Complete gas-phase proton microaffinity analysis of two bulky polyamine molecules.
Density functional theory (DFT) and ab initio (Hartree-Fock) calculations employing the 6-31G* basis set are used to determine gas-phase proton microaffinities (PA(n,i)) of two bulky symmetrical tripodal tetraamine ligands N[(CH2)(4)NH2]3, trbn, and N[(CH2)(5)NH2]3, trpa. The corresponding proton macroaffinities (PA(n)) are calculated not only according to our recently established method but also considering two alternative formulas based on a Boltzmann distribution. The successive protonation macroconstants in aqueous solution for these bulky amines are predicted from the well-defined correlation between the calculated proton macroaffinities, without considering Boltzmann distribution, and the corresponding log Kn for these amines. The overall protonation constants are also predicted by two different methods.
Salehzadeh
Sadegh
S
Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran. saleh@basu.ac.ir
Bayat
Mehdi
M
Hashemi
Mehdi
M