A new lawsone azo-dye for optical sensing of Fe3+ and Cu2+ and their DFT study

A new lawsone-based azo-dye 2-hydroxy-3-((pyridin-2-ylmethyl)diazenyl)naphthalene-1,4-dione (1) was synthesized and applied for sensing of metal ions. Receptor 1 showed selective fluorescent and colorimetric response for the detection of Cu²⁺ and Fe³⁺ over other tested metal ions. The fluorescence intensity of 1 was significantly quenched allowing detection of Fe³⁺ and Cu²⁺ down to 0.61 and 6.06 μM, respectively. The binding has been established by fluorescence spectroscopic method. Receptor 1 provided a 1?:?1 binding scaffold for recognition of Fe³⁺ and Cu²⁺ ions with the association constant of 3.33 × 10⁶ and 3.33 × 10⁵ M^?1, respectively. The B3LYP/6-31G/LANL2DZ method was employed for the optimization of 1 and 1·Fe³⁺ and 1·Cu²⁺.     

Study on the synthesis of novel fluorescent macrocyclic sensors and their sensitive properties for Cu2+ and Fe3+ in aqueous solution

In this work, we synthesised and characterised three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesised compounds with various mental ions (Li⁺, Na⁺, K⁺, Ag⁺, Mg²⁺, Ca²⁺, Ba²⁺, Pb²⁺, Zn²⁺, Co²⁺, Cd²⁺, Hg²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Cr³⁺, Al³⁺, Fe³⁺) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu²⁺ and Fe³⁺ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H₂O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated.     

苯乙烯三嗪衍生物的合成及在重金属离子识别中的应用

合成了2,4-二(2-噻吩乙烯基)-6-(4'-N,N-二甲氨基苯乙烯基)-1,3,5-均三嗪(2)并鉴定了其结构。在乙腈-水混合介质中,化合物2在355和416nm处呈现双吸收峰,加入Cu²⁺,Hg²⁺ 和Fe³⁺ 后,均在520nm附近形成新的吸收峰。化合物2与Cu²⁺、Hg²⁺ 和Fe³⁺ 均形成1:1型配合物,其结合常数分别为1.9×10⁵L·mol^-1,6.6×10³L·mol^-1,2.7×10³L·mol^-1。对照化合物4与金属离子的光谱响应与化合物2相似,仅吸收峰的位置不同。因此,可认为化合物2和4中三嗪环中的N和噻吩环中的S与Cu²⁺、Hg²⁺ 和Fe³⁺ 共同配位形成了稳定的金属配合物。     

Perimedine-linked rhodamine dye in visual sensing of Al3+, Fe3+ and Fe2+ ions in aqueous organic medium under different experimental conditions

ABSTRACT

Perimedine labelled rhodamine dye 1 has been designed and synthesised. Metal ion binding studies of 1 have been performed in CH₃CN/H₂O (3:1, v/v, 10 mM Tris-HCl buffer, pH = 6.90). Compound 1 senses multiple metal ions such as Al³⁺, Fe³⁺ and Fe²⁺ by exhibiting turn on fluorescence and colour change (colourless to pink) under different experimental conditions. Concentration variation distinguishes Al³⁺ from Fe³⁺ ion. At low concentration (c = 1 x 10^?4 M), only Al³⁺ ion can exhibit turn on fluorescence with sharp colour change. Sensing of Fe²⁺ ion through turn on fluorescence and colour change has been possible via in situ oxidation by following Fenton’s reaction.     

An ultra-sensitive and colorimetric sensor for copper and iron based on glutathione-functionalized gold nanoclusters

Here, we report an ultra-sensitive and colorimetric sensor for the detection of Fe³⁺ or Cu²⁺ successively using glutathione-functionalized Au nanoclusters (GSH-AuNCs). For GSH-AuNCs can catalytically oxidize peroxidase substrates, such as 3, 3′, 5, 5′-tetramethylbenzidine (TMB), colored products are formed in the presence of H₂O₂. While upon the addition of Fe³⁺ or Cu²⁺ into the GSH-AuNCs-TMB-H₂O₂ system, diverse color and absorbance of the system was obtained due to the self oxidation of Fe³⁺ and the inhibition of peroxidase-like activity of GSH-AuNCs. With the introduction of ethylene diamine tetraacetic acid (EDTA) or ammonium fluoride (NH₄F) to GSH-AuNCs-TMB-H₂O₂+Cu²⁺ system or GSH-AuNCs-TMB-H₂O₂+Fe³⁺ system respectively, a restoration of color and absorbance of system was realized. On the basis of above phenomenon, a colorimetric and quantitative approach for detecting Fe³⁺ and Cu²⁺ was developed with detection limit of 1.25 × 10⁻⁹ M and 1.25 × 10⁻¹⁰ M respectively. Moreover, the concentration of Fe³⁺ and Cu²⁺ in human serums was also accurate quantified by this method. So this design strategy realized the simple and simultaneous detection of Fe³⁺ and Cu²⁺, suggesting significant potential in clinical diagnosis.     

