NaI in water was added to the host (X= CF3SO3-)
Anion to host ratio of 20:1
The chemical shift related to methylene of the calix shifts down field (higher ppm)
EQNMR software was used to find and model association constant.
K1 = 51 M-1 for Iodide
The same experiment was done for Chloride, Bromide, Nitrate, Acetate, Hydrogen phosphate and sulfate