Stable 1,2-dioxetanes as labels for thermochemiluminescent immunoassay

A new chemiluminescent system is developed in which inherently chemiluminescent compounds—that is, stable 1, 2-dioxetanes—are used as the label. The emission of light from these compounds can be triggered by thermal activation. This chapter describes the principle of this thermochemiluminescence (TCL), the preparation and properties of TCL labels based on adamantylidene adamantane 1, 2-dioxetane, the inclusion of 1, 2-dioxetanes in γ-cyclodextrin, energy transfer TCL, the use of TCL in immunoassay techniques, and the detection of TCL. 1, 2-Dioxetanes decompose thermally into two carbonyl fragments. Because of the release of strain energy and because of a favorable reaction path, a fraction of the carbonyl fragments is formed in the first singlet or triplet electronically excited state (II-S1 and II-T1). Such electronically excited species can emit light either directly (“direct chemiluminescence,” CL) or through energy transfer to a luminescent acceptor molecule A (“indirect chemiluminescence,” ICL).