Biocompatible Two‐Photon Absorbing Dipyridyldiketopyrrolopyrroles for Metal‐Ion‐Mediated Self‐Assembly Modulation and Fluorescence Imaging

Abstract

Diketopyrrolopyrrole (DPP) derivatives are very promising nonlinear optical dyes with excellent thermal resistance and light stability. However, to the best of our knowledge, the fabrication of their organic micro‐ and/or nanostructures through covalent and/or noncovalent interactions to further adjust their corresponding two‐photon absorption (TPA) is rarely reported. In this work, based on previous synthesis method of pyridine‐containing ketopyrrolopyrroles, three dipyridyldiketopyrrolopyrroles (dipyridylDPPs) 1 , 2, and 3 containing 2‐, 3‐, and 4‐pyridyl substituents, respectively, have been prepared, which exhibit strong orange fluorescence and large TPA action cross‐sections in both organic (tetrahydrofuran) and aqueous media. Importantly, fluorescent organic nanoparticles (FONs) of the di(2‐pyridyl)DPP 1 prepared by the reprecipitation method displays strong two‐photon emission. Meanwhile, the FONs of 1 not only exhibit Ag + ions mediated self‐assembly modulation, but also display low cytotoxicity and allow two‐photon bioimaging in HeLa cells.