Synthesis of macrocyclic chromotropic acid-based sulfonamides; their complexation properties and an unexpected photochemical reaction

Chromotropic acid (CTA), a dihydroxynaphthalenedisulfonic acid is a reagent that is widely used for dyestuff manufacture, as a chromogen-forming reagent for the analysis of formaldehyde and as an intermediate for azo derivatives used as analytical reagents. The synthesis of two new CTA-based macrocyclic tetra-sulfonamides 7 and 7a and their corresponding bis-sulfonamides 10 and 10a and their complexation properties toward tetra-n-butylammonium halides were studied. The X-ray structure of 10a was determined and it provided key evidence for an unexpected photochemical reaction that the tetra-sulfonamides underwent.