About: Schiff base is a(n) research topic. Over the lifetime, 19713 publication(s) have been published within this topic receiving 326894 citation(s).
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TL;DR: This chapter discusses methods to determine carbonyl content in oxidatively modified proteins and quantitated protein-bound pyruvoyl groups through formation of a Schiff base with p-aminobenzoic acid followed by reduction with cyanoborohydride.
Abstract: Publisher Summary This chapter discusses methods to determine carbonyl content in oxidatively modified proteins. The methods described are (1) reduction of the carbonyl group to an alcohol with tritiated borohydride; (2) reaction of the carbonyl group with 2,4-dinitrophenylhydrazine to form the 2,4-dinitrophenylhydrazone; (3) reaction of the carbonyl with fluorescein thiosemicarbazide to form the thiosemicarbazone; and (4) reaction of the carbonyl group with fluorescein amine to form a Schiff base followed by reduction to the secondary amine with cyanoborohydride. Van Poelje and Snell have also quantitated protein-bound pyruvoyl groups through formation of a Schiff base with p-aminobenzoic acid followed by reduction with cyanoborohydride. Although a systematic investigation has not appeared, this method should also be useful in detecting other protein-bound carbonyl groups. Carbonyl content of proteins is expressed as moles carbonyl/mole subunit for purified proteins of known molecular weight. For extracts, the results may be given as nanomoles carbonyl/milligram protein. For a protein having a molecular weight of 50,000, a carbonyl content of 1 mol carbonyl/mol protein corresponds to 20 nmol carbonyl/mg proteins.
TL;DR: Practical guidelines for the preparation and use of different Schiff base metal complexes in the field of catalytic transformations are discussed in this tutorial review.
Abstract: Schiff base ligands are considered “privileged ligands” because they are easily prepared by the condensation between aldehydes and imines. Stereogenic centres or other elements of chirality (planes, axes) can be introduced in the synthetic design. Schiff base ligands are able to coordinate many different metals, and to stabilize them in various oxidation states, enabling the use of Schiff base metal complexes for a large variety of useful catalytic transformations. Practical guidelines for the preparation and use of different Schiff base metal complexes in the field of catalytic transformations are discussed in this tutorial review.
Abstract: Many Schiff base complexes of metal ions show high catalytic activity. Chiral Schiff base complexes are more selective in various reactions such as oxidation, hydroxylation, aldol condensation and epoxidation. The catalytic activity of metal complexes of binaphthyl, binaphthol and their combinations with salen Schiff base is presented in this review. The pyridyl bis(imide) and pyridine bis(imine) complexes of cobalt(II), iron(II) ions have been used as catalysts in the polymerization of ethylene and propylene. The phenoxy-imine (FI) complexes of zirconium, titanium and vanadium and Schiff base complexes of nickel(II) and palladium(II) were also used as catalysts in the polymerization of ethylene. Schiff base complexes of metal ions were catalytic in ring opening polymerization processes at low temperature. Schiff base complexes also catalyzed the oxidation of sulfides, thioanisoles, aldehydes, phenol and styrene. Schiff base complexes in super critical carbon dioxide (ScCO2) and in the presence of polar solvents were active catalysts. Schiff base complexes showed significant activity in catalyzing allylic alkylations, hydrosilation, the decomposition of hydrogen peroxide, isomerization, and annulation and carbonylation reactions. The high thermal and moisture stabilities of many Schiff base complexes were useful attributes for their application as catalysts in reactions involving at high temperature.
TL;DR: Two new chemically stable [acid and base] 2D crystalline covalent organic frameworks (COFs) were synthesized using combined reversible and irreversible organic reactions and showed strong resistance toward acid and boiling water and exceptional stability in base.
Abstract: Two new chemically stable [acid and base] 2D crystalline covalent organic frameworks (COFs) (TpPa-1 and TpPa-2) were synthesized using combined reversible and irreversible organic reactions. Syntheses of these COFs were done by the Schiff base reactions of 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1) and 2,5-dimethyl-p-phenylenediamine (Pa-2), respectively, in 1:1 mesitylene/dioxane. The expected enol–imine (OH) form underwent irreversible proton tautomerism, and only the keto–enamine form was observed. Because of the irreversible nature of the total reaction and the absence of an imine bond in the system, TpPa-1 and TpPa-2 showed strong resistance toward acid (9 N HCl) and boiling water. Moreover, TpPa-2 showed exceptional stability in base (9 N NaOH) as well.
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