Substitution Of Hydrogen Atoms Research Articles

Effect of Naringenin and Its Derivatives on the Probing Behavior of Myzus persicae (Sulz.).

Substances that alter insect behavior have attracted a lot of attention as potential crop protection agents. Naringenin (5,7,4′-trihydroxyflavanone) is a naturally occurring bioactive flavanone. We evaluated the influence of naringenin on aphid activities during individual phases of probing and feeding and the effect of structural modifications of naringenin on its activity towards aphids. We monitored the probing behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae) using the Electrical Penetration Graph (EPG) technique. The chemical modifications were the substitution of hydrogen atoms with methyl, ethyl or pentyl groups and the replacement of the carbonyl group in naringenin and its derivatives with an oxime moiety. Depending on the substituents, the activity of naringenin-derived compounds varied in potency and mode of action. Naringenin was an attractant of moderate activity, which enhanced sap ingestion. The naringenin derivative with two methyl groups—7,4′-di-O-methylnaringenin—was a deterrent, which hindered aphid probing in non-phloem tissues. Naringenin oxime derivatives with methyl substituents—7,4′-di-O-methylnaringenin oxime, 7-O-methylnaringenin oxime, and 5,7,4′-tri-O-methylnaringenin oxime—and the derivative with a pentyl substituent—7-O-pentylnaringenin oxime—were strong attractants which stimulated aphid probing in non-phloem tissues and the ingestion of phloem sap.

Theoretical study on the electronic, optoelectronic, linear and non linear optical properties and UV–Vis Spectrum of Coronene and Coronene substituted with Chlorine

We have study electronic, optoelectronic, linear and nonlinear optical; thermodynamic properties and UV–Vis Spectrum of Coronene and Coronene substituted with Chlorine using time-dependent density functional theory TD-DFT (TD-wB97XD, TD-B3LYP, TD-LSDA and TD-CCSD(T)). We quantified the effect of substitution of hydrogen atoms with Chlorine for a series of molecular properties relevant for molecular electronics and photonics. Results obtained with TD-B3LYP and TD-CCSD(T) are closer to experimental results reported in literature for Coronene substituted with Chlorine. Second hyperpolarizability ( $$ \gamma_{av} $$ ) values show that the molecules have very good optoelectronic, linear and non linear optical properties. Eg show that the molecules may have semiconductors properties and hence have applications in photonic, electronic and optoelectronic devices.

Methyl-group functionalization of pyrazole-based additives for advanced lithium ion battery electrolytes

A novel methylated pyrazole derivative, namely 1-methyl-3,5-bis(trifluoromethyl)-1H-pyrazole (MBTFMP) was synthesized for the first time and comprehensively characterized for high voltage application in lithium ion batteries (LIBs). The MBTFMP reactivity and performance was compared to the known 3,5-bis(trifluoromethyl)-1H-pyrazole (BTFMP) functional additive via cyclic voltammetry (CV), constant current cycling as well as post mortem analysis techniques on the graphite and LiNi1/3Mn1/3Co1/3O2 (NMC111) electrodes, such as scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). By means of quantum chemistry (QC) calculations, reductive and oxidative stabilities of MBTFMP and BTFMP functional molecules and their reactivity with the cathode surface were determined. Both reduction and oxidation of BTFMP molecule was coupled with the intermolecular H-transfer that narrowed BTFMP containing electrolyte electrochemical stability window compared to MBTFMP functional additive. The obtained results demonstrate the benefits of hydrogen atom substitution of BTFMP by a methyl-group at the nitrogen atom that resulted in significant improvement of the NMC111||graphite cell cycling performance. This work reveals that with a smart selection of the substitution group and its position in the molecule, functional additives can be tailored in respect of vital physicochemical properties relevant for the high voltage LIB application.

Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline-Earth Elements, Transition Metals, and Lanthanides.

