A combined theoretical and experimental study on the mechanism of spiro-adamantyl-1,2-dioxetanone decomposition

Abstract

Our study on the unimolecular decomposition of a relatively stable 1,2-dioxetanone derivative, model compound for bioluminescence processes, indicates the existence of different reaction pathways for ground and excited state formation.

Mechanistic insights into the efficient intramolecular chemiexcitation of dioxetanones from TD‐DFT and multireference calculations

“…By its turn, for OH, the energy gap is of 4.0‐10.0 kcal mol −1 , between IRC of 0.20 and 9.94 amu 1/2 bohr. It should be noted that previous studies indicate that multireference calculations should predict even smaller gaps between S 0 and S 1 . This was ascribed to the importance of multireference correlation in these systems, which implies that S 0 and S 1 become degenerated in the biradical region.…”

“…An active space of 10‐in‐8 was chosen for the different dioxetanones (Supporting Information Figures S5 and S6). The choice of active space was made based on previous studies and correspond to OO and CC σ bonding and σ* antibonding orbitals, CO π bonding and π* antibonding orbitals, and oxygen lone pairs orbitals . The MS‐CASPT2 eliminate the method was used to compute the dynamical electron correlation .…”

“…It should be noted that previous studies indicate that multireference calculations should predict even smaller gaps between S 0 and S 1 . [22][23][24][34][35][36][37][53][54][55] This was ascribed to the importance of multireference correlation in these systems, which implies that S 0 and S 1 become degenerated in the biradical region. The energetic error present in this region may result from spin contamination in the reference state introduced by a BS technology.…”

Four‐membered cyclic peroxides: Carriers of chemical energy

“…Proper description of bioluminescence and chemiluminescence at the molecular level requires methods able to locate conical intersections and singlet‐triplet crossings along the potential energy surface of chemical reactions involving species with energy‐degenerate open‐shell electronic configurations . Although the use of excited‐state multiconfigurational methods are the state‐of‐the‐art approach for such studies, important insight on the mechanisms of bioluminescent and chemiluminescent transformations came also from simpler approaches, including density functional studies or even from semiempirical calculations (Scheme ).…”

“…The unimolecular decomposition of 1,2‐dioxetanones produces carbon dioxide in the ground state and an excited‐state carbonyl compound (Φ T up to 10% and Φ S < 0.1%) . In contrast with the indirect chemiluminescence of 1,2‐dioxetanes substituted with simple alkyl or aryl groups, attempts to enhance the chemiluminescence of 1,2‐dioxetanones with fluorescent energy acceptors resulted in an increase of the rate of peroxide decomposition that depends on the oxidation potential of the fluorophore.…”