Functionalized adamantylideneadamantane 1,2-dioxetanes: investigations on stable and inherently chemiluminescent compounds as a tool for clinical analysis

Abstract

Photophysical and thermodynamic properties of adamantylideneadamantane 1,2-dioxetane (1) and some functionalized derivatives, useful as thermochemiluminescent labels, are summarized. The emission of light from these compounds is stimulated simply by thermal activation. The low fluorescence efficiency of S1-adamantanone, the emitting product, causes the chemiluminescence efficiency to be moderate (φCL = 10 -4 ). The quantum efficiency of chemiluminescence φCL can be increased effectively through radiationless energy transfer to a fluorescent acceptor. The donor acceptor pair 1 and 9,10diphenylanthracene (DPA) is investigated in terms of Förster's theory. Proteins, labeled with derivatives of both 1 and DPA show increased thermochemiluminescent specific activity, in accord with this theory. Upon complexation with cyclodextrins, the evaporation of 1 and its derivatives at 240°C is inhibited. These complexes show a perfect dose-response linearity over a large range of concentration. Complexation also increases the reproducibility of chemiluminescence detection. Association constants for 1 and a derivative with both βand γ-cyclodextrin are presented.

Dioxetane Scission Products Unchanged by Mechanical Force

“…By comparing this with the direct singlet fluorescence, which has a similar spectral range, we were able to ascertain that the absolute singlet yield is (0.9±0.1) %; from the known triplet/singlet ratio, the absolute triplet yield is, therefore, (8.9±1.2) %. The absolute yields are comparable with the absolute thermal singlet and triplet yields of 2 and 15 %, respectively (50 % errors reported on individual yields) 14…”

“…13 The triplet formation is such that it cannot be explained by a facile intersystem crossing from directly produced excited singlets. For example, the exceptionally stable bis(adamantyl)‐1,2‐dioxetane decomposes when heated to 200 °C (Scheme ) in a first‐order chemiluminescent process with an activation energy of 35 kcal mol −1 and a half‐life of less than a few minutes14 to form singlet and triplet products in a ratio of 1:7.5 and a total chemiexcitation yield of 17 %, as determined by Schuster et al by using chemical titration 15. The vast majority of other dioxetanes are much less stable, although the triplet excesses and total chemiexcitation yields vary widely from dioxetane to dioxetane.…”

“…In principle, the singlet/triplet ratio can be determined from the direct fluorescence and phosphorescence of the excited ketones, but excited adamantanone, in common with other alkyl ketones, is not a very efficient emitter from the singlet state and triplet adamantanones are not known to phosphoresce at room temperature 14. 15 Nevertheless, excited ketones can transfer their excitation energy efficiently to fluorescent or phosphorescent acceptors 20.…”

Autocatalytic-Assisted Photorelease of a Sensitizer Drug Bound to a Silica Support

“…As might have been anticipated, the amount of light emitted by the surface-bound dioxetane during decomposition was far too small to have any significant effect. The thermal decomposition of the adamantylideneadamantane 1,2-dioxetanes 14 only yields ~6×10 19 photons/mol which is insufficient as a light source in our case. Ten or a hundred million-times more photons were produced by the diode laser per mole of reagent in our experiments.…”

Probing Force with Mechanobase‐Induced Chemiluminescence

“…[14] Despite this progress, only one luminescent mechanophore has been developed to date, the bis(adamantyl)dioxetane, and its mechanical reactivity is ultimately determined by the strength of the dioxetane bond, which has an activation energy barrier to decomposition of approximately 150 kJ mol -1 (at zero force). [15] It would be desirable to lower the force threshold at which mechanoluminescence is activated, in part so that mechanical processes operative at lower forces may be characterized. However, direct synthetic modification of the dioxetane structure is far from trivial: thermally more labile dioxetanes are generally more difficult to synthesize and may not necessarily be mechanically more labile.…”