After briefly reviewing the applications of the coordination ability indices proposed earlier for anions and solvents toward transition metals and lanthanides, a new analysis of crystal structures is applied now to a much larger number of coordinating species: anions (including those that are present in ionic solvents), solvents, amino acids, gases, and a sample of neutral ligands. The coordinating ability towards s-block elements is now also considered. The effect of several factors on the coordinating ability will be discussed: (a) the charge of an anion, (b) the chelating nature of anions and solvents, (c) the degree of protonation of oxo-anions, carboxylates and amino carboxylates, and (d) the substitution of hydrogen atoms by methyl groups in NH3 , ethylenediamine, benzene, ethylene, pyridine and aldehydes. Hit parades of solvents and anions most commonly used in the areas of transition metal, s-block and lanthanide chemistry are deduced from the statistics of their presence in crystal structures.

Fluorination of Organic Spacer Impacts on the Structural and Optical Response of 2D Perovskites.

Low-dimensional hybrid perovskites have triggered significant research interest due to their intrinsically tunable optoelectronic properties and technologically relevant material stability. In particular, the role of the organic spacer on the inherent structural and optical features in two-dimensional (2D) perovskites is paramount for material optimization. To obtain a deeper understanding of the relationship between spacers and the corresponding 2D perovskite film properties, we explore the influence of the partial substitution of hydrogen atoms by fluorine in an alkylammonium organic cation, resulting in (Lc)2PbI4 and (Lf)2PbI4 2D perovskites, respectively. Consequently, optical analysis reveals a clear 0.2 eV blue-shift in the excitonic position at room temperature. This result can be mainly attributed to a band gap opening, with negligible effects on the exciton binding energy. According to Density Functional Theory (DFT) calculations, the band gap increases due to a larger distortion of the structure that decreases the atomic overlap of the wavefunctions and correspondingly bandwidth of the valence and conduction bands. In addition, fluorination impacts the structural rigidity of the 2D perovskite, resulting in a stable structure at room temperature and the absence of phase transitions at a low temperature, in contrast to the widely reported polymorphism in some non-fluorinated materials that exhibit such a phase transition. This indicates that a small perturbation in the material structure can strongly influence the overall structural stability and related phase transition of 2D perovskites, making them more robust to any phase change. This work provides key information on how the fluorine content in organic spacer influence the structural distortion of 2D perovskites and their optical properties which possess remarkable importance for future optoelectronic applications, for instance in the field of light-emitting devices or sensors.

Two-dimensional carbon nitride (2DCN) nanosheets: Tuning of novel electronic and magnetic properties by hydrogenation, atom substitution and defect engineering

By employing first-principles calculations within the framework of density functional theory, we investigated the structural, electronic, and magnetic properties of graphene and various two-dimensional carbon-nitride (2DNC) nanosheets. The different 2DCN gives rise to diverse electronic properties such as metals (C3N2), semimetals (C4N and C9N4), half-metals (C4N3), ferromagnetic-metals (C9N7), semiconductors (C2N, C3N, C3N4, C6N6, and C6N8), spin-glass semiconductors (C10N9 and C14N12), and insulators (C2N2). Furthermore, the effects of adsorption and substitution of hydrogen atoms as well as N-vacancy defects on the electronic and magnetic properties are systematically studied. The introduction of point defects, including N vacancies, interstitial H impurity into graphene and different 2DCN crystals, results in very different band structures. Defect engineering leads to the discovery of potentially exotic properties that make 2DCN interesting for future investigations and emerging technological applications with precisely tailored properties. These properties can be useful for applications in various fields such as catalysis, energy storage, nanoelectronic devices, spintronics, optoelectronics, and nanosensors.

Evaluation of Changes in Bond Parameters in Sulfolane Under the Influence of Electron Donating Substituents

