Aggregation-induced Emission Enhancement Effect Research Articles

A new luminescent nickel nanocluster with solvent and ion induced emission enhancement toward heavy metal analysis

Expanding the family of fluorescent metal clusters beyond gold, silver, and copper has always been an issue for researchers to solve. In this study, a novel type of cysteine-capped nickel nanoclusters (Cys-Ni NCs) with bright turquoise emission was developed. The as-synthesized Ni NCs showed aggregation-induced emission enhancement (AIEE) properties across Cd2+ and various polar organic solvents. Concurrently, solvents with different viscosities were used to explore the principle of solvent-induced AIEE of Cys-Ni NCs, revealing a positive correlation between fluorescence intensity and solution viscosity. In addition, the concentration of Cd2+ that induced the AIEE effect was reduced by nearly two orders of magnitude in highly viscous solvents, indicating the possibility of Cys-Ni NCs as a promising nanomaterial platform for Cd2+ sensing analysis. Moreover, we propose a novel fluorescent sensing method for rapid detection of Cu2+ based on the carboxyl group of Cys-Ni NCs coupling with Cu2+. Further, validation of Cu2+ detecting methodologies in environmental water samples with the accuracy up to 93.94% underscores their potential as robust and efficient sensing platforms. This study expands the repertoire of fluorescent metal nanoclusters for highly sensitive and selective sensing of hazardous ions and paves the way for further exploration and wide applications in Cu2+ detection in biological and medicine fields.

Multicomponent Synthesis of New Fluorescent Boron Complexes Derived from 3-Hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde.

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using 1H-, 13C-, 15N-, 19F-, and 11B-NMR, IR spectroscopy, HRMS, and single-crystal X-ray diffraction data. The photophysical properties of the obtained iminoboronates were investigated using spectroscopic techniques, such as UV-vis and fluorescence spectroscopies. Compounds display main UV-vis absorption maxima in the blue region, and fluorescence emission maxima are observed in the green region of the visible spectrum. It was revealed that compounds exhibit fluorescence quantum yield up to 4.3% in different solvents and demonstrate an aggregation-induced emission enhancement effect in mixed THF-water solutions.

Label-free fluorescent aptasensor for myoglobin detection based on an aggregation-induced emission enhancement imidazole compound and a Fe3O4@4-VP platform

Acute myocardial infarction (AMI) is recognized as one of the deadliest cardiovascular diseases in the world, causing serious public health problems worldwide. Myoglobin (Mb) is an important biomarker for AMI. Therefore, the accurate detection of Mb is crucial for the early detection and clinical diagnosis of AMI. In this study, a novel imidazole Compound C and novel Fe3O4@4-VP microspheres were prepared and used to construct an unlabeled fluorescence aptasensor for Mb detection. Compound C can bind to the aptamer of Mb (Mb-Apt) through electrostatic attraction to form a C/Mb-Apt complex and produce the aggregation-induced emission enhancement effect. Then, Mb was added to the C/Mb-Apt solution. Mb could combine with C/Mb-Apt to form a C/Mb-Apt/Mb complex. Subsequently, Fe3O4@4-VP was added to the above mixture. The bases of Mb-Apt already combined with Mb, and thus, C/Mb-Apt/Mb would no longer interact with the pyridine rings on the surface of Fe3O4@4-VP through π-π stacking. After magnetic separation, the C/Mb-Apt/Mb complex remained in the supernate. The supernate exhibited strong fluorescence and its fluorescent intensity was proportional to the level of Mb. Experimental results showed an excellent linear relationship between the fluorescent intensity of the supernate and the level of Mb within the range of 0.167–20 ng/mL, with a detection limit reaching as low as 0.05 ng/mL (S/N = 3). In addition, the aptasensor exhibited high specificity and could be used for detecting Mb in human serum.

Peptide-Directed Synthesis of Aggregation-Induced Emission Enhancement-Active Gold Nanoclusters for Single- and Two-Photon Imaging of Lysosome and Expressed αvβ3 Integrin Receptors.

