Two novel pH probes (L1 and L2) were facilely synthesized by one-step reaction.
Fluorescence intensity ratio of L1 and L2 can quantify the pH fluctuations.
L1 and L2 show high quantum yield and large two-photon absorption cross-section.
L1 and L2 show excellent selectivity response and remarkable color change to H+.
L1 and L2 were successfully utilized to mapping pH difference intracellularly.