A 1,3-Indandione-Functionalized Tetraphenylethene: Aggregation-Induced Emission, Solvatochromism, Mechanochromism, and Potential Application as a Multiresponsive Fluorescent Probe

A red-emitting cationic hyperbranched polymer: facile synthesis, aggregation-enhanced emission, large Stokes shift, polarity-insensitive fluorescence and application in cell imaging

A cationic hyperbranched polymer containing TPE units demonstrates bright and stable red-emission with AEE-characteristics and good performance in cell imaging.

High contrast stimuli-responsive luminescence switching of pyrene-1-carboxylic esters triggered by a crystal-to-crystal transition

Unexpected high contrast mechanochromic, thermochromic and vaporchromic luminescence has been achieved through a simple introduction of an ester group to a pyrene skeleton and a series of stimuli-responsive materials based on pyrene-1-carboxylic esters were efficiently developed.

Tuning the structures and photophysical properties of 9,10-distyrylanthrance (DSA) via fluorine substitution

Because of the differences in the position and degree of fluorine substitution, four fluorinated DSA derivatives, namely 4-BFSA, 3-BFSA, BDFSA and BTFSA, display different crystal packing and photophysical properties in the solid state.

A fluorescent pH probe for acidic organelles in living cells

The molecular design of pH sensor ADA is based on combining photoinduced electron transfer (PET) and intramolecular charge transfer (ICT). The fluorescent emission response against a pH value is suitable for probing acidic organelles in living cells.

An easily accessible aggregation-induced emission probe for lipid droplet-specific imaging and movement tracking

An easily accessible aggregation-induced emission (AIE) probe is developed for LD-specific imaging and dynamic movement tracking with advantages of NIR two-photon excited red emission and fast cell permeability.

E/Z isomerization effects on aggregation-enhanced emission of tetraphenylethene derivatives assisted by host–guest recognition

Pure E and Z stereoisomers of tetraphenylethene derivatives functionalized with dibenzylamine groups were isolated. Both supramolecular polymerization and photophysical changes were more significant in the case of the former than in the latter.

Organic Nanoparticles with Aggregation-Induced Emission for Bone Marrow Stromal Cell Tracking in a Rat PTI Model

Stem-cell based therapy is an emerging therapeutic approach for ischemic stroke treatment. Bone marrow stromal cells (BMSCs) are in common use as a cell source for stem cell therapy and show promising therapeutic outcomes for stroke treatment. One challenge is to develop a reliable tracking strategy to monitor the fate of BMSCs and assess their therapeutic effects in order to improve the success rate of such treatment. Herein, TPEEP, a fluorogen with aggregation-induced emission characteristics and near-infrared emission are designed and synthesized and further fabricated into organic nanoparticles (NPs). The obtained NPs show high fluorescence quantum yield, low cytotoxicity with good physical and photostability, which display excellent tracking performance of BMSCs in vitro and in vivo. Using a rat photothrombotic ischemia model as an example, the NP-labeled BMSCs are able to migrate to the stroke lesion site to yield bright red fluorescence. Immunofluorescence staining shows that the NP labeling does not affect the normal function of BMSCs, proving their good biocompatibility in vivo. These merits make TPEEP NP a potential cell tracker to evaluate the fate of BMSCs in cell therapy.

Bio-inspired sensitive and reversible mechanochromisms via strain-dependent cracks and folds

A number of marine organisms use muscle-controlled surface structures to achieve rapid changes in colour and transparency with outstanding reversibility. Inspired by these display tactics, we develop analogous deformation-controlled surface-engineering approaches via strain-dependent cracks and folds to realize the following four mechanochromic devices: (1) transparency change mechanochromism (TCM), (2) luminescent mechanochromism (LM), (3) colour alteration mechanochromism (CAM) and (4) encryption mechanochromism (EM). These devices are based on a simple bilayer system that exhibits a broad range of mechanochromic behaviours with high sensitivity and reversibility. The TCM device can reversibly switch between transparent and opaque states. The LM can emit intensive fluorescence as stretched with very high strain sensitivity. The CAM can turn fluorescence from green to yellow to orange as stretched within 20% strain. The EM device can reversibly reveal and conceal any desirable patterns.

