A 1:2:2 complex between 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (4,13-diaza-18-crown-6), 2,6-dihydroxyanthraquinone and water

Abstract

A 1:2:2 complex of diaza crown ether 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, anthraflavic acid (2,6-dihydroxyanthraquinone) and water has been synthesized. The crystal is triclinic, P1, with a = 7.705(2), b = 10.871(2), c = 11.540(2) Å, α = 100.40(2), β = 91.38(2), γ = 98.01(2)°, Z = 1, and D_calc = 1.375 mg m⁻³. The main feature of the crystal structure is the formation of a supramolecular sheet by hydrogen bonding of the anthraflavic monoanions, not only head-to-tail through the hydroxyl oxygens, but sideways through the quinone oxygens. This complex represents an intermediate case between total transfer of protons of a hydroxy-guest to crown N-atoms, and no transfer.