Phenylazophenol-Quinone Phenylhydrazone Tautomerism in Chromogenic Cryptands and Corands with Inward-Facing Phenolic Units and Their Acyclic Analogues

Article abstract of DOI:10.1021/jo00007a057

A series of 4-(4'-nitrophenol)azophenol compounds is prepared in which ether oxygen-containing substituents are attached at the 2- and 6-positions or connect the 2- and 6-positions to incorporate the chromophoric unit into corand or cryptand structures with inward-facing phenolic groups.The phenylazophenol-quinone phenylhydrazone tautomerism of these compounds, as probed by ultraviolet-visible spectroscopy, reveals a pronounced effect of the structure of the ether oxygen-containing substituents or bridging unit upon the tautomeric equilibrium.Chromogenic response of five cryptands with inward-facing phenolic groups to sodium and potassium ions are determined and compared.