Experimental and DFT evaluation of the 1H and 13C NMR chemical shifts for calix[4]arenes

The 1H chemical shifts of ptcx4 using B3LYP, B3PW91 and PBE1PBE functionals, as well as experimental values. Eleven exchange-correlation functionals with the 6-31G(d,p) basis set are evaluated for the calculation of 1H and 13C NMR chemical shifts of p-tert-butylcalix[4]arene (ptcx4, R1 = C(CH3)3). The three best performing functionals are employed to compute the chemical shifts of p-sulfonic acid calix[4]arene (sfxcx4, R1 = SO3H), p-nitro-calix[4]arene (ncx4, R1 = NO2) and calix[4]arene (cx4, R1 = H) in chloroform and dichloromethane. The calculated values are in good agreement with the 1H and 13C NMR chemical shift values measured experimentally in the same solvents.184