Fig. 7

Structure-activity relationship investigation of the rhodamine library. a RD53 analogs without the rhodamine core; b RD53 analogs with the adamantine moiety modified; c RD53 analogs with the diethylamino group modified. d Rhodamine dyes mainly adopted the ring-close forms exhibit no antibacterial activity against ATCC43300 or ATCC19606, with MIC > 64 μg mL−1