Lei Ziqiang

A self-assembled triphenylamine-based fluorescent chemosensor for selective detection of Fe3+ and Cu2+ ions in aqueous solution

A novel triphenylamine-based fluorescent sensor tris((4-amino)phenylduryl)amine (m-TAPA) for Fe3+/Cu2+ ion has been developed. m-TAPA shows high selectivity and sensitivity toward Fe3+/Cu2+ over alkali and transition metal ions in aqueous solution. The possible mechanism of fluorescence quenching was that Fe3+/Cu2+ can be captured by the NH2 groups of m-TAPA to form non-fluorescent complexes, resulting in strong quenching. The detection limits of Fe3+ and Cu2+ were calculated to be 230 nM and 620 nM, respectively. Furthermore, fluorescent test strips have been prepared for convenient detection of Fe3+ and Cu2+ ions in environmental water samples, even in drinking water.

Self-assembled triphenylamine derivative for trace detection of picric acid

Detection of explosives is of utmost importance due to the threat to human security as a result of illegal transport and terrorist activities. Picric acid (PA) is widely used in the industrial and military fields, and is inadvertently able to contaminate the environment and groundwater, posing a threat to human health. Achieving the detection of explosives at the parts per billion (ppb) level using chemosensors is a great challenge. Herein, we demonstrate that triphenylamine based fluorescent chemosensors tris(4′-carbethoxybiphenyl) amine (TCEPA) and tris(4′-carboxybiphenyl) amine (TCPA) exhibit superior detection capability for PA in solution state at the ppb level (40 ppb and 5 ppb respectively) and efficient quenching behaviours in the vapor phase at room temperature. In addition, fluorescent test strips have been prepared by dip-coating Thin Layer Chromatography (TCL) for trace detection of PA at the attogram level.

Triphenylamine-decorated BODIPY fluorescent probe for trace detection of picric acid

Triphenylamine-decorated BODIPY derivative TBMA was designed and synthesized. Luminogen aggregation was developed by taking advantage of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) processes. In non-polar solvents, the locally excited (LE) states of BODIPY luminogens emitted intense yellow light. Increasing solvent polarity brought the luminogens from an LE to a TICT state, causing a large bathochromic shift in the emission color and a dramatic decrease in emission efficiency. The red emission was greatly boosted by aggregate formation or AIE effect. We also discovered that TBMA could be applied as an efficient chemical sensor for picric acid (PA) detection. The detection limit and quenching constant (KSV) were determined as 30 ppb and 2.1 × 10−6 M−1 respectively. 19F NMR and 1H NMR titration analysis verified that F⋯H hydrogen bonding is demonstrated as the mode of interaction, which possibly facilitates effective exciton migration.

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradiation. The influence of doping amount of Fe3+ (ω: 0.00%–3.00%) on photocatalytic activities of TiO2 was investigated. Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

Preparation and Characterization of Wool-Pd(0)Catalyst and Its Catalytic Performance for Oxidation of Alcohol in Water

Wool-Pd(0) catalyst was prepared successfully using nature biopolymer wool as stabilizer and supporter. The structure of the palladium catalyst was characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy, and the results showed that Pd(0) particles are well dispersed on the surface of wool. Applying wool-Pd(0) catalyst in the oxidation of alcohol under optimized conditions, several parameters such as catalyst amount, base, reaction temperature, and reaction time were screened. It was found that 35 mg wool-Pd(0) catalyst is available for the oxidation of 0.2 mmol alcohol to corresponding aldehyde or ketone with higher conversion and selectivity in the presence of 0.2 mmol K 2 CO 3 and using water as reaction medium. The heterogeneous catalyst is of good reusability in this reaction system.Wool-Pd(0)catalyst was prepared successfully using nature biopolymer wool as stabilizer and supporter.The structure of the palladium catalyst was characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy,and the results showed that Pd(0)particles are well dispersed on the surface of wool.Applying wool-Pd(0)catalyst in the oxidation of alcohol under optimized conditions,several parameters such as catalyst amount,base,reaction temperature,and reaction time were screened.It was found that 35 mg wool-Pd(0)catalyst is available for the oxidation of 0.2mmol alcohol to corresponding aldehyde or ketone with higher conversion and selectivity in the presence of0.2mmol K2CO3 and using water as reaction medium.The heterogeneous catalyst is of good reusability in this reaction system.

Baeyer-Villiger Oxidation of Cyclohexanone Catalyzed by SBA-15 Supported Silicotungstic Acid

Silicotungstic acid (H4O40SiW12) was supported on SBA-15 with the content of 20% by impregnation. The structure and proper-ties of the catalyst were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and transmis-sion electron microscopy. H4O40SiW12 was highly dispersed on SBA-15 without structural change. The material was applied as an efficient catalyst for the Baeyer-Villiger oxidation of cyclohexanone under different conditions such as the catalyst amount, reaction temperature, and reaction time. When 10 mg of catalyst was used, the cyclohexanone conversion and selectivity for lactone were up to 86% and 99%, respec-tively, at 70 oC for 8 h. The catalyst had moderate reusability in the oxidation system.

The soft interactions of aminated SiO2 nanoparticles with fluorescent partners: a multi-functional sensing platform with a signal amplification effect

Signal amplification, known as the “molecular wire” effect, is greatly desirable and achieved by the electrostatic interactions of aminated SiO2 nanoparticles (SiO2–NH2) with acidic fluorescent partners (NBTA). This explored sensing platform exhibited a multi-responsive capability toward external stimuli, including that of TFA/Et3N, chloroauric acid, as well as the explosive compound PA.

Preparation and Application of SO 4 2– /SnO 2 /SBA-15 Solid Acid Catalyst for Acetalization of Cyclic Ketones: Preparation and Application of SO 4 2– /SnO 2 /SBA-15 Solid Acid Catalyst for Acetalization of Cyclic Ketones

SO42-/SnO2/SBA-15 catalyst samples with different amounts of SnO2 were prepared by a wetness impregnation method and characterized by X-ray diffraction,N2 adsorption-desorption,and transmission electron microscopy.Their catalytic performance for the acetalization of 4-tert-butylcyclohexanone with glycol was investigated.The results showed that SBA-15 supported SO42-/SnO2 improved the catalytic activity markedly,which was caused by the increasing surface area of the sulfated tin oxide.The catalytic performance of SO42-/20%SnO2/SBA-15 for acetalization of several cyclic ketones with diols was also explored.Under the optimum conditions,a series of cyclic ketones such as cyclohexanone,4-methylcyclohexanone,and 4-tert-butylcyclohexanone were well transformed into the corresponding products.The catalyst can be reused for several times without any significant loss in catalytic activity.