Oleg Antzutkin - Academia.edu (original) (raw)

Papers by Oleg Antzutkin

Dalton Transactions, 2022

Solid titanium phosphate, TiP, materials hold great promise for wastewater treatment for removal ... more Solid titanium phosphate, TiP, materials hold great promise for wastewater treatment for removal of metal ions and complexes. A series of TiP materials, synthesised at mild conditions and short reaction times, have been structurally characterised using solid-state X-ray absorption spectroscopy, phosphorus and titanium K edge XANES and EXAFS, and 31 P and 47/49 Ti NMR spectroscopy. The titanium K edge EXAFS data of α-Ti(HPO 4) 2 •H 2 O (α-TiP) revealed octahedral coordination of oxygens around titanium. Repeated washing of primary β-/γ-TiP with hydrochloric acid results in formation of a weakly ordered solid, TiO (OH)(H 2 PO 4)•H 2 O, TiP1-H. The structure of TiP1-H is shown by Ti EXAFS to be a titanyl compound, containing a short TivO bond. The analogous data for linked titanium phosphate compounds (LTP) disclosed that inter-linkage occurs between α-TiP and titanyl phosphate units, supported by 31 P-31 P NOESY NMR data. 47/49 Ti NMR and Ti pre-edge XANES show evidence of two different titanium environments in LTP, one very similar to that observed in TiP1-H and a second more symmetric octahedral environment. Data are discussed in terms of induced acidic hydrolyses of titanium(IV) and phosphate counterpart during washings with hydrochloric acid and water. A straightforward relation between synthesis parameters/post synthetic treatment and structural rearrangement in the materials is established. † Electronic supplementary information (ESI) available: Summary of solid-state structure determinations of TiP compounds, 49 Ti and 47 Ti NMR simulations parameters, transmission absorption spectrum of α-TiP, XRD data for TiP and diffractograms of LTP-H and LTP-Na, titanium K edge XANES spectra of TiP compounds, Fourier transforms of TiP compounds and fits of phosphorus/titanium K edge EXAFS data of TiP compounds.

Mendeleev Communications, Sep 1, 2012

Mendeleev Communications, Mar 1, 2016

Physical Chemistry Chemical Physics, 2023

Some aprotic and protic ionic liquids (ILs) containing nitrate anion demonstrate unusual dynamic ... more Some aprotic and protic ionic liquids (ILs) containing nitrate anion demonstrate unusual dynamic behavior of cations when these ILs are enclosed in micrometer-spaced layers between glass plates. We applied 17 O and 15 N NMR spectroscopy to discover the state and transformations of 17 O and 15 N isotopically enriched nitrate anion of ethylammonium nitrate (EAN) enclosed between glass plates. 15 N NMR spectra demonstrated preferential orientation of the principal axes of the nitrate anions perpendicular to the normal of the glass surface. Therefore, isotropic ionic liquid EAN, when placed within a micrometer-spaced enclosure, forms an ordered phase, which is similar to a liquid crystal. The peculiarity of this phase is that the cations do not have a predominant orientation. Other features of this phase that are typical for liquid crystal phases are the changed local and translational dynamics in comparison with the isotropic state and slow transformation occurring under the action of an external magnetic field.

RSC Advances

A 10-residue peptide segment of β-lactoglobulin (β-LG11–20) forms amyloid-like fibrils as reveale... more A 10-residue peptide segment of β-lactoglobulin (β-LG11–20) forms amyloid-like fibrils as revealed by AFM, NMR, and MD simulations.

A complementary study, using FTICR-MS and solid-state NMR, shows a high degree of polymorphism ex... more A complementary study, using FTICR-MS and solid-state NMR, shows a high degree of polymorphism exhibited by Aβ species in forming hydrogen-bonded networks. Two Alzheimer’s Aβ peptides selectively labeled with 17O and 15N were investigated. Using 15N{17O}REAPDOR solid-state NMR, the peptides involved in forming hydrogen bond were determined, while the total amount of peptides labeled with 17O was measured by FTICR-MS. About one-third of the Aβ peptides were found involved in the formation of the specific >C=17O···H–15N hydrogen bond with their neighbor peptide molecules, and the rest of the molecules likely undergo ± n off-registry shifts.

arXiv: Chemical Physics, 2018

Ethylammonium nitrate (EAN) and propylammonium nitrate ionic liquids confined between polar glass... more Ethylammonium nitrate (EAN) and propylammonium nitrate ionic liquids confined between polar glass plates and exposed to a strong magnetic field demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated a change in the state of residual water. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined ammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases.

