Zhanxian Li

A Novel Sensitive Turn-on Fluorescent Zn2+ Chemosensor Based on an Easy To Prepare C3-Symmetric Schiff-Base Derivative in 100% Aqueous Solution

A C(3)-symmetric Schiff-base example of the new simple, low cost, highly water soluble, and sensitive turn-on fluorescent Zn(2+) chemosensor is described. The sensor was successfully applied to the detection of intracellular Zn(2+). Moreover, the sensor could also serve as a potential recyclable component in sensing materials. Notably, the color change is so obvious that all of the recycling process can be seen clearly by the naked eye.

A “switching on” fluorescent chemodosimeter of selectivity to Zn2+ and its application to MCF-7 cells

A highly sensitive and selective 1,8-naphthyridine-based fluorescent chemodosimeter for Zn(2+) has been designed, synthesized, and applied to the detection of intracellular Zn(2+).

1,8-Naphthyridine-Derived Ni2+/Cu2+-Selective Fluorescent Chemosensor with Different Charge Transfer Processses

A highly fluorescent chemosensor based on 1,8-naphthyridine with high sensitivity and selectivity toward Ni(2+)/Cu(2+) over other cations both in aqueous solution over a wide pH range (4-10) and in cellular environments was developed. Counteranions such as acetate, sulfate, nitrate, and perchlorate have no influence on the detection of such metal ions. Ethylenediamine showed high selectivity toward the in situ-prepared Cu(2+) complex over the Ni(2+) complex, which can be applied to distinguish Ni(2+) and Cu(2+). The Ni(2+)-induced fluorescence on-off mechanism was revealed to be mediated by intramolecular charge transfer from the metal to the ligand, while that by Cu(2+) involves intramolecular charge transfer from the ligand to the metal, as confirmed by picosecond time-resolved fluorescence spectroscopy and time-dependent density functional theory calculations.

Naked-eye detection of C1-C4 alcohols based on ground-state intramolecular proton transfer.

Previous reports of fluorescent sensors for alcohols based on charge-transfer character of their excited state are based on mono-, di-, and tetra-phosphonate cavitands, which are capable of selecting analytes through shape/size selection and various specific H-bonding, CH-π, and cation-dipole interactions. To contrast, color changes based on absorption properties of the ground state are more suitable for direct observation with the naked eye. Three sensitive and selective colorimetric sensors for C1-C4 alcohols have been developed on the basis of alcohol-mediated ground-state intramolecular proton transfer. Reverse proton transfer induced by water achieves a fully reversible reaction. In addition, the solvent color indicates alcohol concentration.

A fluorescent probe for benzenethiols and its application on test paper, in water samples and living cells

It is important to develop probes for rapid, selective, and sensitive detection of highly toxic benzenethiols in both environmental and biological science. In this work, based on the selective cleavage reaction by benzenethiols under mild conditions, a novel naphthalimide-based fluorescent probe was designed and synthesized for the rapid recognition of benzenethiols with excellent selectivity and anti-interference over other various species including some nucleophilic species, aliphatic thiols, anions and metal ions. The limit of quantification (LOQ) value was 0–4.0 μM and the detection limit could be as low as 10.3 nM. The fluorescence enhancement of this probe upon addition of benzenethiol on test paper and the application of the probe for selective detection in water samples and living cells have been successfully demonstrated.

A dual-model and on–off fluorescent Al3+/Cu2+-chemosensor and the detection of F−/Al3+ with ‘in situ’ prepared Al3+/Cu2+ complexes

A multifunctional fluorescent chemosensor for Al3+ and Cu2+ has been developed, which displays a dual-model and on–off fluorescence response upon addition of Al3+ and Cu2+ respectively. The fluorescence signals of the chemosensor can be restored with F− and ethylenediaminetetraacetic acid (EDTA) disodium for Al3+ and Cu2+, showing that the binding of the chemosensor and Al3+/Cu2+ is chemically reversible. The ‘in situ’ prepared Al3+ complex (1·Al) showed high selectivity toward F−, which can be applied to distinguish F− from Cl−, Br− and I−. Moreover, the fluorescence emission intensity of the ‘in situ’ prepared Cu2+ complex (1·Cu) is increased with the addition of Al3+, demonstrating that 1·Cu could be a good off–on Al3+ sensor candidate.

Nanomolar detection of Hcy, GSH and Cys in aqueous solution, test paper and living cells

A novel naphthalimide-based fluorescent probe was designed and synthesized for thiol recognition with high sensitivity and excellent selectivity. The probe can detect thiol quantitatively in a concentration range of 0–6.0 μM and the detection limit could be as low as 1.6 nM. The fluorescence enhancement of this probe upon addition of Cys on test paper and the application of the probe for selective detection of intracellular Hcy, GSH and Cys have been successfully demonstrated.

Naked-eye and fluorescence detection of basic pH and F− with a 1,8-naphthalimide-based multifunctional probe

Based on 1,8-naphthalimide, a novel multifunctional colorimetric and fluorescent probe was designed and synthesized for basic pH and F− naked-eye and fluorescence recognition with high sensitivity and excellent selectivity. The probe can detect F− quantitatively in a concentration range of 0–16.7 μM and 0–20 μM in different methods, and the detection limit could be as low as 25 nM for F−. The detection of F− on chromatography plates and the preliminary application of the probe to detect fluoride contents in toothpaste have been successfully demonstrated.

A new near-infrared ratiometric fluorescent probe for hydrazine

It is important to develop fluorescent probes for rapid, selective, and sensitive detection of highly toxic hydrazine in both environmental and biological science. In this text, under mild conditions, a novel near-infrared (NIR) ratiometric and on–off fluorescent probe 1 was synthesized based on hemicyanine and coumarin derivatives, which can detect hydrazine with high selectivity and anti-interference over other amines, biological species, anions and metal ions. The limit of quantification (LOQ) value was 0–400 μM and the detection limit could be as low as 560 nM.

Near-infrared ratiometric fluorescent detection of arginine in lysosome with a new hemicyanine derivative

A Near-Infrared (NIR) ratiometric and on-off fluorescent probe 1 was synthesized, which exhibited high sensitivity and excellent selectivity in arginine (Arg) recognition. 1 can quantitatively detect Arg in concentration range from 0 to 150μM with the LOD of 138nM. Further, it displayed excellent selectivity and anti-interference over many biological species, metal ions and anions. Due to its ability to target lysosome, the response of Arg to this probe in a living cell was successfully tracked in a ratiometric manner via fluorescence imaging.