Electronegatively Substituted Adamantyl Units Accelerate Chemiexcitation of 1,2-Dioxetane Luminophores while Preserving Chemical Stability

Abstract

Chemiluminescent probes o[er exceptional sensitivity for bioanalytical applications by generating light without external excitation, thereby eliminating background interference. Among these, phenoxy-1,2-dioxetane luminophores are widely used; however, enhancing chemiexcitation rates typically comes at the cost of reduced chemical stability. Here, we present a rational design strategy that overcomes this limitation through the incorporation of electronegatively substituted adamantyl units into the dioxetane sca[old. We show that introducing electron-withdrawing functionality, specifically a lactone-adamantyl moiety, significantly accelerates chemiexcitation kinetics while preserving the inherent stability of the adamantyl framework. These modified luminophores exhibit a transition from prolonged glow-type emission to rapid flash-type chemiluminescence, increasing photon flux without diminishing total light output. As a result, probes incorporating electronegative adamantyl groups demonstrate substantially improved analytical performance. In enzymatic assays, these probes generate faster signal buildup and markedly enhanced signal-to-noise (S/N) ratios compared to classical analogues. This enhancement arises from both accelerated chemiexcitation and reduced background signal due to faster decomposition of residual emissive species. Importantly, stability studies confirm that these structural modifications do not compromise probe integrity under physiological conditions. The practical advantage of this design is clearly demonstrated in bacterial detection assays. Probes bearing the lactone-adamantyl unit achieve signal-to-noise values up to 190-fold higher than those obtained with the corresponding non-substituted adamantyl probes, while maintaining chemical stability under physiological conditions, all within the first minute of measurement. This work establishes substituted adamantyl units as a powerful structural motif for designing next-generation, highly sensitive chemiluminescent tools for rapid diagnostics, bioimaging, and environmental sensing.