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2015 Volume 32 Issue 8
2015, 32(8): 855-872
doi: 10.11944/j.issn.1000-0518.2015.08.150134
Abstract:
Organic light-emitting diodes (OLEDs) have attracted great interest because of their potential applications in full-color flat-panel displays and solid-state lighting.Compared with great progress of organic red-and green-light-emitting materials and diodes,few blue-light-emitting materials and diodes with high performances have been reported.It is really difficult to realize organic deep-blue device with low operating voltage,high luminescent efficiency and good stability because of the relatively wider energy gap of blue-lightemitting materials.In general,white organic light-emitting diodes (WOLEDs) can be obtained by incorporating either three primary colors (red,green and blue) or two complementary colors (blue and yellow or orange).No matter which method,organic blue-light-emitting materials are necessary.In addition,blue light can generate other low-energy emission,such as green and red,by utilizing a color-change medium.So the realization of organic blue-emitting materials with high performances is critical for the development and application of OLEDs.In this paper,we clarified the recent progress of investigations on organic blue fluorescent materials and phosphorescent materials.The application of organic blue light-emitting materials in the blue and white organic light-emitting diodes was also introduced.Based on the present work,the investigation and application of organic blue light-emitting materials were finally prospected.
Organic light-emitting diodes (OLEDs) have attracted great interest because of their potential applications in full-color flat-panel displays and solid-state lighting.Compared with great progress of organic red-and green-light-emitting materials and diodes,few blue-light-emitting materials and diodes with high performances have been reported.It is really difficult to realize organic deep-blue device with low operating voltage,high luminescent efficiency and good stability because of the relatively wider energy gap of blue-lightemitting materials.In general,white organic light-emitting diodes (WOLEDs) can be obtained by incorporating either three primary colors (red,green and blue) or two complementary colors (blue and yellow or orange).No matter which method,organic blue-light-emitting materials are necessary.In addition,blue light can generate other low-energy emission,such as green and red,by utilizing a color-change medium.So the realization of organic blue-emitting materials with high performances is critical for the development and application of OLEDs.In this paper,we clarified the recent progress of investigations on organic blue fluorescent materials and phosphorescent materials.The application of organic blue light-emitting materials in the blue and white organic light-emitting diodes was also introduced.Based on the present work,the investigation and application of organic blue light-emitting materials were finally prospected.
2015, 32(8): 873-883
doi: 10.11944/j.issn.1000-0518.2015.08.140402
Abstract:
Fifteen new tripod type benzimidazolium salts (3a~3o) were synthesized and characterized by IR,NMR and HRMS.The plant growth regulating activities of compound 3 were evaluated.Compounds 3a,3c,3f,3g,3h,3i and 3j exhibit excellent cytokinesis activities up to 88.3% at the concentration of 10 mg/L which are higher than that of the reference triadimefon (50.2%),but their auxin activities are not obviously effective.Nearly all the target compounds have excellent herbicidal activity,while compound 3i is the best with 95.6%.The fluorescent identification of the four representative target molecules on six important anions was explored by fluorescence spectrum.The target compounds can be used as fluorescence probe for I- identification.
Fifteen new tripod type benzimidazolium salts (3a~3o) were synthesized and characterized by IR,NMR and HRMS.The plant growth regulating activities of compound 3 were evaluated.Compounds 3a,3c,3f,3g,3h,3i and 3j exhibit excellent cytokinesis activities up to 88.3% at the concentration of 10 mg/L which are higher than that of the reference triadimefon (50.2%),but their auxin activities are not obviously effective.Nearly all the target compounds have excellent herbicidal activity,while compound 3i is the best with 95.6%.The fluorescent identification of the four representative target molecules on six important anions was explored by fluorescence spectrum.The target compounds can be used as fluorescence probe for I- identification.
2015, 32(8): 884-891
doi: 10.11944/j.issn.1000-0518.2015.08.150005
Abstract:
A practical,mild and highly efficient cyanoalkylation reaction of activated alkenes by copper catalysis has been developed.In the presence of CuI/DTBP (Di-tert-butyl peroxide),N-arylacrylamide undergoes radical cyclization smoothly,and affords a series of pharmaceutically important oxindoles bearing an α-cyano quaternary carbon center.The protocol features broad substrate scope,simplicity of operation and handling,and inexpensive catalytic systems.In addition,the synthetic application and possible mechanism process in the cyclization reaction were also demonstrated.
