Aromatic amines fluorescent labeling

This class of ligands mostly consists of derivatives of pyridine, 2.2 -bipyridinc. 2,2, 2"-ter-pyridine, and 1,10-phenanthroline. Scheme 6 shows the structures of fourEu3+ chelates with aromatic amine derived ligands, that can be covalently bound to proteins, for time-resolved fluorometry, among which 4,7-bis(chlorosulfophenyl)-l,10-phenanthroline-2,9-dicarboxylic acid (BCPDA)-Eu3+ and trisbipyridine cryptate (TBP)-Eu3+ are widely used for europium fluorescence labels in TR-FIA. 

Some reactions used for fluorescence labeling are based on changing the nature of a substituent on an aromatic structure. For example, the reaction of flu-orescamine with amines is quite similar to a labeling reaction, is fast, and specific for primary amines. The reagent itself is not fluorescent and does not hydrolyze to a fluorescent product. Reaction of cyanide with benzoquinone is another example where modification of a substituent eliminates n — n transitions into the basic aromatic structure. Addition of an electron-donating substituent results in a modification of fluorescence properties, such as in the... 

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