Aggregation-Induced Emission from Fluorophore–Quencher Dyads with Long-Lived Luminescence

Biomimetic Approach toward Kinetically Stable AIE-Gens under Physiological Conditions

Many AIE-gens suffer from excessive hydrophobicity, and their kinetic stability in aqueous condition is not warranted. Here, we introduce phosphorylcholine, a zwitterionic group ubiquitously found in biological membranes, onto the tetraphenylethene core structure to yield AIE nanoparticles stable in both PBS buffer and cell culture. We also find that the AIE efficiency is critically reliant on the delicate balance between the hydrophilic phosphorylcholine and hydrophobic moieties.

Aggregation induced emission enhancement (AIEE) of tripodal pyrazole derivatives for sensing of nitroaromatics and vapor phase detection of picric acid

Organosoluble tris-pyrazole compounds aggregate in organic/aqueous solvent mixtures, showing aggregation-induced emission enhancement (AIEE), the latter being quenched by picric acid.

Highly sensitive switching of solid-state luminescence by controlling intersystem crossing

The development of intelligent materials, in particular those showing the highly sensitive mechanoresponsive luminescence (MRL), is desirable but challenging. Here we report a design strategy for constructing high performance On–Off MRL materials by introducing nitrophenyl groups to molecules with aggregation-induced emission (AIE) characteristic. The on–off methodology employed is based on the control of the intersystem crossing (ISC) process. Experimental and theoretical investigations reveal that the nitrophenyl group effectively opens the nonradiative ISC channel to impart the high sensitivity and contrast On–Off behavior. On the other hand, the twisted AIE luminogen core endows enhanced reversibility and reduces the pressure required for the luminescence switching. Thin films can be readily fabricated from the designed materials to allow versatile applications in optical information recording and haptic sensing. The proposed design strategy thus provides a big step to expand the scope of the unique On–Off MRL family.

The development of intelligent materials, in particular those showing the highly sensitive mechanoresponsive luminescence (MRL), remains challenging. Here the authors report a strategy for constructing high performance On-Off MRL materials by introducing nitrophenyl groups to molecules with aggregation-induced emission characteristic.

Waterborne polyurethanes prepared from benzophenone derivatives with delayed fluorescence and room-temperature phosphorescence

Charge-transfer states serve as a bridge between singlet and triplet states and polymerization can further promote communication between them.

Protonation-Induced Room-Temperature Phosphorescence in Fluorescent Polyurethane

Room-temperature phosphorescence (RTP) from purely organic systems is of practical importance in biological imaging, oxygen sensing and displaying technologies. The key step to obtaining RTP from organic molecules is efficient intersystem crossing (ISC), which is usually low compared to inorganic materials. Here we show that protonation of a dye molecule, a thioflavin derivative, in strongly polar polyurethane can be used to effectively harness RTP. Prior to protonation, the predominant transition is π-π* for the polymer, which has nearly undetectable RTP due to the large singlet-triplet energy splitting (0.87 eV); when Brønsted acids are gradually added to the system, increasingly strong RTP is observed due to the presence of a new intramolecular charge-transfer state (ICT). The ICT state serves to lower the singlet-triplet energy gap (0.46 eV). The smaller gap results in more efficient ISC and thus strong RTP under deoxygenated conditions. The thioflavin-polyurethane system can be tuned via proton concentration and counterions and opens new doors for RTP-based polymeric sensors and stimuli-responsive materials.

UV gelation of single-component polyacrylates bearing dinitrobenzoate side groups

Polyacrylates bearing dinitrobenzoate side groups undergo sol–gel–sol transformations in DMF or THF solutions regulated by alternating UV light and dark conditions.