Tetraphenylethene-based mononuclear aggregation-induced emission (AIE)-active mechanofluorochromism gold(I) complexes with different auxiliary ligands.

In this study, a series of tetraphenylethene-containing gold(I) complexes with different auxiliary ligands have been synthesized. These complexes were characterized using a variety of techniques including nuclear magnetic resonance spectroscopy, mass spectrometry, and single crystal X-ray diffraction. Their aggregation-induced emission (AIE) behaviors were investigated through ultraviolet/visible and photoluminescence spectrum analyses, and dynamic light scattering measurements. Meanwhile, their mechanofluorochromic properties were also studied via solid-state photoluminescence spectroscopy. Intriguingly, all these mononuclear gold(I) molecules functionalized by tetraphenylethene group demonstrated AIE phenomena. Furthermore, five gold(I) complexes possessing diverse auxiliary ligands exhibited distinct fluorescence changes in response to mechanical grinding. For luminogens 2-5, their solids showed reversible mechanofluorochromic behaviors triggered by the mutual transformation of crystalline and amorphous states, while for luminogen 1, blue-green-cyan three-color solid fluorescence conversion was realized by sequential mechanical grinding and solvent fumigation. Based on this stimuli-responsive tricolored fluorescence feature of 1, an information encryption system was successfully constructed.

Force-triggered hypso- and bathochromic bidirectional fluorescence switching beyond 120 nm and its anticounterfeiting applications.

Achieving high-contrast tricolor emissive regulation of a single-component molecule using a single type of external stimulus is highly desirable but challenging. In the present study, we report a symmetric acceptor-donor-acceptor (A-D-A)-type aggregation-induced emission-active luminogen, which displays a sequential high-contrast fluorescence switching just by anisotropic mechanical grinding. Specifically, upon light grinding, an orange-yellow-to-blue hypsochromic mechanofluorochromic response with a distinct color contrast (change in the maximum emission wavelength, Δλem,max = 122 nm) is noticed, and the slightly ground solid exhibits a blue-to-red high-contrast (Δλem,max = 185 nm) bathochromic mechanofluorochromic conversion upon vigorous grinding. Thus, using a single luminogen developed here, we can realize wide-range (Δλem,max > 100 nm) hypso- and bathochromic fluorescence mechanochromisms simultaneously. The tricolored mechanofluorochromic phenomenon is attributed to two different morphological transitions involving crystalline-to-crystalline and crystalline-to-amorphous states. Furthermore, three information anticounterfeiting systems are developed using the luminogen presented here.

Full-Color Emissive D-D-A Carbazole Luminophores: Red-to-NIR Mechano-fluorochromism, Aggregation-Induced Near-Infrared Emission, and Application in Photodynamic Therapy.

Invited for the cover of this issue are Zhao Chen at Jiangxi Science and Technology Normal University and Yue Sun at Tiangong University. For this cover picture, yellow ball containing character "D" represents donor, green ball containing character "A" represents acceptor. The image depicts eight donor-donor-acceptor-type carbazole derivatives that display full-color emission, and a luminogen that shows red to near-infrared mechano-fluorochromism and a photodynamic therapy effect. Read the full text of the article at 10.1002/chem.202203797.

Full-Color Emissive D-D-A Carbazole Luminophores: Red-to-NIR Mechano-fluorochromism, Aggregation-Induced Near-Infrared Emission, and Application in Photodynamic Therapy.

The preparation of multifunctionalized luminophores with full-color emission based on an identical core skeleton is a significative but challenging research topic. In this work, eight donor-donor-acceptor (D-D-A)-type luminogens based on a central carbazole core bearing a C6 hydrocarbon chain were designed by using different kinds of donor and acceptor units on the left and right, and synthesized in good yields. These D-D-A carbazole derivatives display deep-blue, sky-blue, cyan, green, yellow-green, yellow, orange and red fluorescence in the solid state, achieving full-color emission covering the whole visible light range under UV light illumination. Notably, the dicyano-functionalized triphenylamine-containing carbazole derivative exhibits rare aggregation-induced near-infrared emission and red-to-near-infrared mechano-fluorochromism with high contrast beyond 100 nm. Furthermore, the red-emissive luminogen can serve as a potential candidate for cell imaging and photodynamic therapy (PDT). This work not only provides reference for the construction of full-color emissive systems but also opens a new avenue to the preparation of multifunctionalized luminophores capable of simultaneous application in near-Infrared mechanical-force sensors and PDT fields.

Triphenylamine, Carbazole or Tetraphenylethylene-Functionalized Benzothiadiazole Derivatives: Aggregation-Induced Emission (AIE), Solvatochromic and Different Mechanoresponsive Fluorescence Characteristics.

The development of mechanochromic fluorophors with high-brightness, solid-state fluorescence is very significant and challenging. Herein, highly solid-state emissive triphenylamine, carbazole and tetraphenylethylene-functionalized benzothiadiazole derivatives were developed. These compounds showed remarkable aggregation-induced emission and solvatochromic fluorescence characteristics. Furthermore, these fluorogenic compounds also displayed different mechanically triggering fluorescence responses.

Highly emissive D-A-π-D type aggregation-induced emission (AIE) or aggregation-induced emission enhancement (AIEE)-active benzothiadiazole derivatives with contrasting mechanofluorochromic features.

