Lei Min, Xintong Li, Weiliang Zhang, Ying Zhang, Haibo Yu

School of Environment, Liaoning University

Xinfu Zhang, Yi Xiao

State Key Laboratory of Fine Chemicals, Dalian University of Technology

Abstract

To confirm the pKa regulation by hydrogen bond, a series of rhodamine alkylamides were developed, and their pKa values were measured in aqueous solution. For Rh-APD, intramolecular hydrogen bond derived from hydroxyl of 2-amino-1,3-propanediol between carbonyl of spirolactam was favorable to the increase of pKa values (pKa 5.7). Gaussian stimulation demonstrated a moderate intramolecular hydrogen bond in Rh-APD at DFT/ B3LYP/6–31 G(d) level. Except for pH, neither protic/aprotic solvents nor metal ions induced ring-opening transformation of Rh-APD. Bio-imaging showed that Rh-APD could specifically accumulate in lysosomes and evaluate lysosomal pH fluctuation in living MCF-7 cells. Moreover, Rh-APD also can indicate the acidity of gut and ovary of Daphnia magna. Rh-APD would be a potential reagent for water-quality monitoring with the help of its pH indication in living cells and water fleas.

Read the full article here:   91-pKa modulation of rhodamine alkylamides by hydrogen-bond and application in bio-imaging.pdf