Rational design of pyrrole derivatives with aggregation-induced phosphorescence characteristics for time-resolved and two-photon luminescence imaging

Abstract

Pure organic room-temperature phosphorescent (RTP) materials have been suggested to be promising bioimaging materials due to their good biocompatibility and long emission lifetime. Herein, we report a class of RTP materials. These materials are developed through the simple introduction of an aromatic carbonyl to a tetraphenylpyrrole molecule and also exhibit aggregation-induced emission (AIE) properties. These molecules show non-emission in solution and purely phosphorescent emission in the aggregated state, which are desirable properties for biological imaging. Highly crystalline nanoparticles can be easily fabricated with a long emission lifetime (20 μs), which eliminate background fluorescence interference from cells and tissues. The prepared nanoparticles demonstrate two-photon absorption characteristics and can be excited by near infrared (NIR) light, making them promising materials for deep-tissue optical imaging. This integrated aggregation-induced phosphorescence (AIP) strategy diversifies the existing pool of bioimaging agents to inspire the development of bioprobes in the future.

A supramolecular photosensitizer derived from an Arene-Ru(II) complex self-assembly for NIR activated photodynamic and photothermal therapy

“…3B , the energy levels of the singlet and triplet excited states of the dimer are much denser than those of the monomer, which is beneficial for decreasing the energy gap between S 1 and T n . It has been reported that the ISC transitions could be realized within small energy gap (Δ E S1-Tn < 0.3 eV) between S 1 and T n 54 . Besides, only one orbital, either the occupied or the unoccupied, should be different in the relevant singlet and triplet states to ensure non-zero SOC integrals 55 .…”

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“…Time responsiveness is an appealing property in optics. [ 99–104 ] The emission color or intensity shows recognizable time‐dependent changes with other conditions remaining consistent. For example, phosphorescent materials always have time‐dependent emission decay after ceasing the excitation source.…”

Two‐Photon Excited Near‐Infrared Phosphorescence Based on Secondary Supramolecular Confinement

“…[9] Zhang et al reported tetraphenylpyrrole derivatives with two-photon excited phosphorescence, and nanoparticles were used for imaging. [10] Nevertheless, to the best of our knowledge, there is no report on the purely organic RTP system with both NIR emission and excitation in an aqueous environment, where it remains a formidable challenge at present.…”