A LUMINESCENT SENSOR RESPONSIVE TO COMMON OXOACIDS - X-RAY CRYSTAL-STRUCTURE OF (ETHYLENEOXYETHYLENEOXY)ANTHRACENE-9,10-DIONE]CLO4

1, 8-Oxybis(ethyleneoxyethyleneoxy)anthracene-9, 10-dione with a reduc ed cavity size, due to the presence of a carbonyl oxygen within the cr own, has been shown by X-ray crystallography to encapsulate a hydroniu m ion. Hydrogen bonds between the hydronium ion and the crown oxygens are particularly strong, averaging 2.56 Angstrom. The polyether ring a lso exhibits a pronounced folding to optimize encapsulation of the hyd ronium ion. The hydronium hydrogen atoms have been unequivocally obser ved, indicating near ideal pyramidal geometry, due to the absence of h ydrogen-bonding disorders previously observed in other [H3O.18-crown-6 ](+) structure analyses. Intense luminescence is concurrently observed with complexation of the hydronium ion within the polyether ring. Com mon oxoacids acids, such as HNO3, H2SO4, HClO4, and CF3SO3H, result in luminescent intensities approximately 40 times larger than that of 1, 8-oxybis(ethyleneoxyethyleneoxy)anthracene-9, 10-dione alone, which a lso correlates with the pK(a)s of these acids. This capability serves a unique pK(a) regimen as a possible sensor molecule for measuring aci dities of potent oxo and superacids.