Quantitative structure-property relationships (QSPRs) on direct photolysisquantum yields of PCDDs

By the use of partial least squares (PLS) method and 16 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, quantitative structure-p roperty relationships (QSPRs) were obtained for direct photolysis quantum y ields of selected polychlorinated dibenzo-p-dioxins (PCDDs). Direct photoly sis quantum yields for PCDDs without experimental quantum yield values were predicted. The QSPR results showed that it was mainly the number of chlori ne atoms bonded to the parent structure, the largest positive atomic charge on a chlorine atom, the dipole moment, and the frontier molecular orbital energies (E-homo and E-lumo) that determine the direct photolysis quantum y ields of the PCDDs. Increasing the number of chlorine atoms, dipole moment, and the largest positive atomic charge on a chlorine atom, leads to decrea se of photolysis quantum yields. Increasing E-lumo E-homo and E-lumo - E-ho mo values lead to increase of log Y values. (C) 2001 Elsevier Science Ltd. All rights reserved.