[en] Three novel triphenylamine-based compounds containing strong electron acceptor groups have been synthesized and their comparative photophysical properties are presented. These compounds were obtained by a two-step method: (i) triphenylamine compounds with one, two and three phenylacetylene arms were synthesized by Sonogashira reaction between iodine-substituted triphenylamines and phenylacetylene, followed by (ii) post-modification of these electron-rich alkynes by addition of the strong electron acceptor, tetracyanoethylene. Characterization of all oligomers was made by FTIR, "1H-NMR, UV–vis and fluorescence spectroscopy. A batochromic shifting of the UV and photoluminescence maxima was observed with the increase of the acceptor group number. The electrochemical behavior was studied by cyclic voltammetry. The cyclic voltammograms have evidenced that triphenylamine-phenylacetylene compounds undergo only oxidation processes while compounds modified with tetracyanoethylene show both oxidation and reduction peaks associated with donor and acceptor groups, respectively. The donor–acceptor compounds coordinate metal ions (i.e., Hg"2"+ and Sn"2"+) by cyano groups resulting in the decreasing of charge transfer band intensity, and they can be used as chemosensors. - Highlights: • Three triphenylamine-based ethynylene compounds were prepared by Sonogashira reaction. • Post-modification of ethynylene linkages by tetracyanethylene cycloaddition and retroconversion led to donor–acceptor compounds. • Photophysical properties of donor–acceptor oligomers were studied in different solvents

[en] We report on the chemiluminescence (CL) of graphene quantum dots (GQDs) induced by direct chemical oxidation. GQDs were prepared by a simple carbonization method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and Raman spectroscopy. It was found that Ce(IV) could oxidize GQDs to produce a relatively intense CL emission. The mechanism of CL generation was investigated based on the fluorescence and CL emission spectra. It was attributed to the radiative recombination of oxidant-injected holes and thermally excited electrons in the GQDs. In order to show the analytical application potential of GQDs-Ce(IV) CL system, it was applied to the determination of uric acid. Under the optimized conditions, the proposed CL system exhibited excellent analytical performance for determination of uric acid in the range of 1.0×10"−"6 M–5.0×10"−"4 M with a limit of detection of 5.0×10"−"7 M. The method was applied to the determination of uric acid in human plasma and urine samples, with satisfactory results. - Highlights: • Chemiluminescence of graphene quantum dots by direct oxidation was studied. • Intense CL is produced by reaction of graphene quantum dots with Ce(IV). • The new CL system was applied to determination of uric acid in plasma and urine

[en] The blue light emitting materials based on a fluoro phenanthro [9,10-d] imidazole derivatives prepared by a facial synthetic process exhibit good thermal stability, highly efficient fluorescence and balanced carrier injection. The multi-layered device based on fluoro phenanthroimidazole derivatives shows a higher luminance in a lower turn-on voltage. The device performance implies that the phenanthroimidazole unit is an excellent building block for tuning the carrier injection properties as well as blue emission. - Highlights: • Phenanthroimidazole exhibits high T_m and T_d_5 values, fluorescent efficiency, preparation cost and charge injection property. • The carrier injection and transport ability can be evidenced from the hole-only and electron-only devices. • These materials are used as building block for efficient blue light emitting materials. • Chemical structure modification improving the materials' properties

[en] A photoinduced electron transfer cation sensor, oxadiazole-bridge-bis(N,N-bis(2-pyridylmethyl)amine), was designed and prepared. This sensor displayed an “off–on–off” fluorescent switch for proton and an “on–off” fluorescent switch for Cu"2"+. The fluorescence emission of the sensor was quenched upon addition of Cu"2"+ and proton in CH_3CN/H_2O solution (v/v, 4:1) due to electron transfer between the N,N-bis(2-pyridylmethyl)amine and the oxadiazole. The sensor presented high selectivity for Cu"2"+ over other metal ions and determined Cu"2"+ concentration in a linear fashion from 5×10"−"7 M to 8×10"−"5 M. Stern–Volmer analysis showed the binding stoichiometry to be 1:2 (host-guest) with a binding constant of 1.8×10"1"0 M"−"2, calculated using the Benesi–Hilderbrand equation. The response of the sensor to Cu"2"+ was instantaneous and reversible, and the usual anions did not influence the selectivity for Cu"2"+. - Highlights: • A new fluorescent sensor based on oxadiazole and N,N-bis-(2-pyridylmethyl)amine was designed. • The sensor displayed sensitive fluorescence response “on–off” to Cu"2"+ and “on–off–on” for protons. • Fluorescence intensity showed good linear correlation with Cu"2"+ concentration from 5×10"−"7 M to 8×10"−"5 M. • The high concentration of metal ions and usual anions did not influence the selectivity for Cu"2"+. • The short response time of the sensor for Cu"2"+ (within 20 s) meets practical requirements

