Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes.

The first crown ether-capped dibenzotetraaza[14]annulenes (DBTAAs), featuring two macrocyclic binding sites fixed in a face-to-face orientation, were synthesized in satisfactory 26-28% isolated yields. Direct N-alkylation of 1,4,10-trioxa-7,13-diazacyclopentadecane by symmetric DBTAA derivatives bearing bromoalkoxy pendants proceed smoothly at a reasonable level of dilution (1.25 mM). The structures were fully characterized by HR-ESIMS, FTIR-ATR, 1H and 13C NMR spectroscopy and elemental analysis.