Strong Fluorescence Emission Research Articles

Synthesis, structural characterization, DNA binding ability and luminescent sensing of nitroaromatics by a mononuclear zinc(II) carboxylate complex

A mononuclear zinc(II) carboxylate complex containing 4-hydroxybenzoic acid and N-donor 2-aminopyridine was synthesized in aqueous methanol and comprehensively characterized by elemental, spectroscopic, and single-crystal X-ray diffraction analyses. The complex crystallized in monoclinic space group P21/c having a distorted square pyramidal structure. Spectral and X-ray diffraction analyses confirm the molecular composition of the complex. The complex has shown strong fluorescence emission, acts as a selective and sensitive chemosensor for nitroaromatics. The complex is able to selectively detect picric acid in the presence of other nitroaromatics. Density Functional Theory (DFT) calculations further elucidate the complex’s preferential binding towards nitroaromatics, revealing the involvement of π-stacking and spodium bonding interactions. This work not only expands the understanding of zinc(II) carboxylate complexes in supramolecular chemistry but also highlights their promising applications in environmental monitoring and biological studies due to their significant fluorescence quenching in the presence of nitroaromatics and moderate DNA binding affinity.

A ratiometric fluorescence and colorimetry dual-signal sensing strategy based on o-phenylenediamine and AuNCs for determination of Cu2+ and glyphosate.

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570nm. Meanwhile, the fluorescence intensity at the wavelength of 682nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0-10 µM and 0.050-3.0µg/mL with a detection limit of 0.547 µM and 0.0028µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0-10 µM and 0.30-3.0µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields.

Non-invasive stratigraphic analyzes of gelatine-based modern painting materials with linear and nonlinear optical methods

Stratigraphic analyzes of polychrome surfaces, such as paintings, often need samples to offer consistent results regarding the sequence and composition of the layers. Non-invasive methodologies based on linear and nonlinear optical techniques limit material removal from the objects. Recently, optical coherence tomography (OCT) has become the preferred choice of heritage scientists because it is a safe and fast alternative for studying transparent or semi-transparent layers. Yet, nonlinear optical microscopy (NLOM)) technique in its modality of multiphoton excitation fluorescence (MPEF) has emerged as a promising tool for the same purpose. Here, we explored linear (OCT and confocal Raman microspectroscopy (CRM)) and nonlinear (NLOM-MPEF) optical methods’ capability to investigate gelatine-based layers in mock-up samples and a painting dated 1939 by an artist from the Surrealistic entourage. The optical behavior of mock-up samples that imitate the painting stratigraphy and of six painting fragments detached from the support was also investigated with fiber optics reflectance spectroscopy and laser induced fluorescence (LIF). Thickness values from the mock-ups obtained with OCT, CRM, and MPEF have provided evidence of the complementarity, from a millimetric to a micrometric scale, and the limitations (e.g. strong fluorescence emission in CRM) of the methods. Moreover, the presence of gelatine was ascertained by LIF spectroscopy applied to the painting fragments and NLOM-MPEF confirmed its suitability as a non-invasive technique for investigating gelatine-based stratigraphic systems.

A Highly Stable Multifunctional Bi-Based MOF for Rapid Visual Detection of S2- and H2S Gas with High Proton Conductivity.

