New cation-‘capped’ complex of the Z-isomer of a crown-containing styryl dye bearing a long N-ammonioalkyl substituent

Two new styryl dyes of the benzothiazole series containing a 18-crown-6 moiety and an N-ammoniohexyl or N-ethyl substituent were synthesised. In acetonitrile, the dye bearing the ammoniohexyl linker forms a stable dimeric complex in the E-form and an intramolecular cation-‘capped’ complex in the Z-form due to ‘host–guest’ hydrogen bonding.