COMPLEXATION OF P-XYLENE WITH P-ISOPROPYLCALIX[4]ARENE - CRYSTAL-STRUCTURES AND THERMAL-ANALYSIS OF THE EMPTY FORM AND THE (1 1) AND (2/1) COMPLEXES/

This paper concerns inclusion complexes of the p-isopropylcalix[4]aren e host with p-xylene as guest. It is shown that from a saturated solut ion in p-xylene, the macrocycle gives a 1:1 complex; on heating, the 1 :1 complex is transformed into a 2:1 complex, and then into the empty macrocycle. The compounds are studied by differential scanning calorim etry, thermogravimetry and X-ray powder diffraction; the three crystal structures are reported showing the arrangements of the macrocycles w ith and without their guests.