Single‐Benzene Dual‐Emitters Harness Excited‐State Antiaromaticity for White Light Generation and Fluorescence Imaging

Abstract

Molecular emitters simultaneously generating light at different wavelengths have wide applications. With a small molecule, however, it is challenging to realize two independent radiative pathways. We invented the first examples of dual-emissive singlebenzene fluorophores (SBFs). Two emissive tautomers are generated by synthetic modulation of the hydrogen bond acidity, which opens up pathways for excited-state proton transfer. White light is produced by a delicate balance between the energy and intensity of the emission from each tautomer. We show that the excitedstate antiaromaticity of the benzene core itself dictates the proton movements driving the tautomer equilibrium. Using this simple benzene platform, a fluorinated SBF was synthesized with a record high solubility in perfluorocarbon solvents. White light-emitting devices and multicolor imaging of perfluorocarbon nanodroplets in live cells demonstrate the practical utility of these molecules.

Analysis of Fluorescent Proteins for Observing Single Gene Locus in a Live and Fixed Escherichia coli Cell

“…Advancements in this field have led to the development of FPs with enhanced brightness, photostability, chemical stability, and photoconversion properties, expanding their utility in different biological contexts. − Consequently, to ensure proper use of FPs, various properties of FPs, such as the excitation/emission spectrum, brightness, photostability, cytotoxicity, and monomeric property, have been typically evaluated in vitro or in bulk using live cells. − However, the behavior of FPs could change when conjugated to other proteins, potentially altering their original properties. ,, Moreover, the performance of FPs can vary according to the cellular environment in which they are expressed, adding another layer of complexity to their application in live-cell imaging . With the advent of advanced fluorescence microscopy techniques, such as super-resolution, single-protein imaging, and single-molecule fluorescence resonance energy transfer, evaluating FPs under conditions that closely mimic their actual usage has become crucial. − …”