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101.
Conrad Wagner Franka Kreis Dennis Popp Dr. Olaf Hübner Dr. Elisabeth Kaifer Prof. Hans-Jörg Himmel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(45):10336-10347
In this work, the change of reactivity induced by the introduction of two para-ethynyl substituents (CCSi(iPr)3 or CCH) to the organic electron-donor 1,2,4,5-tetrakis(tetramethylguanidino)-benzene is evaluated. The redox-properties and redox-state dependent fluorescence are evaluated, and dinuclear CuI and CuII complexes synthesized. The Lewis-acidic B(C6F5)3 substitutes the proton of the ethynyl −CCH groups to give new anionic −CCB(C6F5)3− substituents, leading eventually to a novel dianionic strong electron donor in its diprotonated form. Its two-electron oxidation with dioxygen in the presence of a copper catalyst yields the first redox-active guanidine that is neutral (instead of cationic) in its oxidized form. 相似文献
102.
Lucas Ueberricke Ioana Ciubotaru Farhad Ghalami Felix Mildner Dr. Frank Rominger Prof. Dr. Marcus Elstner Prof. Dr. Michael Mastalerz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11634-11642
Five di- and tetracyano-substituted pyrene-fused pyrazaacenes were synthesized and studied as potential electron acceptors in the solid state. Single crystals of all compounds were grown and the crystal packing studied by DFT calculations (transfer integrals and reorganization energies) to get insight into possible use for semiconducting charge transport. 相似文献
103.
Dr. Vladimir V. Shilovskikh Alexandra A. Timralieva Pavel V. Nesterov Dr. Alexander S. Novikov Dr. Petr A. Sitnikov Prof. Elizaveta A. Konstantinova Prof. Alexander I. Kokorin Prof. Ekaterina V. Skorb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16603-16610
In the last two decades, a large number of self-assembled materials were synthesized and they have already found their way into large-scale industry and science. Hydrogen-bond-based supramolecular adducts are found to have unique properties and to be perfect host structures for trapping target molecules or ions. Such chemical systems are believed to resemble living matter and can substitute a living cell in a number of cases. Herein, a report on an organic material based on supramolecular assembly of barbituric acid and melamine is presented. Surprisingly, the structure is found to host and stabilize radicals under mild conditions allowing its use for biological applications. The number of free radicals is found to be easily tuned by changing the pH of the environment and it increases when exposed to light up to a saturation level. We describe a preparation method as well as stability properties of melamine–barbiturate self-assembly, potentiometric titration, and hydrogen ions adsorption data and EPR spectra concerning the composite. 相似文献
104.
Pieter Bouckenooge Oliver Bauer Kathrin Eckhard Herman Terryn 《Surface and interface analysis : SIA》2020,52(4):174-184
In this paper, the behaviour of the industrial applied Ti/Zr conversion coating (CC) pretreatment on rolled automotive aluminium samples (AA5182) is analysed. Due to its nanometre lateral and depth resolution, Auger electron spectroscopy (AES) is used to analyse the CC distribution at surface cathodic intermetallic particles. As a result of its high surface sensitivity, the AES technique is very susceptible to differences in the top contamination layer thickness. It is demonstrated that AES point measurements performed on aluminium model samples coated with 1.5 and 3 nm of Ti (oxide) layer cannot differentiate the two-layer thicknesses if a difference in the top contamination thickness is not taken into account. A data analysis methodology is introduced, based on the ratio of normalized peak areas (enrichment ratios), to eliminate the effect of the contamination layer thickness. The experimental validation of the methodology is performed on the model samples, demonstrating errors of 2% on the enrichment ratios on similar samples with different contamination layer thicknesses, while the conventional spectra quantification results in errors of 49%. The methodology is also theoretically substantiated within certain constraints. By the use of the AES methodology, an enriched Ti and Zr deposition is confirmed at the cathodic intermetallic particles at the surface of the industrial no-rinse CC sprayed automotive aluminium sheet samples. 相似文献
105.
Swathi K. Manchili Johan Wendel Yu Cao Eduard Hryha Lars Nyborg 《Surface and interface analysis : SIA》2020,52(12):1045-1049
Demand for high-density press and sinter components is increasing day by day. Of the different ways to improve the sinter density, the addition of nanopowder to the conventional micrometer-sized metal powder is an effective solution. The present investigation is aimed at studying the surface chemistry of iron nanopowder coated with graphitic carbon, which is intended to be mixed with the conventional iron powder. For this purpose, iron nanopowder in the size range of 30 nm to submicron (less than 1 micron) was investigated using thermogravimetry at different temperatures: 400°C, 600°C, 800°C, 1000°C, and 1350°C. The X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and high-resolution scanning electron microscopy (HR-SEM) were used for characterizing the powder as well as samples sintered at different temperatures. The presence of iron, oxygen, carbon, chromium, and zinc were observed on the surface of the nanopowder. Iron was present in oxide state, although a small metallic iron peak at 707 eV was also observed in the XPS spectra obtained from the surface indicating the oxide scale to be maximum of about 5 nm in thickness. For the sample treated at 600°C, presence of manganese was observed on the surface. Thermogravimetry results showed a two-step mass loss with a total mass loss of 4 wt.% when heated to 1350°C where the first step corresponds to the surface oxide reduction. 相似文献
106.
A novel, green and effective approach to fabricate uniform functional spherical polymer particles remains a huge challenge. Herein, we present a novel one-pot approach superior to traditional precipitation polymerization, called precipitated droplets in-situ cross-linking (PDIC) polymerization, by which uniform particles are fabricated on large scale without any toxic organic solvents or stabilizers. With this approach, functional spherical polymer particles can be fabricated continuously only relying on gravity, and the preparation process is thus super-fast. For example, polyacrylic acid (PAA) hydrogel particles with ultra-high adsorption capacity are fabricated within only 60 s. Moreover, we have successfully fabricated different functional hydrogel particles, including anticoagulant, reinforced and bactericidal particles, based on the monomers of 2-acrylamide-2-methylpropanesulfonic acid (AMPS), acrylamide (AM) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC), respectively. This approach has several advantages: (i) the technology is green; (ii) the size and porosity of the particles can be well-controlled; (iii) various functional spherical hydrogel particles can be fabricated by using corresponding monomers. More importantly, this approach fits the commercialization of functional hydrogel particles on demand. 相似文献
107.
108.
The LiRh-type crystal structure of the equiatomic intermetallic compound IrZn turns out to be a competitor to the otherwise energetically favored CsCl-type structures of congeneric transition metal zinc phases, thus enlightening the structural impact of element-specific factors beyond the Hume-Rothery concept. 相似文献
109.
110.
A greener and efficient method for the synthesis of ynones and 1,3-diynes using copper oxide nanoparticles (CuONPs) doped reduced graphene oxide (CuO@rGO) catalyst under palladium, ligand and solvent free conditions have been developed. The catalyst was subsequently utilized for the synthesis of biologically active 1,5-benzodiazepines in one pot via sequential addition of acyl chlorides, terminal alkynes and o-phenylenediamines. The methodology initially involves in situ formation of ynones which react with o-phenylenediamines in presence of ethanol to afford a wide variety of benzodiazepines. Mild reaction conditions, good to an excellent yield of the products, cheap and recyclable catalyst make this methodology environmentally benign and sustainable. 相似文献