Two novel symmetrical stilbene optical brighteners based on 1,3,4-oxadiazole bearing sodium sulfonate
unit were synthesized. The two target compounds were characterized by NMR and elemental analysis.
The photophysical processes of the target compounds were investigated by UV–Vis absorption and fluorescence
emission spectra in different solutions. The two optical brighteners were tested as radiation protectants
for the Spodoptera litura nuclear polyhedrosis virus (SINPV) against 2nd-instar S. litura larvae.
The results indicate that the two compounds exhibit strong blue fluorescence emission, and the fluorescence
quantum yield in DMF is 0.86 and 0.75, respectively. The insecticidal effect of SINPV is increased by
the addition of the two compounds and especially the compound 3b shows more obvious synergy effect.
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