Metal organic frameworks (MOFs) constructed with bismuth metal have not been widely reported, especially multifunctional Bi-MOFs. Therefore, developing multifunctional MOFs is of great significance due to the increasing requirements of materials. In this work, a 3D Bi-MOF (Bi-TCPE) with multifunctionality was successfully constructed, demonstrating high thermal stability, water stability, a porous structure, and strong blue fluorescence emission. We evaluated the properties of Bi-TCPE in detecting anions (S2-, Cr2O72-, and CrO42-) in aqueous solution, along with the rapid visual detection of H2S gas and proton conduction. In terms of anion detection, Bi-TCPE achieved the rapid detection of trace S2- in aqueous solutions, while the Ksv value was 1.224 × 104 M-1 with a limit of detection (LOD) value of 1.93 μM through titration experiments. Furthermore, Bi-TCPE could sensitively detect Cr2O72- and CrO42-, with Ksv values of 1.144 × 104 and 1.066 × 104 M-1, respectively, while LOD reached 2.07 and 2.18 μM. Subsequently, we conducted H2S gas detection experiments, and the results indicated that Bi-TCPE could selectively detect H2S gas at extremely low concentrations (2.08 ppm) and with a fast response time (<10 s). We also observed significant color changes under both UV light and sunlight. Therefore, we developed a H2S detection test paper for the rapid visual detection of H2S gas. Finally, we evaluated the proton conductivity of Bi-TCPE, and the experimental results showed that the proton conductivity of Bi-TCPE reached 4.77 × 10-2 S·cm-1 at 98% RH and 90 °C, achieving an excellent value for unmodified and encapsulated MOFs. In addition, Bi-TCPE showed high stability in proton conduction experiments (it remained stable after 21 consecutive days of testing and 12 cycles of testing), demonstrating relatively high application value. These results indicate that Bi-TCPE is a multifunctional MOF material with great application potential.

Electrofluorochromic Hydrogels by Oligothiophene-Based Color-Tunable Fluorescent Dye Doping.

Soft electronic materials hold great promise for advancing flexible functional devices. Among the various soft materials available, hydrogels are particularly attractive for soft electronic device development due to their inherent properties, including transparency, shape adaptability through swelling/deswelling, and self-healing capabilities. Transparent hydrogels contribute to the creation of advanced smart devices such as sensors, smart windows, and anticounterfeiting technologies. Poly(vinyl alcohol) hydrogels are used as a platform for creating electrofluorochromic (EFC) devices in combination with oligothiophene-conjugated benzothiazole derivatives (OCBs) as fluorescent emitters. OCBs demonstrated excited-state intramolecular proton transfer (ESIPT) behavior with a large Stokes shift and emission changes responsive to solvent polarity and pH stimuli. Even in the solid state, OCBs exhibited strong fluorescence emission across a wide range of colors from blue to red, making them exceptionally well-suited for EFC device development. Their quantum yields in the powder state were obtained between 2.3% and 19.9%. Through the incorporation of OCBs into a PVA hydrogel (OCB@PVA), we achieved the successful fabrication of flexible EFC devices, including electronic paper and smart panels. When electric potentials (-2.4 and +2.4 V) were applied in OCB@PVA, fluorescence color changes were observed by an electrochemically induced pH change owing to electrohydrolysis of water. These devices demonstrated the potential of OCB@PVA hydrogels in the realm of flexible electronics. They could be used to create innovative and versatile devices with stimuli-responsive fluorescence properties.

Green synthesis of carbon dots from mangosteen peel for fluorescent cancer cells

Recently, carbon dots (CDs) have received significant attention owing to their outstanding optical properties, good solubility, and low toxicity. In this research, CDs were synthesized by a hydrothermal method based on an environmentally friendly and straightforward strategy, using only mangosteen peel and deionized water. The synthesized CDs had an average size of 3.09 ± 0.38 nm. The absorbance spectrum peak for the CDs was seen at 282 nm, and the central wavelength of fluorescence emission was observed at 433 nm under an excitation wavelength of 355 nm. An aqueous solution of CDs exhibited bright green fluorescence when observed with the naked eye under UV irradiation. Both Fourier transform infrared and X-ray photoelectron spectroscope measurements were taken to determine the elemental compositions of the organic substance functional groups on the surface of the CD, such as hydroxyl, carboxyl, and carbonyl groups. These functional groups originate the different emission centers leading to multicolor fluorescent emissions. Furthermore, the synthesized CDs were found to have good biocompatibility with organic and biological materials. The remarkable properties of CDs, including their nanoscale dimensions, strong multicolor fluorescent emissions, non-toxicity, and excellent cell compatibility, could effectively permeate the cell membrane, cytoplasm, and nucleus and provide fluorescence emission. This suggests a significant potential for CDs in fluorescent cell staining applications. Finally, the CDs were used as a fluorescent dye for human colon cancer cells, as they exhibited excellent fluorescence for cell staining.