Mechanochromic luminophors with strong solid-state emission are promising candidates for high-contrast mechanochromic luminescence materials. Meanwhile, mechanically responsive luminogenic molecules with tricolor switching are highly desirable but are seldom reported. In this work, three anthracene-based donor-acceptor-π-donor (D-A-π-D) type benzothiadiazole derivatives were designed and synthesized. These luminogens showed remarkable aggregation-induced emission (AIE) or aggregation-induced emission enhancement (AIEE) effect. Furthermore, these luminogens exhibited bright and different solid state fluorescence involving yellow-green, yellow and orange colors, and the fluorescence of their solids could be effectively regulated by mechanical grinding. For luminogen 1, its solid displayed reversible two-color mechanofluorochromic property. As for luminogens 2 and 3, their solids displayed fluorescent colors change from yellow to yellow-green upon slight grinding, and the yellow-green light-emitting solids were converted into orange fluorescent solids after heavy grinding, demonstrating interesting three-color mechanofluorochromism features.

Tetraphenylethene-Modified Colorimetric and Fluorescent Chemosensor for Hg2+ With Aggregation-Induced Emission Enhancement, Solvatochromic, and Mechanochromic Fluorescence Features.

A tetraphenylethene (TPE)-modified rhodanine derivative was successfully designed and prepared, and this luminophor showed intramolecular charge transfer nature from the TPE unit to the rhodanine-3-acetic acid unit. Interestingly, this luminogen not only exhibited typical aggregation-induced emission enhancement (AIEE) behavior but also showed good cell imaging performance. Remarkably, this AIEE-active TPE-containing rhodanine derivative possessed noticeable solvatochromic fluorescence effect involving multiple fluorescent colors of green, yellow-green, yellow, orange, and red. Meanwhile, this fluorescigenic compound displayed reversible mechanochromic fluorescence behavior based on the mutual transformation of between stable crystalline and metastable amorphous states. On the other hand, this multifunctional fluorophor could selectively and sensitively detect Hg2+ in an acetonitrile solution. Furthermore, this chemosensor could also be used to detect Hg2+ on test paper strips.

Simultaneous detection of plant growth regulators jasmonic acid and methyl jasmonate in plant samples by a monoclonal antibody-based ELISA.

Methyl jasmonate (MeJA) and its free-acid form, jasmonic acid (JA), collectively referred to as jasmonates (JAs), are natural plant growth regulators that are widely present in higher plants. Simultaneous detection of JA and MeJA in plant samples is of significance and is a great challenging issue. In this study, coupling with two extraction methods, a sensitive monoclonal antibody (mAb) based enzyme-linked immunosorbent assay (ELISA) for simultaneous detection of JA and MeJA in plant samples was developed. The JA-bovine serum albumin (BSA) conjugate was used as an immunogen for the production of mAb. As the produced mAb exhibited higher recognition ability towards MeJA than towards JA, ELISA was established using MeJA as the standard. Under optimal experimental conditions, the IC50 and LOD values of ELISA for MeJA were 2.02 ng mL-1 and 0.20 ng mL-1, respectively. In the first extraction method, MeJA in plant samples was evaporated and only JA was extracted. In the second extraction method, both JA and MeJA were extracted. After methylation, JA in the extracts was converted into MeJA, and the whole MeJA in the extracts was measured by ELISA. Plant samples including the leaves of Salvia splendens, the flowers of Salvia splendens and the fruit of grapes were collected. JA and MeJA in these samples were detected by the proposed ELISA. It was found that the concentrations of JA in these three plant samples were about 3-5 times higher than those of MeJA in those samples. ELISA was also confirmed by HPLC. There was a good correlation between ELISA and HPLC.

Aggregation-induced emission enhancement (AIEE)-active tetraphenylethene (TPE)-based chemosensor for Hg2+ with solvatochromism and cell imaging characteristics.

An aggregation-induced emission enhancement (AIEE)-active fluorescent sensor based on a tetraphenylethene (TPE) unit has been successfully designed and synthesized. Interestingly, the luminogen could detect Hg2+ with high selectivity in an acetonitrile solution without interference from other competitive metal ions, and the detection limit was 7.46 × 10-6 mol L-1. Furthermore, the luminogen also showed interesting solvatochromic behavior and superior cell imaging performance.

Ultrasensitive detection of Sudan I in food samples by a quantitative immunochromatographic assay.

An immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for ultrasensitive determination of Sudan I in food samples was reported. Gold-silver core-shell bimetallic nanorods (referred to as Au@Ag NRs) were synthesized, characterized and used as the substrate for preparation of the ICA. Polyclonal antibody against Sudan I was immobilized on the surface of the Au@Ag NRs carrying the Raman reporter 5,5'-dithiobis (2-nitrobenzoic acid). The Raman scattering intensity on the test line was used for quantitation of Sudan I. The assay was completed in 15 min. IC50 and limit of detection (LOD) were 30 pg mL-1 and 0.2 pg mL-1, respectively. There was no cross-reactivity (CR) of the assay with Sunset Yellow, Lemon Yellow and Brilliant blue FCF, but only 3.53%-9.74% CR with Sudan II, III and IV. The recoveries of Sudan I from spiked food samples were in the range of 88.9-107.6% with relative standard deviation of 3.7-8.7% (n = 3).