Upconversion of Reductants Syroeshkin, Mikhail A.; Kuriakose, Febin; Saverina, Evgeniya A. ...
Angewandte Chemie,
April 16, 2019, Letnik:
58, Številka:
17
Journal Article
Recenzirano
Odprti dostop
The many applications of photon upconversion—conversion of low‐energy photons into high‐energy photons—raises the question of the possibility of “electron upconversion”. In this Review, we illustrate ...how the reduction potential can be increased by using the free energy of exergonic chemical reactions. Electron (reductant) upconversion can produce up to 20–25 kcal mol−1 of additional redox potential, thus creating powerful reductants under mild conditions. We will present the two common types of electron‐upconverting systems—dissociative (based on unimolecular fragmentations) and associative (based on the bimolecular formation of three‐electron bonds). The possible utility of reductant upconversion encompasses redox chain reactions in electrocatalytic processes, photoredox cascades, design of peroxide‐based medicines, firefly luminescence, and reductive repair of DNA photodamage.
Electrons and photons are essential chemical “currencies” that are commonly traded in chemical transformations. The many applications of photon upconversion raises the question of the possibility of “electron upconversion”. This Review describes the two common types of electron‐upconverting systems: dissociative (based on unimolecular fragmentations) and associative (based on the bimolecular formation of three‐electron bonds).
Density functional theory (DFT) simulations of ring-opening copolymerization of ε-caprolactone (CL) and L-lactide (LA) in presence of novel gallium complex on aminobis (phenolate) ligand are ...conducted. The initial steps of polymerization of CL and LA as well as the first steps of propagation which led to LGa-LA-LA-OMe, LGa-LA-CL-OMe, LGa-CL-LA-OMe, or LGa-CL-CL-OMe derivatives have been analyzed in detail. According to these data, the studied catalyst is a rare example of a catalyst in which, during copolymerization, the polymerization of CL should proceed faster than LA. Thus, we predict the formation of a mainly block copolymer poly(CL-block-LA) using this catalyst.
The chemistry of organoelement compounds is now one of the most rapidly developing fields of research, regarding both fundamental science and solution of applied problems. This review covers a ...variety of classes of organoelement compounds, ranging from molecules with highly labile carbon-element bonds to compounds with stable bonds that form the basis of novel structural materials and demonstrates their role in scientific research and industrial production. The use of Grignard reagents in modern organic synthesis and application of catalytic cyclomagnesiation and cycloalumination reactions for the preparation of difficult-to-access metallacycles are considered. The electron transfer processes in redox-active derivatives of Group 14 elements and the role of radical ions in these processes are discussed. Considerable attention is paid to organometallic compounds, first of all, as catalysts; the dynamic nature of catalysis with these compounds is noted. Unusual strained metallacycles of high thermal stability, zirconacyclocumulenes, which also exhibit catalytic activity, are described. Complexes with redox-active ligands that substantially affect the reactivity of the metal centre and directly participate in reactions with various substrates as well as organometallic compounds of lanthanides are considered. Modern environmentally benign methods for the synthesis of organosilicon compounds and production of unique materials based on them are discussed. Particular Sections are devoted to organophosphorus compounds, including those exhibiting therapeutic properties and possessing unusual optical characteristics, and organic chalcogen compounds, which find use as ligands and biologically active molecules. The bibliography includes 1045 references.
We report herein the synthesis and full characterizations of the first examples of gallium complexes based on "privileged" aminobisphenolate ligands which are easily available. These complexes turned ...out to be extremely active in the ring-opening polymerization of ε-caprolactone even at room temperature and highly active in the ROP of L-lactide. The combination of factors such as the easy availability of these compounds and the supposedly low toxicity, together with the extremely high activity in ROP, allows us to consider these compounds as suitable for use on an industrial scale for the synthesis of biodegradable polymers for biomedical applications.
The Pot, Atom, and Step Economy (PASE) approach is based on the Pot economy principle and unites it with the Atom and Step Economy strategies; it ensures high efficiency, simplicity and low waste ...formation. The PASE approach is widely used in multicomponent chemistry. This approach was adopted for the synthesis of previously unknown hydroxyquinolinone substituted chromeno2,3-
pyridines via reaction of salicylaldehydes, malononitrile dimer and hydroxyquinolinone. It was shown that an ethanol-pyridine combination is more beneficial than other inorganic or organic catalysts. Quantum chemical studies showed that chromeno2,3-
pyridines has potential for corrosion inhibition. Real time
H NMR monitoring was used for the investigation of reaction mechanism and 2-((2
-chromen-3-yl)methylene)malononitrile was defined as a key intermediate in the reaction.
Root reinforcement of soils under compression Schwarz, M.; Rist, A.; Cohen, D. ...
