A tetraphenylethylene-based diamidine for the recognition of dicarboxylic acids has been designed and synthesized. The diamidine shows a blue fluorescence after the addition of alpha,omega-dicarboxylic acids (C-5-C-10), such as pimelic acid (C-7)and suberic acid (C-8), due to the formation of a higher aggregate which is determined by a DLS analysis. For the recognition of the shorter and longer methylene chain lengths of alpha,omega-dicarboxylic acids (C-3-C-4, C-11-C-13), no fluorescence was observed, thus a narrow selectivity for the chain length of the alpha,omega-dicarboxylic acids was determined.