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As soft materials represent new features that offer long-range orders, they have received considerable interests in optoelectronic fields. In this contribution, the assembly and characterization of soft materials incorporated by lanthanide complex have been reported. The polymeric hosts are derived from polyvinyl alcohol and polyacrylamide-co-polyacrylic acid. As for the metal complexes, the organic chromophore can sensitize europium or terbium ions simultaneously and green/red emissions are achieved. In the aqueous solution phase, the europium complex generates luminescence quenching effect upon the addition of Cu2+ ions and the detection limit has been determined to be 3.6 μM. In addition, the "on–off" changes can be also observed based on the complex-loaded hydrogels and the mechanical properties are discussed. This responsive soft material will demonstrate great potentials in optical devices, biological analysis, and medical diagnosis fields. [ABSTRACT FROM AUTHOR]

Abstract A simple, rapid and low-cost solar irradiation method to prepare highly fluorescent carbon dots has been demonstrated by using citric acid and o -phenylenediamine as precursors. The whole concentrated light sintering process is completed within 2 min and this nitrogen doped carbon quantum dots exhibit striking blue luminescence. Except the conventional ultra-violet (378 nm) pumped emissions, the specific up-converted photoluminescence signal is able to extend the excitation sources to near-infrared range (750 nm). Moreover, carbon dots are very sensitive and selective to the presence of Hg2+ ions. Two different responsive ways (down-conversion and up-conversion) have been employed for the first time and the limits of detection are determined to be 1.3 nM and 0.06 nM respectively. Its pH dependence has been discussed and the evolution curves indicate such carbon-based nanomaterial possess unique features within a wide pH range. This study focuses on efficient solar energy conversion and provides new insights of carbon dots with multi-modal sensing capabilities. Highlights • Concentrated solar irradiation was used to prepare carbon dots. • Blue carbon dots were synthesized within 2 min. • Up-conversion feature was explored. • Hg2+ ions sensing experiments were investigated. [ABSTRACT FROM AUTHOR]

Abstract A robust, one-pot synthesis of polymeric nanocluster in polar medium has been reported based on the assembly of polyethyleneimine (PEI) and p-phenylenediamine (PPDA). A number of process parameters including molecular weights of PEI, ratios between PEI and PPDA, reaction time, pH condition and solvent polarity have been discussed. This novel nanomaterial can exhibit striking blue-greenish emissions upon the excitation at 377 nm. More importantly, it is highly sensitive to the titration of copper ions and detection limit has been determined to be as low as 11.27 nmol. These results will pave the way for constructing next generation of polymeric devices. [ABSTRACT FROM AUTHOR]

Graphical abstract The micron size Mo 2 C:Eu3+ has been fabricated directly by carburization of molybdenum oxide and p -phenylenediamine together at 800 °C. The structure and crystalline size of the material have been confirmed. In particular, this novel lanthanide-activated phosphor provides striking red luminescence in the form of higher monochromatic purity. The emission intensity increased depending on the incorporation of europium ions and the most suitable doping concentration will be 0.3 mmol. Abstract Europium incorporated molybdenum carbide (Mo 2 C) has been assembled at 800 °C based on a single step and the synthesis processes have been discussed. (NH 4) 6 Mo 7 O 24 ·4H 2 O has been employed as a precursor and p -phenylenediamine has been selected as the carbon source. In contrast to conventional organic dyes, this novel lanthanide-activated phosphor provides red luminescence in the form of higher monochromatic purity due to the parity forbidden transitions. More importantly, the emission intensity of 5D 0 → 7F 2 transition increased depending on the incorporation of europium ions and the most suitable doping concentration will be 0.3 mmol. The utilization of f – f transition of Eu3+ in molybdenum carbide has made the red emission materials accessible for application in the area of display, electronics and bio-imaging. [ABSTRACT FROM AUTHOR]

Alcoholic strength is a fundamental variable in industry production and its determination is crucial in technological developments. This study offers a novel strategy for fluorescent sensing of alcoholic content based on a terbium coordination complex. In pure water, the emissive compound displays blue luminescence. However, the addition of ethanol into the aqueous solution has induced the recovery of terbium green emissions. In another case, the achieved Eu(III)-phenanthroline complex shows high sensitivity to solvent polarity and the detection of trace amount of water can be realized through an “on-off” change with a low detection limit of 32.4 ppm. [ABSTRACT FROM AUTHOR]