This study explores the synthesis and characterization of aggregation-induced emission enhancement (AIEE)-active gold nanoclusters (AuNCs), focusing on their near-infrared luminescence properties and potential applications in biological imaging. These AIEE-active AuNCs were synthesized via the NaBH4-mediated reduction of HAuCl4 in the presence of peptides. We systematically investigated the influence of the peptide sequence on the optical features of the AuNCs, highlighting the role of glutamic acid in enhancing their quantum yield (QY). Among the synthesized peptide-stabilized AuNCs, EECEE-stabilized AuNCs exhibited the maximum QY and a pronounced AIEE effect at pH 5.0, making them suitable for the luminescence imaging of intracellular lysosomes. The AIEE characteristic of the EECEE-stabilized AuNCs was demonstrated through examinations using transmission electron microscopy, dynamic light scattering, zeta potential analysis, and single-particle imaging. The formation of the EECEE-stabilized AuNCs was confirmed by size-exclusion chromatography and mass spectrometry. Spectroscopic and electrochemical examinations uncover the formation process of EECEE-stabilized AuNCs, comprising EECEE-mediated reduction, NaBH4-induced nucleation, complex aggregation, and subsequent cluster growth. Furthermore, we demonstrated the utility of these AuNCs as luminescent probes for intracellular lysosomal imaging, leveraging their pH-responsive AIEE behavior. Additionally, cyclic arginylglycylaspartic acid (RGD)-modified AIEE dots, derived from cyclic RGD-linked peptide-induced aggregation of EECEE-stabilized AuNCs, were developed for single- and two-photon luminescence imaging of αvβ3 integrin receptor-positive cancer cells.

Chromo-Fluorogenic Rhodamine-Based Amphiphilic Probe as a Selective and Sensitive Sensor for Intracellular Cu(I) in Living Cells.

Fluorescent probes are widely studied for metal ion detection because of their multiple favorable properties such as high sensitivity and selectivity, quick response, naked eye detection, and in situ monitoring. However, optical probes that can effectively detect the Cu(I) level in cell interiors are rare due to the difficulty associated with selectively and sensitively detecting this metal ion in a cell environment. Therefore, we designed and synthesized three water-soluble probes (1-3) with a 1,3,5-triazine core decorated by three substituents: a hydrophobic alkyl chain, a hydrophilic maltose, and a rhodamine B hydrazine fluorophore. Among the probes, probe 1, which has an octyl chain and a branched maltose group, was the most effective at sensing Cu+ in aqueous solution. Upon addition of Cu+, this probe showed a dramatic color change from colorless to pink in daylight and displayed an intense yellow fluorescence emission under 365 nm light. The limit of detection and dissociation constant (Kd) of this probe were 20 nM and 1.1 × 10-12 M, respectively, which are the lowest values reported to date. The two metal ion-binding sites and the aggregation-induced emission enhancement effect, endowed by the branched maltose group and the octyl chain, respectively, are responsible for the high sensitivity and selectivity of this probe for Cu+ detection, as demonstrated by 1H NMR, dynamic light scattering, and transmission electron microscopy studies. Furthermore, the probe successfully differentiated the Cu(I) level of cancer cells from that of the normal cells. Thus, the probe holds potential for real-time monitoring of Cu(I) level in biological samples and bioimaging of cancer cells.

Aggregation-induced emission enhancement of gold nanoclusters triggered by sodium heparin and its application in the detection of sodium heparin and alkaline amino acids

This work first reported that sodium heparin could cause the aggregation-induced emission enhancement (AIEE) effect of GSH-AuNCs (Glutathione functionalized gold nanoclusters). While it was interestingly found that the addition of alkaline amino acids would greatly weaken this effect. Thus, fluorescent system was designed for the quantitative detection of sodium heparin and alkaline amino acids. Negatively charged sodium heparin would connect with GSH-AuNCs through electrostatic attraction, leading to a significant AIEE effect. Then alkaline amino acids would competitively bind with sodium heparin, causing this effect to almost disappear. The reasons were as follows: (I) The hydrogen bonding between sodium heparin and alkaline amino acids was much stronger than electrostatic force, causing GSH-AuNCs to be competitively replaced. (II) Alkaline amino acids and GSH-AuNCs were both positively charged and repelled each other. The presence of alkaline amino acids would hinder the AIEE effect. (III) AIEE effect was confirmed to have a close relationship with the pH value which could be greatly affected by alkaline amino acids. (Ⅳ) Not only the hydrogen bonding, the electrostatic force also existed between the alkaline amino acids and sodium heparin. All the above reasons worked together to weaken the AIEE effect of GSH-AuNCs triggered by sodium heparin. Finally, both sodium heparin and alkaline amino acids were accurately detected, showing good correlation coefficients of 0.99 with the LODs of 0.0100 mg/mL (sodium heparin), 1.05 μM (histidine), 3.38 μM (arginine) and 6.16 μM (lysine), respectively.

