Yunyou Zhou

Long wavelength red fluorescent dyes from 3,5-diiodo-BODIPYs

Amphiphilic and long wavelength red fluorescent dyes (4 and 7) were prepared from the Sonogashira coupling reactions of 3,5-diiodo-BODIPYs (1 and 6). One of these compounds, BODIPY 7, readily accumulated within human carcinoma HEp2 cells and was found to localize mainly within the endoplasmic reticulum (ER).

Bifunctional polydopamine@Fe3O4 core–shell nanoparticles for electrochemical determination of lead(II) and cadmium(II)

The present paper has focused on the potential application of the bifunctional polydopamine@Fe3O4 core-shell nanoparticles for development of a simple, stable and highly selective electrochemical method for metal ions monitoring in real samples. The electrochemical method is based on electrochemical preconcentration/reduction of metal ions onto a polydopamine@Fe3O4 modified magnetic glassy carbon electrode at -1.1 V (versus SCE) in 0.1 M pH 5.0 acetate solution containing Pb(2+) and Cd(2+) during 160 s, followed by subsequent anodic stripping. The proposed method has been demonstrated highly selective and sensitive detection of Pb(2+) and Cd(2+), with the calculated detection limits of 1.4×10(-11)M and 9.2×10(-11) M. Under the optimized conditions, the square wave anodic stripping voltammetry response of the modified electrode to Pb(2+) (or Cd(2+)) shows a linear concentration range of 5.0-600 nM (or 20-590 nM) with a correlation coefficient of 0.997 (or 0.994). Further, the proposed method has been performed to successfully detect Pb(2+) and Cd(2+) in aqueous effluent.

A Preliminary Investigation of the Complexation of Dopamine by p‐Sulfonated Calix[4, 6] Arene and β‐Cyclodextrin Using Fluorescence Spectrometry

Abstract The inclusion complexes of p‐sulfonated calix[4, 6] arene and β‐cyclodextrin with dopamine were studied by fluorescence spectrometry in aqueous media. It was found that the fluorescence intensity of dopamine regularly decreased upon the addition of p‐sulfonated calix[4, 6] arene, on the contrary, it increased upon the addition of β‐cyclodextrin. 1H NMR spectra were applied to verify the formation of the complexes. According to the experimental results, 1:1 stoichiometry for the complexes was established and their association constants at 25°C were calculated by applying a deduced equation. Judging from the magnitude of their inclusion constants, the p‐sulfonated calix[4, 6] arene showed better inclusion capability than β‐cyclodextrin. The probable interaction mechanisms are proposed.

A novel spectrofluorometric method for the determination of methiocarb using an amphiphilic p-sulfonatocalix[4]arene

The characteristics of host-guest complexation between tetrabutyl ether derivatives of p-sulfonatocalix[4]arene (SC4Bu) and methiocarb [3,5-dimethyl-4-(methylthio) phenyl methylcarbamate] were investigated by fluorescence spectrometry. Upon addition of methiocarb, the fluorescence intensity of SC4Bu was quenched regularly and a slight red shift was observed for the maximum emission peak. These results indicated that the SC4Bu-methiocarb complex was formed a 1:1 mole ratio. An association constant of 1.67×10(4) L mol(-1) was calculated by applying a deduced equation. The interaction mechanism of the inclusion complex was discussed. Based on the results, a novel spectrofluorimetric method was described for the determination of methiocarb with a detection limit at 0.05 μg mL(-1). This method is very simple and shows high sensitivity and selectivity. Moreover, the proposed method was successfully applied to the determination of methiocarb in water samples.

Spectrofluorometric study on the inclusion behavior of p-(p-carboxyl benzeneazo) calix[4]arene with norfloxacin.

Spectrofluorometric titrations have been performed to investigate the inclusion behavior of p-(p-carboxyl benzeneazo) calix[4]arene (CBC4A) with norfloxacin (NFLX) in NaAc-HAc buffer solution (pH=5.0). It was found that the fluorescence intensity of NFLX quenched regularly upon the addition of CBC4A. The results indicated 1:1 complex stoichiometry and an association constant of 8.21 x 10(5) L mol(-1) at 20.0 degrees C were calculated by applying a deduced equation. Jobs plot also verified the existence of 1:1 inclusion complex. The proposed interaction mechanism indicates that NFLX goes into (or partially goes into) the cavity of CBC4A with the help of hydrogen bonding and other forces. The various factors (pH value, ionic strength, and surfactants) affecting the inclusion process were examined in details.