Construction of the Red‐Green‐Blue Luminescence Conversion System Based on Donor‐Acceptor Dyes Exchange with Diels‐Alder Dynamic Covalent Bonds

AbstractThe construction of full‐color fluorescence systems has received widespread attention because of their applications in lighting materials, optoelectronic materials, and fluorescent probes. However, for the full‐color luminescence system based on trichromatic materials, there are no connections between materials of different luminescent colors. Herein, A new donor‐acceptor dye with red fluorescence was synthesized. The dye displays excellent optical properties of short half‐peak width and strong fluorescence emission. An effective energy transfer process from the dansyl donor to the acceptor was observed with a transfer efficiency of 81 %. Further, dyes with green and blue fluorescence were introduced to construct a full‐spectrum fluorescent system. Through exchange reactions of Diels‐Alder dynamic covalent bonds, red, green, and blue luminescence can be converted. This work provides a new idea for the design of full‐color fluorescent materials.

A structure-guided strategy to design Golgi apparatus-targeted type-I/II aggregation-induced emission photosensitizers for efficient photodynamic therapy

The Golgi apparatus (GA) is a vital target for anticancer therapy due to its sensitivity against reactive oxygen species (ROS)-induced oxidative stress that could lead to cell death. In this study, we designed a series of aggregation-induced emission (AIE)-based photosensitizers (TPAPyTZ, TPAPyTC, TPAPyTM, and TPAPyTI) carrying different ROS with selective GA-targeted ability. The in vitro study showed that TPAPyTZ and TPAPyTC displayed strong AIE characteristics, robust type-I/II ROS production capabilities, specific GA-targeted, high photostability, and high imaging quality. The cell-uptake of TPAPyTZ was found primarily through an energy-dependent caveolae/raft-mediated endocytosis pathway. Remarkably, TPAPyTZ induced GA-oxidative stress, leading to GA fragmentation, downregulation of GM130 expression, and activation of mitochondria caspase-related apoptosis during photodynamic therapy (PDT). In vivo experiments revealed that TPAPyTZ significantly inhibited tumor proliferation under lower-intensity white light irradiation with minimal side effects. Overall, our work presents a promising strategy for designing AIEgens for fluorescence imaging-guided PDT. Additionally, it enriched the collection of GA-targeted leads for the development of cancer theranostics capable of visualizing dynamic changes in the GA during cancer cell apoptosis, which could potentially enable early diagnosis applications in the future. Statement of significanceAIE luminogens (AIEgens) are potent phototheranostic agents that can exhibit strong fluorescence emission and enhance ROS production in the aggregate states. In this study, through the precise design of photosensitizers with four different electron-acceptors, we constructed a series of potent AIEgens (TPAPyTZ, TPAPyTC, TPAPyTM, and TPAPyTI) with strong fluorescence intensity and ROS generation capacity. Among them, TPAPyTZ with an extended π-conjugation displayed the strongest ROS generation ability and anti-tumor activity, resulting in an 88 % reduction in tumor weight. Our studies revealed that the enhanced activity of TPAPyTZ may be due to its unique Golgi apparatus (GA)-targeted ability, which causes GA oxidative stress followed by effective cancer cell apoptosis. This unique GA-targeted feature of TPAPyTZ remains rare in the reported AIEgens, which mainly target organelles such as lysosome, mitochondria, and cell membrane. The successful design of a GA-targeted and potent AIEgen could enrich the collection of GA-targeted luminogens, providing a lead theranostic for the further development of fluorescence imaging-guided PDT, and serving as a tool to explore the potential mechanism and discover new GA-specific drug targets.

