The fluorescence emission of the parent 2-aminobenzimidazole
(ABZ, 1), the mono- and disubstituted derivatives (2, 3), 2-aminonaphthoimidazole (4), and
4-amino dinaphthodiazepine 5 (λem =
315–400 nm) is strongly quenched in the presence of aqueous
hydrogen peroxide. The quenching process is dual: for diazepine 5, quenching is dynamic at lower H2O2 concentrations with linear reduction of the fluorescence lifetime
from 4.3 to 2.6 ns. At higher H2O2 concentrations,
a second species appears in the absorption and emission spectra with
fluorescence lifetimes of 1.3 ns, indicating the formation of a new
(ground-state) hydrogen-bonded ABZ-H2O2 complex
(static quenching). Sensors 1 and 2 show
also dual quenching that fits with a static 1:1 and 1:2 model with K
1:1 = 8(11) M–1 and K
1:2 = 21(147) M–1 for 1(2). The formation of a 1:2 complex (1:(H2O2)2) is also supported by density
functional theory (DFT) calculations and spectra simulations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.