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Chemical Bond

Physics advocates research on unifying chemical bonds and recognized parallels on a different (and non-reductive) level, as per the concept of the Great Unification of Forces in Nature. From this perspective, a Physicochemical Grand Unification of Forces would be a worthy project for humankind in order to increase our undertanding of existence and to improve our lives. This entry collection aims to present an account of chemical bonds and interactions in nano- to maco-environments.

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Topic review
Updated time: 17 Jun 2021
Submitted by: samy shaban
Definition: Recently, aptamers have attracted attention in the biosensing field as signal recognition elements because of their high binding affinity toward specific targets such as proteins, cells, small molecules, and even metal ions. Aptamers have intrinsic advantages, such as their availability for both chemical modifications and conjugation with different labels, facilitating their ability to be used to construct a sensitive and highly selective platform sensor. Aptamers can be easily functionalized and engineered, providing several signaling modes such as colorimetric, fluorometric, and electrochemical, in what is known as aptasensors.
Entry Collection : Chemical Bond
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Topic review
Updated time: 18 May 2021
Submitted by: Alexandru C. Razus
Definition: The nonalternant aromatic azulene, an isomer of alternant naphthalene, differs from the latter in peculiar properties. The large polarization of the π-electron system over the seven and five rings gives to azulene electrophile property a pronounced tendency to donate electrons to an acceptor, substituted at azulene 1 position. This paper presents cases in which azulene transfers electrons to a suitable acceptor as methylium ions, positive charged heteroaromatics and examples of neutral molecules that can accept electrons.
Entry Collection : Chemical Bond
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Topic review
Updated time: 18 Dec 2020
Submitted by: Pierina Visciano
Definition: The occurrence of biogenic amines in fish is directly associated with microorganisms withdecarboxylase activity. These compounds are generally detoxified by oxidases in the intestinal tract ofhumans, but some conditions, such as alcohol consumption, enzyme deficiency, or monoamino-oxidaseantidepressant use, can make their intake by food dangerous. Due to its toxicity, histamine is a uniquebiogenic amine with regulatory limits for fishery products. This review focuses on biogenic amines infish, with a detailed picture of the number of alert notifications or intoxication events reported in thelast years. The favoring conditions for their formation, as well as the main preventive and controlmeasures to ensure public health, are also reviewed.
Entry Collection : Chemical Bond
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Topic review
Updated time: 17 Jun 2021
Submitted by: Stoyan Nihtianov
Definition: The discovery of the extremely shallow amorphous boron-crystalline silicon heterojunction occurred during the development of highly sensitive, hard and robust detectors for low-penetration-depth ionizing radiation, such as ultraviolet photons and low-energy electrons (below 1 keV). For many years it was believed that the junction created by the chemical vapor deposition of amorphous boron on n-type crystalline silicon was a shallow p-n junction, although experimental results could not provide evidence for such a conclusion. Only recently, quantum-mechanics based modelling revealed the unique nature and the formation mechanism of this new junction. Here, the entry reviews the initiation and the history of understanding the a-B/c-Si interface (henceforth called the “boron-silicon junction”).
Entry Collection : Chemical Bond
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Topic review
Updated time: 08 Oct 2021
Submitted by: Junnian Wei
Definition: Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono-carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize unstable organocopper compounds. Bidentate ligands can chelate to the same copper atom via η2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via η1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles. The anionic coordinating sites of the bidentate ligand can also bridge two metals via μ2-mode, forming organocopper aggregates with Cu-Cu interactions and organocuprates with contact ion pair structures. The reaction chemistry of some selected organocopper compounds is highlighted, showing their unique structure–reactivity relationships.
Entry Collection : Chemical Bond
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Topic review
Updated time: 24 Nov 2020
Submitted by: Wei Chen
Definition: Using renewable energy to convert CO2 to a clean fuel ethanol can not only reduce carbon emission by the utilization of CO2 as feedstock, but also store renewable energy as the widely used chemical and high-energy-density fuel, being considered as a perfect strategy to address current environment and energy issues. Developing efficient electrocatalysts, photocatalysts, and photoelectrocatalysts for CO2 reduction is the most crucial keystone for achieving this goal. Considerable progresses in CO2-based ethanol production have been made over the past decades. This review provides the general principles and summarizes the latest advancements of electrocatalytic, photocatalytic and photoelectrocatalytic CO2 conversion to ethanol. Furthermore, the main challenges and proposed future prospects are illustrated for further development of the clean fuel ethanol production.
Entry Collection : Chemical Bond
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Topic review
Updated time: 17 Jun 2021
Submitted by: Albert Rimola
Definition: The main objective of computational chemistry is to solve chemical problems by simulating chemical systems (molecular, biological, materials) in order to provide reliable, accurate and comprehensive information at an atomic level. To this end, there are two main methodological families: those based on quantum chemical methods and those based on molecular mechanics. The former are methods in which the electrons are explicitly accounted for, while in the latter their presence is hidden in the force field.
Entry Collection : Chemical Bond
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Topic review
Updated time: 21 Jun 2021
Submitted by: SHERIFF BALOGUN
Definition: Potassium bromate (KBrO3), a renowned oxidizing agent, has a huge reputation for being one of the best and least expensive dough-improving substances in the baking industry. As such, its importance in the baking industry cannot be overemphasized. KBrO3 produced the desired result in baking by influencing the physical and chemical properties of macromolecules such as protein and starch often found in the dough. Precisely, the viscosity, extent of gelatinization, swelling characteristics of the dough, and disulfide linkage formation (in gluten proteins) are affected by the use of KBrO3 as an additive in bread baking. Bromate has been found to be a product of water treatment due to bromide ion oxidation that occurs during ozonation.
Entry Collection : Chemical Bond
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Topic review
Updated time: 20 Aug 2021
Definition: Electrophoretic deposition (EPD) is a powerful technique to assemble metals, polymer, ceramics, and composite materials into 2D, 3D, and intricately shaped implants. Polymers, proteins, and peptides can be deposited via EPD at room temperature without affecting their chemical structures. Furthermore, EPD is being used to deposit multifunctional coatings (i.e., bioactive, antibacterial, and biocompatible coatings).
Entry Collection : Chemical Bond
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Topic review
Updated time: 15 Apr 2021
Definition: The crucial role played by compounds bearing amide functions, not only in biological processes but also in several fields of chemistry, life polymers and material sciences, has brought about many significant discoveries and innovative approaches for their chemical synthesis. Within this context, and following the development of C-H functionalization strategies, C-H amidation reactions have only recently emerged as valuable approaches for the construction of amide functions. These methodologies have been successfully used for both C(sp2)- and C(sp3)-H activations and blossoming synthetic applications have appeared in the last two years (2019-2020 timeframe).
Entry Collection : Chemical Bond
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