Sulfolane is a promising solvent for electrolytes in lithium-ion batteries, because it possesses high thermal and oxidative stability, high flash point, well dissolves lithium salts. However, sulfolane has a high melting point (27.5 °C) and viscosity (0.01029 Pa • s at 30 °C). High melting point and viscosity due to the tendency of sulfolane to self-association. To reduce the degree of self-association is possible by introducing various substituents into the sulfolane molecule. The aim of the work was to investigate how the introduction of substituents into the sulfolane molecule affects its chemical stability. Chemical resistance was judged by changes in bond orders. Presented work summarizes the results of quantum-chemical calculations of the bond orders in the sulfolane molecule and its substituted analogs, including methyl-, ethyl-, propyl-, vinyl- and allylsulfolanes (Figure 2). Quantum chemical calculations were performed using the Gaussian09 software package. The optimization procedure was performed using the TPSS/cc-pVTZ method. Analysis of wave functions and calculation of bond orders by “fuzzy” method were performed in MultiWfn software package. The objects of study were sulfolane and analogs with electron donor substituents. A total of 21 structures. The nature of the change in bond orders shows the influence of the position of substituents on electron density distribution. It has been established that the substitution of hydrogen atoms for this groups has the greatest influence on the order of the C – S and C – C bonds, reducing it, and the smallest on the S = O bond. This is especially clearly observed when hydrogen atoms attached to carbons connected to sulfur are substituted. These data show the possible paths of reduction reactions. This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7) Russia and was also financially supported by the Russian Science Foundation (project No 17-73-20115). Figure 1

Directing Traffic: Halogen-Bond-Mediated Membrane Transport.

The plasma membrane regulates the transport of molecules into the cell. Small hydrophobic molecules can diffuse directly across the lipid bilayer. However, larger molecules require specific transporters for their entry into the cell. Regulating the cellular entry of small molecules and proteins is a challenging task. The introduction of halogen, particularly iodine, to small molecules and proteins is emerging to be a promising strategy to improve the cellular uptake. Recent studies reveal that a simple substitution of hydrogen atom with iodine not only increases the cellular uptake, but also regulates the membrane transport. The strong halogen-bond-forming ability of iodine atoms plays a crucial role in the transport and the introduction of iodine may provide an efficient strategy for studying membrane activity and cellular functions and improving the delivery of therapeutic agents. This Concept article does not provide a comprehensive picture of membrane transport but highlights halogen-substitution as a novel strategy for understanding and regulating the cell-membrane traffic.

Process-dependent mechanical and optical properties of nanostructured silicon carbonitride thin films

Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films were grown using electron cyclotron resonance chemical vapour deposition using a mixture of methane, nitrogen, and silane as precursors. The origin of the variation of macroscopic properties such as hardness (H), elastic modulus (E), photoluminescence (PL), and the optical band gap was investigated through their correlation with the microscopic features of a-SiCN:H thin films as a function of the process parameters, including the deposition temperature and methane gas flow rate. From a microstructural perspective, the thin films were investigated using x-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, elastic recoil detection, transmission electron microscopy, and x-ray diffraction. It is verified that an increase of the substrate temperature resulted in the substitution of hydrogen atoms mainly by carbon atoms, causing the density of the silicon carbide-related structures to increase in the amorphous structure of the a-SiCN:H thin films. Hardness and elastic modulus were found to increase with the deposition temperature and decreased with an increase of the methane gas flow during the deposition, resulting in higher carbon content in the films. The observed changes are ascribed to the reduced density of the weak hydrogen terminated bonds and the variation of the relative bond density of Si–C to Si–N bonds. In addition, the thin films were depth profiled using a slow positron beam to investigate the role of vacancies. The observed increase of the positronium formation with increasing deposition temperature was found to correlate with the variation of PL, where an enhancement of the visible emission originating from carbon-related defects was observed. A set of optimized process parameters to fabricate a-SiCN:H thin films with improved visible emission and hardness properties is suggested.

Evaluation of Changes in Bond Parameters in Sulfolane Under the Influence of Electron-Withdrawing Substituents

The results of quantum-chemical calculations of the bond orders in the sulfolane molecule during the substitution of hydrogen atoms for fluorine atoms are presented. The change in the bond parameters were estimated. Quantum chemical calculations were performed using the Gaussian09 software package. The optimization procedure and the calculation of the vibrational problem were performed using the TPSS/aug-cc-pVTZ method. Analysis of wave functions and calculation of bond orders by “fuzzy’ method were performed in MultiWFN software package. The objects of study were sulfolane, monosubstituted and disubstituted fluorosulfolanes. A total of 15 structures. The nature of the change in bond orders shows the influence of the position of substituents on bond strength. It has been established that the substitution of hydrogen atoms for fluorine atoms has the greatest influence on the order of the C–S bond, reducing it, and the smallest on the S=O bond. This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7). Figure 1

Role of the Ring Methyl Groups in 2',3'-Benzoabscisic Acid Analogues.

