Rate constants of quenching of triplet excited ketones by several monomers
were determined through time-resolved laser spectroscopy or culled from the
literature. The semi-empirical calculation method PM3 allows the quenching
mechanisms to be refined and can be used to predict the reactivity of arom
atic ketones toward monomers. It is apparent from both experimental results
and theoretical calculations that the rate constant (k(q)) measured for th
e bimolecular quenching between the triplet state of a given aromatic keton
e and both electron-rich as well as electron-poor monomers, depends linearl
y on the free enthalpy of formation of the regioselectively favored 1,4-bir
adical, which is the primary reaction step of the ketone/monomer interactio
n. (C) 2000 John Wiley & Sons, Inc.