Qingfen Niu

A highly selective and sensitive fluorescent sensor for the rapid detection of Hg2 + based on phenylamine-oligothiophene derivative

A fast-responsive fluorescent phenylamine-oligothiophene sensor 3TDDA was reported. This sensor exhibited highly selective and sensitive detection of Hg(2+) ion in aqueous solution (THF/CH3CN/H2O, 45/50/5, v/v) through fluorescence quenching. The detection was not affected by the coexistence of other competitive metal ions such as Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A stoichiometric ratio (1:1) of the sensor and Hg(2+) was determined by a Jobs plot and mole-ratio curves. The binding of sensor 3TDDA and Hg(2+) was also chemically reversible with EDTA. The detection limit was calculated as low as 4.392×10(-7) M.

Highly selective, sensitive and fast-responsive fluorescent sensor for Hg2 +

A phenylamine-oligothiophene-based fluorescent sensor 2TBEA was reported. This sensor exhibited highly selective, sensitive and rapid detection of Hg(2+) ion in THF/H2O (7/3, v/v) solution through fluorescence quenching. The detection was unaffected by the coexistence of other competitive metal cations including Na(+), K(+), Ag(+), Ca(2+), Fe(3+), Al(3+), Co(2+), Cu(2+), Ni(2+), Zn(2+), Pb(2+), Cd(2+), Fe(2+) and Cr(3+). A1:1 binding ratio for 2TBEA - Hg(2+) was demonstrated by Jobs plot and mole-ratio curves. The coordination process was chemically reversible with EDTA. The detection limit was evaluated to be as low as 6.164×10(-8)M.

A Fast-Responsive Fluorescent Sensor for Hg 2+ with High Selectivity and Sensitivity in Aqueous Media

A fast-responsive fluorescent phenylamine-oligothiophene sensor 2TBDA was reported. This sensor exhibited highly selective and sensitive detection of Hg2+ ion in THF/H2O (7/3, v/v) solution through fluorescence quenching. The detection was not affected by the coexistence of other competitive metal ions. In addition, the detection limit was found to be as low as 3.841 × 10−7 M.

Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN- on the vinyl CC bond has been successfully confirmed by the optical measurements, 1H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19μM, which is much lower than the maximum permission concentration in drinking water (1.9μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN- in field measurements.

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor for the naked-eye detection of Cu2 + in ~ 100% aqueous media and application to real samples

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor ADA for the naked-eye detection of Cu2+ was developed. Sensor ADA showed high selectivity and sensitivity toward Cu2+ in ~100% aqueous media over wide pH range. Sensor ADA exhibited a red-shift in the absorption spectra from 466 to 480nm that is accompanied by significant color change from light yellow to yellowish brown instantaneously. The Cu2+ recognition is based on the chelation-enhanced fluorescence quenching (CHEQ) effect of the paramagnetic nature. The lowest detection limit is determined to be 15.8nM, which is much lower than the allowable level of Cu2+ in drinking water set by U.S. Environmental Protection Agency (~20μM) and the World Health Organization (~30μM). The 1:1 binding process was confirmed by fluorescence measurements, IR analysis and DFT studies. Moreover, sensor ADA was successfully applied for determination of trace level of Cu2+ with 4 reuse cycles in various water samples, which affords promising potential in ion-detection field.

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3 + and its practical application

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe3+ detection was designed and synthesized. In presence of Fe3+, sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe3+ complex was found as 2.4×104 with the lower detection limit of 14.3nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1H NMR spectra. Sensor L for Fe3+ detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe3+ ions in practical water samples with good recovery.

The synthesis and properties of linear A–π–D–π–A type organic small molecule containing diketopyrrolopyrrole terminal units

A novel linear A-π-D-π-A-type organic small molecule Ph2(PDPP)2 consisting diketopyrrolopyrrole (DPP) as acceptor unit, biphenylene as donor unit and acetylene unit as π-linkage has been successfully designed and synthesized. Its corresponding thermal, photophysical and electrochemical properties as well as the photoinduced charge-separation process were investigated. Ph2(PDPP)2 exhibits high thermal stability and it can be soluble in common organic solvents such as chloroform and tetrahydrofuran. The photophysical properties show that DPP2Ph2 harvests sunlight over the entire visible spectrum range in the thin-film state (300-800nm). DPP2Ph2 has lower band gaps and appropriate energy levels to satisfy the requirement of solution-processable organic solar cells. The efficient photoinduced charge separation process was clearly observed between DPP2Ph2 with PC61BM and the Ksv value was found to be as high as 2.13×104M-1. Therefore, these excellent properties demonstrate that the designed A-π-D-π-A-type small molecule Ph2(PDPP)2 is the prospective candidate as donor material for organic photovoltaic material.

Highly selective and sensitive determination of Cu 2+ in drink and water samples based on a 1,8-diaminonaphthalene derived fluorescent sensor

A new simple and efficient fluorescent sensor L based on 1,8‑diaminonaphthalene Schiff-base for highly sensitive and selective determination of Cu2+ in drink and water has been developed. This Cu2+-selective detection over other tested metal ions displayed an obvious color change from blue to colorless easily detected by naked eye. The detection limit is determined to be as low as 13.2 nM and the response time is very fast within 30 s. The 1:1 binding mechanism was well confirmed by fluorescence measurements, IR analysis and DFT calculations. Importantly, this sensor L was employed for quick detection of Cu2+ in drink and environmental water samples with satisfactory results, providing a simple, rapid, reliable and feasible Cu2+-sensing method.

Novel thiophene-based colorimetric and fluorescent turn-on sensor for highly sensitive and selective simultaneous detection of Al3+ and Zn2+ in water and food samples and its application in bioimaging

A novel bifunctional thiophene-based Schiff base TS as a colorimetric and fluorescent turn-on sensor for rapid and simultaneous detection of Al3+ and Zn2+ ions with high selectivity and sensitivity has been developed. The sensor shows remarkable fluorescence enhancement response for Al3+ and Zn2+ over a broad pH range with good anti-interference capability, which accompanied with an obvious color change easily detected by naked eyes. Sensor TS can detect as low as 3.7 × 10-9 M for Al3+ and 3.0 × 10-8 M for Zn2+, whereas respective association constants are 1.16 × 104 M-1 and 2.08 × 104 M-1. With the help of fluorescence titration and Jobs plot, the stoichiometric ratio of TS with Al3+/Zn2+ was determined to be 1:1. The sensing mechanism of sensor TS with Al3+/Zn2+ based on the chelation-enhanced fluorescence (CHEF) was analyzed in detail through 1H NMR titration, FTIR, HRMS and DFT studies. Moreover, sensor TS has been applied to the detection of Al3+ and Zn2+ in real environmental water and food samples as well as the filter paper-based test strips. Furthermore, sensor TS has good cell-permeability and can be used to selectively sense intracellular Al3+ and Zn2+ by bioimaging.

Novel one-pot synthesis of symmetrically substituted ureas

ABSTRACT We demonstrated a novel, facile, high-yield, and efficient one-pot approach for the synthesis of symmetrically disubstituted ureas from isocyanates in the presence of trimethylsilanol. This novel protocol boasts the use of inexpensive reagents, operational simplicity, excellent yields of products, environmentally friendly conditions, and easy workup. To the best of our knowledge, this is the first example of the synthesis of symmetrically disubstituted ureas from isocyanates in the presence of trimethylsilanol in one pot. GRAPHICAL ABSTRACT