Rational design of ratiometric near-infrared fluorescent pH probes with various pKa values, based on aminocyanine

Takuya Myochin, Kazuki Kiyose, Kenjiro Hanaoka, Hirotatsu Kojima, Takuya Terai, Tetsuo Nagano

Research output: Contribution to journalArticlepeer-review

225 Citations (Scopus)


Novel ratiometric, near-infrared fluorescent pH probes with various pK a values have been designed and synthesized on the basis of aminocyanine bearing a diamine moiety, and their photochemical properties were evaluated. Under acidic conditions, these pH probes showed a 46- to 83-nm red shift of the absorption maximum. This change is sufficiently large to permit their use as ratiometric pH probes, and is reversible, whereas monoamine-substituted aminocyanines showed irreversible changes because of their instability under acidic conditions. Furthermore, the pKa values of these probes can be predicted from the calculated pKa values of the diamine moieties, obtained from the SciFinder database. This design strategy is very simple and flexible, and should be applicable to develop NIR pH probes for various applications.

Original languageEnglish
Pages (from-to)3401-3409
Number of pages9
JournalJournal of the American Chemical Society
Issue number10
Publication statusPublished - 2011 Mar 16
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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