Executive Summary : | Advancements in fluorescence imaging technologies have led to the development of specialized organic fluorophores that can capture biological information at the single-molecule level. This is crucial for producing smart fluorophores with superior output. Environmentally sensitive fluorescent probes are essential for studying biological systems with high spatio-temporal resolution and cellular specificity. Fluorescence properties, such as fluorescence intensities, energies, and lifetime, are sensitive to environmental changes, allowing for the capture of information about a biological system. Fluorescent probes that emit through twisted intramolecular charge transfer mechanisms are known for their sensitiveness in studying viscosity, polarity, and temperature changes in living cells.
However, traditional biocompatible fluorophores, such as fluorescein- and rhodamine-class dyes, have low environmental sensitivities due to inefficient charge transfer. To improve these sensitivities, researchers aim to tune their excited state properties, such as the excited state (anti)aromaticity character, which is powerful in understanding photophysical and photochemical processes. They hypothesize that push-pull organic fluorophores form twisted intramolecular charge transfer states undergoing a change of excited state (anti)aromaticity. Quantum chemical calculations and fluorescence spectroscopic experiments will be integrated to establish a correlation between excited state (anti)aromaticity and intramolecular charge transfer. These frameworks will guide the design of efficient charge transfer probes and open new research opportunities for enlightening various photophysical phenomena for targeted applications. |