h beiginejad - Faculty of chemistry, Bu-Ali Sina University, Hamedan ۶۵۱۷۴, Iran
m bayat - Faculty of chemistry, Bu-Ali Sina University, Hamedan ۶۵۱۷۴, Iran
y Gholiee - Faculty of chemistry, Bu-Ali Sina University, Hamedan ۶۵۱۷۴, Iran

For each polybasic m olecule there may be several ways for protonation depending on which site is protonated. Proto nation of different sites for each polybasic m olecule will release different amounts of energy and therefore the term ‘‘proton affinity” for protonation of a special site on a polybasic molecule c an be replaced by term ‘‘proton microaffinity”. Two other types of defined gas-phase proton affinities for such molecules are “proton macroaffinity” and “proton overallaffinity”[۱]. The proton macroaffinity is a weighted mean of various prot on microaffinities involved in each ste p of protonation of a po lybasic molecule and corresponds to its proton ation macroco nstant in solution. Fo r calculati on of proton macroaffinities, PA n , of poly basic molecules with any type of symmetry, Eq. (۱) is used.(...)The prot on overall affinity, PAov, is also defined as the negative of th e electronic energy difference between L and it’s fu lly protonated form together. According to Hess’s law the summation of the calculated proton macroaffinities for one polybasic must be the same as or very close to its PAov .(...)So far, t he proton microaffinity analysis for Hematoxylin (Fig. ۱), a polybasic molecule, in the gas phas e has not investigated.

Hematoxylin, DFT Study, Proton microaffi nity, Proton macroaffinity.