A General Strategy to Enhance Donor‐Acceptor Molecules Using Solvent‐Excluding Substituents

Abstract

While organic donor‐acceptor (D‐A) molecules are widely employed in multiple areas, the application of more D‐A molecules could be limited because of an inherent polarity sensitivity that inhibits photochemical processes. Presented here is a facile chemical modification to attenuate solvent‐dependent mechanisms of excited‐state quenching through addition of a β‐carbonyl‐based polar substituent. The results reveal a mechanism wherein the β‐carbonyl substituent creates a structural buffer between the donor and the surrounding solvent. Through computational and experimental analyses, it is demonstrated that the β‐carbonyl simultaneously attenuates two distinct solvent‐dependent quenching mechanisms. Using the β‐carbonyl substituent, improvements in the photophysical properties of commonly used D‐A fluorophores and their enhanced performance in biological imaging are shown.

Small Molecular Fluorescent Probes for Imaging of Viscosity in Living Biosystems

“…One of the current challenges is how to rationally control the viscosity sensitivity of molecular rotor‐based probes. In this aspect, the Zhang group [108, 109] has presented excellent work by exploring the influence of π‐rich alternating carbon–carbon linkages or substituents on molecular rotor‐based fluorophores. It has been revealed that the length of the linkage strongly affects the viscosity sensitivity, likely resulting from the varying height of the energy barriers between the fluorescent planar and the dark twisted configurations.…”

A General Method to Develop Highly Environmentally Sensitive Fluorescent Probes and AIEgens

“…Many existing TICT‐based fluorescent probes are push‐pull dyes employing dialkylated amino groups as the electron‐donating group (EDG). [ 15 , 16 , 17 , 18 , 19 , 20 ] Upon photoexcitation, the amino group could experience an intramolecular rotation of ≈90° with respect to the fluorophore scaffold, resulting in a perpendicular alignment in the excited state. [ 7 , 8 ] This rotation is accompanied by a complete charge separation between the EDG and the fluorophore scaffold.…”

Photophysical properties and fluorosolvatochromism of D–π–A thiophene based derivatives

“…Due to the important applications of D-p-A type of molecules, most attention has been given to emissive conjugated systems other than thiophene-based systems mainly because of their lower emission quantum yields, short excitedstate lifetimes, and an inherent polarity sensitivity that leads to rapid nonradiative decay. 47 Studied compounds showed relatively high quantum yields even in strong polar solvents.…”