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Supramolecular Ga4L612– Cage Photosensitizes 1,3-Rearrangement of Encapsulated Guest via Photoinduced Electron Transfer

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journal contribution
posted on 19.08.2015, 00:00 by Derek M. Dalton, Scott R. Ellis, Eva M. Nichols, Richard A. Mathies, F. Dean Toste, Robert G. Bergman, Kenneth N. Raymond
The K12Ga4L6 supramolecular cage is photoactive and enables an unprecedented photoreaction not observed in bulk solution. Ga4L612– cages photosensitize the 1,3-rearrangement of encapsulated cinnamyl­ammonium cation guests from the linear isomer to the higher energy branched isomer when irradiated with UVA light. The rearrangement requires light and guest encapsulation to occur. The Ga4L612– cage-mediated reaction mechanism was investigated by UV/vis absorption, fluorescence, ultrafast transient absorption, and electrochemical experiments. The results support a photoinduced electron transfer mechanism for the 1,3-rearrangement, in which the Ga4L612– cage absorbs photons and transfers an electron to the encapsulated cinnamyl­ammonium ion, which undergoes C–N bond cleavage, followed by back electron transfer to the cage and recombination of the guest fragments to form the higher energy isomer.