•Green and Facile Synthesis of fluorescent quantum yield Nitrogen-doped carbon dots (N-CDs).•N-CDs exhibit excellent biocompatibility, low-toxicity, and satisfactory chemical stability.•N-CDs have been applied in Fe3+ sensing, cell multicolor imaging.Herein, a simple, green, and low-cost way was developed in the synthesis of fluorescent carbon dots (CDs) with well-distributed size, using one-pot hydrothermal treatment of rose-heart radish. The as-prepared carbon dots exhibit exceptional advantages including high fluorescent quantum yield (13.6%), excellent biocompatibility, low-toxicity, and satisfactory chemical stability. More strikingly, as-synthesized N-CDs generate strong response to Fe3+ ions and gives rise to the fluorescence quenching. This phenomenon was used to develop a fluorescent method for facile detection of Fe3+ with a linear range from 0.02 to 40 μM and a detection limit of 0.13 μM (S/N = 3), and further extended to measure environmental water samples with satisfactory recoveries. Eventually, the low toxicity and strongly fluorescent carbon dots were applied for cell imaging and the quenched fluorescence by adding Fe3+, demonstrating their potential towards diverse applications.Figure optionsDownload full-size imageDownload high-quality image (115 K)Download as PowerPoint slide

The ligand- and copper-free Sonogashira reaction of (Het)aryl halides (Br and Cl) with various terminal alkynes and the Heck coupling of (Het)aryl halides (Br and Cl) with a series of olefins, catalyzed by palladium nanoparticles supported on newly generated Al(OH)3, were developed. The catalyst can be readily recovered and reused 6 times without significant loss of activity and palladium leaching.

•Series of Cn-8-Cn (n = 8, 10, 12, 14, 16) Gemini biquaternary ammonium salt surfactants were prepared.•Cn-8-Cn Gemini surfactants changed their wettability on coal pitch surface by changing charge and polarity.•The wettability of Gemini surfactants on coal pitch surface is the result of electrostatic interaction and van der Waals adsorption.The purpose of this experiment is to confirm the adsorption characteristics at liquid–gas and CP–liquid interfaces in relation to CP wetting with a sequence of cationic Gemini surfactant solutions and to reduce the workload of screening of surfactant. A series of cationic Gemini surfactants with different hydrophobic chain length was synthesized (Cn-8-Cn, n = 8, 10, 12, 14, 16). Their wettability and adsorption mechanism for coal pitch (CP) were investigated by the sessile drop analysis and electrophoresis. Within the whole range of concentration, the Zisman theory is not in accordance with the wettability on the coal tar pitch when carbon atoms of hydrophobic chains exceed 12. Meanwhile, no liner dependence was observed between adhesion tension (γlg cos θ) and surface tension (γlg). In addition, with the increase of surfactant concentration, Zeta potential on the surface of the CP changed from negative to positive and finally leveled off after a certain concentration. The corresponding concentration of zero potential was at least an order of magnitude lower than CMC. C12-8-C12 can significantly change the wettability of the CP. According to the wetting data and Zeta potential of Gemini surfactant on CP, it can be inferred that wetting was a concerted action as a result of electrostatic interaction and van der waals adsorption. Therefore, wetting process can be generally divided into three stages.

A ligand-free Pd/Al(OH)3 nano-catalyst which is prepared by one-pot three-component method using Pd(PPh3)4, tetra (ethylene glycol), and aluminum tri-sec-butoxide exhibits excellent catalytic activity in Stille cross-couplings of (Het)aryl chlorides, arenediazonium tetrafluoroborate salts with phenyltributylstannane, respectively, and Kumada couplings of (Het)aryl chlorides with various Grignard reagents. More importantly, these two processes show excellent functional group compatibility with moderate to good yields and they are also versatile with respect to not only (Het)aryl chlorides, but also diazonium salts, and heteroaryl Grignard reagents. The nano-catalyst could also be recycled and reused 5 times without loss of activity and decrease of yield.

Palladium nanoparticles supported on newly generated Al(OH)3 was found to be a highly efficient catalyst in oxidative homo-couplings of (Het)aryl alkynes, (Het)arylboronic acids and potassium (Het)aryltrifluoroborates, respectively. Moderate to excellent yields of symmetrical 1,3-diynes and biaryls were obtained under mild conditions.

⿢Cn-OH (n = 10,12,14,16,18)were synthesized in our laboratory.⿢The spreading behavior on the surface could be divided into two processes: fast spreading and the slow spreading.⿢A linear relationship exists between the adhesional and surface tension in a range of certain concentrations for PTFE.⿢The wettability of C10-OH solution on PTFE is best, and C14-OH solution has the best wetting effect on Paraffin.The surface tension of five biquaternary ammonium salt Gemini surfactants with hydroxyl and the corresponding contact angles (θ) on Polytetrafluoroethylene (PTFE) and Paraffin are measured. The interfacial properties of surfactant solution in liquid-air-solid are investigated and changes in spreading coefficient (S), adhesive tension (γLVcosθ) and the work of adhesion (WA) are discussed. The obtained results indicate that the surface tension decreases with the increase of surfactant concentration, and it tends to be stable when the concentration is more than CMC. The contact angle has the similar trend with surface tension. A linear relationship exists between the adhesional and surface tension in a range of certain concentrations, the slope is less than 1. It means that the adsorption amount of the surfactant solution at the liquid-air interface is larger than that at the PTFE-water interfaces. However, there is no linear relationship between the adhesional and surface tension for Paraffin-surfactant solution systems. The adhesional tension increases with the increase of concentration, and it keeps constant when the saturated adsorption film has been formed at both liquid-air and solid-liquid interfaces. The wettability of biquaternary ammonium salt Gemini surfactants with hydroxyl solutions on PTFE is poorer than that of Paraffin. The wettability of C10-OH solution on PTFE surface is best, and C14-OH solution has the best wetting effect on Paraffin.Download high-res image (143KB)Download full-size image

FeX3 (X = Cl, Br) were found to be very effective reagents and powerful catalysts for regioselective ring openings of a variety of N-tosylaziridines with them to afford the corresponding β-haloamines in good to excellent yields with high regioselectivity under mild conditions. At the same time, 13 new compounds were obtained firstly. Moreover, the β-bromoamine prepared could be transferred into β-nitroamine with NaNO2 in moderate yield.FeX3 (X = Cl, Br) were effective reagents for regioselective ring openings of various N-tosylaziridines with them to afford the β-haloamines in good to excellent yields and with high regioselectivity, and the β-haloamines obtained can be easily transferred into nitro compounds through the nucleophilic substitution to the Br with NaNO2.