Tuning Directed Photooxidation-Induced Conversion of Pyrrole-Based Styryl Coumarin Dual-Color Photoconverters.

Invited for the cover of this issue is the group of Mayeul Collot at the University of Strasbourg (CNRS). The image depicts the effect of simple chemical tuning on coumarin dyes to tune and improve the DPIC photoconversion mechanism. Read the full text of the article at 10.1002/chem.202203933.

Tuning Directed Photooxidation-Induced Conversion of Pyrrole-Based Styryl Coumarin Dual-Color Photoconverters.

Dual-emissive photoconvertible fluorophores (DPCFs) are powerful tools to unambiguously track labeled cells in bioimaging. We recently introduced a new rational mechanism called directed photooxidation-induced conversion (DPIC) enabling efficient DPCFs to be obtained by conjugating a coumarin to aromatic singlet-oxygen reactive moieties (ASORMs). Pyrrole was found to be a suitable ASORM as it provided a high hypsochromic shift along with a fast and efficient conversion. By synthesizing various pyrrole-based styryl coumarin dyes, we showed that the photoconversion properties, including the quantum yield of photoconversion and the chemical yield of conversion can be tuned by chemical modification of the pyrrole. These modifications led to an improved dual emissive converter, SCP-Boc, which displayed a high brightness and an enhanced photoconversion yield of 63 %. SCP-Boc was successfully used to sequentially photoconvert cells by laser scanning confocal microscopy.

Dual-Color Photoconvertible Fluorescent Probes Based on Directed Photooxidation Induced Conversion for Bioimaging.

We herein present a new concept to produce dual-color photoconvertible probes based on a mechanism called Directed Photooxidation Induced Conversion (DPIC). As a support of this mechanism, styryl-coumarins (SCs) bearing Aromatic Singlet Oxygen Reactive Moieties (ASORMs) like furan and pyrrole have been synthesized. SCs are bright fluorophores, which undergo a hypsochromic conversion upon visible light irradiation due to directed photooxidation of the ASORM that leads to the disruption of conjugation. SC-P, a yellow emitting probe bearing a pyrrole moiety, converts to a stable blue emitting coumarin with a 68 nm shift allowing the photoconversion and tracking of lipid droplet in live cells. This new approach might pave the way to a new generation of photoconvertible dyes for advanced bioimaging applications.