Determination of 1-naphthol with denatured DNA-modified pretreated glassy carbon electrode

Abstract A highly sensitive electrochemical biosensor for the detection of trace amount of 1‐naphthol was designed. Acid‐denatured DNA were immobilized onto the pretreated glassy carbon electrode (GCE(ox)) surface. Two well‐defined oxidation peaks were observed on the denatured DNA‐modified GCE(ox) at about +0.80 V and +1.10 V (vs. Ag/AgCl) in 0.10‐M acetate buffer (pH 5.0). The peak current of the guanine residue decreased with increasing concentration of 1‐naphthol. The optimum experimental conditions for the detection of 1‐naphthol were explored, and the calibration was linear for 1‐naphthol in the range of 1.0×10−8−1.1×10−6 M, with a correlation coefficient of 0.998. The limit of detection (LOD) was 5.0×10−9 M (S/N=3).

Spectrofluorimetric study on the inclusion interaction between vitamin K3 with p-(p-sulfonated benzeneazo)calix[6]arene and determination of VK3.

The characteristics of host-guest complexation between p-(p-sulfonated benzeneazo) calix[6]arene (SBC6A) and vitamin K3 (VK3) were investigated by fluorescence spectrometry. A 1:1 stoichiometry for the complexation was established and was verified by Jobs plot. An association constant of 4.95 x 10(3)L mol(-1) at 20 degrees C was calculated by applying a deduced equation. The interaction mechanism of the inclusion complex was discussed. It was found that the fluorescence of SBC6A could be remarkably quenched by an appropriate amount of VK3 especially when non-ionic surfactant Triton X-100 existed. According to the obtained results, a novel sensitive spectrofluorimetric method for the determination of VK3 based on supramolecular complex was developed with a linear range of 5.0 x 10(-7) -3.0 x 10(-5)mol L(-1) and a detection limit of 2.0 x 10(-7)mol L(-1). The proposed method was used to determine VK3 in commercial preparations with satisfactory results.

Spectrofluorometric studies on the interaction between oxacalix[6]arene-locked trizinc(II)porphyrins and crystal violet.

A new fluorogenic oxacalix[6]arene bearing three zinc(II) porphyrin groups (1) was prepared. When crystal violet (CV) was bound to 1, fluorescence intensity of 1 was quenched regularly. This indicates that 1 and CV formed a 1:1 complex and the association constant was calculated. The inclusion mechanism was also discussed. This new fluorometric method was developed for rapid determination of CV with a good linearity in the concentration range of 1.40-37.4 micromolL(-1). The method was applied for the determination of CV in synthetic samples successfully.

Preparation and Property Screening of the Solid Inclusion Complex of Norfloxacin with p-Sulfonated Calix[4]arene

The complexation of norfloxacin (NFLX) by p-sulfonated calix[4]arene (SC4A) in aqueous solution has been studied by fluorescence spectroscopy and 1H NMR spectroscopy. A 1:1 stoichiometry and a 8086 L mol(-1) stability constant of the NFLX-SC4A complex was obtained by spectrofluorometric titrations. The equimolar solid state inclusion complex of NFLX-SC4A was prepared by the co-precipitation method and then characterized by various techniques, including differential scanning calorimetry (DSC), X-ray powder diffractometry (XRD), Fourier-transform infrared analysis (FT-IR) and scanning electron microscopy (SEM). The experimental results of these chemical property screenings confirmed that NFLX and SC4A can form a stable host-guest complex in the solid state, and SC4A appears to function as a complexing and solubilizing agent for NFLX.

Inclusion complex of riboflavin with cucurbit[7]uril: study in solution and solid state

The aqueous solution of riboflavin and cucurbit[7]uril complex has been studied based on fluorescence and 1H NMR spectroscopic results. Upon addition of cucurbit[7]uril, the fluorescence intensity of riboflavin was quenched and a slight red shift was observed for the maximum emission peak. These results indicated that the cucurbit[7]uril–riboflavin complex was formed at a 1:1 mole ratio. The temperature-dependent inclusion constants were calculated, from which ΔH and ΔS values were calculated. Meanwhile, rationale of the interaction mechanism was also discussed based on 1H NMR results. The solid inclusion complex was prepared from co-evaporation method and characterised by differential thermal analysis and fluorescence lifetime analysis methods. The experimental results indicated that riboflavin and cucurbit[7]uril formed stable host–guest inclusion complex in both solution and solid states.