Interaction of Hydride Silica Surfaces with N-Vinyl-2-Pyrrolidone

The solid-phase thermal and catalytic hydrosilylation of N-vinyl-2-pyrrolidone on the surface of hydride silicas has been studied. It was established that thermal polymerization of N-vinyl-2-pyrrolidone occurs as a side reaction during the thermal hydrosilylation of N-vinyl-2-pyrrolidone. It has also been found that the interaction of silicon hydride groups with water and propan-2-ol, as well as the formation of metallic platinum occur as side reactions during the catalytic hydrosilylation of N-vinyl-2-pyrrolidone on the surface of hydride silicas. Thermal hydrosilylation of N-vinyl-2-pyrrolidone in the absence of a catalyst and solvent is much preferred for the chemical bonding of N-vinyl-2-pyrrolidone in the surface layer of hydride silicas.

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OxymaPure Coupling Reagents: Beyond Solid-Phase Peptide Synthesis

Synthesis ◽

10.1055/s-0040-1706296 ◽

2020 ◽

Vol 52 (21) ◽

pp. 3189-3210

Author(s):

Ayman El-Faham ◽

Fernando Albericio ◽

Srinivasa Rao Manne ◽

Beatriz G. de la Torre

Keyword(s):

Solid Phase ◽

Solid Phase Peptide Synthesis ◽

Coupling Efficiency ◽

Side Reaction ◽

Solution Phase ◽

Amide Bond ◽

Side Reactions ◽

Phosphonium Salts ◽

Coupling Reagents ◽

Peptide Chemistry

AbstractOxymaPure [ethyl 2-cyano-2-(hydroxyimino)acetate] is an exceptional reagent with which to suppress racemization and enhance coupling efficiency during amide bond formation. The tremendous popularity of OxymaPure has led to the development of several Oxyma-based reagents. OxymaPure and its derived reagents are widely used in solid- and solution-phase peptide chemistry. This review summarizes the recent developments and applications of OxymaPure and Oxyma-based reagents in peptide chemistry, in particular in solution-phase chemistry. Moreover, the side reaction associated with OxymaPure is also discussed.1 Introduction2 Oxyma-Based Coupling Reagents2.1 Aminium/Uronium Salts of OxymaPure2.2 Phosphonium Salts of OxymaPure2.3 Oxyma-Based Phosphates2.4 Sulfonate Esters of OxymaPure2.5 Benzoate Esters of OxymaPure2.6 Carbonates of OxymaPure Derivatives3 OxymaPure Derivatives4 Other Oxime-Based Additives and Coupling Reagents5 Side Reactions Using OxymaPure Derivatives6 Conclusion7 List of Abbreviations

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Energetic Control of Redox-Active Polymers Towards Safe Organic Bioelectronic Materials

10.26434/chemrxiv.11366186.v1 ◽

2019 ◽

Author(s):

Alexander Giovannitti ◽

Reem B. Rashid ◽

Quentin Thiburce ◽

Bryan D. Paulsen ◽

Camila Cendra ◽

...

Keyword(s):

Molecular Oxygen ◽

Organic Semiconductors ◽

Side Reaction ◽

Semiconducting Polymers ◽

Side Reactions ◽

Redox Active ◽

Donor Acceptor ◽

Electrochemical Devices ◽

Biological Environment ◽

Device Operation

Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side‑products. This is particularly important for bioelectronic devices which are designed to operate in biological systems. While redox‑active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side‑reactions with molecular oxygen during device operation. We show that this electrochemical side reaction yields hydrogen peroxide (H2O2), a reactive side‑product, which may be harmful to the local biological environment and may also accelerate device degradation. We report a design strategy for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevent the formation of H2O2 during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte‑gated devices in application-relevant environments.

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Improvement of long-term cycling performance of high-nickel cathode materials by ZnO coating

Nanotechnology Reviews ◽

10.1515/ntrev-2021-0020 ◽

2021 ◽

Vol 10 (1) ◽

pp. 210-220

Author(s):

Fangfang Wang ◽

Ruoyu Hong ◽

Xuesong Lu ◽

Huiyong Liu ◽

Yuan Zhu ◽

...

