5 (6) -Carboxyfluorescein diisobutyrate

CC(C(OC1=CC=C2C(OC3=CC(OC(C(C)C)=O)=CC=C3C24OC(C5=CC(C(O)=O)=CC=C54)=O)=C1)=O)C.CC(C(OC6=CC=C7C(OC8=CC(OC(C(C)C)=O)=CC=C8C79OC(C%10=CC=C(C(O)=O)C=C%109)=O)=C6)=O)C

[1]Sarka Bidmanova, et al. Conjugation of 5 (6) -carboxyfluorescein and 5 (6) -carboxynaphthofluorescein with bovine serum albumin and their immobilization for optical pH sensing. Sensors and Actuators B: Chemical. Volume 161, Issue 1, 3 January 2012, Pages 93-99.