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
Synthesis and Vibrational Properties of Conducting Polymers Composites
From composites based on carbon nanotubes (CNTs) and conducting polymers (CPs) to their biggest competitor, namely composites based on graphene or graphene derivate (GD) and CPs, there are many methods of synthesis that influence the morphology and the functionalization inside the composite, making them valuable candidates for EM both inside DSSCs and in supercapacitors devices. From the combination of CPs with carbon-based materials, such as CNT and graphene or GD, the perfect network is created, and so the charge transfer takes place faster and more easily.
  • 353
  • 26 Jan 2024
Topic Review
Electronic Structure and Chemical Bonding of Transition-Metal Monoborides
Boron presents an important role in chemistry, biology, and materials science. Diatomic transition-metal borides (MBs) are the building blocks of many complexes and materials, and they present unique electronic structures with interesting and peculiar properties and a variety of bonding schemes which are analyzed here. Comparisons between MB molecules along the three rows are presented, and their differences and similarities are analyzed. The bonding of the diatomic borides is also described. Three of them RhB(X1Σ+), RuB(X2Δ) and TcB(X3Σ−)  form quadruple σ2σ2π2π2 bonds in their X states. The RhB form quadruple bond also in two low-lying excited states.
  • 197
  • 11 Dec 2023
Topic Review
Principles of Prototropic Equilibria
Prototropic tautomers always differ by the positions of labile proton(s) and π-electrons. The number of possible tautomeric forms is an internal property of the tautomeric molecule. It is a consequence of the number of labile protons and the number of conjugated tautomeric sites.
  • 387
  • 01 Nov 2023
Topic Review
Interplay between Polyphenols and Lysyl Oxidase Enzymes
Collagen, the most abundant structural protein found in mammals, plays a vital role as a constituent of the extracellular matrix (ECM) that surrounds cells. Collagen fibrils are strengthened through the formation of covalent cross-links, which involve complex enzymatic and non-enzymatic reactions. Lysyl oxidase (LOX) is responsible for catalyzing the oxidative deamination of lysine and hydroxylysine residues, resulting in the production of aldehydes, allysine and hydroxyallysine. These intermediates undergo spontaneous condensation reactions, leading to the formation of immature cross-links, which are the initial step in the development of mature covalent cross-links. Additionally, non-enzymatic glycation contributes to the formation of abnormal cross-linking in collagen fibrils. During glycation, specific lysine and arginine residues in collagen are modified by reducing sugars, leading to the creation of Advanced Glycation End-products (AGEs). These AGEs have been associated with changes in the mechanical properties of collagen fibers.
  • 581
  • 13 Jul 2023
Topic Review
Hydrogels Based on Supramolecular Strategies
Supramolecular structures are of great interest due to their applicability in various scientific and industrial fields. The sensible definition of supramolecular molecules is being set by investigators who, because of the different sensitivities of their methods and observational timescales, may have different views on as to what constitutes these supramolecular structures. The supramolecular interaction between some materials and guest molecules has endowed gels with the capacity for reversible gel−sol transformation. A plausible example has to do with self-healing, which is one of the most intriguing characteristics of biological or artificial systems, such as the particular and specific applications described below, due to its intrinsic importance. Thermodynamic stability plays an important role, for example, in the preparation of ophthalmic hydrogels and metallo-supramolecular hydrogels.
  • 697
  • 19 Jun 2023
Topic Review
Silanes, as organic-inorganic hybrid modifiers of hyperbranched polymer (HBP), are of great interest as they resulted in a tremendous improvement in HBP properties like increasing thermal, mechanical and electrical properties compared to that of organic-only moieties. The basic components of silanes are monomeric silicon (Si) compounds with four substituent groups attached to the Si atom, which can be of any combination of reactive or non-reactive inorganic or organic groups, which are the fundamental building blocks of silanes.
  • 701
  • 14 Jun 2023
Topic Review
Applications of Polyvinyl Alcohol-Chitosan Hydrogel
Tissue engineering and regenerative medicine (TERM) holds great promise for addressing the growing need for innovative therapies to treat disease conditions. To achieve this, TERM relies on various strategies and techniques. The most prominent strategy is the development of a scaffold. Polyvinyl alcohol-chitosan (PVA-CS) scaffold emerged as a promising material in this field due to its biocompatibility, versatility, and ability to support cell growth and tissue regeneration. 
  • 559
  • 07 Jun 2023
Topic Review
Metal Hydrides and Graphene Supports
Energy production, distribution, and storage remain paramount to a variety of applications that reflect on our daily lives, from renewable energy systems, to electric vehicles and consumer electronics. Hydrogen is the sole element promising high energy, emission-free, and sustainable energy, and metal hydrides in particular have been investigated as promising materials for this purpose. While offering the highest gravimetric and volumetric hydrogen storage capacity of all known materials, metal hydrides are plagued by some serious deficiencies, such as poor kinetics, high activation energies that lead to high operating temperatures, poor recyclability, and/or stability, while environmental considerations related to the treatment of end-of-life fuel disposal are also of concern. Graphene is a 2D material with very appealing properties, highlighting its potential use as support for various reactive species, including metals and metal hydrides. By embedding hydride species into graphene supports, valuable nanocomposites can be obtained with direct use for energy storage applications.
  • 403
  • 01 Jun 2023
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’.
  • 2.3K
  • 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. 
  • 688
  • 14 Apr 2023
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