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 1 】 10?2 M Bu4NCF3SO3 in 40% CH2Cl2/CH3OH at 25 oC determined by potentiometric titration are log K1 = 10.91, log K2 = 10.30, log K3 = 6.24 and log K4 = 2.55. Stability constants for the receptor L complexes with Cu(II) and Zn(II) in 1 】 10?2 M Bu4NCF3SO3 in 40% CH2Cl2/CH3OH at 25 oC were determined by UV-VIS spectrometric titration. Stability constants of the CuL and ZnL complexes as log モ 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 ?E1 = -290.1, ?E2 = -205.0, ?E3 = -124.9 and ?E4 = -26.9 kcal/mol and complexation energy of ZnL complex is -370.3 kcal/mol.