Synthesis and spectroscopic characterization of a fluorescent phenanthrene-rhodamine dyad for ratiometric measurements of acid pH values

Priyanka Srivastava,Ute Resch-Genger,Paul Christian Fürstenwerth,Jan Felix Witte

doi:10.1039/d1nj01573g

Abstract

Ratiometric pH sensing by multichannel emission response utilizing excimer/monomer emissions of phenanthrene and rhodamine emission at single excitation wavelength.

Highlights

We present the rational design, synthesis and spectroscopic characterization of a novel dual excitation, three color emitting, pH-responsive fluorescent probe consisting of two phenanthrene and one rhodamine B units linked by click chemistry
We present the synthesis of this first example of a bichromophoric, three color-emissive ratiometric pH probe and its spectroscopic properties as well as selectivity studies
The synthesis of the bichromophoric pH sensor 8, obtained from two phenanthrene and one rhodamine B units via Click chemistry, is summarized in Fig. 1.39 A detailed description of the preparation procedures of the different intermediates and the challenging purifications is given in the (ESI†)

Summary

Introduction

PH can be measured electrochemically or optically,[15,16] in the latter case utilizing an optical probe, i.e., a sensor molecule or a chemodosimeter, that signals changes in pH by changes in its absorption[1] and/or fluorescence properties.[17,18,19,20] Very sensitive pH measurements with a high spatiotemporal resolution can be best done with pH-responsive molecular or nanoscale optical probes[20,21,22,23,24,25,26] which can be exploited for intracellular pH studies.[1]. 0.32 0.026a 0.022 0.004 0.045 0.017 0.028 0.061 0.7 0.451 0.507 the pH from 4.5 to 2.0, leads to a diminution of the phenanthrene excimer emission at 500 nm and the appearance of a new fluorescence band at 582 nm corresponding to the rhodamine B derivative with the open spirolactam ring (Table 2 and Fig. 4, Table S1, ESI†).

Results

Conclusion