MULTIPLE-PHOTON CHEMISTRY OF 9-(PHENOXYMETHYL)ANTHRACENES AND 9,10-BIS(PHENOXYMETHYL)ANTHRACENES IN THE LASER-JET - GENERATION, PHOTOCHEMISTRY, AND TIME-RESOLVED LASER-FLASH SPECTROSCOPY OF ANTHRACENYLMETHYL RADICALS AND PULSE-RADIOLYSIS OF 9-(BROMOMETHYL)ANTHRACENE

In the high-intensity laser-jet (LJ) photolysis of 9-(phenoxymethyl)an thracene (1a) and 9,10-bis(phenoxymethyl)anthracene (1b) multiple-phot on chemistry was observed. Thus, while the [4 + 4] photodimer 8a was f ormed as the one-photon product in the low-intensity conventional phot olysis of monoether 1a, the high-intensity irradiation in the laser-je t yielded 1,2-bis(9-anthracenyl)ethane (3a), lepidopterene (4a), bipla nene (5a), 9-(chloromethyl)anthracene (6a), and 9-(methoxymethyl)anthr acene (7a) as main products. The product distribution depended on the solvent used: after C-O homolysis of the ether 1a, for which at least two photons are required, the resulting arylmethyl radical 2a dimerize s in benzene, in methylene chloride it engages in photoinduced electro n transfer, while in methanol it undergoes photoionization. With the h elp of time-resolved laser-flash photolysis of the monoether la it was confirmed that the homolysis of the C-O bond leads to the 9-anthracen ylmethyl radical 2a. The authentic radical 2a was generated independen tly by time-resolved pulse radiolysis and laser-flash photolysis of 9- (bromomethyl)anthracene. Analogous to the monoether 1a, the bisether 1 b gave under the high intensity conditions of the laser-jet irradiatio n tetrabenzo[2.2]paracyclophane (3b), its photodimer (5b), 9,10-(bisch loromethyl)anthracene (6b), and 9-(chloromethyl)-10-(phenoxymethyl)ant hracene (9b); their distribution depended also on the solvent used. Me chanistic pathways are offered for these multiple-photon processes.