549 results match your criteria: "Institute of Problems of Chemical Physics[Affiliation]"

A combination of in situ nanocalorimetry with simultaneous nanofocus 2D Wide-Angle X-ray Scattering (WAXS) was used to study polymorphic behaviour and structure formation in a single micro-drop of isotactic polypropylene (iPP) with defined thermal history. We were able to generate, detect, and characterize a number of different iPP morphologies using our custom-built ultrafast chip-based nanocalorimetry instrument designed for use with the European Synchrotron Radiation Facility (ESRF) high intensity nanofocus X-ray beamline facility. The detected iPP morphologies included monoclinic alpha-phase crystals, mesophase, and mixed morphologies with different mesophase/crystalline compositional ratios.

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Nitric oxide (NO) mediates diverse physiological processes in living organisms. Small molecular NO donors usually lack stability and have a short half-life in human tissues, limiting the therapeutic application. The anionic tetranitrosyl iron complex with thiosulfate ligands (TNIC) is one of the most promising NO donors.

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The reduction of metal(II) tetraphenylporphyrins, where metal(II) is copper, nickel or iron, has been performed in toluene solution in the presence of a cryptand. Cesium anthracenide was used as a reductant. Crystalline salts {cryptand(Cs)}{Cu(TPP)} (1) and {cryptand(Cs)}{Ni(TPP)}·CHCH (2) have been obtained.

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Spin Vortex Crystal Order in Organic Triangular Lattice Compound.

Phys Rev Lett

October 2021

Department of Physics and Center for Functional Materials, Wake Forest University, Winston-Salem, North Carolina 27109, USA.

Organic salts represent an ideal experimental playground for studying the interplay between magnetic and charge degrees of freedom, which has culminated in the discovery of several spin-liquid candidates such as κ-(ET)_{2}Cu_{2}(CN)_{3} (κ-Cu). Recent theoretical studies indicate the possibility of chiral spin liquids stabilized by ring exchange, but the parent states with chiral magnetic order have not been observed in this material family. In this Letter, we discuss the properties of the recently synthesized κ-(BETS)_{2}Mn[N(CN)_{2}]_{3} (κ-Mn).

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Three tetraphenylborates of mononuclear Mn(III) cation complexes with hexadentate ligands, the products of the reaction between a N,N'-bis(3-aminopropyl)ethylenediamine and salicylaldehydes with the different haloid substitutions at the 5 or 3,5 positions, have been synthesized: [Mn(5-F-sal-N-1,5,8,12)]BPh (1), [Mn(3,5-diCl-sal-N-1,5,8,12)]BPh (2) and [Mn(3,5-Br,Cl-sal-N-1,5,8,12)]BPh (3). Their crystal structure, dielectric constant (ϵ) and magnetic properties have been studied. Ligand substituents have a dramatic effect on the structure and magnetic properties of the complexes.

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Oxidative C-H/C-H coupling reactions of dipyrromethanes with azines in the presence of a heterophase oxidative photocatalytic system (O/TiO/visible light irradiation) were carried out. As a result of cyclization of obtained compounds with boron trifluoride etherate, new hetaryl-containing derivatives of 4,4-difluoro-4-boron-3,4-diaza--indacene were synthesized. For the obtained compounds, absorption and luminescence spectra, quantum yields of luminescence as well as cyclic volt-amperograms were measured.

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In the case of various pathologies, an imbalance between ROS generation and the endogenous AOS can be observed, which leads to excessive ROS accumulation, intensification of LPO processes, and oxidative stress. For the prevention of diseases associated with oxidative stress, drugs with antioxidant activity can be used. The cytotoxic, antioxidant, and NO-donor properties of the new hybrid compound B6NO (di(3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridinium) salt of 2-(nitrooxy)butanedioic acid) were studied.

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Potato virus Y (PVY) is one of the most common and harmful plant viruses. Translation of viral RNA starts with the interaction between the plant cap-binding translation initiation factors eIF4E and viral genome-linked protein (VPg) covalently attached to the viral RNA. Disruption of this interaction is one of the natural mechanisms of plant resistance to PVY.

