Ratiometric spiropyran-based fluorescent pH probe

Qi Hua You, Li Fan, Wing Hong CHAN*, Albert W M LEE, Shaomin Shuang

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

24 Citations (Scopus)


Spiropyran (SP) is an attractive molecular platform for the design of fluorescent OFF-ON probes for the detection of cations and anions operative on a ring-opening/closing mechanism. By incorporating a benzimidazole moiety at the ortho-position of the oxygen atom of the pyran unit, a ratiometric fluorescent probe in the NIR range for the measurement of pH change in aqueous ACN solution was designed and investigated. The ring-opening mechanism and cis-trans interconversion of the probe are also substantiated by 1H NMR titration. The probe showed a ratiometric change in the pH range from 7.0 to 5.5 and the pKa of the probe was calculated to be 5.9. The relative intensity ratio (I690 nm/I517 nm) changed from 0.08 to 2.11 with a more than 26-fold enhancement in response to the pH variation.

Original languageEnglish
Pages (from-to)15762-15768
Number of pages7
JournalRSC Advances
Issue number36
Publication statusPublished - 28 Sept 2013

Scopus Subject Areas

  • Chemistry(all)
  • Chemical Engineering(all)


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