Synthesis of acridinyl- and fluorenylidenehydrazido derivatives of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-Butylcalix[4]arene

p-tert-Butylcalix4]arenes substituted at the lower rim by acetic acid hydrazide residues reacted with methoxy(ethoxy)acridine and fluoren-9-one derivatives to give a series of calixarenes containing N′-fluorenylidene- and N′-acridinylacetohydrazide residues. It was found that modification of the hydrazide moiety does not affect the conformation of the initial macroring and that it can lead in some cases to unsymmetrically substituted calixarenes.