SYNTHESIS, ACID-BASIC AND COMPLEXING PROPERTIES OF CYCLENE BASED CRYPTANDS

The protonation of 1,4,7,10-tetraazabicyclododecane (L-2), 4,7-dioxa 1 ,10,13,16-tetraazabicyclo[8.8.2]eicosane (L-3) and 1,4,7,10,13,16-hexa azabicyclo[8.8.2]eicosane (L-7) was studied by potentiometric methods at 18 degrees C and ionic strength of 0.1 (NaClO4) in aqueous medium. In all instances, two buffer regions have been observed. The logarithm s of the protonation constants were equal to 10.55, 9.50, 3.00 for L-2 , 10.80, 9.95, 8.60, 3.30 for L-3 and 10.25, 9.00, 7.80, 5.70, 2.80, 1 .20 for L-7. The stability constants for copper(II) complexes were det ermined. The methods of synthesis of cryptands L-3, L-7 are presented. (C) 1997 Elsevier Science Ltd.