Chemiexcitation Acceleration of 1,2‐Dioxetanes by Spiro‐Fused Six‐Member Rings with Electron‐Withdrawing Motifs

The chemiluminescent light‐emission pathway of phenoxy‐1,2‐dioxetane luminophores attracts growing interest within the scientific community. Dioxetane probes undergoing rapid flash‐type chemiexcitation exhibit higher detection sensitivity than those with a slow glow‐type chemiexcitation rate. We discovered that dioxetanes fused to non‐strained six‐member rings, with hetero atoms or inductive electron‐withdrawing groups, present both accelerated chemiexcitation rates and elevated chemical stability compared to dioxetanes fused to four‐member strained rings. DFT computational simulations supported the chemiexcitation acceleration observed by spiro‐fused six‐member rings with inductive electron‐withdrawing groups of dioxetanes. Specifically, a spiro‐dioxetane with a six‐member sulfone ring exhibited a chemiexcitation rate 293‐fold faster than that of spiro‐adamantyl‐dioxetane. A turn‐ON dioxetane probe for the detection of the enzyme β‐galactosidase, containing the six‐member sulfone unit, exhibited a S/N value of 108 in LB cell growth medium. This probe demonstrated a substantial increase in detection sensitivity towards E. coli bacterial cells expressing β‐galactosidase, with an LOD value that is 44‐fold more sensitive than that obtained by the adamantyl counterpart. The accelerated chemiexcitation and the elevated chemical stability presented by dioxetane containing a spiro‐fused six‐member ring with a sulfone inductive electron‐withdrawing group, make it an ideal candidate for designing efficient turn‐on chemiluminescent probes with exceptionally high detection sensitivity. New phenoxy‐1,2‐dioxetanes bearing a spiro‐fused six‐member ring with different electron‐withdrawing motifs were shown to have an accelerated chemiexcitation and increased stability compared to previously reported 1,2‐dioxetanes. A turn‐ON dioxetane probe containing a six‐member sulfone unit exhibited increased detection sensitivity toward β‐galactosidase expressing bacteria in growth medium.