A near-infrared AIEE fluorescent chemosensor for Cu2+ through an IPT process

A near-infrared AIEE fluorescent chemosensor 2-(2-(4-(((3-methyl-5-oxo-1- phenyl-4,5-dihydro-1H-pyrazol-4-yl)methylene)amino)styryl)-4H-chromen-4-ylidene)malono- nitrile (HL1) was synthesized. In DMSO solution, HL1 showed fluorescence emission at 570 nm, and the fluorescence emission peak red shifted to 675 nm with the addition of H2O, which was attributed to the tautomerism of ketone (K) and enol (E) caused by intramolecular proton transfer (IPT) and aggregation-induced emission enhancement (AIEE). For comparison, 2-(2-(4-(((1-phenyl-1H-pyrazol-4-yl)methylene)amino)styryl)-4H-chromen-4-ylidene)malononitrile (HL) without CO was synthesized. The results show that HL cannot coordinate with metal ions due to the absence of CO, but AIEE effect also exists. The sensor HL1 can coordinate with Cu2+ to cause fluorescence quenching in the near-infrared region, and the fluorescence intensity recovered after the addition of Na2EDTA, indicating that the probe HL1 can reversibly recognize Cu2+. Job's curve showed that the stoichiometric ratio of HL1 to Cu2+ was 1:1, and the detection limit for Cu2+ could reach at 4.68 × 10-8·mol•L-1 level. The experimental results are verified by theoretical calculation. In addition, the probe HL1 can be used to detect Cu2+ in actual drinking water.

Enhanced-sensitivity and rapid-response for the detection of kanamycin based on ethanol-assisted AIEE effect in silver-doped gold nanoclusters

In this study, a novel solvent-assisted strategy was developed for the rapid and sensitive detection of kanamycin (KAN) based on glutathione-capped silver-doped gold nanoclusters (AuAg NCs). Ethanol solvent played a key role in disrupting the hydration shell of metal(I)-thiolate complexes in AuAg NCs. KAN, as a specific linker between AuAg NCs through electrostatic interaction and metal-amine coordination, induced the formation of large aggregates and thus triggered prolonged photoluminescence lifetime as well as strong luminescence enhancement by restricting molecular motions in AuAg NCs. The KAN-stimulated turn-on principle allows AuAg NCs to exhibit 4-fold sensitivity in 40% ethanol/water (V/V) mixed solution compared to that in water. The improved aggregation-induced-emission enhancement (AIEE) feature endows the AuAg NCs with selective recognition for KAN and realizes rapid detection in a short response time of 60 s with a low detection limit of 8.6 nM. By integrating AuAg NCs with a Pasteur pipette, a facile sample-to-answer test kit for on-site determination with low cost and high efficiency was constructed, offering potential applications in the timely analysis of contaminants in environmental emergencies.

Comparison of aggregation-induced emission enhancement effect between π-σ* and σ-σ* conjugation on silole and application in explosives detection

Herein we have synthesized and characterized the novel π-σ* conjugated 1,4-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadienyl)benzene nanoaggregates based on aggregation-induced emission enhancement (AIEE) property for the detection of nitroaromatic compounds by fluorescence quenching. The new photoluminescent silole nanoaggregates exhibited unique AIEE property by increasing the emission intensity 180 times in THF/water mixtures. We investigated that the π-σ* hyper conjugation of Si–C phenyl ring is more effective on AIEE due to the less non-radiative decay than the σ-σ* hyper conjugation of Si–Si bond of 1,4-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadienyl). The π-σ* conjugated nanoaggregates showed excellent sensitivity for sensing explosives. High Stern-Volmer constant was observed during quenching of photoluminescence (PL) intensity upon adding explosives. The absolute quantum yield and average particle size were measured for the nanoaggregates and tuned by controlling at different fraction of water. These results demonstrate that AIEE property of π-σ* conjugated silole nanoaggregates will provide guidance to develop fluorescent materials for detecting explosives.

