Protonation and Energetical Investigations of Calix[4]-cyclen-benzo-crown-6 and Its Complexes with Zinc and Copper

摘要

Protonation constants of calix[4]-cyclen-benzo-crown-6,L in 1X10~(-2) M Bu_4NCF_3SO_3 in 40% CH_2C1_2/ CH_3OH at 25 deg C determined by potentiometric titration are log K_1=10.91,log K_2=10.30,log K_3=6.24 and log K_4=2.55.Stability constants for the receptor L complexes with Cu(II) and Zn(II) in 1 x 10~2 M Bu_4NCF_3SO_3 in 40% CH_2C1_2/CH_3OH at 25 deg C were determined by UV-VIS spectrometric titration.Stability constants of the CuL and ZnL complexes as logbeta are 4.37 and 3.45,respectively.Stabilization energies for protonations of receptor L,derived from ab initio Hartree-Fock method with 6-31G basis set,are DELTAE_1=-290.1,DELTAE_2=-205.0,DELTAE_3=-124.9 and DELTAE_4=-26.9 kcal/mol and complexation energy of ZnL complex is -370.3 kcal/mol.