A Reversible Rhodamine B Based pH Probe with Large Pseudo-Stokes Shift

Guochen Bao; Ka-Leung Wong; Peter A Tanner

doi:10.1002/cplu.201900263

A Reversible Rhodamine B Based pH Probe with Large Pseudo-Stokes Shift

Chempluschem. 2019 Jul;84(7):816-820. doi: 10.1002/cplu.201900263.

Authors

Guochen Bao^{1

2}, Ka-Leung Wong¹, Peter A Tanner¹

Affiliations

¹ Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong S.A.R., P. R. China.
² Institute for Biomedical Materials & Devices (IBMD) School of Mathematical and Physical Sciences Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia.

PMID: 31943984
DOI: 10.1002/cplu.201900263

Abstract

A reversible and sensitive pH probe DPE-Rh operates by Förster resonance energy transfer from 1,2-diphenylethyne (DPE) to Rhodamine B (Rh). In the presence of H⁺ , the spirolactam ring of the Rhodamine B unit was opened and this resulted in ca. 1000-fold enhancement of fluorescence intensity with linear change over the pH range of 2.0 to 5.5. The Förster resonance energy transfer offered this probe an effective excitation-emission wavelength shift of around 240 nm with about 100 % quenching of the donor emission. The response of the sensor is tolerant towards a wide range of metal ions and the sensing mechanism was deduced by ¹ H NMR spectrometry. This FRET-based molecule not only provides a sensitive pH probe, but also suggests an effective strategy to eliminate the interference of excitation light.

Keywords: FRET; fluorescence; pH sensors; rhodamine; spirolactams.

Publication types

Research Support, Non-U.S. Gov't