Abstract: In order to study the chemiluminescent reaction mechanism of Cypridina luciferin, a series of 6-aryl-2-methyllimidazo[1,2-a]pyrazin-3-(7H)-ketone rings based derivetives(named MIPa—MIPd) was chosen as studied objectives in this work. We employed the DFT//B3LYP/6-31G* method to calculate the activation energy and the fluorescence lifetime(τ) of the products in the reaction from the dioxetanones to amidopyrazines in the gas phase, dimethyl sulfoxide(DMSO), and diglyme(DG). The calculated results indicate that Cypridina luciferin analogues possessing the electron-donating aryl group have lower activation energy(ΔEa) and the solvent has significant effect on activation energy(ΔEa), which is lowest in DMSO. The fluorescence-quantum-yield of path Ⅱ is higher in DMSO than that in path Ⅰ, but it reverses in DG.

Key words: Cypridina luciferin, Chemiluminescence, Activation energy, Fluorescence lifetime, Density functional theory(DFT)