Hongdong Duan

Fluorescence sensors for Cu 2+ based on conjugated indole Schiff base

Two new conjugated Schiff bases were prepared by condensation reactions between indole derivatives and o-phenylenediamine, respectively. The structures of the synthetic compounds were characterized by IR, 1H NMR, and elemental analysis. And the melting point determination revealed that both compounds have good thermal stability. Their fluorescence measurements indicated that both compounds in solution have excellent performance on fluorescence emission, and the intensity of fluorescence emissions was quenched sharply by adding copper (II) nitrate. And the spectral changes were examined upon addition of various metal ions, such as Cu2+, Cd2+, Co2+, Ni2+, and Zn2+. The results indicated that the fluorescence intensity of two compounds quenched dramatically, and the quenching efficiency of Cu2+ was the highest.

Fluorescence sensors for Zn2+ based on conjugated indole Schiff base

Two novel fluorescence probes based on conjugated Schiff base for the detection of Zn(2+) were developed. Corresponding molecular geometries, orbital energies, electron contributions and absorption properties of the fluorescence probes were calculated at B3LYP/6-31G(∗) by density functional theory. The fluorescence properties of the probes were investigated by UV-vis and fluorescence spectrometer. Results indicate that the probes exhibit excellent sensitivity and selectivity for Zn(2+) compared with metal ions examined. For example, the enhancement efficiency of the compound 2 for Zn(2+) is up to 846%. The detection limit of the sensor toward Zn(2+) could low to 1.0×10(-7)M. Moreover, mechanisms for the high selectivity and sensitivity of the probes to Zn(2+) were studied.

Original and Efficient Synthesis of D-Cycloserine

A simple pathway for the preparation of D‐cycloserine is presented. The intermediates and D‐cycloserine were characterized by FT‐IR, 1H‐NMR spectra and elemental analysis. D‐Cycloserine can inhibit the growth of Mycobacterium tuberculosis and can be used as a second‐line drug for the treatment of tuberculosis, especially for the use in developing countries.

New turn-on fluorescence sensors for Co2+ based on conjugated carbazole Schiff base

Two novel conjugated Schiff bases were prepared and characterized by IR, 1H NMR, and elementary analysis. Their fluorescence measurements indicated that both compounds have excellent performance on fluorescence emission, and the intensity of fluorescence emissions was enhanced sharply by adding Co2+. These compounds can be used as highly sensitive fluorescence turn-on sensors for Co2+ with the detection limit below 10−14 M.

Synthesis and Characterization of Some New Star-Shaped Polydentate Ligands from 2,4,6-Trichloro-1,3,5-triazine

Some new star-shaped polydentate ligands were synthesized using 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine as a template and were characterized by infrared, 1H NMR, and 13C NMR spectra and elemental analysis. These products may form polynuclear complexes with metal ions, and the complexes may possess potential applications in the area of electromaterials, optomaterials, magnetic materials, and bio-organic materials.

Design, synthesis, and characterization of indole derivatives

In this work, two novel indole–hydrazone analogues were prepared by condensation reactions between 5-methoxyindole-3-carboxaldehyde and isobutyric acid hydrazide or hydrazine hydrate, respectively. The structural properties of the synthetic products were confirmed by FT-IR, 1H NMR, and elemental analysis, while the thermal stabilities and purities were measured by melting point determination. The inhibition effect of compounds was predicted by quantum treatment. The results showed that these compounds can be used as inhibitors.

Real-Time Monitoring on the Kinetics of the Toluene Diisocyanate–Polyol Reaction

In-situ Fourier Transform infrared (FTIR) spectroscopy was employed to investigate the kinetics of the non-catalyzed polycondensation reaction between toluene-2,4-diisocyanate (TDI) and polyether diol. By monitoring the decrease in the NCO absorption band of TDI, the kinetic constants at different temperatures in the range from 50°C to 90°C were obtained and hence the activation energies. These studies showed that the reaction was divided into two phases, and a reasonable fit of the reaction profile could be obtained from combining the rate equations of each of the two phases.

High-yield synthesis and characterisation of a potential chelating agent 2,4,6-triamino-1,3,5-triazine-N,N,N',N',N ,N -hexaacetic acid

A useful and potential chelating agent, 2,4,6-triamino-1,3,5-triazine-N,N,N′,N′,N″,N″-hexaacetic acid (melamine hexaacetic acid), was synthesised by nucleophilic substitution through three steps and its structure was confirmed by IR, 1H NMR, 13C NMR and elemental analyses. The chelation value of melamine hexaacetic acid was determined, by calcium oxalate titration. In comparison with EDTA, melamine hexaacetic acid has better chelating ability.