A mitochondrion-targeted cyanine agent for NIR-II fluorescence-guided surgery combined with intraoperative photothermal therapy to reduce prostate cancer recurrence

Poorly identified tumor boundaries and nontargeted therapies lead to the high recurrence rates and poor quality of life of prostate cancer patients. Near-infrared-II (NIR-II) fluorescence imaging provides certain advantages, including high resolution and the sensitive detection of tumor boundaries. Herein, a cyanine agent (CY7-4) with significantly greater tumor affinity and blood circulation time than indocyanine green was screened. By binding albumin, the absorbance of CY7-4 in an aqueous solution showed no effects from aggregation, with a peak absorbance at 830 nm and a strong fluorescence emission tail beyond 1000 nm. Due to its extended circulation time (half-life of 2.5 h) and high affinity for tumor cells, this fluorophore was used for primary and metastatic tumor diagnosis and continuous monitoring. Moreover, a high tumor signal-to-noise ratio (up to ~ 10) and excellent preferential mitochondrial accumulation ensured the efficacy of this molecule for photothermal therapy. Therefore, we integrated NIR-II fluorescence-guided surgery and intraoperative photothermal therapy to overcome the shortcomings of a single treatment modality. A significant reduction in recurrence and an improved survival rate were observed, indicating that the concept of intraoperative combination therapy has potential for the precise clinical treatment of prostate cancer.Graphical

Nitrogen-doped carbon dots for 3D printed smartphone-assisted cascade visual detection of morin and aluminium ion, solid fluorescence ink

With the growing emphasis on health management, individuals increasingly focus on monitoring drug molecular residues and harmful ions. Motivated by the concepts of the intelligent system and quantitative detection, we develop a smartphone-assisted cascade visual sensing device based on nitrogen-doped carbon dots (N-CDs) for in-site quantitative detection of morin and aluminium ion (Al3+). Initially, citric acid and o-phenylenediamine are identified as precursors for N-CDs synthesis via the microwave-assisted hydrothermal treatment. Subsequently, systematic studies reveal that the fluorescence of N-CDs is quenched upon the introduction of morin because of the inner filter effect (IFE). Conversely, the fluorescence recovery phenomenon occurs after the cascade addition of Al3+ since the morin binds with Al3+, resulting in the inhibition of IFE. Simultaneously, the fluorescence recovery of N-CDs enhances the cyan fluorescence emission of morin/Al3+. Based on the fluorescence quenching and recovery behavior, morin and Al3+ can be detected in the ranges of 0.070–50 μM and 0.124–40 μM with low detection limits of 0.070 μM and 0.124 μM, respectively. Furtherly, a smartphone-assisted cascade visual sensing device is designed for in-site quantitative detection of morin and Al3+. Moreover, based on the strong fluorescence and concentration-dependent emission behavior of N-CDs, the multi-color fluorescent ink is developed successfully. This work not only offers an excellent solution for simultaneous detection of morin and Al3+ but also shows numerous opportunities for solid lighting, information encryption and flexible optics.

Fluorometric Determination of Fe3+ Ions using Carbon Dots Prepared from the Extract of Singapore Cherry

Background: The development of affordable and ecologically acceptable technologies for heavy metal detection and removal is required due to the rising levels of water and soil pollution. Carbon Dots (CDs) have emerged as a promising nanomaterial for heavy metal detection due to their unique properties. In this study, we report a simple and eco-friendly method to produce CDs using Muntingia calabura fruit extract as a precursor. Methods: The hydrothermal method produced a well-defined size, structure, and optical properties of CDs, which were analyzed by using various characterization techniques, including Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), Elemental mapping (E-map), UV-visible spectroscopy, X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Photoluminescence (PL) spectroscopy, and Transmission Electron Microscopy (TEM). Additionally, Zeta potential and DLS analysis were used to characterize the CDs. Results: As-synthesized CDs exhibited strong fluorescence emission, making them suitable for the selective determination of Fe3+ ions. The detection limit was found to be 3.6 μM for Fe3+ ions, which highlighted the potential application of as-prepared CDs in environmental monitoring. Conclusion: The green synthesized CDs from Muntingia calabura fruit extract provided a sustainable approach for developing efficient nanoprobes for detecting Fe3+ ions in environmental and biological samples.

