Give or Take: Effects of Electron-Accepting/-Withdrawing Groups in Red-Fluorescent BODIPY Molecular Rotors.

Karolina Maleckaitė,Domantas Narkevičius,Sigitas Tumkevičius,Jelena Dodonova-Vaitkūnienė,Rugilė Žilėnaitė,Stepas Toliautas,Aurimas Vyšniauskas

doi:10.3390/molecules27010023

Karolina Maleckaitė, Domantas Narkevičius + Show 5 more

Open Access

https://doi.org/10.3390/molecules27010023

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Abstract

Mapping microviscosity, temperature, and polarity in biosystems is an important capability that can aid in disease detection. This can be achieved using fluorescent sensors based on a green-emitting BODIPY group. However, red fluorescent sensors are desired for convenient imaging of biological samples. It is known that phenyl substituents in the position of the BODIPY core can shift the fluorescence spectra to longer wavelengths. In this research, we report how electron-withdrawing (EWG) and -donating (EDG) groups can change the spectral and sensory properties of -phenyl-substituted BODIPYs. We present a trifluoromethyl-substituted (EWG) conjugate with moderate temperature sensing properties and a methoxy-substituted (EDG) molecule that could be used as a lifetime-based polarity probe. In this study, we utilise experimental results of steady-state and time-resolved fluorescence, as well as quantum chemical calculations using density functional theory (DFT). We also explain how the energy barrier height () for non-radiative relaxation affects the probe’s sensitivity to temperature and viscosity and provide appropriate ranges for the best possible sensitivity to viscosity and temperature.

Highlights

Fluorophores that are sensitive to environmental properties are very useful in biological studies and help to understand changes in the intracellular environment
We present how the addition of an electron-withdrawing group (EWG) or an electron-donating group (EDG) to β-phenyls allows the tuning of the absorption and fluorescence spectra of the fluorophores
We begin by investigating basic spectroscopic properties of the new fluorophores and compare them to those of BP-PH and BODIPY-C10

Summary

Introduction

Fluorophores that are sensitive to environmental properties are very useful in biological studies and help to understand changes in the intracellular environment. Some of the most popular microviscosity probes are based on the BODIPY group [8,23,24], such as BODIPY-C10 (Figure 1) They are generally used as fluorescence lifetime probes rather than simple fluorescence intensity probes due to the independence of lifetime on local concentration of fluorophores and the conditions of excitation and detection [25]. It has already been shown that a single BODIPY fluorophore can be partially sensitive to all three parameters: polarity, temperature, and microviscosity [29]. All this indicates that the BODIPY group is a perfect platform for the development of all mentioned types of environmental sensors

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