Polyvalency (chemistry) in the context of "Mordant"

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⭐ Core Definition: Polyvalency (chemistry)

In chemistry, polyvalency (or polyvalence, multivalency) is the property of molecules and larger species, such as antibodies, medical drugs, and even nanoparticles surface-functionalized with ligands, like spherical nucleic acids, that exhibit more than one supramolecular interaction. For the number of chemical bonds of atoms, the term "valence" is used (Fig. 1). For both atoms and larger species, the number of bonds may be specified: divalent species can form two bonds; a trivalent species can form three bonds; and so on.

Species that have polyvalency usually show enhanced or cooperative binding compared to their monovalent counterparts. Nanoparticles with multiple nucleic acid strands on their surfaces (e.g., DNA) can form multiple bonds with one another by DNA hybridization to form hierarchical assemblies, some of which are highly crystalline in nature.

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👉 Polyvalency (chemistry) in the context of Mordant

A mordant or dye fixative is a substance used to set (i.e., bind) dyes on fabrics. It does this by forming a coordination complex with the dye, which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in cell or tissue preparations. Although mordants are still used, especially by small batch dyers, they have been largely displaced in industry by substantive dyes.

The term mordant comes from the Latin mordere, "to bite". In the past, it was thought that a mordant helped the dye "bite" onto the fiber so that it would hold fast during washing. A mordant is often a polyvalent metal ion, and one example is chromium (III). The resulting coordination complex of dye and ion is colloidal and can be either acidic or alkaline.

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Polyvalency (chemistry) in the context of Sulfur

Sulfur (American spelling and the preferred IUPAC name) or sulphur (Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with the chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature.

Sulfur is the tenth most abundant element by mass in the universe and the fifth most common on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". Almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. Sulfur is used in matches, insecticides, and fungicides. Many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, bad breath, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes.

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