[en] The interaction of Ligupurpuroside A with bovine serum albumin (BSA) has been investigated by fluorescence spectra, UV–vis absorption spectra, three-dimensional (3D) fluorescence spectra, synchronous fluorescence spectra and circular dichroism (CD) spectra along with a molecular docking method. The fluorescence experiments indicate that Ligupurpuroside A can quench the intrinsic fluorescence of BSA through a combined quenching way at the low concentration of Ligupurpuroside A, and a static quenching procedure at the high concentration. The thermodynamic analysis suggests that hydrogen bonds and van der Waals forces are the main forces between BSA and Ligupurpuroside A. According to the theory of Förster's non-radiation energy transfer, the binding distance between BSA and Ligupurpuroside A was calculated to be 2.73 nm, which implies that energy transfer occurs between BSA and Ligupurpuroside A. All these experimental results have been validated by the protein–ligand docking studies which show that Ligupurpuroside A binds to the residues located in the hydrophobic cavity on subdomain IIA of BSA. In addition, conformation change of BSA was observed from three-dimensional fluorescence spectra, synchronous fluorescence spectra and circular dichroism spectra under experimental conditions. - Highlights: • The interaction of Ligupurpuroside A with BSA was investigated. • The fluorescence quenching of BSA induced by Ligupurpuroside A is a combined quenching process. • The main interaction forces were hydrogen bonds and van der Waals forces. • Ligupurpuroside A binding results in a decrease in α-helix

[en] A novel solution processable charge generating layer (CGL) that consists of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN₆)/Poly(N-vinylcarbazole) (PVK): 1,1-bis-(4-bis(4-tolyl)-aminophenyl) cyclohexene (TAPC) for a tandem green phosphorescent organic light emitting diode (PHOLED) is demonstrated. The use of orthogonal solvent to dissolve HATCN₆ and PVK:TAPC is the key to overcome the interface erosion problem for the solution processed CGL. The current efficiency of the 2 wt% TAPC mixed with PVK is the highest at 24.2 cd/A, which is more than three-folds higher than that of the single device at 1000 cd/m². - Highlights: • A solution processable tandem OLED is built using a novel charge generating layer. • HATCN₆ and PVK:TAPC are shown to be effective charge generating layers. • The turn on voltages for tandem devices are almost similar to single unit. • 2 wt% TAPC blended with PVK exhibits three-folds increase in efficiency

[en] A novel flow-injection chemiluminescence (CL) method for the determination of ascorbic acid (AA) is proposed, based upon its enhancing effect on the CL reaction of luminol with ferricyanide catalyzed by gold nanoparticles in alkaline solution. Different sizes gold nanoparticles exhibited different catalyzing effect towards luminol CL and 38 nm gold nanoparticles exhibited the best enhancing effect. Under the optimal experimental conditions, a linear relationship was obtained between the CL intensity and the concentration of ascorbic acid in the range of 1.0×10⁻¹⁰–1.0×10⁻⁶ mol L⁻¹. The detection limit was 2.0×10^–11 mol ⁻¹ and the relative standard deviation for 1.0×10⁻⁶ mol L⁻¹ ascorbic acid was 0.71% (n=10). This method has been successfully applied in the determination of ascorbic acid in several real samples. - Highlights: • Gold nanoparticles could enhance luminol–K₃Fe(CN)₆ CL signal. • 38 nm gold nanoparticles exhibited the best catalyzing effect. • Ascorbic acid could further enhance luminol–K₃Fe(CN)₆–gold nanoparticles CL. • Ascorbic acid could be detected sensitively based on its enhancing effect

