Color-Tunable Indolizine-Based Fluorophores and Fluorescent pH Sensor.

Taegwan Kim,Jonghoon Kim

doi:10.3390/molecules27010012

Abstract

A new fluorescent indolizine-based scaffold was developed using a straightforward synthetic scheme starting from a pyrrole ring. In this fluorescent system, an N,N-dimethylamino group in the aryl ring at the C-3 position of indolizine acted as an electron donor and played a crucial role in inducing a red shift in the emission wavelength based on the ICT process. Moreover, various electron-withdrawing groups, such as acetyl and aldehyde, were introduced at the C-7 position of indolizine, to tune and promote the red shift of the emission wavelength, resulting in a color range from blue to orange (462–580 nm). Furthermore, the ICT effect in indolizine fluorophores allowed the design and development of new fluorescent pH sensors of great potential in the field of fluorescence bioimaging and sensors.

Highlights

Optical fluorescence imaging for the non-invasive study of living systems has contributed to the organic fluorophore and fluorescent probe exploitation in the fields of life sciences, medicine, chemical biology, and biotechnology [1,2,3,4,5,6,7,8]
A novel 3,7-disubstituted indolizine-based fluorophore, whose emission wavelengths were tunable to cover a wide color range from blue to red-orange (462–580 nm), was designed and synthesized through a straightforward synthetic scheme starting from the pyrrole ring
Most of the functional groups introduced into the aryl ring at the C-3 position of indolizine did not induce changes in the photophysical properties, such as the absorption and emission wavelength

Summary

Introduction

Optical fluorescence imaging for the non-invasive study of living systems has contributed to the organic fluorophore and fluorescent probe exploitation in the fields of life sciences, medicine, chemical biology, and biotechnology [1,2,3,4,5,6,7,8]. Despite the notable advances in indolizine-based fluorophores, the development of a straightforward synthetic strategy for the versatile functionalization of the indolizine core, providing convenient access to new indolizine fluorophores with unique photophysical properties, is challenging. To this end, we conceived a new synthetic route to prepare 3,7-disubstitued indolizine from the pyrrole ring (Figure 1b). The introduction of a pH-sensitive functional group into this new indolizine-based fluorescent scaffold allowed the successful development of a fluorescent pH sensor

Methods

Results

Conclusion