Color modulation for intramolecular charge-transfer-induced chemiluminescence of 1,2-dioxetanes

Dioxetanes bearing an aromatic electron donor decompose with an accompanying emission of light by an intramolecular charge-transfer-induced chemiluminescence (CTICL) mechanism. The color of the chemiluminescence from CTICL-active aryl-substituted dioxetanes is controlled by the design of the aromatic moiety and its substitution pattern, and the substituent on the carbon of the dioxetane ring. In addition to these color modulations, a change in the conformation of dioxetanes bearing a biaryl group was also found to cause a change in the color of CTICL in the coordination sphere of a crown ether complex. This new color modulation system was further developed for optically active dioxetanes bearing 2-hydroxy-1,1'-binaphthyl, the CTICL of which took place under the chiral recognition of optically active crown ether complexes. The spectra of the chemiluminescence from biaryl-type dioxetanes did not coincide with the fluorescence spectrum from the authentic emitter in the coordination sphere, but they did coincide with each other in a completely homogeneous system. This finding suggests that the emitter of CTICL possesses a transient structure, which retains the afterimage of the conformation of the dioxetane.