraction of this component from the total integral intensity of the 1H NMR signal does depend on the sonication time but it does not change during NMR measurements and the following storage of the sample. In all samples a large fraction of the peptide adopts the a-helical secondary structure as revealed by circular dichroism measurements. Upon ultrasonication this secondary structure changes only insignificantly. Therefore, ultrasonication leads to aggregation of Aβ(1-40)-peptide in TFE, without a detectable (by CD) disruption of its a-helical secondary structure. An increase in the integral intensity of the 1H NMR signal in sonicated samples of Aβ(1-40) in TFE may be interpreted in terms of the transverse relaxation times, T2, of the solvent and Aβ(1-40) monomers: these times do increase as the fraction of Aβ(1-40) aggregates increases in the sample upon sonication. This effect can be further explained by either a concentration dependence of T2 (that reflects a changing ratio of "free" and "bound" solvent to the peptide molecules) or/and by a conformational change in Aβ(1-40) monomers as a result of sonication. Additional spin-echo T2-relaxation time measurements and 1H 2D NOESY NMR may assist in understanding of these interesting effects in sonicated solutions of Aβ(1-40) in TFE. Putative aggregation mechanisms and structures of monomers and oligomers in Aβ(1‑40)/TFE solutions at different duration of sonication are also discussed.
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| 42. |
- Filippov, Andrei, PhD, 1957-, et al.
(författare)
-
CO2 absorption and ion mobility in aqueous choline-based ionic liquids
- 2019
-
Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 276, s. 748-752
-
Tidskriftsartikel (refereegranskat)abstract
- CO2 absorption and ion mobility are investigated in a series of 50/50 wt% aqueous solutions of choline-based ionic liquids with different cations and anions: [N1,1,4,2OH][Threo], [N1,1,5,2OH][Threo], [N1,1,6,2OH][Threo], [N1,1,5,2OH][β-ala] and [N1,1,5,2OH][Tau]. The process of CO2 absorption was completed in an hour reaching maximum of absorption capacity 0.07–0.10 wt% to ionic liquid (by 0.4–0.6 molar ratios). A rapid CO2 absorption is observed by the formation of solid product as a result of reaction between CO2 molecule and the ionic liquid. Diffusion coefficients of the cation and anion in the mixture are comparable while the diffusivity of water molecules is found to be quite different from the ions. In the process of CO2 absorption, an increase in the diffusivity of ions is observed due to the precipitation of solid products and depletion of ions contents in the liquid phase of the system. 13C NMR measurements of diffusivity of CO2 enriched with 13C isotope showed that a part of the absorbed CO2 remained in the liquid phase being physically and chemically bound to ions. The ionic liquid is re-cycled by evaporating water and releasing CO2 molecules using vacuum and temperature.
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| 43. |
- Filippov, Andrei, PhD, 1957-, et al.
(författare)
-
Diffusion of Ions in Phosphonium Orthoborate Ionic Liquids Studied by 1H and 11B Pulsed Field Gradient NMR
- 2020
-
Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Non-halogenated boron-based ionic liquids (ILs) composed of phosphonium cations and chelated orthoborate anions have high hydrolytic stability, low melting point and exceptional properties for various applications. This study is focused on ILs with the same type of cation, trihexyltetradecylphosphonium ([P6,6,6,14]+), and two orthoborate anions, such as bis(salicylato)borate ([BScB]−) and bis(oxalato)borate ([BOB]−). We compare the results of this study with our previous studies on ILs with bis(mandelato)borate ([BMB]−) and a variety of different cations (tetraalkylphosphonium, dialkylpyrrolidinium and dialkylimidazolium). The ion dynamics and phase behavior of these ILs is studied using 1H and 11B pulsed-field-gradient (PFG) NMR. PFG NMR is demonstrated to be a useful tool to elucidate the dynamics of ions in this class of phosphonium orthoborate ILs. In particular, the applicability of 11B PFG NMR for studying anions without 1H, such as [BOB]−, and the limitations of this technique to measure self-diffusion of ions in ILs are demonstrated and discussed in detail for the first time.