Five analogues of iso-PhABA (20) developed earlier by our research group were designed and synthesized. The bioassay results show that the number and position of methyl groups along with the substitution of hydrogen atoms of the methyl group have a great influence on the activity. Compared with iso-PhABA, the inhibitory activity of diMe-PhABA (21) on seed germination and rice seedling growth decreased slightly; however, it significantly reduced the capability of inhibiting wheat embryo germination. Both 3'-deMe- iso-PhABA (22) and 2'-deMe-PhABA (23) exhibited weak inhibitory activities, and 11'-methoxy iso-PhABA (24a/24b) was much more efficient than its isomer 24c/24d in all bioassays. These results reveal the preservation of quaternary carbon at the 2' or 3' position is necessary to maintain its ABA-like biological activity, and demethylation at the 3' position has a more significant effect. The selectivity of these compounds to different physiological processes makes them available as selective probes for different ABA receptors.

Nucleophilic Substitution of Hydrogen Atom in Initially Inactivated Pyrrole Ring.

It has been found that 1-dialkylamino-8-(pyrrolyl-1)naphthalenes 1 and 6, upon treatment with an equimolar amount of HBF4 under ambient conditions, produce 1-dialkylammonium salts which are transformed into 7,7-dialkyl-7 H-pyrrolo[1,2- a]perimidine-7-ium tetrafluoroborates 5 and 7, respectively. The reaction proceeds in a highly selective manner and represents the first case of nucleophilic substitution of hydrogen in the initially inactivated pyrrole ring. The scope and limitations of the transformation, apparently operating due to the joint action of the "proximity effect" and proton catalysis, are outlined.

Электронная структура молибдена, окисленного на воздухе

In situ photoelectron spectroscopy studies in ultrahigh vacuum of the electronic structure of the surface of molybdenum oxidized in air and during the adsorption of sodium Na with submonolayer coatings were carried out. The spectra of photoemission from the valence band and the core levels O 1s, O 2s, Mo 4s and Na 2p were studied under synchrotron excitation in the photon energy range of 80 – 600 eV. The change in the spectrum of the oxygen core levels associated with the substitution of hydrogen atoms in the hydroxyl group by sodium atoms was found. The surface topography and cathodoluminescence of molybdenum oxide were studied.

Sulfoethylated polyaminostyrene – polymer ligand with high selective interaction with silver ions in multicomponent solutions

The paper describes a simple and an effective method for preparation of sulfoethylated polyaminostyrene-based sorbents with different fixed degrees of substitution of hydrogen atoms of amino groups. The chemical structure of the obtained polymers was characterized by Fourier transform infrared (FT-IR) spectroscopy. Thermogravimetric study of the sulfoethylated polyaminostyrene coupled with FT-IR analysis has shown stability of the polymer up to 250 °C, which almost does not change with the increase in the degree of substitution (DS). The study reports the influence of different factors on the selectivity of sorption of sulfoethylated polyaminostyrene-based sorbents towards alkaline earth and transition metal ions from their solutions of complex composition. The analyzed materials have shown selectivity towards copper(II) and silver(I). The selectivity towards the stipulated ions is higher when using an ammonium acetate buffer solution vs. an ammonium buffer solution. Wherein the selectivity of sorption towards silver(I) over copper(II) of sulfoethylated polyaminostyrene increases significantly with the increase in the DS of the sorbent. It was shown, that the equilibrium in the “solution of metal salts-sorbent” system was achieved within 30 min.

Novel Reactions of Tropylium Salts with Heterocyclic Diamines

The reactions of tropylium salts with 2,5-diamino-1,3,4-thiadiazol, 3,5-diamino-1,2,4-thiadiazol, and 2,6-diaminopyridine have given novel products of substitution of hydrogen atoms of two amino groups in thiadiazols and of hydrogen atoms at С3 and С5 positions in 2,6-diaminopyridine.

