The last decade has seen a rapid development of activity-based spiroadamantane 1,2-dioxetane chemiluminescent probes for <i>in vivo</i> imaging of hypoxia in tumors, pH and biologically relevant analytes including reactive nitrogen, oxygen, and sulfur species. Unlike their well-established fluorescent cousins, these self-immolating probes do not suffer from light scattering or autofluorescence and thus can provide improved imaging depth. With practical biological applications as the motivation, current research has been directed towards synthetic modifications which can shift the emission of these scaffolds (450-530 nm) in to the near-infrared region and beyond. In this work, we describe our approach to develop near-infrared emitting chemiluminescent probes by coupling spiroadamantane 1,2-dioxetane-based adducts to emissive transition metal complexes. The resulting probes depict ratiometric chemiluminescence in the near-infrared region, attributed to energy transfer from the chemiexcited benzoate moiety to the corresponding metal complex. Significantly, the oxygen sensitivity of the phosphorescent metal complexes allowed us to employ these probes for <i>in vitro</i> ratiometric oxygen imaging, as well as for intraperitoneal, intramuscular and intratumoral imaging in live mice.

Near infrared chemiluminescent 1,2-dioxetane transition metal complexes for oxygen sensing

ACS Spring 2022

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