A new hydroxyl group functionalized Zn-MOF as an efficient fluorescent probe for sulfasalazine residue detection in water, milk and soil

Sulfasalazine (SSZ) is a typical sulfonamide antibiotic. The extensive use of SSZ in animal husbandry and agriculture has lead to antibiotic residue in the environment, which ultimately harm human health. The pursuit of simple and efficient methods for the detection of SSZ is highly desirable, yet it remains a challenging task. Herein, a new hydroxyl group functionalized Zn-MOF probe (MOF-1) was revealed for the highly selective and sensitive sensing of SSZ. MOF-1 was constructed with Zn(NO3)2·6H2O, 3,3′-dihydroxy-4,4′-biphenyl dicarboxylic acid (DDA) and 1, 2, 4, 5-tetra(4-pyridyl)benzene (TPB) by using the solvothermal method. Strong fluorescent emission centered at 460 nm was observed for MOF-1 which could be quenched by SSZ. Selectivity experiments indicate that MOF-1 is highly selective response to SSZ among 18 antibiotics. Fluorescence titration experiments suggest that MOF-1 is highly sensitive to SSZ with a detection limitation of 31 nM. Based on the impressive characteristics of MOF-1 such as fast response and good reusability, portable test strips were prepared and used as naked eye kits for real-time SSZ detection. Moreover, the sensing mechanism was proposed based on the experimental and theoretical calculation results.

Quinoline-based hydrophilic flavonol fluorescent probe for specific and sensitive detection of Zn2+

It is important to develop fluorescent sensors for the detection and quantification of Zn2+ ions related to life health issues and other problems. The 3-hydroxyflavone derivatives has excellent photophysical properties and stable ability to coordinate with metal ions. In this study, a new fluorescent probe (HQC) toward to the detection of Zn2+ based on 3-hydroxylflavone and 8-hydroxyquinoline was designed and synthesized. In ethanol–water (1:9, v/v) solution, the probe HQC displays highly selective response to Zn2+ with remarkable emission enhancement through its binding of Zn2+. The sensing of Zn2+ was nearly free from interference of other relevant metal ions. The proposed binding modes are also proved by density functional theory (DFT) calculations, IR and HRMS analysis. The detection limit for Zn2+ is calculated to be 4.99 μM. Furthermore, the probe HQC displays good biological compatibility and was employed to detect Zn2+ in zebrafish. The strong fluorescence emission could be observed in the presence of Zn2+ in living cells. These results indicate that the probe HQC possesses good potential application values in the detection of Zn2+ in environmental and biological systems.

Ultrabright quantum dots assisted in vivo NIR-II fluorescence microscopic imaging for brain metastases in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive and often fatal disease, especially since the brain metastasis of TNBC has been a particularly severe manifestation. However, brain metastasis in TNBC at early stages often lacks noticeable symptoms, making it challenging to detect. Near-infrared II (NIR-II) fluorescence microscopic imaging obtains long wavelength, which enables reduced scattering, high spatial resolution and minimal autofluorescence, it is also a favorable imaging method for tumor diagnosis. PbS@CdS quantum dots (QDs) are one of the popular NIR-II fluorescence nanoprobes for well brightness. In this study, NIR-II emissive PbS@CdS QDs were utilized and further encapsulated with thiol-terminated poly(ethylene oxide) (SH-PEG, MW = 5000) to form PbS@CdS@PEG QDs nanoparticles (NPs). The obtained PbS@CdS@PEG QDs NPs were then characterized and further studied in detail. The PbS@CdS@PEG QDs NPs had large absorption spectra, exhibited strong NIR-II fluorescence emission at approximately 1300[Formula: see text]nm, and possessed good NIR-II fluorescence properties. Then, the mice model of early-stage brain metastases of TNBC was established, and the PbS@CdS@PEG QDs NPs were injected into the tumor-bearing mice for NIR-II fluorescence microscopic bioimaging. The brain vessels and tumors of the living mice were detected with high spatial resolution under the NIR-II fluorescence microscopic imaging system with irradiation of 808[Formula: see text]nm laser. The tumor tissues were further restricted and prepared as thin slices. The NIR-II fluorescence signals were collected from the tumor slices with high spatial resolution and signal-to-background ratio (SBR). Thus, the PbS@CdS@PEG QDs NPs-assisted NIR-II fluorescence microscopic system can effectively achieve targeting brain metastases of TNBC imaging, offering a novel and promising approach for TNBC-specific diagnosis.