Alzheimer's disease is a progressive neurodegenerative disorder affecting millions of people ... more 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 ...

Chinese Chemical Letters, 2003

Two polymeric complexes, [Cd(BTP)(2)](n) and [Cd(i-BTP)(2)](n) 2, were prepared and investigated ... more Two polymeric complexes, [Cd(BTP)(2)](n) and [Cd(i-BTP)(2)](n) 2, were prepared and investigated by solid P-31 and Cd-113 NMR spectroscopies. The crystal structure of 2 was determined by X-ray diff ...

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Journal of Molecular Liquids, 2019

We used 1 H NMR diffusometry to study mixtures of ethylammonium nitrate (EAN) with water (3.1-12.... more We used 1 H NMR diffusometry to study mixtures of ethylammonium nitrate (EAN) with water (3.1-12.4 mol% of added H 2 O) confined between polar glass plates and exposed to a static magnetic field of 9.4 T. The presence of such restrictions reverses the concentration dependence of the diffusivities of the EA (ethylammonium) cation and water typical for the bulk system. The presence of water weakens the effects of a static magnetic field on diffusion of the EA cation as well as on proton exchange of-NH 3 groups. Surprisingly, the amplitude of the echo signal of water protons decreases during exposure to the magnetic field and finally disappears, a phenomenon that depends on the concentration of water in the system. Based on experimental data, we suggest that water in the system is present in two states with different dynamic properties. One type of water formed in confinement possesses NMR relaxation time typical for liquids; its diffusivity can be measured by 1 H NMR. The second type of water is formed upon exposure of the sample of the first type to the magnetic field and eventually includes all the water in the system. This type of water possesses "solid-like" NMR relaxation features that makes it "invisible" to the NMR diffusometry technique. We suggest that this second type of water is adsorbed onto the glass plates. Correspondingly, EAN exists in two liquid phases: the first one contains an EAN-water mixture, while the second one contains neat EAN, and forms on the microscopic scale range under the influence of a static magnetic field.

$Research paper thumbnail of Bi(III) Complexes Containing Dithiocarbamate Ligands: Synthesis, Structure Elucidation by X‐ray Diffraction, Solid‐State 13C/15N NMR, and DFT Calculations$

ChemistrySelect, 2020

We report on syntheses, characterisation by nuclear magnetic resonance (NMR) spectroscopy, X‐ray ... more We report on syntheses, characterisation by nuclear magnetic resonance (NMR) spectroscopy, X‐ray diffraction (XRD) measurements, and density functional theory (DFT) calculations of electronic/molecular structure and NMR chemical shifts of complexes of Bi(III), having the molecular formulae: [Bi{S2CN(C2H5)2)}3] (1), [Bi{S2CN(C2H5)2)}2(C12H8N2)NO3)] (2), and [Bi2{S2CN(CH2)5}6 H2O] (3). The powder XRD patterns of complexes (1) and (2) resembled the corresponding calculated powder XRD patterns for previously reported single crystal structures. Single crystal XRD structure of complex (3), reported in this work, adopted an orthorhombic system with a space group Pbca with a=10.9956(3) Å, b=27.7733(8) Å, c=35.1229(10) Å and α=β=γ=90°. The experimental solid‐state 13C/15N NMR data of the complexes (1)‐(3) were in accord with their X‐ray single crystal structures. The unit cell of the complex (3) shows a weak supramolecular Bi S interaction leading to the formation of a non‐centrosymmetric bi...

Journal of Molecular Liquids, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Frontiers in Chemistry, 2020

Non-halogenated boron-based ionic liquids (ILs) composed of phosphonium cations and chelated orth... more 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 ([P 6,6,6,14 ] +), 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 1 H and 11 B 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 11 B PFG NMR for studying anions without 1 H, 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.