A practical,mild and highly efficient cyanoalkylation reaction of activated alkenes by copper catalysis has been developed.In the presence of CuI/DTBP (Di-tert-butyl peroxide),N-arylacrylamide undergoes radical cyclization smoothly,and affords a series of pharmaceutically important oxindoles bearing an α-cyano quaternary carbon center.The protocol features broad substrate scope,simplicity of operation and handling,and inexpensive catalytic systems.In addition,the synthetic application and possible mechanism process in the cyclization reaction were also demonstrated.
2015, 32(8): 892-899
doi: 10.11944/j.issn.1000-0518.2015.08.140456
Abstract:
Polymer microgel-supported Ni particles were prepared by impregnation first with a small amount of Ni seeds on microgels,then by electroless nickel plating on the seeded microgels.The nickel particles exhibit good catalytic activity in hydrogen transfer reactions of aromatic nitro compounds with hydrazine hydrate as the hydrogen donor.Dynamic light scattering characterization shows that Ni embedded gel particles have hydrodynamic diameters of approximately 411.9 nm.Results from high resolution transmission electron microscopy and X-ray photoelectron spectroscopy demonstrate that Ni is mainly in the form of NiO.The effect of the hydrazine hydrate amount on the reaction was examined for the reduction of nitrobenzene.The result show that a molar ratio of 1:15 for the substrate to hydrazine hydrate is optimal for the reduction.The optimized conditions are used for reduction of a series of aromatic nitro compounds,giving rise to high yields of aromatic amines.Kinetic analysis shows that the Arrhenius activation energy is 133.7 k J/mol,the enthalpy is130.9 k J/mol,and the entropy is 102.8 J/(mol·K).
Polymer microgel-supported Ni particles were prepared by impregnation first with a small amount of Ni seeds on microgels,then by electroless nickel plating on the seeded microgels.The nickel particles exhibit good catalytic activity in hydrogen transfer reactions of aromatic nitro compounds with hydrazine hydrate as the hydrogen donor.Dynamic light scattering characterization shows that Ni embedded gel particles have hydrodynamic diameters of approximately 411.9 nm.Results from high resolution transmission electron microscopy and X-ray photoelectron spectroscopy demonstrate that Ni is mainly in the form of NiO.The effect of the hydrazine hydrate amount on the reaction was examined for the reduction of nitrobenzene.The result show that a molar ratio of 1:15 for the substrate to hydrazine hydrate is optimal for the reduction.The optimized conditions are used for reduction of a series of aromatic nitro compounds,giving rise to high yields of aromatic amines.Kinetic analysis shows that the Arrhenius activation energy is 133.7 k J/mol,the enthalpy is130.9 k J/mol,and the entropy is 102.8 J/(mol·K).
2015, 32(8): 900-908
doi: 10.11944/j.issn.1000-0518.2015.08.140423
Abstract:
One linear and one macrocyclic tetrapepitides (4 and 5) with Fmoc were synthesized by two ways of Trt protection group cleavage in the preparation of symmetrical tetrapepitides using cysteine-modified cyclo (L-Lys-L-Lys) diketopi-perazines.Both tetrapepitides show excellent capability to gelate a number of organic solvents to give thermo-reversible organogels.The self-assembled fibrillar networks in the organogels were distinctly observed by SEM.Interestingly,two organogelators could selectively gelate common chlorinated organic solvents from their mixture with water,even at a concentration as low as 0.1%(volume fraction).Moreover,the xerogel obtained from the organogel of compound 4 in chloroform can high efficiently adsorb various tested dyes from aqueous solutions due to the larger specific surface area of 3D xerogel network showing a micro-and nano-sized structure and the π-π interaction between dye molecules and Fmoc protection groups.The absorption capacity of the xerogel for those dyes increases with the temperature.
One linear and one macrocyclic tetrapepitides (4 and 5) with Fmoc were synthesized by two ways of Trt protection group cleavage in the preparation of symmetrical tetrapepitides using cysteine-modified cyclo (L-Lys-L-Lys) diketopi-perazines.Both tetrapepitides show excellent capability to gelate a number of organic solvents to give thermo-reversible organogels.The self-assembled fibrillar networks in the organogels were distinctly observed by SEM.Interestingly,two organogelators could selectively gelate common chlorinated organic solvents from their mixture with water,even at a concentration as low as 0.1%(volume fraction).Moreover,the xerogel obtained from the organogel of compound 4 in chloroform can high efficiently adsorb various tested dyes from aqueous solutions due to the larger specific surface area of 3D xerogel network showing a micro-and nano-sized structure and the π-π interaction between dye molecules and Fmoc protection groups.The absorption capacity of the xerogel for those dyes increases with the temperature.