Keyword(s):

Electrochemical Performance ◽

Lithium Ion Batteries ◽

Solid Phase ◽

Low Cost ◽

Specific Capacity ◽

High Capacity ◽

Lithium Ion ◽

Side Reaction ◽

Chemical Route ◽

High Nickel

Abstract The high-nickel cathode material of LiNi0.8Co0.15Al0.05O2 (LNCA) has a prospective application for lithium-ion batteries due to the high capacity and low cost. However, the side reaction between the electrolyte and the electrode seriously affects the cycling stability of lithium-ion batteries. In this work, Ni2+ preoxidation and the optimization of calcination temperature were carried out to reduce the cation mixing of LNCA, and solid-phase Al-doping improved the uniformity of element distribution and the orderliness of the layered structure. In addition, the surface of LNCA was homogeneously modified with ZnO coating by a facile wet-chemical route. Compared to the pristine LNCA, the optimized ZnO-coated LNCA showed excellent electrochemical performance with the first discharge-specific capacity of 187.5 mA h g−1, and the capacity retention of 91.3% at 0.2C after 100 cycles. The experiment demonstrated that the improved electrochemical performance of ZnO-coated LNCA is assigned to the surface coating of ZnO which protects LNCA from being corroded by the electrolyte during cycling.

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Preparation of Peptide o-Aminoanilides Using a Modified Dawson's Linker for Microwave-Assisted Peptide Synthesis

Synlett ◽

10.1055/s-0036-1588862 ◽

2017 ◽

Vol 28 (15) ◽

pp. 1956-1960 ◽

Cited By ~ 4

Author(s):

Shugo Tsuda ◽

Taku Yoshiya ◽

Tsuyoshi Uemura ◽

Masayoshi Mochizuki ◽

Hideki Nishio

Keyword(s):

Amino Acid ◽

Peptide Synthesis ◽

Solid Phase ◽

Side Reactions ◽

Microwave Assisted Synthesis ◽

Terminal Amino Acid ◽

Nitrobenzoic Acid ◽

Microwave Assisted ◽

Peptide Thioester ◽

Terminal Amino

Based on the structure of Dawson’s 3,4-diaminobenzoic acid (Dbz) linker designed for Fmoc solid-phase peptide-thioester synthesis, the 4-amino-3-nitrobenzoic acid [Dbz(NO2)] linker was developed for microwave-assisted synthesis. The Dbz(NO2) linker can be readily converted into the Dbz linker by on-resin reduction with SnCl2 after construction of the protected peptide resin. Although epimerization of C-terminal amino acid restricts the use of Dbz(NO2) linker to the synthesis of peptide-Gly-thioester, use of this linker can prevent side reactions that arise when Dbz or Dbz(Aloc) linkers are used in the microwave-assisted synthesis of Gly-rich peptides.

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Thermodynamic Study of Tl6SBr4 Compound and Some Regularities in Thermodynamic Properties of Thallium Chalcohalides

Advances in Materials Science and Engineering ◽

10.1155/2017/5370289 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Dunya Mahammad Babanly ◽

Qorkhmaz Mansur Huseynov ◽

Ziya Saxaveddin Aliev ◽

Dilgam Babir Tagiyev ◽

Mahammad Baba Babanly

Keyword(s):

Phase Diagram ◽

Thermodynamic Properties ◽

Thermodynamic Functions ◽

Chemical Bonding ◽

Electromotive Force ◽

Solid Phase ◽

Thermodynamic Study ◽

Degree Of Ionization ◽

Emf Measurements ◽

Concentration Cells

The solid-phase diagram of the Tl-TlBr-S system was clarified and the fundamental thermodynamic properties of Tl6SBr4 compound were studied on the basis of electromotive force (EMF) measurements of concentration cells relative to a thallium electrode. The EMF results were used to calculate the relative partial thermodynamic functions of thallium in alloys and the standard integral thermodynamic functions (-ΔfG0, -ΔfH0, and S0298) of Tl6SBr4 compound. All data regarding thermodynamic properties of thallium chalcogen-halides are generalized and comparatively analyzed. Consequently, certain regularities between thermodynamic functions of thallium chalcogen-halides and their binary constituents as well as degree of ionization (DI) of chemical bonding were revealed.

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Simulation of crystallization of the melt modified by nanoscale particles during laser treatment of a metal surface

Physics and Chemistry of Materials Treatment ◽

10.30791/0015-3214-2021-1-5-14 ◽

2021 ◽

Vol 1 ◽

pp. 5-14

Author(s):

V.N. Popov ◽

Keyword(s):

