Charge-transfer inclusion complex formation of tropylium cation with pillar[6]arenes

The complexation behavior of pillar[6] arene hosts towards a carbonium ion, tropylium tetrafluoroborate (T center dot BF4), and the formation of novel charge-transfer (CT) inclusion complexes are described. In contrast, smaller pillar[5]arenes and larger pillar[7]arenes cannot form such complexes due to the unsuitable cavity dimensions.