Journal of geophysical research. Earth surface,
10/2015, Letnik:
120, Številka:
10
Journal Article
Recenzirano
Odprti dostop
It is well recognized that roots reinforce soils and that the distribution of roots within vegetated hillslopes strongly influences the spatial distribution of soil strength. Previous studies have ...focussed on the contribution of root reinforcement under conditions of tension or shear. However, no systematic investigation into the contribution of root reinforcement to soils experiencing compression, such as the passive Earth forces at the toe of a landslide, is found in the literature. An empirical‐analytical model (CoRoS) for the quantification of root reinforcement in soils under compression is presented and tested against experimental data. The CoRoS model describes the force‐displacement behavior of compressed, rooted soils and can be used to provide a framework for improving slope stability calculations. Laboratory results showed that the presence of 10 roots with diameters ranging from 6 to 28 mm in a rectangular soil profile 0.72 m by 0.25 m increased the compressive strength of the soil by about 40% (2.5 kN) at a displacement of 0.05 m, while the apparent stiffness of the rooted soil was 38% higher than for root‐free soil. The CoRoS model yields good agreement with experimentally determined values of maximum reinforcement force and compression force as a function of displacement. These results indicate that root reinforcement under compression has a major influence on the mechanical behavior of soil and that the force‐displacement behavior of roots should be included in analysis of the compressive regimes that commonly are present in the toe of landslides.
Key Points
Root reinforcement has a major influence on soil compression behaviors
The CoRoS model describes the force‐displacement behavior of compressed rooted soils
The CoRoS model can be used in an upscaling framework for slope stability
Aminobisphenol supported germylenes, stannylenes and plumbylenes were prepared starting from the reaction of corresponding Lappert’s tetrylene with aminobisphenols. XRD analysis revealed different ...coordination mode for germylene and stannylene with additional nitrogen donor in the structure of the ligand. Germylene was converted to the rhenium complex in reaction with Re(CO)5Br featuring Re←:Ge dative bond.
Display omitted
•Heavier carbene analogues based on aminobisphenols were successfully synthesized.•Different coordination mode for Ge, Sn tetrylenes with additional N donor was found.•Reaction of germylene with Re(CO)5Br gives complex with Re–Ge bond.
Aminobisphenol supported germylenes (1a–3a), stannylenes (1b–3b) and plumbylenes (1c–3c) were synthesized by reaction of Lappert’s tetrylenes, (Me3Si)2N2M (M=Ge, Sn, Pb), with corresponding aminobisphenols R1N(CH2C6H2(OH)(t-Bu)R2)2, 1–3 (1: R1=Et, R2=Me; 2: R1=Et, R2=t-Bu; 3: R1=CH2(Py-2), R2=t-Bu). X-ray diffraction analysis revealed different coordination mode for germylene 3a and stannylene 3b with additional nitrogen donor in the structure of the ligand. Germylene 1a was converted to the rhenium complex 1aa by the reaction with Re(CO)5Br.
Wiener filter and neural network filter are considered in relation to the problem of measuring the road profile. Road profile is identified using the inertial data from a smartphone rigidly fixed ...inside a moving car. The effectiveness of the approaches is compared by experimentally driving a car through a series of speed bumps.
Inverted perovskite solar cells with a p-i-n configuration have attracted considerable attention from the research community because of their simple design, insignificant hysteresis, improved ...operational stability, and low-temperature fabrication technology. However, this type of device is still lagging behind the classical n-i-p perovskite solar cells in terms of its power conversion efficiency. The performance of p-i-n perovskite solar cells can be increased using appropriate charge transport and buffer interlayers inserted between the main electron transport layer and top metal electrode. In this study, we addressed this challenge by designing a series of tin and germanium coordination complexes with redox-active ligands as promising interlayers for perovskite solar cells. The obtained compounds were characterized by X-ray single-crystal diffraction and/or NMR spectroscopy, and their optical and electrochemical properties were thoroughly studied. The efficiency of perovskite solar cells was improved from a reference value of 16.4% to 18.0-18.6%, using optimized interlayers of the tin complexes with salicylimine (1) or 2,3-dihydroxynaphthalene (2) ligands, and the germanium complex with the 2,3-dihydroxyphenazine ligand (4). The IR s-SNOM mapping revealed that the best-performing interlayers form uniform and pinhole-free coatings atop the PC
BM electron-transport layer, which improves the charge extraction to the top metal electrode. The obtained results feature the potential of using tin and germanium complexes as prospective materials for improving the performance of perovskite solar cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Electrochemical synthesis suggested a mild, green and atom-efficient route to interesting and useful molecules, thus avoiding harsh chemical oxidizing and reducing agents used in traditional ...synthetic methods. Organic electrochemistry offers an excellent alternative to conventional methods of organic synthesis and creates a modern tool for carrying out organic synthesis, including cascade and multicomponent ones. In this research, a novel electrocatalytic multicomponent transformation was found: the electrochemical multicomponent assembly of arylaldehydes, N,N′-dimethylbarbituric acid and 4-hydroxy-6-methyl-2H-pyran-2-one in one pot reaction was carried out in alcohols in an undivided cell in the presence of alkali metal halides with the selective formation of substituted unsymmetrical 1′,3′,6-trimethyl-3-aryl-2′H,3H,4H-spirofuro3,2-cpyran-2,5′-pyrimidine-2′,4,4′,6′(1′H,3′H)-tetraones in 73–82% yields. This new electrocatalytic process is a selective, facile and efficient way to obtain spirofuro3,2-cpyran-2,5′-pyrimidines. According to screening molecular docking data using a self-made Python script in Flare, all synthesized compounds may be prominent for different medical applications, such as breast cancer, neurodegenerative diseases and treatments connected with urinary tract, bones and the cardiovascular system.
PDF