Numerical Simulation ◽

Surface Layer ◽

Stokes Equations ◽

Solid Phase ◽

Laser Action ◽

Heat Removal ◽

Boussinesq Approximation ◽

Grain Structure ◽

Homogeneous Distribution ◽

Dissolved Carbon

A 2D mathematical model is proposed for the modification of an iron-based alloy with refractory nanosized particles. Numerical simulation of the processes during the modification of the surface layer of the substrate metal using the energy of a laser pulse has been carried out. Within the framework of the proposed model, the processes of heating and melting of metal on a substrate covered with a layer of nanosized refractory particles penetrating into the molten metal, convective heat transfer in the melt, and solidification after the end of the pulse are considered. Metal melting is considered in the Stefan approximation, and when the melt is cooled, the model of heterogeneous nucleation and subsequent crystallization is used. The fluid flow is described by the Navier-Stokes equations in the Boussinesq approximation. The distribution of nanoparticles in the melt is modeled by moving markers. Based on the results of calculations, the mode of pulsed laser action is determined, in which a flow is formed for a homogeneous distribution of particles of the modifying substance in the presence of a surfactant in the metal. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The liquidus temperature changes depending on the concentration of dissolved carbon in the melt. In the numerical simulation of the solidification of the surface layer of the metal, it was found that the conditions of nucleation and crystallization differ significantly in the volume of the melt. It is determined that the duration of nucleation in a supercooled melt is several tens of microseconds. The maximum number of crystallization centers occurs in areas where heat removal occurs most rapidly. With the growth of the solid phase in the melt and the release of the latent heat of crystallization, the value of supercooling decreases, the nucleation stops and the number of formed crystallization centers does not change further. The distribution of the dispersion of the crystal structure over the volume of the melted metal is estimated. It was found that as the melt cools, sequential-volume crystallization occurs.

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Basic principles

Fmoc Solid Phase Peptide Synthesis ◽

10.1093/oso/9780199637256.003.0006 ◽

1999 ◽

Author(s):

Peter D. White ◽

Weng C. Chan

Keyword(s):

Amino Acid ◽

Amino Acid Residue ◽

Solid Phase ◽

Analytical Techniques ◽

Amide Bond ◽

Peptide Chain ◽

Side Reactions ◽

Protecting Group ◽

Solution Synthesis ◽

Resin Loading

Construction of a peptide chain on an insoluble solid support has obvious benefits: separation of the intermediate peptides from soluble reagents and solvents can be effected simply by filtration and washing with consequent savings in time and labour over the corresponding operations in solution synthesis; many of the operations are amenable to automation; excess reagents can be employed to help to drive reactions to completion; and physical losses can be minimized as the peptide remains attached to the support throughout the synthesis. This approach does, however, have its attendant limitations. By-products arising from either incomplete reactions, side reactions, or impure reagents will accumulate on the resin during chain assembly and contaminate the final product. The effects on product purity of achieving less than 100% chemical efficiency in every step are illustrated dramatically in Table 1. This has serious implications with regard to product purification as the impurities generated will, by their nature, be very similar to the desired peptide and therefore extremely difficult to remove. Furthermore, the analytical techniques employed for following the progress of reactions in solution are generally not applicable, and recourse must generally be made to simple qualitative colour tests to detect the presence of residual amines on the solid phase. The principles of solid phase synthesis are illustrated in Figure 1. The C-terminal amino acid residue of the target peptide is attached to an insoluble support via its carboxyl group. Any functional groups in amino acid side chains must be masked with permanent protecting groups that are not affected by the reactions conditions employed during peptide chain assembly. The temporary protecting group masking the α-amino group during the initial resin loading is removed. An excess of the second amino acid is introduced, with the carboxy group of this amino acid being activated for amide bond formation through generation of an activated ester or by reaction with a coupling reagent. After coupling, excess reagents are removed by washing and the protecting group removed from the N-terminus of the dipeptide, prior to addition of the third amino acid residue.

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Optical and Structural Properties of MeV Erbium Implanted LiNbO3

MRS Proceedings ◽

10.1557/proc-316-463 ◽

1993 ◽

Vol 316 ◽

Author(s):

M. Fleuster ◽

CH. Buchal ◽

E. Snoeks ◽

A. Polman

Keyword(s):

Surface Layer ◽

Single Crystals ◽

Structural Properties ◽

Maximum Concentration ◽

Solid Phase ◽

Optically Active ◽

Layer By Layer ◽

Warm Up

ABSTRACTLiNbO3 single crystals were implanted with Er ions at 3.5 MeV with fluences up to 3*1016 Er/cm2 and subsequently annealed at 1060°C. The warm-up rate of the sample determines whether the implanted, amorphized surface layer recrystallizes via columnar or via layer-by-layer solid phase epitaxial (SPE) growth. The maximum concentration of optically active Er ions is determined to be 0.18 at.%.

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