25,26,27-Triacetoxy-28-hydroxycalix[4]arene (I) was synthesized and characterized by 1H NMR, 13C NMR, IR, and elemental anal. A single crystal of its (1:1) acetonitrile clathrate was obtained by recrystg. the compound from acetonitrile. The results of x-ray anal. show that the crystal is monoclinic and its space group belongs to P21/n and the clathrate is an intermol. one. In the crystal, triacetoxyhydroxycalix[4]arene exits in an "inside" partial cone conformation and a residual OH group lies in the center of the mol., which is surrounded with three OAc groups and four benzene rings. Thus, the conformation is unfavorable for attacking the OH group.

Key words: CRYSTAL STRUCTURE DETERMINATION, ACETIC ACID ESTER, X-RAY DIFFRACTION ANALYSIS, PROTON MAGNETIC RESONANCE SPECTROMETRY, MACROCYCLIC COMPOUNDS, ACYLOXY, CONFORMATION, ACETONITRILE, CLATHRATES, CALIXARENE