Quantitative structure-property relationships on photodegradation of PCDD/Fs in cuticular waxes of laurel cherry (Prunus laurocerasus).

By the use of the partial least squares (PLS) method and 13 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, a OSPR model was developed for first order rate constants of photodegradation of 10 PCDD/Fs dissolved in cuticular wax from laurel cherry (Prunus laurocerasus) leaves and exposed to sunlight. The QSPR showed that photodegradation rates increase with the degree of chlorination of the homologues. PCDD/Fs with large values of Q(Cl) (the largest positive atomic charge on a chlorine atom in a molecule), Q(O)- (the most negative atomic charge on the oxygen atoms in a molecule), and mu (dipole moment) tend to photodegrade fastest. PCDD/Fs with large values of E(lumo) (the energy of the lowest unoccupied molecular orbital), E(homo) (the energy of the highest occupied molecular orbital), and E(lumo) - E(homo) tend to have the lowest photodegradation rates.