Quinoline-Derived Two-Photon-Sensitive Octupolar Probes.

Petra Dunkel,Morgane Petit,Peter I Dalko,Hamid Dhimane,Mireille Blanchard‐Desce,David Ogden

doi:10.1002/open.201700097

Abstract

A systematic study on quinoline‐derived light sensitive probes, having third‐order rotational symmetry is presented. The electronically linked octupolar structures show considerably improved linear and nonlinear photophysical properties under one‐ and two‐photon irradiation conditions compared to the corresponding monomers. Photolysis of the three acetate derivatives shows strong structure dependency: whereas irradiation of the 6‐ and 7‐aminoquinoline derivatives resulted in fast intramolecular cyclization and only trace amounts of fragmentation products, the 8‐aminoquinoline derivative afforded clean and selective photolysis, with a sequential release of their acetate groups (δ u [730]=0.67 GM).

Highlights

The combined use of two-photon (TP)-sensitive probes with highenergy pulsed laser-light excitation enables higher spatiotemporal resolution at greater depth within biological tissues than conventional one-photon excitation.[1,2] This is a significant improvement that enables optical imaging and photoactivation at depth in tissues in vivo or in vitro
In the context of caged compounds, many TP chromophores have been developed, none satisfy the stringent conditions of TP activation of high water solubility and low pharmacological interference in the target tissues.[1r,5] We showed recently a simple algorithm to improve probe design rationally by 1) the optimization of the substitution pattern of the dipole; 2) the increase of the conjugation length, and 3) the incorporation of allowed symmetry elements in the chromophore, allowing access to improved nonlinear properties
We investigated the incorporation of thirdorder rotational symmetry that might further improve absorption parameters by resonance, enhancing the corresponding transition dipole moments and the magnitude of TP absorption and uncaging cross sections (s2 and du, respectively)

Summary

Introduction

The combined use of two-photon (TP)-sensitive probes (switches, actuators and “caged” compounds) with highenergy pulsed laser-light excitation enables higher spatiotemporal resolution at greater depth within biological tissues than conventional one-photon excitation.[1,2] This is a significant improvement that enables optical imaging and photoactivation at depth in tissues in vivo or in vitro. This field of interest spans from cell biology to targeted therapeutic applications.[3] The availability of tunable ultrashort-pulse lasers at near-IR wavelengths and progress in our understanding of TP chromophore design[4] have contributed to a rapid emergence of TP techniques in biological applications. Blanchard-Desce UniversitØ de Bordeaux, ISM (CNRS UMR5255) Bâtiment A12, 351, Cours de la LibØration, 33405 Talence Cedex (France)

Methods

Results

Conclusion