Figure 1 - full size

Figure 1. Fig. 1. Structures of OBA and derivatives. 1, OBA; 2, 3-(oxalylamino)-naphthalene-2-carboxylic acid; 3, 6-(oxalylamino)-1H-indole-5-carboxylic acid; 4, 6-(oxalylamino)-1H-indole-7-carboxylic acid; 5, 5-iodo-2-(oxalylamino)-benzoic acid.