Novel fluorescent pH sensors based on intramolecular hydrogen bonding ability of naphthalimide.
4-Piperidine-naphthalimide derivatives containing potential acceptors for hydrogen bonding were synthesized, and their fluorescence properties were examined. Some of the compounds with a 2-imino-oxalidin (thiazolidin) side chain at the imide moiety exhibit a strong fluorescence quench and some red shift in weakly acidic conditions, caused by the formation of an intramolecular hydrogen bond. Their pK(a) values were estimated to be about 6.4-7.5. The results showed that these compounds could serve as novel fluorescent pH sensors for further application. [structure: see text]
Cui
Dawei
D
State Key Laboratory of Fine Chemicals, Dalian University of Technology, PO Box 89, Zhongshan Road 158, Dalian 116012, Liaoning Province, China.
Qian
Xuhong
X
Liu
Fengyu
F
Zhang
Rong
R