Kinetic studies of calixarene-based cyclic and non-cyclic ‘super-uranophiles’

The kinetic parameters for the binding of UO22+ to calixarene-based ‘super-uranophiles’, para-sulphonatocalix[n]arenes (n= 5, 6 and 8: 1n) and their non-cyclic analogue, 3,5-bis{[2-hydroxy-3-(2-hydroxy-3-methyl-5-sulphonatophenyl)methyl-5-sulphonatophenyl]methyl}-4-hydroxybenzene-sulphonate (2) have been evaluated at 25 °C and pH 10.40. The reaction of UO22+ and 2 is speeded up by a factor of 85 compared to that of UO22+ and 16.