K. Ito et al., Synthesis and properties of calixarene analogs incorporating a thiophene unit in the macrocyclic ring, J HETERO CH, 38(1), 2001, pp. 293-298
Calixarene analogs containing a thiophene unit in the macrocyclic ring were
prepared by a stepwise method. The macrocycles adopt a cone-like form as t
he preferred conformation in solution. The induced chemical shift change, n
Oe experiment, and H-1 relaxation time (T-1) measurement supported the fact
that the macrocycle forms a complex with the N-methylpyridinium salt. In c
ontrast, O-tetramethylated macrocycles and linear phenol-formaldehyde tetra
mer, could not efficiently include the N-methylpyridinium salt.