Phenanthroline-based fluorescence sensors for Eu3+ ion and subsequent enantioselective discriminating of malate

A pair of novel chiral fluorescent and colorimetric sensors L1 and D1 had been designed and synthesized, which were based on phenanthroline as the fluorophore and mandelohydrazide as the binding site. They showed selective recognition toward Eu³⁺ ion as ‘turn-off’ mode in DMSO-H₂O solution (v/v = 1:5, 10 mM HEPES, pH = 7.4). The fluorescence discrimination towards chiral carboxylate anions had been studied for L1-Eu³⁺ and D1-Eu³⁺ complex and they showed good enantioselective recognition ability towards malate as ‘turn-on’ mode. The interaction of sensor L1, D1 with Eu³⁺ and L1-Eu³⁺, D1-Eu³⁺ towards malate caused different color changes in the naked eye.     

Highly selective colorimetric naked-eye Cu2+ detection using new bispyrazolone silver nanoparticle-based chemosensor

In this work, we have successfully developed novel silver nanoconjugates of pyrazolone analogue and screened its chemosensing potential in aqueous medium. Bispyrazolone silver nanoparticles (Bispyra-AgNPs) were synthesised and characterised through FTIR, UV-visible spectroscopy and atomic force microscopy. The sensing ability was explored towards Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Li⁺, Pb²⁺, La³⁺, Hg²⁺, Mg²⁺, Ni²⁺ and Ba²⁺ metal ions, respectively. Bispyra-AgNPs showed a highly quenching potential in selective recognition of Cu²⁺and colour of the solution immediately turned from yellow to purple, after the addition of Cu²⁺ in to the solution. The developed method also displayed a remarkable selectivity for Cu²⁺ over others interfering metal ions. The binding ratio and stoichiometry of host-guest complex was found to be 1:1 and determined by Job’s method. The propose method is facile and sensitive to detect Cu²⁺ with detection limit of 10 µM.     

ABSORPTIVE IONOPHORES FOR Fe3+ CATION BY PARENT CALIX[n]ARENES

The absorption of Fe³⁺ ion from the aqueous phase to the solid phase was carried out by using p-tert-butyl calix[6]arene (L₁), calix[6]arene (L₂), p-tert-butyl calix[8]arene (L₃), and calix[8]arene (L₄). The effect of varying pH upon the absorption capability of parent calixarenes was examined. It was found that the compounds (L₁, L₂, L₃, and L₄) showed the highest extractability toward Fe³⁺ ion at 4.5–5.4. The calixarene L₂ shows a strong binding ability to Fe³⁺ ion. Based on the continuous variation method, calixarene L₂ formed 1:1 complex with Fe³⁺ ion.     

八肋游仆虫中心蛋白N-端半分子与Tb3+，Ca2+的结合

用分子生物学方法表达、纯化了游仆虫中心蛋白及N-端半分子，用铽荧光探针法、离子竞争法研究了pH 7.4，0.01 mol· L^-1 Hepes条件下中心蛋白与铽、钙的结合性质。结果表明中心蛋白有4个铽结合部位，其中2个为高亲合结合部位、2个为低亲合结合部位。具有2个低亲合结合部位的中心蛋白半分子与铽结合的条件常数是(2.13±0.10)×10⁵ L·mol^-1，与钙结合的条件常数是(7.52±0.02)×10² L·mol^-1。     

A novel method for the simple and simultaneous preconcentration of Pb2+, Cu2+ and Zn2+ ions with aid of diethylenetriamine functionalized SBA-15 nanoporous silica compound

A rapid method for the extraction and monitoring of nanogram level of Pb²⁺, Cu²⁺ and Zn²⁺ ions using uniform silanized mesopor (SBA-15) functionalized with diethylenetriamine groups and flame atomic absorption spectrometry (FAAS) is presented. The preconcentration factor of the method is 100 and detection limit of the technique is 5.5?ng?mL^?1 and 1.4?ng?mL^?1 and 0.1?ng?mL^?1 for Pb²⁺, Cu²⁺ and Zn²⁺ respectively. The time and the optimum amount of the sorbent, pH and minimum amount of acid for stripping of ions from functionalized SBA-15 were tested. The maximum capacity the functionalized SBA-15 was found to be 183.0 (±1.9) µg, 156.0 (±1.5) µg and 80.0 (±1.6) µg of Pb²⁺, Cu²⁺ and Zn²⁺/mg functionalized SBA-15, respectively.     