2015, 32(8): 909-915
doi: 10.11944/j.issn.1000-0518.2015.08.140425
Abstract:
A series of NN-bidentate nickel (Ⅱ) complexes bearing pyrazolylimine ligands (4a~4e) was synthesized and characterized by FTIR and elemental analysis.Determined by X-ray single crystal diffraction,complex 4b adopted distorted trigonal bipyramidal geometry around the central metal.Activated by ethylaluminum sesquichloride (EASC),all complexes exhibited high cis-1,4 selectivity towards 1,3-butadiene polymerization to afford liquid polybutadienes (PB) with relative molecular mass of 4500~9000 and 91% cis-1,4 content.The catalytic activity of the complex decreased as the hindrance of the substituent on the ligand increased.The effects of Al/Ni molar ratio and polymerization temperature on the polymerization were further investigated in details.The catalytic activity increased with the increase of polymerization temperature from20℃ to 60℃,and the polymer yield only slightly decreased even at a high temperature of 80℃,indicating high thermal stability of the active species generated by the present catalytic system.
A series of NN-bidentate nickel (Ⅱ) complexes bearing pyrazolylimine ligands (4a~4e) was synthesized and characterized by FTIR and elemental analysis.Determined by X-ray single crystal diffraction,complex 4b adopted distorted trigonal bipyramidal geometry around the central metal.Activated by ethylaluminum sesquichloride (EASC),all complexes exhibited high cis-1,4 selectivity towards 1,3-butadiene polymerization to afford liquid polybutadienes (PB) with relative molecular mass of 4500~9000 and 91% cis-1,4 content.The catalytic activity of the complex decreased as the hindrance of the substituent on the ligand increased.The effects of Al/Ni molar ratio and polymerization temperature on the polymerization were further investigated in details.The catalytic activity increased with the increase of polymerization temperature from20℃ to 60℃,and the polymer yield only slightly decreased even at a high temperature of 80℃,indicating high thermal stability of the active species generated by the present catalytic system.
2015, 32(8): 916-921
doi: 10.11944/j.issn.1000-0518.2015.08.140416
Abstract:
With the introduction of flexible epoxy-terminated polyether (ETPE) as the monomer,herein,we reported a facile and efficient synthesis approach for novel epoxy vinyl ester resin (EVER-2) with high impact toughness.The resin was analyzed by Fourier-transform infrared (FTIR),1H nuclear magnetic resonance (1H NMR) and 13C nuclear magnetic resonance (13C NMR) spectroscopy.Mechanical properties such as tensile strength,flexural strength,impact strength and heat distortion temperature were also determined for EVER-2.The cured resin containing 7.9% mass fraction of ETPE has outstanding performance on impact strength.SEM (scanning electron microscopy) analysis reveals that EVER-2 matrix displays a single-phase morphology and its galss fiber/EVER-2 composite (EVERL-2) exhibits better bonding between the matrix and glass fiber,which means that EVERL-2 can bear more impact strength than galss fiber/EVER-1 composite (EVERL-1).Moreover,plausible toughening mechanisms of EVER-2 and EVERL-2 were proposed.
With the introduction of flexible epoxy-terminated polyether (ETPE) as the monomer,herein,we reported a facile and efficient synthesis approach for novel epoxy vinyl ester resin (EVER-2) with high impact toughness.The resin was analyzed by Fourier-transform infrared (FTIR),1H nuclear magnetic resonance (1H NMR) and 13C nuclear magnetic resonance (13C NMR) spectroscopy.Mechanical properties such as tensile strength,flexural strength,impact strength and heat distortion temperature were also determined for EVER-2.The cured resin containing 7.9% mass fraction of ETPE has outstanding performance on impact strength.SEM (scanning electron microscopy) analysis reveals that EVER-2 matrix displays a single-phase morphology and its galss fiber/EVER-2 composite (EVERL-2) exhibits better bonding between the matrix and glass fiber,which means that EVERL-2 can bear more impact strength than galss fiber/EVER-1 composite (EVERL-1).Moreover,plausible toughening mechanisms of EVER-2 and EVERL-2 were proposed.
