Synthesis and properties of calixarene analogs incorporating a thiophene unit in the macrocyclic ring

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.