High‐Order Non‐Linear Optical Effects in Organic Luminogens with Aggregation‐Induced Emission

Abstract

2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl)fumaronitrile (TTF) shows unique aggregation-induced emission (AIE) characteristics. Under the excitation of a 1560 nm femtosecond laser, simultaneous three-photon-excited luminescence (3PL) and third-harmonic-generation signals can be observed from its nanoaggregate and the solid state. TTF is further encapsulated with DSPE-mPEG (a type of amphiphilic polymer) to form AIE-active nanoparticles. 3PL brain imaging of mice is achieved based on the nanoparticles.

Biocompatible Green and Red Fluorescent Organic Dots with Remarkably Large Two-Photon Action Cross Sections for Targeted Cellular Imaging and Real-Time Intravital Blood Vascular Visualization

“…The values of δ and Φδ are much higher than the widely used commercial dyes, such as Evans Blue and other nanoparticles in the literatures. 26,28,38,[45][46][47] These results indicate that PIPBT-TPE dots and PITBT-TPE dots are promising luminescent reagents for TPA imaging.…”

Functionalized AIE nanoparticles with efficient deep-red emission, mitochondrial specificity, cancer cell selectivity and multiphoton susceptibility

“…55 A series of non-linear optical characterization experiments were performed to see if the TPE-TETRAD NPs possess similar characteristics.…”

“…7E. 55 We propose that THG photons are directly generated under femtosecond excitation and may be reabsorbed by the TPE-TETRAD molecules in NPs to produce fluorescence in a process known as THG-induced fluorescence. This may be a more efficient pathway to achieve 3PL signals, since direct 3PL is a fifth-order non-linear optical process, while 3PL induced by one-photon excitation of THG is a linear absorption based on a third-order NLO process.…”

“…53 A recent study reported AIE molecules which exhibited two-, three- and even four-photon excited fluorescence (2PL/3PL/4PL) and other unique non-linear optical properties. 54,55 TPE-TETRAD is also expected to show similar 2PL/3PL properties because of its large π-electron delocalization and D–A structure. As there are relatively few reports of AIE NPs that combine the unique advantages of deep-red emission, mitochondrial specificity, high photostability, cancer cell identification and multiphoton imaging, we hope that our attempt to successfully demonstrate these will inspire more exciting research into this emerging interdisciplinary field of AIE-based bioimaging and diagnostics.…”

Organic Dots Based on AIEgens for Two‐Photon Fluorescence Bioimaging

“…In addition to great potential in two‐photon fluorescence bioimaging of TPETPAFN dots, Qian et al further found that these dots possess excellent three‐photon and even four‐photon absorption and fluorescence properties, owing to the extend π‐conjugation and electron‐donor and acceptor interaction in TPETPAFN molecule . The three‐photon fluorescence as well as third harmonic generation (THG) of TPETPAFN are enhanced as the aggregates form, under fs laser excitation at 1560 nm.…”