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The viscosity effects on the emission of two 1,2-dioxetanes with high aqueous quantum yields provide empirical evidence for a stepwise mechanism with viscosity-dependent pathways that reduce chemiluminescence emission. 

A near-infrared (NIR) chemiluminescent probe using energy transfer to a silicon rhodamine scaffold has been developed for in vivo imaging applications. 

Reactive oxygen and nitrogen species are small reactive molecules derived from elements in the air─oxygen and nitrogen. They are produced in biological systems to mediate fundamental aspects of cellular signaling but must be very tightly balanced to prevent indiscriminate damage to biological molecules. Small molecule probes can transmute the specific nature of each reactive oxygen and nitrogen species into an observable luminescent signal (or even an acoustic wave) to offer sensitive and selective imaging in living cells and whole animals. This review focuses specifically on small molecule probes for superoxide, hydrogen peroxide, hypochlorite, nitric oxide, and peroxynitrite that provide a luminescent or photoacoustic signal. Important background information on general photophysical phenomena, common probe designs, mechanisms, and imaging modalities will be provided, and then, probes for each analyte will be thoroughly evaluated. A discussion of the successes of the field will be presented, followed by recommendations for improvement and a future outlook of emerging trends. Our objectives are to provide an informative, useful, and thorough field guide to small molecule probes for reactive oxygen and nitrogen species as well as important context to compare the ecosystem of chemistries and molecular scaffolds that has manifested within the field. 

Abstract Chemiluminescence imaging of bioanalytes using spiroadamantane 1,2‐dioxetanes has gained significant attention due to improved signal‐to‐noise ratios and imaging depth compared to excitation‐based probes, as well as their modifiable scaffolds that offer analyte‐specific responses and tunable emissive properties. Among several strategies employed to amplify signals under aqueous conditions and to shift the emission into the bio‐relevant red region, energy transfer to an adjacent fluorophore is a popular and effective method. This Minireview highlights spiroadamantane 1,2‐dioxetane‐based probes that operate via an energy transfer mechanism to detect bioanalytes both in vitro and in vivo. Probes that display both non‐covalent and covalent interactions with fluorophores, as well as their applications in imaging specific analytes will be discussed.