Fluorescence has been well documented and the optical feature of carbon dots generates considerable interests. Here the nitrogen-doped carbon dots with a relative quantum yield of 25% have been prepared. It displays stable blue emission based on the excitation at 355 nm. The carbon nanomaterial is highly dispersible in aqueous solution and can be employed as an effective optical probe for label-free detection of Fe3+ (0.87 μM) via a switched off change. Additionally, such sensing nanoplatform can be recovered in the presence of pyrophosphate (PPi) and an "off-on" process has been identified. It is expected that this on-off-on strategy will allow new possibilities for developing efficient sensors in industrial fields. The nitrogen-doped carbon dots with aqueous solubility display stable blue emission based on the excitation at 355 nm. It can be employed as an effective optical probe for label-free detection of Fe3+ (0.87 μM) through an "on-off" change. Furthermore, such sensing nanoplatform can be recovered in the presence of pyrophosphate (PPi) and the "off-on" process has been identified. It is expected that this on-off-on strategy will allow new possibilities for developing efficient sensors in industrial fields. Unlabelled Image • A carbon nanodot-based chemical sensor has been designed. • A stepwise assembly method has been used to generate responses. • Two targets could be determined by this functional sensor. [ABSTRACT FROM AUTHOR]

Abstract Efficient ways for the trace level monitoring of Cr 2 O 7 2− have generated considerable attention in the fields of medical diagnosis and environmental protection. In current research, the water-soluble carbon dots (CDs) have been developed via the precursors of 1,3-phenylenediamineand citric acid. The quantum dots with particle size of 3–4 nm have been prepared based on a simple one-pot ultrasonic irradiation method and demonstrate bright blue emission at 440 nm. Its excitation-dependent feature has been explored and the achieved emission evolves from blue (440 nm) to green luminescence (528 nm). Photophysical studies support that CDs can be remarkably quenched by the presence of chromate due to inner filter effect. In addition, the absorption curves demonstrate that carbon dots possess highly selective and sensitive responses to Cr 2 O 7 2− through color changes. The dual sensing modes (fluorescence and colorimetric detection) can be well-established for the recognition of chromate and the detection limits are calculated to be as low as 140 nM and 410 nM respectively. To further evaluate the analytical potentials of such nano-platform, the concentration of Cr 2 O 7 2− have been determined in real water and river samples. Highlights • Ultrasonic irradiation was used to assemble carbon dots. • Blue-emissive carbon dots were prepared. • Excitation-dependent feature was explored. • Dual sensing modes were developed. [ABSTRACT FROM AUTHOR]

Abstract A novel strategy to highly sensitize terbium luminescence through 3-carboxyphenylboronic acid as the antenna ligand has been realized and the hybrid inorganic-organic probe has been assembled based on the silver nanoparticles. Its green emission is turned off in the presence of dopamine and the detection process is within 2–3 s. Cyclic voltammetry curves showed that a glassy carbon electrode modified with this lanthanide nanostructure demonstrated favorable electrocatalytic activity for the oxidation of dopamine in phosphate buffer. The developed nanosensor gave rise to a linear correlation depending on dopamine concentration and the detection limit was determined to be 0.41 μM. This dual-modal (optical and electrochemical) probe exhibited excellent selectivity and enough stability. The feasibility of the terbium sensitized nanosensor for cellular imaging has also been reported. Two adherent cell lines (Hela cells and THP-1 cells) exposed to the nanoprobe demonstrated striking green luminescence and showed on-off changes in the regulation of dopamine. Highlights • Terbium complex was covalently modified onto silver nanostructures. • Fluorescence and cyclic voltammetry exhibited signal changes to dopamine. • Real-time monitoring of dopamine in two cell lines has been realized. [ABSTRACT FROM AUTHOR]

Abstract Hybrid organic-inorganic perovskites are a new class of photoluminescent and low-cost nanomaterials. Chemical transformation using less-toxic elements under ambient reaction conditions has emerged as a major issue due to pressures on environment and human health. Herein, the synthesis of copper-incorporated CH 3 NH 3 Pb 1-x Cu x Br 3 based on a ligand-assisted reprecipitation (LARP) technique has been reported. The achieved quantum dots have an average size of 8 nm and the existence of copper has been verified by morphological studies. The nanoscale particles exhibited strong blue luminescence upon the excitation at 370 nm. The replacement by Cu2+ resulted in emission evolution from 468 to 513 nm and the photophysical properties were discussed. This study will open a new approach to control the fluorescence of perovskite-type quantum dots, which will extend its application in different areas. Highlights • Copper-incorporated hybrid perovskite has been prepared. • The internal structure and morphology were discussed. • The replacement by Cu2+ resulted in emission evolution. [ABSTRACT FROM AUTHOR]