condensation reaction. The tetrapropoxycalix[4]arene pseudopeptide 33 shows conformational and self-assembly properties quite different to those of the dipropoxy derivatives 12–21. The observed differences are explained on the basis of the different conformational flexibilities of the twocalix[4]arene scaffolds. Calixarene 5 is more rigid than 27 thanks to the presence of two OH groups at the lower (narrow) rim