2015, 32(8): 922-930
doi: 10.11944/j.issn.1000-0518.2015.08.140439
Abstract:
Under the action of catalyst,the nonylphenol betaine amphoteric surfactant (NSZ) was synthesized from nonylphenol,epichlorohydrin,dimethylamine and 3-chloro-2-hydroxy propyl sulfonic acid sodium by etherification,amination,and quaternization,and the optimum reaction conditions were determined.The optimum synthesis conditions of nonylphenol chlorohydrin ether are:the material ratio n (nonylphenol):n(epichlorohydrin) was 1:4,the total amount of the catalyst tetrabutyl ammonium bromide was 4%(molar fraction) relative to nonylphenol,the reaction time was 4 h and the reaction temperature was 95℃.The optimum synthesis conditions of nonylphenol tertiary amine are:the material ratio n(nonylphenol chloro ether):n(dimethylamine):n(NaOH) was 1:2.5:1.1,the reaction time was 4 h and the reaction temperature was60℃.The optimum synthesis conditions of NSZ are:the volume ratio of isopropanol to water was 2:1,the reaction temperature was 85℃,the reaction time was 24 h,the material ratio n(3-chloro-2-hydroxypropanesulfonate):n(nonylphenol tertiary) was 1.2:1,the pH of the reaction system was 8~9.The interface properties,emulsifying properties and thermal stability of NSZ were measured under the condition of high temperature and high salinity,the results showed that NSZ had a good tolerance to temperature and salt.
Under the action of catalyst,the nonylphenol betaine amphoteric surfactant (NSZ) was synthesized from nonylphenol,epichlorohydrin,dimethylamine and 3-chloro-2-hydroxy propyl sulfonic acid sodium by etherification,amination,and quaternization,and the optimum reaction conditions were determined.The optimum synthesis conditions of nonylphenol chlorohydrin ether are:the material ratio n (nonylphenol):n(epichlorohydrin) was 1:4,the total amount of the catalyst tetrabutyl ammonium bromide was 4%(molar fraction) relative to nonylphenol,the reaction time was 4 h and the reaction temperature was 95℃.The optimum synthesis conditions of nonylphenol tertiary amine are:the material ratio n(nonylphenol chloro ether):n(dimethylamine):n(NaOH) was 1:2.5:1.1,the reaction time was 4 h and the reaction temperature was60℃.The optimum synthesis conditions of NSZ are:the volume ratio of isopropanol to water was 2:1,the reaction temperature was 85℃,the reaction time was 24 h,the material ratio n(3-chloro-2-hydroxypropanesulfonate):n(nonylphenol tertiary) was 1.2:1,the pH of the reaction system was 8~9.The interface properties,emulsifying properties and thermal stability of NSZ were measured under the condition of high temperature and high salinity,the results showed that NSZ had a good tolerance to temperature and salt.
2015, 32(8): 931-939
doi: 10.11944/j.issn.1000-0518.2015.08.140387
Abstract:
Micron-sized thiocyanate anion-imprinted microspheres (IIPMs) were prepared successfully with inverse suspension polymerization method.In the inverse suspension polymerization system,cyclohexane was used as dispersion medium and Span-60 was used as dispersant in the oil phase,cationic monomer of acryloxyethyltrimethyl ammonium chloride (DAC),the crosslinker N,N'-methylene bisacrylamide (MBA) and the template SCN- anion were dissolved in aqueous phase.The crosslinking copolymerization of DAC in waterin-oil droplets was carried out and SCN- IIPMs with diameter of about 200 μm were obtained.The ion recognition selectivity and binding property were investigated with monovalent anions,NO3-and I-,as the references.In water-in-oil droplets,since cationic monomer DAC associates with SCN- anion by strong electrostatic interaction,SCN- anions are imprinted while DAC produces crosslinking polymer.The prepared IIPMs possess strong binding ability (3.3 mmol/g (192 mg/g)) and selectivity.The IIPMs can selectively recognize and bind SCN- anion from a mixture with NO3-and I- ions.The coefficients of the selectivity of IIPMs are 3.24 and 6.78,respectively.The IIPMs also exhibit excellent reusability.