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| 44. |
- Filippov, Andrei, PhD, 1957-, et al.
(författare)
-
Diffusivity of ethylammonium nitrate protic ionic liquid confined in porous glasses
- 2022
-
Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 356
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the diffusion of ionic liquid ethylammonium nitrate confined within pores of two types of porous glass, Vycor and Varapor, with average pore sizes of 4 nm and 9.8 nm, respectively, by 1H NMR in the temperature range of 295–325 K. The diffusional behavior of the ionic liquid corresponds to long-term diffusion in a system of interconnected pores. It was shown that the diffusivity of EAN confined in Varapor is controlled by the porous system’s tortuosity and does need to take into consideration the interaction with the surface of the discrete pore walls. In the case of Vycor, the long-term diffusivity is a factor 1.5 lower than that expected in the absence of interaction with the pore walls. Two possible mechanisms that may explain this discrepancy are the EAN-surface interaction and retardation of EAN diffusion compared to n-decane in smaller pores present in Vycor porous glass due to pore size distribution. Confinement of EAN in nanoporous glass does not leads to the EAN phase transformation observed earlier for alkylammonium nitrates enclosed in a micrometer-sized layer. Prolonged exposure of EAN to a strong static magnetic field does not leads to changes in the NMR and diffusivity of EAN over time.
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| 45. |
- Filippov, Andrei, et al.
(författare)
-
Disordering of phospholipid headgroups induced by a small amount of polyethylene oxide
- 2013
-
Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 51:1, s. 1-3
-
Tidskriftsartikel (refereegranskat)abstract
- We present a 31P NMR spectroscopy study of planar glass-plate-oriented multi-bilayers of dimyristoylphosphatidylcholine (DMPC) with addition of polyethylene oxide (PEO). This work revealed the presence of a new component in the spectra that appeared only with addition of a small fraction of PEO (up to one PEO segment per dimyristoylphosphatidylcholine molecule) and disappeared when larger amounts of PEO were added. We explained this phenomenon as an effect of an inhomogeneous force field induced by the PEO molecules located at a certain depth in the lipid membrane interface region
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| 46. |
- Filippov, Andrei, et al.
(författare)
-
Dynamic Properties of Imidazolium Orthoborate Ionic Liquids Mixed with Polyethylene Glycol Studied by NMR Diffusometry and Impedance Spectroscopy
- 2018
-
Ingår i: Magnetic Resonance in Chemistry. - : John Wiley & Sons. - 0749-1581 .- 1097-458X. ; 56:2, s. 113-119
-
Tidskriftsartikel (refereegranskat)abstract
- We used 1H pulsed field gradient (PFG) NMR to study the self-diffusion of polyethylene glycol (PEG) with average molecular mass of 200 and ions in mixtures of PEG with imidazolium bis(mandelato)borate (BMB) and imidazolium bis(oxalato)borate (BOB) ionic liquids (ILs). The ionic liquid was mixed with PEG in the concentration range of 0–100 wt%. Within the temperature range of 295 to 353 K, the diffusion coefficient of BMB is slower than that of the imidazolium cation. The diffusion coefficients of PEG, as well as the imidazolium cation and BMB anions, differ under all experimental conditions tested. This demonstrates that the IL in the mixture is present in at least a partially dissociated state. Generally, increasing the concentration of PEG leads to an increase in the diffusion coefficients of PEG and both the ions, and decreases their activation energy for diffusion. NMR chemical shift alteration analysis showed that the presence of PEG changes the chemical shifts of both ions but in different directions. Impedance spectroscopy was used to measure the ionic conductivity of the ionic liquids mixed with PEG.
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| 47. |
- Filippov, Andrei, et al.