Ab initio study of hydrocarbon prismanes and their substituted derivatives

Density functional calculations of hydrocarbon prismanes C2nH2n (where n = 3–10) and their substituted derivatives are carried out to analyze their structures, binding energies and electronic properties. Five substituting radicals (F, Cl, CH3, OH, NO2) are considered. The results indicate the different behavior of the prismanes by substitutions of hydrogen atoms with different radicals. Effective repulsion of substituting radicals on the pentaprismane cage is detected. The dependences of binding energies on number of substituted radicals demonstrate increasing or decreasing trends for different radicals. HOMO-LUMO gaps are slightly changed by substituting doping. All substituting reactions are found to be endothermal. Fluorination is more energetically feasible than other considered reactions.

α-GLUCOSIDASE INHIBITORY EFFECT OF SULOCHRIN FROM ASPERGILLUSTERREUS AND ITSBROMINATED DERIVATIVES

Use of I±-glucosidase inhibitorsis one of the therapeutic approaches for decreasing postprandial hyperglycemia. Sulochrin (1) from Aspergillus terreus as well as two synthetic sulochrin derivatives were assessed for antidiabetic activity against yeast and rat intestine I±-glucosidase. Sulochrin showed potential inhibition against yeast I±-glucosidase, through a non-competitive mode with an IC50 value of 133.79 µM, and rat intestine I±-glucosidase by uncompetitive mode with an IC50 value of 144.59 µM.. Two synthetic derivatives of sulochrin were also prepared by bromination which resulted in dibromo-sulochrin (2) and tribromo-sulochrin (3). Preliminary SAR studies of sulochrin derivatives revealed that the yeast I±-glucosidase inhibitory activity of compound 2 and 3 increased than 1 due to substitution of hydrogen atom with bromine with IC50 values of 122.65 and 49.08 µM, respectively. However, the inhibitory activity against rat intestine I±-glucosidase of 2 and 3 was decreased compared to 1. To the best our knowledge, this is the first report of structure-activity relationship of sulochrin and its derivatives as I±-glucosidase inhibitors. These results suggested that sulochrin can potentially be used as a lead compound to develop new I±-glucosidase inhibitor from microorganisms. Keywords: Aspergillus terreus, I±-glucosidase inhibitory activity, sulochrin, bromination

Reaction of Amides of Sulfanyl, Thio-, and Carbonic Acids with Tropylium Salts

By the reaction of urea, thiourea, sulfanilamide or sulfadimethoxine with tropylium tetrafluoroborate new products of substitution of hydrogen atom by the tropylium motif at the amide nitrogen atom or at the amino group of the benzene ring have been obtained.

Temperature Dependence of the Bulk Elasticity Modulus of Aliphatic Alcohols and Their Fluorinated Analogs

The density of some fluorinated and non-fluorinated normal monoatomic alcohols and the sound propagation velocity in them have been studied experimentally in a temperature interval of 293–363 K. The bulk modulus of elasticity is calculated, and its relation with the intermolecular interaction energy is analyzed. The energy of intermolecular interaction in fluorinated alcohols is shown to be lower than in their non-fluorinated analogs. The substitution of hydrogen atoms by fluorine ones in the molecules of aliphatic alcohols increases the equilibrium distance between the molecules.

Synthesis of pH indicators for Cerenkov imaging by electrophilic substitution of bromine by fluorine in an aromatic system

Direct electrophilic fluorination using molecular fluorine gas is used in organic synthesis to create novel fluorine-containing compounds with potential beneficial activity that could not be obtained by nucleophilic substitution. In this paper, we report a novel electrophilic substitution of bromine by fluorine in an aromatic system. The mechanism of this type of fluorination was explored using the reaction between bromothymolsulfonphthalein (Bromothymol Blue) and dilute fluorine gas under acidic conditions. Substitution occurs in the bromine atoms located in the ortho-position relative to the hydroxyl group. A similar electrophilic fluorination of thymolsulfonphthalein (Thymol Blue) leads to a substitution of hydrogen atoms in the same position (ortho to hydroxyl). NMR spectroscopy was used to confirm the fluorination sites. NMR spectra of thymolsulfonphthalein and its derivatives under basic conditions can be explained by considering the absence of resonance between the two phenolic rings. Both dibromothymol blue and fluorobromothymol blue intermolecularly attenuate Cerenkov radiation selectively near their maximum absorbance in a pH dependent manner.