Micron-sized thiocyanate anion-imprinted microspheres (IIPMs) were prepared successfully with inverse suspension polymerization method.In the inverse suspension polymerization system,cyclohexane was used as dispersion medium and Span-60 was used as dispersant in the oil phase,cationic monomer of acryloxyethyltrimethyl ammonium chloride (DAC),the crosslinker N,N'-methylene bisacrylamide (MBA) and the template SCN- anion were dissolved in aqueous phase.The crosslinking copolymerization of DAC in waterin-oil droplets was carried out and SCN- IIPMs with diameter of about 200 μm were obtained.The ion recognition selectivity and binding property were investigated with monovalent anions,NO3-and I-,as the references.In water-in-oil droplets,since cationic monomer DAC associates with SCN- anion by strong electrostatic interaction,SCN- anions are imprinted while DAC produces crosslinking polymer.The prepared IIPMs possess strong binding ability (3.3 mmol/g (192 mg/g)) and selectivity.The IIPMs can selectively recognize and bind SCN- anion from a mixture with NO3-and I- ions.The coefficients of the selectivity of IIPMs are 3.24 and 6.78,respectively.The IIPMs also exhibit excellent reusability.
2015, 32(8): 940-947
doi: 10.11944/j.issn.1000-0518.2015.08.140436
Abstract:
Adsorbent composites comprising of bentonite/sodium lignosulfonate graft-polymerized with acrylamide and maleic anhydride (BLPAMA) were prepared and used to investigate the effect of ionic strength on the adsorption of Pb2+ or Cu2+ onto BLPAMA in single or binary metal ion solutions,the adsorption isotherms,kinetics and thermodynamics of Pb2+ and Cu2+ onto BLPAMA with or without addition of 0.2 mol/L NaNO3 in the binary metal ion solutions.The results show that the increase of ionic strength leads the adsorption capacity of Pb2+ or Cu2+ to decrease in the single metal ion solution,the adsorption capacity of Pb2+ to decrease while the adsorption capacity of Cu2+ to increase in the binary metal ion solution.
Adsorbent composites comprising of bentonite/sodium lignosulfonate graft-polymerized with acrylamide and maleic anhydride (BLPAMA) were prepared and used to investigate the effect of ionic strength on the adsorption of Pb2+ or Cu2+ onto BLPAMA in single or binary metal ion solutions,the adsorption isotherms,kinetics and thermodynamics of Pb2+ and Cu2+ onto BLPAMA with or without addition of 0.2 mol/L NaNO3 in the binary metal ion solutions.The results show that the increase of ionic strength leads the adsorption capacity of Pb2+ or Cu2+ to decrease in the single metal ion solution,the adsorption capacity of Pb2+ to decrease while the adsorption capacity of Cu2+ to increase in the binary metal ion solution.
2015, 32(8): 948-954
doi: 10.11944/j.issn.1000-0518.2015.08.140427
Abstract:
For humanbeings,radicals scavenging plays an important role for maintaining the fundamental physiological and anti-ageing need.Comparison for competing scavenging ability of Vitamin C (VC) with salicylic acid gives optimal scavenging condition for VC.By fitting the Alberty equation,the maximum46.23% clearance of·OH by VC reached when VC concentration is 4.54 mmol/L at 47℃ for 90 min,and the maximum reaction rate is 0.11 mmol/(L·min).The dissociation constant for salicylic acid and VC is 30.2 mmol/L and 1.2×10-3mmol/L,respectively.The experimental data are well-fitted with relative error of 1.66%~5.40%.This is helpful for the effective and scientific usage of VC.
For humanbeings,radicals scavenging plays an important role for maintaining the fundamental physiological and anti-ageing need.Comparison for competing scavenging ability of Vitamin C (VC) with salicylic acid gives optimal scavenging condition for VC.By fitting the Alberty equation,the maximum46.23% clearance of·OH by VC reached when VC concentration is 4.54 mmol/L at 47℃ for 90 min,and the maximum reaction rate is 0.11 mmol/(L·min).The dissociation constant for salicylic acid and VC is 30.2 mmol/L and 1.2×10-3mmol/L,respectively.The experimental data are well-fitted with relative error of 1.66%~5.40%.This is helpful for the effective and scientific usage of VC.
2015, 32(8): 955-962
doi: 10.11944/j.issn.1000-0518.2015.08.140434
Abstract:
The anodic behavior of Al/Pb-0.3% Ag-0.06% Ca/β-PbO2 composite electrode in the acidic zinc sulphate containing different concentrations of Cl- was studied.The microstructures were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD).With the increase of Cl- concentration,the oxygen evolution overpotential,impedance and corrosion rate increase gradually;the intensity of diffraction peak of β-PbO2 and α-PbO2 decreases gradually;the dendritic crystal clusters on the anode surface disappear.When the Cl- concentration is 300 mg/L,the apparent current density (i0) of the anode reaches maximum and the anode shows the best electrochemical properties and corrosion resistance.
