Marked difference in singlet-chemiexcitation efficiency between syn-anti isomers of spiro[1,2-dioxetane-3,1'-dihydroisobenzofuran] for intramolecular charge-transfer-induced decomposition

摘要

Spiro[1,2-dioxetane-3,1'-dihydroisobenzofuran] syn-3 bearing a hydroxy group at the 6-position (as a model syn-rotamer of parent dioxetane 4 bearing a 3-hydroxypheny! group) and its isomer anti-3 (as a model anti-rotamer of 4) were synthesized. When these spiro-dioxetanes were treated with tetrabutyl-ammonium fluoride (TBAF) in DMSO, anti-3 emitted light with high efficiency (Φ~(CL) = 0.41), while the respective value for syn-3 was only 1/10 for anti-3. This significant difference in Φ~(CL) between syn-3 and anti-3 was attributed to the difference in their singlet-chemiexcitation efficiencies.