A highly selective fluorescent chemosensor for Fe (III) based on rhodamine 6G dyes derivative

A new fluorescent probe L based on the rhodamine 6G platforms for Fe³⁺ has been designed and synthesised. L showed excellent selectivity and high sensitivity for Fe³⁺ against other metal ions such as K⁺, Na⁺, Ag⁺, Cu²⁺, Co²⁺, Mg²⁺, Cd²⁺, Ni²⁺, Zn²⁺, Fe²⁺, Hg²⁺, Ce³⁺ and Y³⁺ in HEPES buffer (10 mM, pH 7.4)/CH₃CN (40:60, V/V). The distinct color change and the rapid emergence of fluorescence emission provided naked-eyes detection for Fe³⁺. The recognition mechanism of the probe toward Fe³⁺ was evaluated by Job’s plots, IR and ESI-MS. In order to further study their fluorescent properties, L + Fe³⁺ fluorescence lifetime was also measured. Moreover, the test strip results showed that these probes could act as a convenient and efficient Fe³⁺ test kit.     

Determination of Trace Copper by Fluorescence Spectrophotometry Based on Cu(DP)2+ and Cu‐4.0‐Generations Polyamidoamine Dendrimers Catalyze Cu2+ to Oxidize Fluorescein

Abstract

Fluorescein can emit strong and stable fluorescence. Cu²⁺ can oxidize fluorescein, which causes the fluorescence signal to diminish. Cu(DP)²⁺ (DP refers to α,α′‐dipyridyl) and Cu‐GPD‐4.0 (GPD‐4.0 refers to 4.0‐generations polyamidoamine dendrimers) both can catalyze Cu²⁺ to oxidize fluorescein, which causes the fluorescence signal to diminish sharply. The ΔF is directly proportional to the content of copper. Based on the facts above, a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)²⁺ and Cu‐GPD‐4.0 was established. The linear range of this method is 0.040–28 pg mL^?1. The regression equation for working curve is ΔF=209.5+14.39 C_Cu ²⁺ (pg mL^?1), n=7; correlation coefficient is 0.991. The detection limit of this method is 1.0×10^?14 g mL^?1. After replicate measurement times, RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL^?1 Cu²⁺, respectively. This method is rapid and precise with high sensitivity and good repeatability. The method has been applied to the determination of trace copper in tea and human hair with satisfactory results. Meanwhile, the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)²⁺ and Cu‐GPD‐4.0 was also discussed.     

Naphthalene and pyrrole substituted guanidine in selective sensing of Cu2+, Hg2+, Pb2+ and CN− ions under different conditions

Naphthalene and pyrrole substituted guanidine 1 has been designed and synthesised. Compound 1 efficiently distinguishes Cu²⁺, Hg²⁺ and Pb²⁺ ions by exhibiting different responses in fluorescence. While compound 1 exhibited turn-on emission selectively in the presence of Hg²⁺ and Pb²⁺ ions in CH₃CN and CH₃CN–H₂O (1:1, v/v), respectively, it showed decrease in emission upon interaction with Cu²⁺ ion in CH₃CN. Furthermore, the Cu-1 ensemble has been established as a potential probe for selective detection of CN^? ion over a series of other anions involving colour change (in ordinary light: colourless to light yellow and under UV light: colourless to sky blue). Theoretical insight has been invoked to understand the mode of metal–ligand interaction.     

Preparation and characterization of nylon 6/Cu2+-exchanged and Fe3+-exchanged montmorillonite nanocomposite

Nylon 6/Cu²⁺-exchanged and Fe³⁺-exchanged montmorillonite nanocomposites have been prepared by a melt intercalation technique directly from Cu²⁺-exchanged and Fe³⁺-exchanged montmorillonite. Hexadecyltrimethylammonium bromide was chosen as the clay/matrix reactive compatibilizer. The intercalation spacing and the degree of dispersion were determined by X-ray diffraction and transmission electron microscopy. Also the thermal character of the nanocomposites prepared was analyzed by thermogravimetric analysis.     

Metal Chelates of Cerium (III), Thorium(IV) and Dioxouranium(VI) with Some Heterocyclic AZO Dyes; Potentiometric and Spectrophotometric Studies

ABSTRACT

The stepwise formation constants of Ce³⁺, Th⁴⁺ and UO₂ ²⁺ complexes with four azo compounds based on I-phenyl-2, 3-dimethylpyrazoline-5-one nucleus namely; 4-phenylazo- (2-hydroxy, 5-x) 1-pheny1-2, 3-dimethy1-pyrazoline-5-one, where x= H (1), OH (II), COOH (III) and NH₂ (IV) have been determined potentiometrically at different temperatures and ionic strengths in 30% (v/v) ethanol-water solutions, then the thermodynamic parameters are calculated.

