Rhodamine‐Sensitized Two‐Photon Activation of a Red Light‐Absorbing BODIPY Photocage

Abstract

AbstractTwo‐photon (2P) activatable probes are of high value in biological and medical chemistry since near infrared (NIR) light can penetrate deeply even in blood‐perfused tissue and due to the intrinsic three‐dimensional activation properties. Designing two‐photon chromophores is challenging. However, the two‐photon absorption qualities of a photocage can be improved with an intramolecular sensitizer, which transfers the absorbed light onto the cage. We herein present the synthesis and photophysical characterization of a 2P‐sensitive uncaging dyad based on rhodamine 101 as donor fluorophore and a redshifted BODIPY as acceptor photocage. Liberation of p‐nitroaniline (PNA) upon one‐photon photolysis was confirmed by HPLC analysis. The photoreaction was found to be accompanied by a considerable change of the fluorescence properties of the chromophores. The possibility of a fluorescent read‐out enabled the detection of two‐photon induced uncaging by confocal fluorescence microscopy.