Novel nitrogen-doped carbon dots for “turn-on” sensing of ATP based on aggregation induced emission enhancement effect

In this work, a nitrogen-doped carbon dots (CDs) was successfully synthesized by hydrothermal synthesis of polyethylenimine (PEI) and citric acid. The as-prepared CDs suffered from aggregation-caused quenching (ACQ) with a high concentration, but after adding adenosine triphosphate (ATP), the CDs aggregated. The generation of aggregates caused the rotation of the surface groups on CDs and reduced the non-radiation decay. The QY of CDs in water was 9.25 %, and increased to 16.60 % and 63.38% in the addition of 100 and 1000 μM ATP. And then, the enhancement of the radiation rate led to the aggregation induced enhancement effect (AIEE). Moreover, we also found that the proportion of precursors for CDs synthesis was a key factor in the occurrence of AIEE. Therefore, such CDs would be excellent candidates as fluorescent probes for the label-free detection of ATP. Our proposed method exhibited simple and easy preparation of nanoprobe, quick response (3 min), wide range of linear rage (1–2000 μM) and eco-friendly. In addition, the method performed successfully as a “turn-on” sensor for detection of ATP in the tablet with a recovery of 100.1~106.9% and RSD below 3.5%.

Ratiometric fluorescent sensor based on MoS2 QDs and AuNCs for determination and bioimaging of alkaline phosphatase

Herein, a ratiometric fluorescent sensor based on MoS2 quantum dots (QDs) and glutathione-capped gold nanoclusters (AuNCs) was developed for determination and imaging of alkaline phosphatase (ALP). The sensor was developed by covalently linking QDs with AuNCs to form stable MoS2@AuNCs nanohybrids that exhibited the blue fluorescence of MoS2 QDs and the red fluorescence of AuNCs. In the presence of Ce3+, the fluorescence intensity of AuNCs was increased due to the aggregation-induced emission enhancement (AIEE), while that of MoS2 QDs remained unchanged, thus could be used as a reference signal. After adenosine 5′-monophosphate (AMP) and ALP were introduced into the system, AMP was hydrolyzed to adenosine and phosphate ions (PO43−). Owing to higher affinity between Ce3+ and PO43−, the AIEE effect was inhibited, in turn resulting in the decrease of AuNCs fluorescence. The developed ratiometric fluorescent sensor had a linear response to ALP concentration ranging from 0.5 to 50 U L−1 with a detection limit (LOD) of 0.08 U L−1. Moreover, the sensor had low cytotoxicity and was successfully employed in lysosome localization and bioimaging of intracellular ALP in living cells.

Different fluorescence emitting copper nanoclusters protected by egg white and double-emission fluorescent probe for fast detection of ethanol

Green emitting copper nanoclusters (G-Cu NCs), yellow emitting Cu NCs(Y-Cu NCs), orange emitting Cu NCs (O-Cu NCs) and red emitting Cu NCs(R-Cu NCs) were prepared using chicken egg white as the stabilizer by changing the reaction conditions. This is a green, facile and cheap method to explore different color emitting CuNCs by the same precursor and stabilizers. The G-Cu NCs were employed for the detection of ethanol due to their aggregation induced emission enhancement (AIEE) effect. The fluorescence emission of Cu NCs at 526nm under the excitation of 444nm can be effectively enhanced in the presence of ethanol due to AIEE effect, thus realizing the quantitative determination of ethanol content in the range 5-60%. In addition, a visual dual-emission fluorescence probe with the combination of G-Cu NCs and silicon nanoparticles (Si NPs/G-Cu NCs) was designed to evaluate ethanol content conveniently and rapidly. Desirable linear relationship is observed between ratio of fluorescence intensity (I525/I441) and ethanol content under the excitation of 383nm. Visible color transformation of this probe is observed in the ethanol content range 2-20%. Moreover, the ethanol sensing platforms were applied to the detection and evaluation of the alcohol content of liquor, and the recoveries in liquor were in the range 99.7% to 113%, broadening the applications of Cu NCs and providing a sensitive detection method for ethanol.

Aggregation-Induced Emission Behavior of Dual-NIR-Emissive Zinc-Doped Carbon Nanosheets for Ratiometric Anthrax Biomarker Detection

The development of near-infrared (NIR) emission nanoprobes for the ratiometric fluorescent determination of living cells in vitro/vivo is of great analytical importance. In this work, dual-NIR-emissive Zn-doped carbon-based nanosheets (Zn-CNSHs) were prepared with a beneficial and special donor-π-acceptor-conjugated (D-π-A-conjugated) spatial framework, which resulted in not only a much lower HOMO-LUMO energy level but also excellent biocompatibility and physicochemical properties. The Zn-CNSHs were prepared by simple one-pot solvothermal synthesis with zinc gluconate (ZGN) and a strong acid and exhibited two distinctive photoluminescence (PL) peaks at 620 and 720 nm with the 600 nm excitation. The 620 nm peak intensity was dependent on dipicolinic acid (DPA) owing to the aggregation-induced emission enhancement effect via the strong intersheet hydrogen bonds between Zn-CNSHs and DPA, enabling the ratiometric fluorescent determination of DPA, an important clinical anthrax biomarker. An excellent calibration curve showed linear regions over the range of 0.05-500 μM between the ratio of PL intensity (PL620nm/PL720nm) and the concentrations of DPA. The detection limit was down to 21.7 nM. Based on the high stability, low cytotoxicity, high selectivity, and outstanding PL-reliant sensitivity for the DPA assay, the nanoprobe has been successfully used to monitor DPA in serum, wastewater, and cells.