Green Synthesis of Baby Pumpkin Derived Fluorescent Carbon Dots – A Potent Label‐Free Probe for Cd2+ Determination

AbstractThis study demonstrates a facile solvothermal approach to synthesizing green fluorescent carbon dots (G‐CDs) using baby pumpkin as a natural precursor. The G‐CDs exhibit strong fluorescence emission at 547 nm under excitation at 467 nm, and the highest quantum yield reaching 17.5 % in acetone, making them suitable for a range of applications including sensing, bioimaging, catalysis, and drug delivery. The G‐CDs demonstrate excellent stability under various conditions, such as prolonged light exposure, high salt concentration, extended periods, and elevated temperatures. Furthermore, the G‐CDs show a good linear relationship with Cd2+ within the concentration range of 0 to 16.5 μmol/L, with a linear correlation coefficient of 0.9920. The detection limit (LOD) was calculated to be 0.68 μmol/L. The recovery rate ranges between 85.66% to 97.43%, indicating their potential for use in environmental metal ion detection. This study provides a convenient and economical method for the synthesis of G‐CDs using baby pumpkin as a precursor, offering a sustainable alternative for various applications in sensing, imaging, catalysis, and drug delivery.

One‐Pot Rh(III)‐Catalyzed Twofold C−H Activation/Oxidative Annulation of N‐Arylpyrroles with Alkynes to Fluorescent Ullazines

AbstractA range of densely functionalized ullazines have been synthesized by a one‐pot Rh(III)‐catalyzed twofold C−H activation/oxidative annulation of N‐arylpyrroles with alkynes. Electrophilic bromination at 5‐ or 5,7‐ positions of the EWG‐substituted ullazine core offers an interesting single or double entry for further extended functionalization. Mechanistic considerations suggest two complementary paths, EWG‐assisted and SEAr, for the C−H activations. All ullazines exhibit strong fluorescence emissions. Ullazines bearing thiophene and triarylamine units at 5‐ and 5,7‐ positions show a significant bathochromic shift in their emission spectra, attributed to the more extended electronic circuits present.

Sterically Twisted Mitochondria‐Targeting Photosensitizers for Augmented Near‐Infrared II Fluorescence‐Guided Photodynamic Immunotherapy

AbstractNear‐infrared (NIR) fluorescent mitochondria‐targeting photosensitizers (PSs) hold great potential for efficient image‐guided cancer phototherapy, but it remains challenging to develop PSs concurrently integrating high‐contrast NIR‐II fluorescence imaging and efficient therapeutic capabilities. Herein, a heptamethine cyanine (HCy) PS (termed I2HCy‐TPE nanoparticles (NPs)) by a molecular engineering strategy combining the heavy atom effect and structural distortion is reported. The heavy atom iodine is introduced to boost the intersystem crossing process, and the bulky tetraphenylethylene (TPE) moiety placed at the meso‐position of the heptamethine chain creates a highly distorted conformation in I2HCy‐TPE, theoretically verified by density functional theory calculations. This strategy synergistically promotes the 1O2 generation efficiency and assure the strong NIR fluorescence emission in aggregated states. Combining with the intrinsic mitochondria‐targeting capability, I2HCy‐TPE NPs are able to cause mitochondria‐targeted damage of cancer cells via the PDT and immunogenetic cell death‐triggered immune responses under NIR laser irradiation. In vivo experiments demonstrate that the biocompatible I2HCy‐TPE NPs present exceptional capability for in vivo NIR‐II fluorescence bioimaging of whole‐body and blood vessels, and exert efficient NIR‐II fluorescence‐guided photodynamic immunotherapy against triple‐negative breast cancer.