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Synthesis and characterization of structure and magnetic properties of the quasi-octahedral complex (pipH)[Co(TDA)] 2HO (I), (pipH = piperazine dication, TDA = thiodiacetic anion) are described. X-ray diffraction studies reveal the first coordination sphere of the Co(II) ion, consisting of two chelating tridentate TDA ligands with a mixed sulfur-oxygen strongly elongated octahedral coordination environment. SQUID magnetometry, frequency-domain Fourier-transform (FD-FT) THz-EPR spectroscopy, and high-level SA-CASSCF/NEVPT2 quantum chemical calculations reveal a strong "easy-plane" type magnetic anisotropy ( ≈ +54 cm) of complex I.

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Resist or Oxidize: Identifying Molecular Structure-Photostability Relationships for Conjugated Polymers Used in Organic Solar Cells.

ChemSusChem

February 2022

Institute of Problems of Chemical Physics, Russian Academy of Sciences, Academician Semenov avenue 1, Chernogolovka, Moscow Region, 142432, Russian Federation.

Although organic solar cells have started to demonstrate competitive power conversion efficiencies of >18 %, their operational lifetimes remain insufficient for wide practical use and the factors influencing the photostability of absorber materials and completed devices are still not completely understood. A systematic study of two series of structurally similar [XTBT] and [XTTBTBTT] polymers (16 structures in total) reveals the building blocks that enable the highest material stability towards photooxidation: fluorene, silafluorene, carbazole, diketopyrrolopyrrole, and isoindigo. Furthermore, a direct correlation is evident between the electronic properties of the conjugated polymers and their reactivity towards oxygen.

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Inductors of myogenic stem cell differentiation attract attention, as they can be used to treat myodystrophies and post-traumatic injuries. Functionalization of fullerenes makes it possible to obtain water-soluble derivatives with targeted biochemical activity. This study examined the effects of the phosphonate C fullerene derivatives on the expression of myogenic transcription factors and myogenic differentiation of human mesenchymal stem cells (MSCs).

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The main purpose of the study was the development of a new method for synthesis of 1,3,4-thiadiazol-2-amine derivatives in a one-pot manner using the reaction between a thiosemicarbazide and carboxylic acid without toxic additives such as POCl or SOCl. The reaction was investigated in the presence of polyphosphate ester (PPE). It was found that, in the presence of PPE, the reaction between the thiosemicarbazide and carboxylic acid proceeds in one-pot through three steps with the formation of corresponding 2-amino-1,3,4-thiadiazole.

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First-principles density functional theory calculations on neutral and singly negatively and positively charged iron clusters Fe and iron nitride clusters FeN and FeN ( = 1-10) in the range of 1 ≤ ≤ 10 revealed that there is a strong competition between ferromagnetic and antiferromagnetic states especially in the FeN cluster series. This phenomenon was related to superexchange via a bridging N atom between two iron atoms in the FeN cluster series and to a double superexchange effect via a Fe atom shared by two N atoms in the FeN series. A thorough examination of the structure-energy-spin state relationships in these clusters is conducted, leading to new insights and confirmation of available experimental results on structural parameters and dissociation energetics.

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Cisplatin is one of the most commonly used drugs for the treatment of various solid cancers. However, its efficacy is restricted by severe side effects, especially dose-limiting nephrotoxicity. New platinum-based compounds are designed to overcome this limitation.

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An improved procedure for the preparation of aerogel granules of polytetrafluoroethylene-graphene oxide (PTFE-GO) with a composition of 50:50 (in wt %) and a specific density of 35 ± 2 mg/cm is described. The technique practically excludes the granule cracking. The specific density of the pellets after reduction using hydrazine vapor and annealing at 370 °C decreased to 29 ± 2 mg/cm.

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Low chemical durability of proton exchange membranes is one the main factors limiting their lifetime in fuel cells. Ceria nanoparticles are the most common free radical scavengers. In this work, hybrid membranes based on Nafion-117 membrane and sulfonic or phosphoric acid functionalized ceria synthesized from various precursors were prepared by the in situ method for the first time.

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A new approach for the annulation of a thiopyrane ring to an indole core under mild conditions was developed. Treating 2-methyl-3-acylindoles with lithium diisopropyl amide leads to the elimination of a proton from the 2-methyl group. The lithium indole-2,3-dienolates obtained were found to react with CS to give the corresponding thiopyrano[4,3-]indole-3(5)-thiones.

