Ratiometric pH responsive fluorescent probes operative on ESIPT

Yim Pan Chan, Li Fan, Qihua You, Wing Hong CHAN*, Albert W M LEE, Shaomin Shuang

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

33 Citations (Scopus)


A series of C-8′-oxime-appended spirobenzopyrans 4a-4d were synthesized and developed as fluorescent pH ratiometric probes operative in HEPES/ACN (8:2, v/v) buffer solutions. Acidochromic conversion of spirobenzopyran to merocyanine open form can facilitate the subsequent enol-keto tautomerization giving dual emissive peaks via the excited state intramolecular proton transfer (ESIPT) mechanism. The pH titrations of 4a show a 68-fold increase in ratiometric intensities ratio (I645 nm/I 522 nm) when the pH was switched from 8.0 to 4.0 with a pK a value of 5.90.

Original languageEnglish
Pages (from-to)5874-5879
Number of pages6
Issue number29
Publication statusPublished - 22 Jul 2013

Scopus Subject Areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

User-Defined Keywords

  • pH sensing
  • Ratiometric fluorescent probe
  • Spirobenzopyran


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