Indole-5-carboxylic acid trimer

We have previously considered [8,9] the redox behaviour and film structure of indole-5-carboxylic acid trimer (ICA trimer) films formed by the electrooxidation of indole-5-carboxylic acid (ICA, Fig. 11.2). We have shown that electrooxidation involves the production and deposition of an asymmetric cyclic trimer (Fig. 11.3) onto the electrode surface... 

Figure 5.40 Molecular structure of the trimer formed during electropolymerization of (indole-carboxylic acid). Journal of the Chemical Society, Faraday Transactions, 1994, 90, 1121, J. G. Mackintosh, A. R. Mount. Reproduced by permission of The Royal Society of Chemistry.)...

The trimerization of indole-5-carboxylic acid gives one of the following two isomers ... 

The reaction of peroxynitrite with the melanin precursor 5,6-dihydroxyindole-2-carboxylic acid (DHICA) produces polymeric products. The reaction proceeds through unstable intermediates including dimers and trimers of DHICA in addition to indole-5,6-quinone-2-carboxylic acid thus peroxynitrite, which nitrates phenolic compounds. 

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