Crown-containing arylimines of 5-hydroxy-and 5-hydroxy-6-nitro-2, 3-diphenylbenzo [b] furan-4-carbaldehydes were synthesized and their structure, spectral, luminescent, and complexing properties were studied by means of 1H and 13C NMR, IR, UV, and mass- spectrometry. In solution, these compounds exist as equilibrium mixtures of benzenoid and quinoid tautomers. The relative concentration of the quinoid form increases in the order of ...