Chemi- and Bioluminescence of Cyclic Peroxides

Abstract

Bioluminescence is a phenomenon that has fascinated mankind for centuries. Today the phenomenon and its sibling, chemiluminescence, have impacted society with a number of useful applications in fields like analytical chemistry and medicine, just to mention two. In this review, a molecular-orbital perspective is adopted to explain the chemistry behind chemiexcitation in both chemi- and bioluminescence. First, the uncatalyzed thermal dissociation of 1,2-dioxetane is presented and analyzed to explain, for example, the preference for triplet excited product states and increased yield with larger nonreactive substituents. The catalyzed fragmentation reaction and related details are then exemplified with substituted 1,2-dioxetanone species. In particular, the preference for singlet excited product states in that case is explained. The review also examines the diversity of specific solutions both in Nature and in artificial systems and the difficulties in identifying the emitting species and unraveling the color modulation process. The related subject of excited-state chemistry without light absorption is finally discussed. The content of this review should be an inspiration to human design of new molecular systems expressing unique light-emitting properties. An appendix describing the state-of-the-art experimental and theoretical methods used to study the phenomena serves as a complement.

Unprecedented Formation of 2,5‐Diaminoquinones from the Reaction of Vanillin with Secondary Amines in Aerobic Conditions

“…The conversion of vanillin to 2,5diamino-1,4-benzoquinones starts with the dehydrative con-densation of the aldehyde with the secondary amine (exemplified by morpholine 2a in Scheme 2) to give the intermediate iminium ion 5a, deprotonated to give the morpholinoquinomethide 6a. The unstable four-membered ring immediately fragments [25] generating 2-methoxy-1,4-benzoquinone 8a and the observed byproduct N-formylmorpholine 4a. [22] Aerobic oxidation of the enamine moiety [23] of the quinomethide is known to take place through a SET mechanism [24] leading to the formation of the dioxetane 7a.…”

Updating the Chemiluminescence Oxygen‐Aftereffect Method for Determining the Rate Constant of the Peroxy‐Radical Self‐Reaction: Oxidation of Cyclohexene

“…upon the abrupt change of oxygen concentration from 0 to 0.00236 m at the moment t = 0. Curves 1‐6 represent the results of modeling the chemiluminescence kinetics at the values of rate constant k 13 of reaction stage 13 (Scheme ) equal to 2.8x10 6 m −1 s −1 () and 2.8x10 7 m −1 s −1 ( 2 and 6 ) and at different ratios φ * 13 / φ * 16 of the chemiexcitation yields φ * 13 and φ * 16 in stages 13 and 16: 100 ( 1 and 2 ), 1 (), 0.1 ( 4 ), 10 (5 and 6). Symbols ○ and ■ placed on the computed curves correspond to the two sets of experimental data acquired with the two different samples of AIBN .…”

A Chemiluminescent Probe for HNO Quantification and Real‐Time Monitoring in Living Cells

“…[29] Despite progress,q uantification and real-time monitoring of HNO dynamics using reaction-based probes remain an unsolved problem. [34] This strategy has been used to image numerous analytes in vitro,i nl iving cells,a nd in whole animals. [31,32] In particular, sterically stabilized 1,2-dioxetanes,s uch as Schaapsd ioxetane [33] enable reaction-based triggering of chemiluminescence emission using ac hemically initiated electron exchange luminescence (CIEEL) mechanism.…”

“…[35][36][37][38][39][40][41][42][43] Recent advances in molecular design have yielded structures with high emission under aqueous conditions without the need for polymeric "Enhancer" solutions. [34] Ester coupling using EDC and DMAP was performed after preparation of the dioxetane 1 to avoid phosphine oxidation. Upon reaction with HNO,t he triaryl phosphine is converted to an azaylide,f ollowed by ester cleavage (Supporting Information, Scheme S2).…”