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Derivatives of 2-(2-indolyl)-cyclopenta[b]pyrrole-3,4-diones and pyrindino[1,2-a]indoles were synthesized by a new reaction of contraction of the -quinone ring, and their structures were investigated by X-ray crystallography and nuclear magnetic resonance spectroscopy. The mechanisms of the reactions were suggested based on density functional theory calculations of the critical parts of the potential energy surfaces.

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A novel approach to obtaining nanocomposite materials using anionic sequential polymerization and post-synthetic esterification reactions with chemically modified graphene sheets (CMGs) is reported. The anionically synthesized diblock copolymer precursors of the PS--PI-OH type were grafted to the chemically modified -COOH groups of the CMGs, giving rise to the final composite materials, namely polystyrene--poly(isoprene)--CMGs, which exhibited enhanced physicochemical properties. The successful synthesis was determined through multiple molecular characterization techniques together with thermogravimetric analysis for the verification of increased thermal stability, and the structure/properties relationship was justified through transmission electron microscopy.

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Combined treatment of murine leukemia P388 with doxorubicin and platinum(IV)-nitroxyl complex ВС118 administered in low doses improved efficiency of treatment (cure of 83% of animals) without increasing toxicity.

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Electrochemical operational principles and analytical performance of Pd-based amperometric nanobiosensors.

Analyst

July 2021

Institute of Problems of Chemical Physics RAS, 1 Ac. Semenov avenue, Chernogolovka, 142432, Moscow region, Russia. and Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, 141700, Moscow region, Russia.

Palladium nanoparticles (Pd-NPs) have been approved as an effective catalyst for hydrogen peroxide decomposition which is released during specific enzymatic reactions. However, the general operational principles and electrochemical performance of Pd-NPs-based nanobiosensors have been poorly exploited. Here, the electrochemical behavior of oxidase-associated peroxide oxidation co-catalysis of the modelled microanalytical system based on screen-printed electrodes modified by electroplated Pd-NPs as an electrocatalyst, glucose oxidase (GOx) or alcohol oxidase (AOx) as a bioreceptor and the ionomer Nafion as a polymeric binding agent was studied in detail.

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We discuss the possibility of using mixed-valence (MV) dimers comprising paramagnetic metal ions as molecular cells for quantum cellular automata (QCA). Thus, we propose to combine the underlying idea behind the functionality of QCA of using the charge distributions to encode binary information with the additional functional options provided by the spin degrees of freedom. The multifunctional ("smart") cell is supposed to consist of multielectron MV dn-dn+1-type (1 ≤ n ≤ 8) dimers of transition metal ions as building blocks for composing bi-dimeric square planar cells for QCA.

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Molecular patterns of oligopeptide hydrocarbons on graphite.

Colloids Surf B Biointerfaces

October 2021

Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Malaya Pirogovskaya 1a, Moscow 119435 Russian Federation; Sirius University of Science and Technology, 1 Olympic Ave, 354340, Sochi, Russian Federation. Electronic address:

Graphitic materials including graphene, carbon nanotubes and fullerenes, are promising for use in nanotechnology and biomedicine. Non-covalent functionalization by peptides and other organic molecules allows changing the properties of graphitic surfaces in a controlled manner and represents a big potential for fundamental research and applications. Recently described oligopeptide-hydrocarbon derivative N,N'-(decane-1,10-diyl)bis(tetraglycineamide) (GM) is highly prospective for the development of graphitic interfaces in biosensor application as well as in structural biology for improving the quality of high-resolution atomic force microscopy (AFM) visualization of individual biomacromolecules.

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The influence of different synthesis routes on the structure and luminescent properties of KTb(MoO) (KTMO) was studied. KTMO samples were prepared by solid-state, hydrothermal, and Czochralski techniques. These methods lead to the following different crystal structures: a triclinic scheelite-type α-phase is the result for the solid-state method, and an orthorhombic KY(MoO)-type γ-phase is the result for the hydrothermal and Czochralski techniques.

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Metal complexes of trithiadodecaazahexaphyrin (Hhp) that contain MO clusters inside a π-extended trianionic (Hhp) macrocycle have been prepared. Studies of the magnetic properties of NiO(Hhp) and CuO(Hhp) reveal a diamagnetic and EPR-silent trianionic (Hhp) macrocycle and diamagnetic Ni(O) or paramagnetic Cu(O) tetracations. The positive charge of MO(Hhp) is compensated by one acetate anion {MO(Hhp)}(CHCO).

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