Radical-Triggered Chemiluminescence of PhenanthrolineDerivatives: An Insight into Radical–Aromatic Interaction

摘要

The hitherto unknown influence of 1,10-phenonthroline (1,10-phen) and its derivatives on the weak chemiluminescence (CL) of periodate-peroxide has been investigated, and a novel method for CL catalysis is described. Herein, we have deconvoluted the variation in CL intensity arising from the addition of various derivatives of 1,10-phen. Interestingly, similar derivatives of 1,10-phen show interesting differences in their reactivity toward CL. Electron-withdrawing substituents on 1,10-phen boosted the CL signals, indicating a negative charge buildup on 1,10-phen in the rate-determining step. The 1,10-phen derivatives having substitution at the C⁵=C⁶ position resulted in no CL signals due to the blockage of the reactive site. Mechanistic investigations are interpreted in terms of free radical (H2O2 reaction), followed by the oxygen atom transfer via an electrophilic attack of IO4^– (IO4^– reaction) on 1,10-phen resulting in dioxetane with enhanced CL emission. Additionally, the relationship between electronic structures and photophysical properties was investigated using density functional theory. Our results are expected to open up promising application of 1,10-phen as a molecularcatalyst, providing a new strategy for metal-free catalytic CL enhancementreaction. We believe that this would foster in gleaning more detailedinformation on the nature of these reactions, thereby leading to adeeper understanding of the CL mechanism.