Manipulating the through-space spin-spin interaction of organic radicals in the confined cavity of a self-assembled cage.
We show a new approach to manipulating the through-space spin-spin interaction by utilizing the confined cavity of a self-assembled M6L4 coordination cage. The coordination cage readily encapsulates stable organic radicals in solution, which brings the spin centers of the radicals closer to each other. In sharp contrast to the fact that the radical in solution in the absence of the cage is in a doublet state, in the presence of the cage through-space spin-spin interaction is induced through cage-encapsulation effects in solution as well as in the solid state, resulting in the triplet state of the complex. These results were confirmed by ESR spectroscopy and X-ray crystallography. The quantity of triplet species generated by encapsulation in the cage increases with increasing affinity of the radicals to the cage. We estimated the affinity between several types of guests and the cage in solution by cyclic voltammetry. We also demonstrate that the through-space interaction of organic radicals within the self-assembled coordination cage can be controlled by external stimuli such as heat or pH.
Nakabayashi
Koji
K
Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, CREST, Japan, Science and Technology Corporation, Bunkyo-ku Tokyo 113-8656, Japan.
Kawano
Masaki
M
Kato
Tatsuhisa
T
Furukawa
Ko
K
Ohkoshi
Shin-ichi
S
Hozumi
Toshiya
T
Fujita
Makoto
M