Fabrication of Double Emission Enhancement Fluorescent Nanoparticles with Combined PET and AIEE Effects.

The major challenge in the fabrication of fluorescent silica nanoparticles (FSNs) based on dye-doped silica nanoparticles (DDSNs) is aggregation-caused fluorescence quenching. Here, we constructed an FSN based on a double emission enhancement (DEE) platform. A thio-reactive fluorescence turn-on molecule, N-butyl-4-(4-maleimidostyryl)-1,8-naphthalimide (CS), was bound to a silane coupling agent, (3-mercaptopropyl)-trimethoxysilane (MPTMS), and the product N-butyl-4-(3-(trimethoxysilyl-propylthio)styryl)-1,8-naphthalimide (CSP) was further used to fabricate a core–shell nanoparticle through the Stöber method. We concluded that the turn-on emission by CSP originated from the photoinduced electron transfer (PET) between the maleimide moiety and the CSP core scaffold, and the second emission enhancement was attributed to the aggregation-induced emission enhancement (AIEE) in CSP when encapsulated inside a core–shell nanoparticle. Thus, FSNs could be obtained through DEE based on a combination of PET and AIEE effects. Systematic investigations verified that the resulting FSNs showed the traditional solvent-independent and photostable optical properties. The results implied that the novel FSNs are suitable as biomarkers in living cells and function as fluorescent visualizing agents for intracellular imaging and drug carriers.

Deciphering the Dynamics of Organic Nanoaggregates with AIEE Effect and Excited States: Lipophilic Benzothiadiazole Derivatives as Selective Cell Imaging Probes.

An aggregation-induced emission enhancement (AIEE) effect in fluorescent lipophilic 2,1,3-benzothiadiazole (BTD) derivatives and their organic nanoaggregates were studied. A set of techniques such as single-crystal X-ray, dynamic light scattering (DLS), electron paramagnetic resonance (EPR), UV-vis, fluorescence, and density functional theory (DFT) calculations have been used to decipher the formation/break (kinetics), properties, and dynamics of the organic nanoaggregates of three BTD small organic molecules. An in-depth study of the excited-state also revealed the preferential relaxation emissive pathways for the BTD derivatives and the dynamics associated with it. The results described herein, for the first time, explain the formation of fluorescent BTD nanoaggregate derivatives and allow for the understanding of their dynamics in solution as well as the ruling forces of both aggregation and break processes along with the involved equilibrium. One of the developed dyes could be used at a nanomolar concentration to selectively stain lipid droplets emitting an intense and bright fluorescence at the red channel. The other two BTDs could also stain lipid droplets at very low concentrations and were visualized preferentially at the blue channel.

Ultrashort peptide-stabilized copper nanoclusters with aggregation-induced emission

Here, we report a facile, one-pot strategy for the fabrication of copper nanoclusters (CuNCs) with orange-red fluorescent emission in the presence of an ultrashort peptide, I3R, and GSH. The effects of the reaction temperature, pH value, GSH and I3R concentrations on the fluorescence properties of I3R-GSH-CuNCs were investigated in detail. By forming compact and ordered self-assembled microstructures, such as nanofibers and helical nanofibers, the as-prepared I3R-GSH-CuNCs exhibit an aggregation-induced emission enhancement effect. Due to the coordination interaction between the Cu core and the capping ligands, which facilitates ligand-to-metal charge transfer (LMCT), the photoluminescence lifetime of I3R-GSH-CuNCs can be prolonged to 19.3 μs. The CD spectra of samples with helical nanofibers exhibit a negative band in the range of 300 ∼ 320 nm, indicating that the CuNCs obtained in this work are chiral, and their chirality was induced by the chiral ligands GSH and I3R. A possible mechanism of the self-assembly-induced emission enhancement is proposed. Furthermore, stable CuNCs were used to fabricate prototype down conversion LEDs with orange emission.

