Abstract Preview Page

This is an automatically generated preview of the abstract you selected.

Reversible thermal formation of excited states in donor assisted dioxetane CL Edwin F. Ullman*1; M Pirio2; S Singh3 (1) 135 Selby Lane, Atherton, Ca 94027, USA; (2) Dade Behring Inc., PO Box 49013, San Jose, CA 95161-9013; (3) Aclara BioScience, 1288 Pear Ave, Mountain View, CA 94043-1432      *(tullman@blueskyweb.com) Ring scission of dioxetanes fused to a 1,4-dioxane and to 1,4-oxathianes that have internal electron donating groups is catalyzed by an octa-coordinated europium complex that acts as a triplet energy acceptor. The rate acceleration plateaus at high acceptor concentrations. Both singlet and triplet excited state intermediates are formed. Decay of the singlet intermediate to ground state 1,4-oxathiane dioxetane competes with intersystem crossing and with inefficient formation of the excited singlet state of the di-ester ring scission product. The triplet intermediate yields ground state di-ester without light emission. Chemiexcitation yields of 40-57% are observed. It is suggested that ring scission occurs concomitantly with transfer of energy from the reversibly formed internally excited exciplexes. The proposed mechanism is similar to other non-adiabatic energy transfer processes and may account for the observed failure to transfer energy to certain acceptors that undergo large geometrical changes upon excitation. Reversible formation of excited peroxide charge transfer states permits rationalization of flavin chemiluminescence and may be a general mechanism for many bioluminescent and chemiluminescent reactions. [Talk: ullman.edwinf.09461]

Return to the list of abstracts

E-mail   |  Conference Info  |   Index of Abstracts