[en] Fluorescence spectroscopy was used to study the complexation of different ligands containing multiple diglycolamide (DGA) pendent arms such as T-DGA (tripodal diglycolamide), C4DGA (upper rim functionalized calix [4] arene with four DGA moieties), and C8DGA (both side functionalized calix [4] arene with eight DGA moieties) with Eu³⁺ in ionic liquids such as C₄mimNTf₂ and C₈mimNTf₂ (1-alkyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide). Mainly five sets of emission profiles were observed in all the spectra (1st set at∼580 nm assigned as the ⁵D₀→⁷F₀ transition, 2nd set at∼593 nm assigned as the ⁵D₀→⁷F₁ transition, 3rd set at∼613 nm assigned as the ⁵D₀→⁷F₂ transition, 4th set at∼650 nm assigned as the ⁵D₀→⁷F₃ transition, and 5th set at∼700 nm assigned as the ⁵D₀→⁷F₄ transition). The difference in the spectral features revealed that the nature of the complexes differs significantly from one another. Judd–Offelt constant Ω₂, which is a measure of the covalency of the metal–ligand bond, follows the order Eu³⁺–C4DGA (C₈mimNTf₂)>Eu³⁺–C8DGA (C₈mimNTf₂)>Eu³⁺–TODGA (C₄mimNTf₂)>Eu³⁺–T-DGA (C₄mimNTf₂)>Eu³⁺_aq. The high intensity of the ⁵D₀→⁷F₂ transitions in all complexes suggests that Eu³⁺ resides in a highly asymmetric environment. From the splitting patterns of the transitions, the local site symmetry around Eu³⁺ was found to be C_2V for the Eu³⁺–T-DGA complex in both C₄mimNTf₂ and a 1:5 acetonitrile–water mixture, C_4V for Eu³⁺–C8DGA and Eu³⁺–TODGA complexes, and either C₁, C₂, or C_S for the Eu³⁺–C4DGA complex. A linear relationship between the ⁵D₀–⁷F₁ splitting vs E(⁵D₀–⁷F₀) and E(⁵D₀–⁷F₀) vs E(⁵D₀–⁷F₁) was observed. The crystal field parameters in the different complexes follow the trend Eu³⁺–C4DGA>Eu³⁺–TODGA>Eu³⁺–T-DGA in C₄mimNTf₂∼Eu³⁺–C8DGA>Eu³⁺–T-DGA in 5:1 acetonitrile-water mixture. - Highlights: • J–O parameters were obtained from luminescence data of Eu³⁺ –DGA complexes. • The studies involved ionic liquid extracts or those in acetonitrile–water mixture. • Local site symmetry around Eu³⁺–DGA complexes was found out. • The crystal field parameters in different complexes were calculated

[en] Hexagonal gadolinium fluorides doped with Ce³⁺ ions and co-doped with Sm³⁺, Eu³⁺, Tb³⁺ or Dy³⁺ were successfully synthesized via a simple co-precipitation approach, in the presence of glycerin as a capping agent. These fluorides, as solids or in aqueous solutions, showed intense, multicolored luminescence depending on the lanthanide ions used. The structures of the products were confirmed by powder X-ray diffraction (XRD). The morphologies of the synthesized nanophosphors were examined using transmission electron microscopy (TEM). The TEM results showed that the crystallites had shapes that varied with the dopant ion used. The spectroscopic properties: excitation spectra, emission spectra and luminescence decays were recorded and studied in detail. Bright luminescences from all of the products were triggered by effective energy transfer between the ions embedded in their structures. The mechanism for this phenomenon was also proposed. All of the synthesized products formed stable aqueous colloids, exhibiting brightly multicolored luminescence under UV light irradiation. - Highlights: • Hexagonal GdF₃:Ce³⁺, Ln³⁺ nanocrystals were synthesized by a co-precipitation method. • Nanocrystals formed stable water colloids. • Multicolor luminescence under UV light was observed. • Energy transfer mechanism between Gd³⁺, Ce³⁺ and Ln³⁺ ions was proposed

[en] A new pyrene–pyridine dithiocarbamate based fluorescent chemodosimeter, potassium (pyren-1-ylmethyl)(pyridin-2-ylmethyl)dithiocarbamate (L1) has been designed and synthesized. The chemodosimeter shows high selectivity and sensitivity (5.2 ppb) for Hg²⁺ in pure aqueous medium in which emission intensity was quenched by ≈80% due to the formation of new cyclized species, 1. The probe behaves as a chemodosimeter for Hg²⁺ ions and forms Hg²⁺ triggered cyclised imidazoline species with approximate detection time of 50 s and exhibits both colorimetric and fluorometric changes on detection of Hg²⁺ ion. Color of the probe (L1) changed from green to colorless visible to the naked eye and from green to dark blue upon the addition of Hg²⁺ ions under UV light. The Hg²⁺ triggered cyclization reaction was confirmed by spectral data analysis and a single crystal structure determination of the cyclised entity 2 obtained from the model compound potassium benzyl(pyridin-2-ylmethyl) dithiocarbamate (L2). L1 finds its application for detection of Hg²⁺ ions on paper strips, and in BSA (bovine serum albumin) medium. L1 is also applicable for the monitoring of Hg²⁺ ion in NIH3T3 live cells. - Highlights: • Efficient chemodosimeter to detect Hg²⁺ ions in pure aqueous medium. • Hg²⁺ triggered cyclisation and formation of imidazoline species. • Probe exhibit both colorimetric and fluorometric changes • Probe is applicable to detect Hg²⁺ in live cells and on cellulose paper strips