Fluorescent Properties of Morin in Aqueous Solution: A Conversion from Aggregation Causing Quenching (ACQ) to Aggregation Induced Emission Enhancement (AIEE) by Polyethyleneimine Assembly.

Unlike normal conversion from aggregation caused quenching (ACQ) to aggregation induced emission enhancement (AIEE) by introducing aromatic rotors tuning aggregation modes, in this study, it is achieved through a supramolecular assembly with polymer. Thus, it provides an easy approach for the inhibition of unwanted H-aggregation between luminogens. As a kind of flavonoid, morin has shown great potential in therapeutics. However, its poor solubility and weak emission in aqueous solution greatly limit its bioapplications. When morin is dissolved in aqueous solution, the presence of 30× 10-6 m polyethyleneimine (PEI) induces significant emission enhancement and bathochromic shift. Consequently, the quantum yield (QY) of 24.5% is either achieved by assembling with PEI, versus 0.76% of its ACQ state composed of H-aggregation in aqueous solution. Particularly, the in-depth mechanism studies reveal that it is the assembly with PEI that disassociates the H-aggregation in aqueous solution and further restricts the stretching and/or rotation of morin, which eventually reduce the nonradiative decays and enhance the emission. Therefore, the present study reports a unique phenomenon of AIEE effects on morin. Particularly the in-depth investigation on intrinsic mechanisms will highlight and greatly expand the development of more luminogens from traditional Chinese herbals.

Facile structure-modification of xanthenone based OLED emitters exhibiting both aggregation induced emission enhancement and thermally activated delayed fluorescence

Four new donor-acceptor compounds were designed, synthesized and investigated by theoretical and experimental approaches aiming to estimate effect of the structure of a donor on the properties of potential OLED emitters. Because of the different electron-donating abilities of the nitrogen-containing heterocycles, derivatives of xanthenone containing di-tert-butyl-carbazolyl, di-tert-butyl-acridanyl, di-tert-butyl-phenothiazinyl and penoxazinyl moieties exhibited different photophysical behavior. Because of big dihedral angles between the donors and acceptor as well as because of possibility of rotation around N–C bond, the designed compounds were characterized by thermally activated delayed fluorescence and aggregation induced emission enhancement effect. Twice higher photoluminesce quantum yields reaching 38% in doped films were obtained for compounds containing di-tert-butyl-carbazolyl and di-tert-butyl-acridanyl moieties as compared to those observed for compounds with the donors containing S and O heteroatoms. Strong effect of the donor substituents on charge injection (ionization potentials were in the range of 5.67–5.96 eV) and charge-transporting properties (hole and electron mobilities were in a wide range from 6.3 × 10−8 to 6.3 × 10−4 cm2V−1s−1 at electric field of 2.5 × 105 V cm−1) was detected. The differently substituted compounds were utilized as emitters in OLEDs. Higher maximum values of external quantum efficiency (up to 3.5%) were observed for OLEDs based on emitters with nitrogen containing donors relative to estimated for OLEDs based on emitters containing di-tert-butyl-phenothiazinyl and penoxazinyl moieties.

Interaction of Glutathione-Stabilized Gold Nanoclusters with Doxorubicin and Polycation

Glutathione-capped gold nanoclusters display polyanionic properties that are manifested in the interaction with cationic species. The nanoclusters form complexes with doxorubicin with effective dissociation constant about 10 µM that increased by an order of magnitude in the presence of 0.15 M NaCl confirming electrostatic character of binding. Adsorption of polylysine arose an increase in the fluorescence of gold nanoclusters due to aggregation induced emission enhancement effect. Fluorescence of the complexes increased several-fold upon addition of up to 1 M of KCl suggesting contribution of non-Coulombic forces in the stabilization of aggregates of gold nanoclusters.

Nickel-Catalyzed Defluorinative Reductive Cross-Coupling Reaction of gem-Difluoroalkenes with Thiosulfonate or Selenium Sulfonate.

A nickel-catalyzed defluorinative reductive cross-coupling of gem-difluoroalkenes with thiosulfonate or selenosulfonates is described. The reaction involves the formation of thiolated or selenylated monofluoroolefins via regioselective C-F bond cleavage and C-S or C-Se bond formation and features easily available substrates, mild reaction conditions, and high E-selectivity. One of the derivatives by further cross coupling with PhMgBr exhibited an aggregation-induced emission enhancement effect.