Dicyanopyridine derivatives: One-pot preparation, ACQ-to-AIE transformation, light-conversion quality and photostability

Low cost and strong fluorescence emission are two important guarantees for luminogens used as light conversion agents. By one-pot multicomponent approach and inexpensive starting materials, three dicyanopyridine (DP) derivatives named as DCP (2-amino-6-methoxy-4-phenylpyridine-3,5-dicarbonitrile), DCO (2-amino-6-methoxy-4-(4-methoxyphenyl) pyridine-3,5-dicarbonitrile) and DCC (2-amino-4-(4-cyanophenyl)-6-methoxypyridine-3,5-dicarbonitrile) were designed and synthesized.Meanwhile, the ACQ-to-AIE transformation was successfully realized by altering substituent groups rather than traditional rotor–stator theory. Based on crystal analysis and theoretical calculations, the ACQ-to-AIE transformation is attributed to the tunable stacking modes and intermolecular weak interactions. Owing to matched fluorescence emission, low lost, high yield, and AIE activity, DCC is used as light conversion agents and doped in EVA matrix. The light conversion quality confirms that DCC can not only convert ultraviolet light, but also significantly improve the transmittance of 25 %/40 % EVA, whose photosynthetic photon flux density at 400–500 nm and 600–700 nm increased to 30.67 %/30.21 % and 25.37 %/37.82 % of the blank film, respectively. After 20 h of UV irradiation (365 nm, 40 W), the fluorescence intensities of DCC films can maintain 92 % of the initial values, indicating good photostability in the doping films. This work not only provides an excellent and low-cost light conversion agent, but also has important significance for ACQ-to-AIE transformation of luminogens.

A blue fluorescent waterborne polyurethane-based Zn(ii) complex with antibacterial activity

Abstract Polymer-based transition metal complexes have attracted much attention in many fields of application. In this article, a fluorescent polymer-based transition metal complex was prepared by bonding the transition metal complex with the polymer. First, Schiff base salicylaldehyde ethanolamine (HL) as a ligand was prepared by the reaction of salicylaldehyde with ethanolamine. Then, salicylaldehyde glycolamine Zn(ii) transition metal complexes (ZnL2) were synthesized with HL and Zn2+ as the central ion. Finally, a blue fluorescent waterborne-based polyurethane Zn(ii) complex (ZnL2-WPU) with an antibacterial function was prepared with ZnL2 as a chain extender by modified acetone method. The characteristics of fluorescence, heat stability, and bacteriostasis were characterized. Compared with ZnL2, the UV–vis absorption peak of ZnL2-WPU shows a blue shift of about 20 nm. ZnL2-WPU has a strong blue fluorescence emission at 450 nm, and the intensity increases significantly with ZnL2 content. Surprisingly, the fluorescence lifetime of ZnL2-WPU is obviously increased, reaching more than one time that of ZnL2. Interestingly, the antibacterial efficiency of ZnL2-WPU against E. coli reached an incredible 99%. More importantly, ZnL2-WPU uses water as the dispersing medium, which is more environmentally friendly.

Encapsulation of Pure Water-Stable Perovskite Nanocrystals (PNCs) into Biological Environment-Stable PNCs for Cell Imaging.

Recently emerging perovskite nanocrystals (PNCs) are very attractive fluorescence nanomaterials due to their very narrow emission peak, tunable wavelength, and extremely high quantum yield, but their chemosensing, biosensing and bioimaging applications suffer from the poor stability of ordinary PNCs in aqueous media, especially in biological matrices. Recently developed water-stable 2D CsPb2Br5-encapsulated 3D CsPbBr3 PNCs (i.e., CsPbBr3/CsPb2Br5 PNCs) show extremely stable light emission in pure water, but their fluorescence is seriously quenched in aqueous media containing biological molecules due to their chemical reactions. In this work, we used a facile method to encapsulate pure water-stable CsPbBr3/CsPb2Br5 PNCs in water with SiO2 and polyethylene glycol hexadecyl ether (Brij58) into a new kind of biological environment-stable PNCs (CsPbBr3/CsPb2Br5@SiO2-Brij58). The synthesis of the target PNCs can be accomplished in a fast, easy, and green way. The obtained CsPbBr3/CsPb2Br5@SiO2-Brij58 PNCs maintain strong fluorescence emission for a long time, all in pH 7.4 PBS, BSA, and minimum essential medium, exhibiting excellent biological environment stability. Moreover, the developed biological environment-stable PNCs show good biocompatibility and have been successfully used in cell imaging. Overall, the work provides an easy, low-cost, and efficient application of PNCs in bioimaging.