(författare)
-
Dynamic properties of water in silicalite-1 powder
- 2012
-
Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X .- 1873-5894. ; 30:7, s. 1022-1031
-
Tidskriftsartikel (refereegranskat)abstract
- Self-diffusion of D2O in partially filled silicalite-1 crystals was studied at 25 degrees C by H-2 nuclear magnetic resonance (NMR) with bipolar field gradient pulses and longitudinal Eddy-current-delay. For the first time, reliable experimental diffusion data for this system were obtained. Analysis of NMR diffusion decays revealed the presence of a continuous distribution of apparent self-diffusion coefficients (SDCs) of water, ranging from 10(-7) to similar to 10(-10) m(2)/s, which include values much higher and lower than that of bulk water (similar to 10(-9) m(2)/s) in liquid phase. The observed distribution of SDC changes with variation of the diffusion time in the range of 10-200 ms. A two-site Karger exchange model was successfully fitted to the data. Finally, the water distribution and exchange in silicalite-1 pores were described by taking into account (a) a gas-like phase in the zeolite pores, a gas-like phase in mesopores and an intercrystalline gas-like phase and (b) intercrystalline liquid droplets with intermediate exchange rate with the other phases. The other phases experience fast exchange on the NMR diffusion time scale. Diffusion coefficients and mean residence times of water in some of these states were estimated.
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| 48. |
- Filippov, Andrei, et al.
(författare)
-
Dynamics and Structure of a Bitumen Emulsion as Studied by 1H NMR Diffusometry
- 2023
-
Ingår i: ACS Omega. - : Amer Chemical Soc. - 2470-1343. ; 8:39, s. 36534-36542
-
Tidskriftsartikel (refereegranskat)abstract
- Self-diffusion in a bitumen emulsion was studied by H-1 NMR. The emulsion forms two phases: continuous and dispersed. The continuous aqueous phase contains mainly water, with the energy of activation of the diffusion process equal to that of bulk water, while its diffusivity is smaller than that of bulk water by a factor of 2. The dispersed phase consists of bitumen droplets containing confined water, whose dynamics is characterized by a fully restricted diffusion regime in cavities with sizes of similar to 0.11 mu m. Therefore, the studied bitumen emulsion can be described by a model of a complex multiple emulsion of the water/oil/water (WOW) type. The suggested model does agree well with data from H-1 NMR spectroscopy and diffusometry of the bitumen emulsion doped with paramagnetic MnSO4(aq) as well as with an additional H-1 NMR study of the emulsion structure, in which emulsion stability was compromised by freezing at 253 K.
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| 49. |
- Filippov, Andrei, PhD, 1957-, et al.
(författare)
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Dynamics of ethylammonium nitrate near PTFE surface
- 2022
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Ingår i: Magnetic Resonance Imaging. - : Elsevier. - 0730-725X .- 1873-5894. ; 85, s. 102-107
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Tidskriftsartikel (refereegranskat)abstract
- Self-diffusion of ions in the protic ionic liquid ethylammonium nitrate (EAN) was studied by 1H NMR pulsed field gradient techniques between 294 and 393 K in the presence of a PTFE insert in a 5-mm NMR tube. At all temperatures, the bulk diffusion of ions (measured by 1H and 15N NMR) can be described by a unique diffusion coefficient. The presence of solid hydrophobic surfaces of PTFE induces regions of EAN in their vicinity, where diffusion of ions, both cations and anions, is reduced compared to the bulk values. An additional line-shape analysis in 1H NMR spectra showed that local mobility of ethylammonium cations in the surface layers near PTFE is also reduced.
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| 50. |
- Filippov, Andrei, et al.
(författare)
-
Effect of curcumin on lateral diffusion in lipid bilayers
- 2016
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Ingår i: Mendeleev communications (Print). - : Elsevier BV. - 0959-9436 .- 1364-551X. ; 26:2, s. 109-110
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Tidskriftsartikel (refereegranskat)abstract
- Lateral diffusion in dimyristoylphosphatidylcholine lipid bilayers decreases in the presence of cholesterol and curcumin, as measured by 1H NMR spectroscopy, but the mechanisms of action of these two compounds are different.
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