A nine-ring fused terrylene diimide exhibits switching between red TADF and near-IR room temperature phosphorescence

Herein, we report the first example of a terrylene diimide derivative that switches emission between thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) in the red region. By design, the molecule TDI-cDBT boasts a symmetrical, consecutively fused nine-ring motif with a kite-like structure. The rigid core formed by the annulated dibenzothiophene moiety favoured efficient intersystem crossing and yielded a narrow-band emission with a full-width half maxima (FWHM) of 0.09 eV, along with high colour purity. A small ΔE S1-T1 of 0.04 eV facilitated thermally activated delayed fluorescence, enhancing the quantum yield to 88% in the red region. Additionally, it also prefers a direct triplet emission from the aggregated state. The room temperature phosphorescence observed from the aggregates has a longer emission lifetime of 1.8 ms, which is further prolonged to 8 ms at 77 K in the NIR region. Thus, the current strategy is successful in not only reducing ΔE S1-T1 to favour TADF but also serves as a novel platform that can switch emission from TADF to RTP depending upon the concentration.

A cationic on–off fluorescent sensor with AIE properties for heparin and protamine detection

In this research, a distyryl-anthracene derivative (DSAI) with two quaternary ammonium groups was synthesized for highly sensitive detection of heparin and protamine.

A highly efficient near infrared organic solid fluorophore based on naphthothiadiazole derivatives with aggregation-induced emission enhancement for a non-doped electroluminescent device

Two regioisomers of naphthothiadiazole derivatives with aggregation-induced emission enhancement exhibited a strong solid-state fluorescence emission in the range of 666-760 nm. A non-doped EL device emitted brilliant near infrared emission peaked at 754 nm with a high maximum radiance of 22 050 mW Sr-1 m-2, an EQE as high as 1.48%, and relatively low efficiency roll-off.

A red fluorogen: AIEE characteristic, photoluminescence mechanism and its application as chemosensor for ClO. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020;228:117794. [PMID: 31757700 DOI: 10.1016/j.saa.2019.117794]

Red material is widely used in many fields because it has a lot of high performances such as strong penetrability, little trauma to cell and tissue, easy to prepare, and low background interference. However, a lot of organic materials were troubled with the aggregation caused emission quenching (ACQ) effect, which really limits their practical applications. In contrast, aggregation induced emission (AIE) and aggregation-induced enhanced emission (AIEE) effects provide an efficient method to break the obstacle of ACQ effect. Herein, a red light molecule was developed by integrating cyano and alkyl sulfide moieties. Its photoluminescence mechanism was further revealed by fluorescence spectrum, density functional theory (DFT) and X-ray single crystal diffraction, respectively. It is found that this compound has good planar construction and has no rotatory unit, it showed typical AIEE performance because of intramolecular D-π-A structure and the formation of J-aggregation. This molecular design principle may be able to offer an effective strategy to exploit red AIE/AIEE organic materials. Meanwhile, this fluorogen showed excellent response capability to ClO^- including high selectivity and sensitivity, and cell imaging performance.

Designing a near-infrared circularly polarized luminescent dye by dissymmetric spiro-fusion

A novel spiro-fused terrylene dimer (SDT) was designed and synthesized by a dissymmetric spiro-fusion strategy. The spiro-conjugation effect caused a distinct red-shift and enhancement of the absorption spectrum. Two chiral enantiomers of SDT have been absolutely resolved and identified in combination with theoretical calculations. Circularly polarized luminescence (CPL) measurement revealed its potential as a near-infrared chiral luminescent material.

Deciphering Erasing/Writing/Reading of Near-Infrared Fluorophore for Nonvolatile Optical Memory

A near-infrared fluorescence-switchable molecule, dithienylethene-terrylenediimide (TDI-4DTE) exhibits high near-infrared fluorescence and on/off ratio, decent reversibility, and fatigue resistance upon alternating UV/vis (305/621 nm) irradiation. Photoinduced electron transfer mainly contributes to the fluorescence quenching of TDI-4DTE. As an information storage unit, single molecular TDI-4DTE in the polymer film can be written by red light (621 nm) and erased by UV light (305 nm), while nondestructive fluorescence readout (750 nm) of a single molecular memory has been obtained upon excitation with near-infrared light (720 nm). The fluorescence patterning of TDI-4DTE in the polymer film demonstrates that the erasing/writing/reading wavelengths are deciphered to minimize the signal crosstalk in nonvolatile fluorescent molecular memories.