Multiple-color aggregation-induced emission (AIE) molecules as chemodosimeters for pH sensing

A series of 4-N,N-dimethylaminoaniline salicylaldehyde Schiff-base derivatives (DAS) were facilely prepared. They exhibit typical AIE properties with various fluorescence emissions and high fluorescence quantum yields in an aggregated state. DAS exhibit unique pH-dependent optical properties, which indicated their potential applications in pH sensing.

Mechanoresponsive Luminescent Molecular Assemblies: An Emerging Class of Materials

The possibility to change the molecular assembled structures of organic and organometallic materials through mechanical stimulation is emerging as a general and powerful concept for the design of functional materials. In particular, the photophysical properties such as photoluminescence color, quantum yield, and emission lifetime of organic and organometallic fluorophores can significantly depend on the molecular packing, enabling the development of molecular materials with mechanoresponsive luminescence characteristics. Indeed, an increasing number of studies have shown in recent years that mechanical force can be utilized to change the molecular arrangement, and thereby the optical response, of luminescent molecular assemblies of π-conjugated organic or organometallic molecules. Here, the development of such mechanoresponsive luminescent (MRL) molecular assemblies consisting of organic or organometallic molecules is reviewed and emerging trends in this research field are summarized. After a brief introduction of mechanoresponsive luminescence observed in molecular assemblies, the concept of "luminescent molecular domino" is introduced, before molecular materials that show turn-on/off of photoluminescence in response to mechanical stimulation are reviewed. Mechanically stimulated multicolor changes and water-soluble MRL materials are also highlighted and approaches that combine the concept of MRL molecular assemblies with other materials types are presented in the last part of this progress report.

Preparation of organic mechanochromic fluorophores with simple structures and promising mechanochromic luminescence properties

An efficient method to design and synthesize simple organic mechanochromic molecules based on pyrene skeleton is reported. Based on this method, a broad range of phosphonium materials with promising mechanochromic luminescence have been developed.

Development of green to near-infrared turn-on fluorescent probes for the multicolour imaging of nitroxyl in living systems

The green to near-infrared turn-on fluorescent probes were developed for the multicolour imaging of nitroxyl in living systems.

Strategy to enhance solid-state fluorescence and aggregation-induced emission enhancement effect in pyrimidine boron complexes

The synthesis and the solution/solid-state fluorescence properties of pyrimidine-based monoboron complexes differing in terms of the substituents [either two fluorine atoms (BF2 complex) or two phenyl groups (BPh2 complex)] on the boron atom are reported herein. Unrestricted C-Ar intramolecular rotation in the non-, trifluoromethyl-, and cyano-substituted derivatives resulted in negligible fluorescence in solution. On the other hand, methoxy- and dimethylamino-substituted analogues caused the restriction of the C-Ar intramolecular rotation and consequently resulted in relatively strong fluorescence in solution. The non-, trifluoromethyl-, and cyano-substituted derivatives showed a pronounced aggregation-induced emission enhancement effect. Dimethylamino-substituted derivatives exhibited solvatochromism in the fluorescence spectra. Substitution with BPh2 effectively enhanced the fluorescence quantum yield compared to the corresponding BF2 complexes in the solid-state.

Facile synthesis of a class of aminochromene–aniliniumion conjugated far-red to near-infrared fluorescent dyes for bioimaging

An innovative class of aminochromene–aniliniumion conjugated far-red to near-infrared dyes, namely ACA, was developed.

A two-photon fluorescent turn-on probe for nitroxyl (HNO) and its bioimaging application in living tissues

The first two-photon fluorescent probe for specific detection of nitroxyl is designed and synthesized, and we have further demonstrated that the new two-photon fluorescent probe could be employed to image nitroxyl in living cells and tissues.

A fluorescent turn-on low dose detection of gamma-radiation based on aggregation-induced emission

A new sensitive fluorescence turn-on detection of gamma-radiation is reported by taking advantage of AIE property of the tetraphenylethylene unit and the cascade radiochemical and protonation reactions.

Amphiphilic benzothiadiazole–triphenylamine-based aggregates that emit red light in water

An amphiphilic donor–acceptor dye can provide red light emission in water in an aggregate state.

A multi-functional probe to discriminate Lys, Arg, His, Cys, Hcy and GSH from common amino acids

A smart probe to classify and differentiate basic amino acids, thiol-containing amino acids and GSH in selected environments.