Anion complexation by calix[4]arene–TTF conjugates

Calix[4]arenes bearing tetrathiafulvalene (TTF) moieties appended to the upper rim via the amidic functions were synthesized and used for 1H NMR and UV/Vis complexation studies towards selected anions. It was found that the complexation affinity towards H2PO4− dramatically depends on the substitution pattern of the calixarene moiety. As a result, the proximally disubstituted derivative has a complexation constant by two orders of magnitude higher than the distally disubstituted analogue. The differences between proximal and distal receptors were also documented by their behaviour during the oxidation of the attached TTF units.

► Calix[4]arene derivatives bearing TTF moieties as a colour spectroscopic marker were prepared.
► Two different regioisomers (distal and proximal) were used as anion receptors.
► The complexation of H2PO4− dramatically depends on the substitution pattern of the calixarene moiety.