(E) -2,6-Di-tertbutyl-4 (4- (diethylamino) styryl) pyrylium TFA

(E) -2,6-Di-tert-butyl-4- (4- (diethylamino) styryl) pyrylium TFA (Compound 4a) functions as a Gram-negative outer membrane permeabilizer by targeting Met47 in LptA to disrupt LptA/LptC interactions, exhibiting synergistic antibacterial activity. This compound, when in the form of (trifluoromethanesulfonate), enhances the efficacy of pol B against both wild-type and multi-drug resistant A. baumannii and E. coli strains. Additionally, (E) -2,6-Di-tert-butyl-4- (4- (diethylamino) styryl) pyrylium (trifluoromethanesulfonate) serves as an adjuvant for antibiotics combating multi-drug resistant Gram-negative bacteria.