Quantitative structure property relationships on photodegradation of PCDD Fs in cuticular waxes of laurel cherry ž Prunus laurocerasus

By the use of the partial least squares ŽPLS. method and 13 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, a QSPR model was developed for first order rate constants of photodegradation of 10 PCDD Fs dissolved in cuticular wax from laurel cherry ŽPrunus 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 QCl Žthe largest positive atomic charge on a chlorine atom in a molecule., Q O Žthe most negative atomic charge on the oxygen atoms in a molecule., and Ždipole moment. tend to photodegrade fastest. PCDD Fs with large values of Elumo Žthe energy of the lowest unoccupied molecular orbital., Ehomo Žthe energy of the highest occupied molecular orbital., and Elumo Ehomo tend to have the lowest photodegradation rates.