ACS Sustainable Chemistry & Engineering, 2019

Boric acid is known to enhance the kinetics of CO2 absorption by some active aqueous solutions. H... more Boric acid is known to enhance the kinetics of CO2 absorption by some active aqueous solutions. However, the mechanism of interaction of boric acid with CO2 in the presence of active molecules is not yet fully understood. In this work, the interaction and dynamics of ions in aqueous solutions of functionalized choline-based ionic liquids [N1,1,5,2OH][Threo] and [N1,1,5,2OH][Tau] in the presence of boric acid and CO2 was thoroughly investigated using a multinuclear NMR approach: 13 C and 11 B NMR spectroscopy, 11 B NMR transverse relaxation as well as 1 H and 11 B NMR diffusometry. 13 C and 11 B NMR spectroscopy revealed the formation of borate-based complexes as a result of a reaction between boric acid and the anions of the ILs at ionic liquid/boric acid molar ratios larger than ca. 0.15. The formation of these complexes and their dynamics were further investigated using 11 B relaxation, and 1 H and 11 B pulse-field-gradient (PFG) NMR. Plausible reaction mechanisms of boric acid with the anions of the IL, formation of the borate complexes and dissociation of these complexes facilitated by CO2 molecules are suggested.

Physical Chemistry Chemical Physics, 2019

1-Ethyl-3-methyl-imidazolium acetate ([EMIM][OAc]) is one of the most widely used ionic liquids f... more 1-Ethyl-3-methyl-imidazolium acetate ([EMIM][OAc]) is one of the most widely used ionic liquids for various applications.

Journal of Molecular Liquids, 2018

Ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) ionic liquids confined between polar... more Ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) ionic liquids confined between polar glass plates and exposed to a strong magnetic field of 9.4 T demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated decrease in the 1 H NMR signal of residual water. 1 H NMR spectroscopy with presaturation demonstrates that the most probable mechanism of the decrease of the bulk water signal is adsorption of water on polar surfaces of glass plates. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined alkylammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases.

Applied Magnetic Resonance, 2018

In this work, we compared the effects of curcumin and cholesterol directly competing to insert in... more In this work, we compared the effects of curcumin and cholesterol directly competing to insert into the DMPC lipid bilayer during bilayer formation from an initially non-ordered state. 2 H and 14 N nuclear magnetic resonance spectroscopy showed that curcumin is not embedded deep in the lipid bilayer and interacts mainly with the head group of the lipid. In a more complex system of DMPC/CHOL/CUR, curcumin amplifies the effect of cholesterol on the ordering of lipid acyl chains.

The Journal of Physical Chemistry C, 2018

Absorption modes and reactivity of non-halogenated ionic liquids (ILs) at inorganic oxide surface... more Absorption modes and reactivity of non-halogenated ionic liquids (ILs) at inorganic oxide surfaces of γ-Al 2 O 3 , MgO and SiO 2 particles were characterized using multinuclear (11 B, 31 P and 29 Si) solid-state magic-angle-spinning NMR, FTIR and Raman spectroscopy. ILs are composed of the trihexyl(tetradecyl)phosphonium cation, [P 6,6,6,14 ] + , and bis(mandelato)borate, [BMB]-, or bis(salicylato)borate, [BScB]-, anions. Spectroscopic measurements were performed on room temperature (298 K) samples and samples exposed to 15 hours of heating at 373 K. The single pulse 11 B NMR data of heated [P 6,6,6,14 ][BMB] mixed with the inorganic oxides showed a significant change in spectra of the anion for all three

Physical chemistry chemical physics : PCCP, Jan 28, 2018

Self-diffusion and NMR relaxation of the ethylammonium (EA) cation were studied in the protic ion... more Self-diffusion and NMR relaxation of the ethylammonium (EA) cation were studied in the protic ionic liquid, ethylammonium nitrate (EAN), confined between polar glass plates separated by a few μm distance and exposed to an external magnetic field of 9.4 T. The diffusion coefficient of EA (D) and the transverse NMR relaxation rate (1/T) of -NH protons were increased immediately after placing the sample in the magnetic field by factors of ∼2 and ∼22, respectively, in comparison with those of bulk EAN. Further exposure of the sample to the magnetic field led to gradual changes in D, T and T towards their bulk values with a time constant of ∼70 min. Complete "recovery" of the sample to the "accelerated" D and "shortened" T values occurred at longer than 24 hours after the removal of the EAN sample from the magnet. Because the observed characteristic times of the change far exceed the times of molecular processes in EAN, we suggested that this phenomenon is r...