Supramolecular Ga4L6(12-) Cage Photosensitizes 1,3-Rearrangement of Encapsulated Guest via Photoinduced Electron Transfer

Derek M Dalton; Scott R Ellis; Eva M Nichols; Richard A Mathies; F Dean Toste; Robert G Bergman; Kenneth N Raymond

doi:10.1021/jacs.5b06317

Supramolecular Ga4L6(12-) Cage Photosensitizes 1,3-Rearrangement of Encapsulated Guest via Photoinduced Electron Transfer

J Am Chem Soc. 2015 Aug 19;137(32):10128-31. doi: 10.1021/jacs.5b06317. Epub 2015 Aug 10.

Authors

Derek M Dalton^{1

2}, Scott R Ellis^{1

2}, Eva M Nichols^{1

2}, Richard A Mathies^{1

2}, F Dean Toste^{1

2}, Robert G Bergman^{1

2}, Kenneth N Raymond^{1

2}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, California 94720-1460, United States.
² Division of Chemical Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.

PMID: 26256754
DOI: 10.1021/jacs.5b06317

Abstract

The K12Ga4L6 supramolecular cage is photoactive and enables an unprecedented photoreaction not observed in bulk solution. Ga4L6(12-) 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 Ga4L6(12-) 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 Ga4L6(12-) 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.