Summary

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
Advantages and Disadvantages of Covalent Inhibitors
The formation of covalent bonds that target proteins can offer drugs diverse advantages in terms of target selectivity, drug resistance, and administration concentration. The most important factor for covalent inhibitors is the electrophile (warhead), which dictates selectivity, reactivity, and the type of protein binding (i.e., reversible or irreversible) and can be modified/optimized through rational designs. Furthermore, covalent inhibitors are becoming more and more common in proteolysis, targeting chimeras (PROTACs) for degrading proteins, including those that are currently considered to be ‘undruggable’.
  • 3.9K
  • 10 May 2023
Topic Review
Processes for Obtaining Syngas and Hydrogen
The growing demand for high-quality chemical products has already stimulated an increased interest in the conversion of hydrocarbon gases (natural gas, methane, biogas) into motor fuels and high value-added chemical products, as well as into hydrogen, which is increasingly in demand on the market. The conversion of natural gas into hydrogen and syngas is still the most complex and costly stage of modern gas chemical processes, the low efficiency of which hinders the development of modern gas chemistry. 
  • 1.4K
  • 14 Apr 2023
Topic Review
Chemically Activated Glass-Ionomer Cements as Bioactive Materials
Glass-ionomer cement (GIC) is a long-established restorative dental material with several clinical applications that have remained relevant because of the chemical adhesive bond it forms at the tooth-restoration interface and its fluoride-releasing and recharging properties. It was invented by Wilson and Kent in 1969 and successfully introduced into clinical practice in 1972. Chemically activated GICs, commonly referred to as conventional GICs, typically consist of ion-leachable glasses based on calcium or strontium alumino-fluorosilicate and weak polymeric water-soluble acids of polyacrylic acid (PAA) homopolymer, or acrylic acid, maleic/itaconic acid copolymer. They set by an acid-base reaction, and the setting reaction is initiated by mixing glass powder and polymeric acids. 
  • 1.0K
  • 30 Mar 2023
Topic Review
Aminoacid Surfactants
Aminoacid surfactants are a type of surfactant that is composed of both an amino acid and a hydrophobic tail. They have both hydrophilic and hydrophobic properties, which allows them to lower the surface tension between two immiscible phases, such as oil and water. Aminoacid surfactants are becoming increasingly popular in personal care and cosmetic products due to their mildness and biocompatibility. They are often used as alternatives to traditional surfactants, which can be harsh and irritating to the skin and eyes. Here are several types of amino acid surfactants, each with its own unique properties and applications. Alkyl-L-glutamate, alkyl-L-amino acids, alkyl-D-amino acids, alkyl-amino acids, and dipeptide surfactants are just a few examples of the different types of amino acid surfactants available. With their biodegradability, low toxicity, and excellent foaming and emulsifying properties, amino acid surfactants are a valuable addition to the surfactant industry.
  • 4.3K
  • 24 Mar 2023
Topic Review
Insights into Si-Si and Si-H Bond
During the last decades, the search for new methodologies for the synthesis of organosilicon compounds have increased due to the multiple applications in industry, in academy, among other areas. Silicon-hydrogen and silicon-silicon bond activation by d-block metals still represent the most important pathways for obtaining molecular entities that contain, witihin their structures, silane motifs. Although the chemistry of Si-H bond activation is under continue development, Si-Si bonds are poorly characterized and less used and thus, disilanes represent good starting precursors because of their stability towards ambient conditions. The present entry will focus on the physicochemical properties of Si-H and Si-Si bonds, some trends and finally highlighting their impact on the synthesis of metal complexes.
  • 7.5K
  • 15 Feb 2023
Topic Review
Phenolics against the Oxidation of o/w Emulsions
Lipid oxidation is a serious problem for scientists since it adversely affects the product quality in the food, cosmetic, and pharmaceutical sectors.
  • 631
  • 30 Dec 2022
Topic Review
Structure and Bonding in Planar Hypercoordinate Carbon Compounds
The term hypercoordination refers to the extent of the coordination of an element by its normal value. In the hypercoordination sphere, the element can achieve planar and/or non-planar molecular shape. Hence, planar hypercoordinate carbon species violate two structural rules: (i) The highest coordination number of carbon is four and (ii) the tetrahedral orientation by the connected elements and/or groups. The unusual planar orientations are mostly stabilized by the electronic interactions of the central atom with the surrounding ligands. Primary knowledge of the planar hypercoordinate chemistry will lead to its forthcoming expansion. Experimental and theoretical interests in planar tetracoordinate carbon (ptC), planar pentacoordinate carbon (ppC), and planar hexacoordinate carbon (phC) are continued. The proposed electronic and mechanical strategies are helpful for the designing of the ptC compounds. Moreover, the 18-valence electron rule can guide the design of new ptC clusters computationally as well as experimentally. However, the counting of 18-valence electrons is not a requisite condition to contain a ptC in a cluster. Furthermore, this ptC idea is expanded to the probability of a greater coordination number of carbon in planar orientations. Unfortunately, until now, there are no such logical approaches to designing ppC, phC, or higher-coordinate carbon molecules/ions. There exist a few global minimum structures of phC clusters identified computationally, but none have been detected experimentally. All planar hypercoordinate carbon species in the global minima may be feasible in the gas phase.
  • 2.3K
  • 26 Dec 2022
Topic Review
Thia-Michael Reaction
While the Michael addition has been employed for more than 130 years for the synthesis of a vast diversity of compounds, the reversibility of this reaction when heteronucleophiles are involved has been generally less considered. First applied to medicinal chemistry, the reversible character of the hetero-Michael reactions has been explored for the synthesis of Covalent Adaptable Networks (CANs), in particular the thia-Michael reaction and more recently the aza-Michael reaction. In these cross-linked networks, exchange reactions take place between two Michael adducts by successive dissociation and association steps. In order to understand and precisely control the exchange in these CANs, it is necessary to get an insight into the critical parameters influencing the Michael addition and the dissociation rates of Michael adducts by reconsidering previous studies on these matters. 
  • 1.3K
  • 28 Nov 2022
Topic Review
Polymeric Emissive Materials Based on Dynamic Covalent Bonds
Dynamic covalent polymers, composed of dynamic covalent bonds (DCBs), have received increasing attention due to their adaptive and reversible nature compared with common covalent linked polymers. Incorporating the DCBs into the polymeric material endows it with advanced performance including self-healing, shape memory property, and so forth.
  • 895
  • 25 Nov 2022
Topic Review
Reactive Species on Amino Acids
Reactive oxygen species ROS can be triggered by exogenous sources (tobacco, pollution, xenobiotics, drugs, ionizing radiation and so on), but they can also be generated inside the cell by two different mechanisms: enzymatic and non-enzymatic; in both cases, they can have irreversible effects on animal and plant cells and tissues. The superoxide anion •O2− is unstable and cannot pass through membranes, but is rapidly converted to hydrogen peroxide H2O2 and it is membrane-permeable. In the Fenton reaction, H2O2 produces the hydroxyl radical •OH + −OH, which is highly reactive in the mitochondrial matrix. Elevated levels of ROS lead to increased mtDNA damage.
  • 1.2K
  • 23 Nov 2022
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