Color in Chelate Complexes

Of special interest are the chelate complexes that form when mordanting takes place in the dyeing process. One more metaphor associated with chelates the Latin word mordere means to bite, and a mordant is a substance that allows the dye molecule to bite into it. In so doing, the dye and the mordant form a new chemical substance as we see above in the reaction of the copper(II) ion with two molecules of 2,4-pentanedione. Using a mordant with a dye has some important effects  

Some examples of mordants are salts of aluminum, copper, iron and chromium in each case it is the metal ion that is the mordanting agent. A comprehensive table showing the effect of mordanting on plant dyestuffs from ancient Israel is in reference [38]. Numerous other chelates are known, and their usefulness spans the various branches of theoretical and applied chemistry and allied fields. 

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