Negatives values of both ∠H and ∠G are obtained indicating the exothermic and spontaneous nature of complexation reactions, whereas positive values of ∠S show that entropy consideration favour complex formation. The study at different ionic strengths shows that an increase in the latter causes a decrese in the pK values. The azo compounds are also tested as new reagents for the spectrophotometric determination of Ce³⁺, Th4⁺ and UO₂ ²⁺ ions in synthetic and natural solutions by extensive investigation of the optimum conditions favoring the formation of colored complexes.     

A novel Hg2+ fluorescence sensor TPE-TSC based on aggregation-induced emission

Abstract

A fluorescent sensor TPE-TSC with aggregation induced emission (AIE) characteristic is synthesized for detecting Hg²⁺ by attaching thiosemicarbazide (TSC) unit into tetraphenylethylene (TPE) group. TPE-TSC exhibits intense green emission in DMSO/H₂O (V:V?=?1:9) solution with the formation of the aggregation. TPE-TSC shows outstanding fluorescence quenching toward Hg²⁺ over other metal ions due to the formation of complex TPE-TSC/Hg²⁺ with a 2:1 binding ratio. The detection limit of TPE-TSC for Hg²⁺ is 1?×?10^?5 mol·L^?1.     

A rapid selective colorimetric and ‘On–Off’ fluorimetric sensor for detecting Cu2+ ions in aqueous media based on a simple bis-schiff-base derivative

A simple colorimetric and fluorimetric ‘On–Off’ sensor L (3,3′-dimethyl -[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) for Cu²⁺ ions bearing o-tolidine substituents has been designed and synthesised, and exhibits significant fluorimetric and colorimetric response for Cu²⁺ in DMSO/H₂O (8:2, v/v) HEPES buffer (pH 7.2) solution. The detection limit of the sensor towards Cu²⁺ is 7.25 × 10^? 8 M and the association constant K_a of 9.86 × 10⁴ M^? 1 was determined. Furthermore, other anions, including Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺ and Mg²⁺ have almost no influence on the probe's behaviour. Test strips based on the sensor L were fabricated, which could act as convenient and efficient Cu²⁺ test kits.     

1-(d-Glucopyranosyl-2′-deoxy-2′-iminomethyl)-2-hydroxynaphthalene as chemo-sensor for Fe in aqueous HEPES buffer based on colour changes observable with the naked eye

A new glucose-based C2-derivatized colorimetric chemo-sensor (L₁) has been synthesized by a one-step condensation of glucosamine and 2-hydroxy-1-naphthaldehyde for the recognition of transition metal ions. Among the eleven metal ions studied, viz., Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Hg²⁺, L₁ results in visual colour change only in the presence of Fe²⁺, Fe³⁺and Cu²⁺ in methanol. However, in an aqueous HEPES buffer (pH 7.2) it is only the Fe³⁺ that gives a distinct visual colour change even in the presence of other metal ions, up to a concentration of 280 ppb. The changes have been explained based on the complex formed, and the composition has been determined to be 2:1 between L₁ and Fe³⁺ based on Job’s plot as well as ESI MS. The structure of the proposed complex has been derived based on HF/6-31G calculations.     

Indication Ion Square Wave Voltammetric Determination of Thiamine and Ascorbic Acid

Abstract

Cd²⁺ ion was used as an electrochemical indicator to detect V_B1 or Vc using square ware voltammetry (SWV) at a mercury film‐coated glassy carbon (GC) electrode. At pH=10 NH₃‐NH₄Cl buffer, a new cathodic peak was found at ?0.360 V (vs.SCE) by addition of thiamine, and the peak current of SWV was linear with the concentration of thiamine in the range of 1×10^?6 to 4×10^?3 M. On the other hand, the SWV peak current of Cd²⁺ at ?0.856 V linearly decreased with addition of ascorbic acid in the range of 6×10^?6～10^?3 M. The effects of interference, such as citric acid, DL‐malic acid, and calcium panlothenate, on thiamine or ascorbic acid determination were investigated. This method was successfully applied to the determination of thiamine or in pharmaceutical preparation.     

Highly sensitive and selective ratiometric fluorescent copper sensors: Different binding affinities modulated by three separate side chains of naphthalimide

A series of compounds 1-11 with different side chains of naphthalimide as fluorescent copper sensors were designed and synthesized. Compounds 1, 9, 10 and 11 presented a high selectivity to Cu2+ in a neutral aqueous environment. Here 1, 9 and 10 showed selectivity and affinity to Cu2+ with an association constant of about ～106. It gave somewhat response to Ag+, Co2+, Ni2+ and Fe2+ while 1 detected copper. 9 and 10 displayed better selectivity by changing their hydrophobic side chains to the hydrophilic ones...