The anodic behavior of Al/Pb-0.3% Ag-0.06% Ca/β-PbO2 composite electrode in the acidic zinc sulphate containing different concentrations of Cl- was studied.The microstructures were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD).With the increase of Cl- concentration,the oxygen evolution overpotential,impedance and corrosion rate increase gradually;the intensity of diffraction peak of β-PbO2 and α-PbO2 decreases gradually;the dendritic crystal clusters on the anode surface disappear.When the Cl- concentration is 300 mg/L,the apparent current density (i0) of the anode reaches maximum and the anode shows the best electrochemical properties and corrosion resistance.
2015, 32(8): 963-968
doi: 10.11944/j.issn.1000-0518.2015.08.140358
Abstract:
A dry biochemical method for simple and rapid measurement of carbon dioxide-combining capacity,glucose and uric acid in the blood was developed.Appropriate polymeric membrane materials were selected as dry slide carrier.Standard curves were established for the quantization of carbon dioxide-combining capacity,glucose and uric acid by using the dry biochemical analyzer.The dry biochemical analysis method was evaluated by linear test,stability experiment,repetitive experiment and the comparison with wet chemistry method.The three dry slides prepared above have obvious color gradient and color uniformity.The linear range of dry biochemical method established is wide.This method also has a good repeatability as its interassay and intraassay coefficient of variation are all less than 5%.The dry chemistry method and wet chemistry method shows good correlation with the correlation coefficient more than 0.99.The dry slide can be applied to the clinical detection.
A dry biochemical method for simple and rapid measurement of carbon dioxide-combining capacity,glucose and uric acid in the blood was developed.Appropriate polymeric membrane materials were selected as dry slide carrier.Standard curves were established for the quantization of carbon dioxide-combining capacity,glucose and uric acid by using the dry biochemical analyzer.The dry biochemical analysis method was evaluated by linear test,stability experiment,repetitive experiment and the comparison with wet chemistry method.The three dry slides prepared above have obvious color gradient and color uniformity.The linear range of dry biochemical method established is wide.This method also has a good repeatability as its interassay and intraassay coefficient of variation are all less than 5%.The dry chemistry method and wet chemistry method shows good correlation with the correlation coefficient more than 0.99.The dry slide can be applied to the clinical detection.
2015, 32(8): 969-976
doi: 10.11944/j.issn.1000-0518.2015.08.140418
Abstract:
CdS quantum dots capped by citrate (Cit-Cd S QDs) were synthesized in aqueous solution.TEM analysis indicates that the Cit-Cd S QDs are well-dispered with the diameter of 4 to 6 nm.The influence of silver (Ⅰ),cadmium (Ⅱ),thioglycolic acid,cysteine and the complexes formed by silver (Ⅰ)/cadmium (Ⅱ) with the thiol compounds (thioglycolic acid or cysteine) on the fluorescence of Cit-CdS QDs was investigated.All above modifiers can enhance the fluorescence intensity of Cit-CdS QDs.The complexes above have much greater fluorescence enhancement effect than that of the solely metal ions or thiol compounds.In addition,the CdS QDs modified by the complexes also have much higher sensitivity for copper (Ⅱ) sensing.Based on this phenomenon,a highly sensitive and selective fluorescence probe for Cu2+ was developed with a wide range of 1.0×10-8~1.0×10-6mol/L and a low detection limit of 1.0×10-9mol/L.It may open up new opportunity for the synthesis and application of complex modified quantum dots in analytical chemistry.
CdS quantum dots capped by citrate (Cit-Cd S QDs) were synthesized in aqueous solution.TEM analysis indicates that the Cit-Cd S QDs are well-dispered with the diameter of 4 to 6 nm.The influence of silver (Ⅰ),cadmium (Ⅱ),thioglycolic acid,cysteine and the complexes formed by silver (Ⅰ)/cadmium (Ⅱ) with the thiol compounds (thioglycolic acid or cysteine) on the fluorescence of Cit-CdS QDs was investigated.All above modifiers can enhance the fluorescence intensity of Cit-CdS QDs.The complexes above have much greater fluorescence enhancement effect than that of the solely metal ions or thiol compounds.In addition,the CdS QDs modified by the complexes also have much higher sensitivity for copper (Ⅱ) sensing.Based on this phenomenon,a highly sensitive and selective fluorescence probe for Cu2+ was developed with a wide range of 1.0×10-8~1.0×10-6mol/L and a low detection limit of 1.0×10-9mol/L.It may open up new opportunity for the synthesis and application of complex modified quantum dots in analytical chemistry.
