Diazotizable supports of potential interest as affinity chromatography matrices

Immobilization of affinity ligands, proteins, enzymes and other functional groups by azo coupling is based on the high reactivity of the support‐carrying diazonium groups towards both low‐ and high‐molecular weight compounds containing certain groupings such as phenols, imidazole and some other heterocycles, thiols and amines. The precursor of diazonium group is a diazotizable amine on the matrix. Remarkable progress in its preparation was achieved by application of (4‐amino‐phenyl)‐(2‐sulphatoxyethyl) sulphone‐type reagents for functionalization of the matrix. A similar type of amine precursor is prepared by the reaction of monosubstituted sulphanilamide with epoxide‐containing matrix. The presence of a SO2 group in the para position to diazonium group of these supports (after diazotization) enhances reactivity in azo coupling. ‘Reversed’ azo coupling is the reaction of a matrix containing functional groups capable of reacting with diazonium groups of a ligand. Preparation of a suitable matrix and examples of diazotizable ligands are given.