Water-soluble and highly emissive near-infrared nano-probes by co-assembly of ionic amphiphiles: towards application in cell imaging

Highly emissive near-infrared nano-emitters formed by co-assembly of ionic amphiphiles were applicable in cell imaging.

Photoswitchable Self-Assembly/Disassembly of Near-Infrared Fluorophores

A new photoswitchable near-infrared fluorophore (TDI-4DTE) with a symmetric structure exhibited reversible photo-controllable self-assembly and disassembly. The modification of π-conjugated terrylenediimide with four dithienylethene groups not only induced photoswitchable near-infrared fluorescence, but also photoregulated reversible precipitation-dissolution with microscopic and macroscopic polymorphism. Upon 302 nm UV-light irradiation, a noticeable precipitation was observed within seconds. The precipitate was gradually dissolved again in half an hour upon visible light irradiation. Different microscopic morphologies of the precipitates, including nanoparticles, nanofibrils and nanosheets, were observed when altering the intensity of the 302 nm light irradiation, indicating the dynamic control process of self-assembly. Upon UV-light irradiation, TDI-4DTE nanosheets were also obtained as a solid polymeric film, whereas well-defined nanoribbons with molecular monolayer thickness formed at the oil/water interface with slower assembly dynamics.

Tunable Aggregation-Induced Emission Nanoparticles by Varying Isolation Groups in Perylene Diimide Derivatives and Application in Three-Photon Fluorescence Bioimaging

The development of fluorogens with deep-red emission is one of the hottest topics of investigation in the field of bio/chemosensors and bioimaging. Herein, the tunable fluorescence of perylene diimide (PDI) derivatives was achieved by the incorporation of varied isolation groups linked on the PDI core. With the enlarged sizes of isolation groups, the conversion from aggregation caused quenching to aggregation-induced emission was obtained in their fluorescence variations from solutions to nanoparticles, as the result of the efficient inhibition of π-π stacking by the larger isolation groups. Accordingly, DCzPDI bearing 1,3-di(9H-carbazol-9-yl)benzene as the biggest isolation group exhibited the bright deep-red emission in the aggregated state with a quantum yield of 12.3%. Combined with the three-photon excited fluorescence microscopy (3PFM) technology, through-skull 3PFM imaging of mouse cerebral vasculature can be realized by DCzPDI nanoparticles with good biocompatibility, and the penetration depth can be as deep as 450 μm.

Geminal cross-coupling synthesis, ion-induced emission and lysosome imaging of cationic tetraarylethene oligoelectrolytes

Novel ratiometric AIE-active tetraarylethene oligoelectrolytes synthesized by geminal cross-coupling show ion-induced emission and are applied as bioprobes for lysosome tracing.

Near-Infrared Emissive Discrete Platinum(II) Metallacycles: Synthesis and Application in Ammonia Detection

Two novel discrete organoplatinum(II) metallacycles are prepared by means of coordination-driven self-assembly of a 90° organoplatinum(II) acceptor, cis-(PEt3)2Pt(OTf)2, with two donors, a pyridyl donor, 9,10-di(4-pyridylvinyl)anthracene, and one of two dicarboxylate ligands. Both metallacycles display aggregation-induced emission as well as solvatochromism. More interestingly, both metallacycles exhibit near-infrared fluorescent emission in the solid state and can be used to detect ammonia gas.

Enhancing optical anisotropy of crystals by optimizing bonding electron distribution in anionic groups

Contrivable deep-UV coherent light from an originally non-phase-matchable crystal was achieved by optimizing bonding electron distribution in anionic groups.

Polyyne bridged AIE luminogens with red emission: design, synthesis, properties and applications

Construction of a donor–acceptor (D–A) structure and extension of π-conjugation are the commonly used strategies to shift the emission of luminophores to the red region.

From ACQ to AIE: the suppression of the strong π–π interaction of naphthalene diimide derivatives through the adjustment of their flexible chains

The adjustment of flexible chains can realize the transformation from ACQ to AIE with the tunable packing modes, providing an alternative approach for the inhibition of unwanted π–π stacking.