A New Disubstituted Polyacetylene for the Detection of α‐Amino Acids

New imidazole‐functionalized disubstituted polyacetylene was synthesized by utilizing the postfunctional strategy. In addition, its ability to sense copper ions and α‐amino acids by fluorescence quenching has been studied. The quenching of the fluorescence of the imidazole‐functionalized disubstituted polyacetylene was observed at a very low level of Cu²⁺ (7.0 × 10⁻⁷ mol · L⁻¹). The fluorescent intensity decreased rapidly upon the increase of the concentration of the added solution of Cu²⁺. It was expected that the addition of α‐amino acids to the solution of the polyacetylene/Cu²⁺ complex could turn on the fluorescence of the polyacetylene, if α‐amino acids could remove the copper ions from the complex. Glycine, was used for testing: upon the addition of glycine the quenched fluorescence of P1 turned on immediately. The detection limit was as low as 6.0 × 10⁻⁵ mol · L⁻¹.

     

Hyperbranched copolymer containing triphenylamine and divinyl bipyridyl units for fluorescent chemosensors

A fluorescent hyperbranched copolymer (HTP) and a linear copolymer (PTP) as a reference sample to HTP both containing triphenylamine and divinyl bipyridyl units were synthesized via Heck coupling reaction from 5,5′‐Divinyl‐2,2′‐bipyridyl with tris(4‐bromophenyl)amine and with 4,4′‐dibromotriphenylamie, respectively. The chemical structure of HTP was confirmed by FTIR, ¹H NMR, and ¹³C NMR. The polymer HTP had a number‐average molecular weight of 1895 and a weight‐average molecular weight of 2315, and good solubility in conventional organic solvents, such as THF, DMF, and chloroform, and exhibited good thermal stability. The UV–vis absorption and photoluminescence (PL) spectra exhibited absorption maximum at 428 nm and emissive maximum at 531 nm for the HTP solution. The spectroscopic results of HTP and PTP indicated that hyperbranched conjugated structure increases the effective conjugation length, as compared with corresponding linear conjugated structure. The fluorescence of the polymer in solution can be quenched by various transition metal ions. The effect of backbone structure of the conjugated polymer‐based chemosensors on the sensitivity and selectivity in metal ions sensing have been investigated, and the quenching effect of HTP is more sensitive toward transition metal than linear copolymer PTP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 222–230, 2009     

Determination of Cysteine using the Fluorescence from a L-Tyrosine-Copper(II) Complex

A simple and sensitive method for the determination of cysteine is reported based on fluorescence quenching and recovery of L-tyrosine. At pH 10, copper(II) reacted with L-tyrosine to form a 1:1 complex that resulted in the quenching of L-tyrosine. However, the quenched fluorescence of L-tyrosine was recovered upon adding cysteine due to the strong affinity between these components. Under the optimized conditions, the recovered fluorescence was linearly proportional to the concentration of cysteine from 6.5?×?10^?7 to 4?×?10^?5?mol?L^?1 with a detection limit of 7.32?×?10^?8?mol?L^?1, demonstrating high sensitivity for the determination of cysteine. The mechanisms of fluorescence quenching and recovery were characterized and the method was used to determine cysteine in a pharmaceutical product with satisfactory results.     

A fluorescence “on–off” sensor for the highly selective and sensitive detection of Cu2+ ion

In an attempt to obtain a model of copper(II) ion-selective sensors, a new 1,8-naphthalimide-based fluorescence chemosensor, N-allylamine-4-[(E)-4-(([2-aminoethyl]imino)methyl) benzene-1,3-diol]-1,8-naphthalimide (NABN), was designed and synthesized. The sensor NABN is fully characterized by melting point analysis, fourier transform infrared spectra, Ultraviolet–visible (UV–vis) spectra, fluorescence spectra, ¹H NMR and ¹³C NMR spectroscopy, and mass spectrometry. NABN showed an unrivaled sensing behavior and an ardent selectivity toward copper(II) ion over other competitive metal ions tested in solution (N,N-Dimethylformamide (DMF)/Tris–HCl buffer, 1:1, v/v, pH = 7.2). The sensor showed a linear fluorescence quenching toward copper(II) ion in the range 0–50 μM, with a detection limit of 1.92 × 10⁻⁷ M estimated. Job's method indicated the formation of a 2:1 coordinative mode of the sensor with copper(II) ion with a high threshold of binding constant of 4 × 10¹² M⁻¹. Combining the above results, the quenching response of NABN toward Cu(II) ions could be ascribed to the strong, intrinsic paramagnetic behavior of Cu(II).     

Highly sensitive fluorescent sensor for copper (II) based on amplified fluorescence quenching of a water-soluble NIR emitting conjugated polymer

We have synthesized the near-infrared water-soluble conjugated polymer poly[2,5-di(propyloxysulfonate)-1,4-phenylene-ethynylene-9,10-anthrylene (referred to as PPEASO3). Its fluorescence (at wavelengths between 650 and 800?nm following photoexcitation at 550?nm) is efficiently quenched by Cu(II) ions, while other physiologically relevant metal ions do not cause significant quenching at the same concentrations. Under optimum conditions, fluorescence intensity is inversely proportional to the concentration of Cu (II). The calibration curve displays two linear regions over the range of 0–3.2?×?10^?7 mol L^?1 and 3.2?×?10^?7 mol L^?1 to 1.0?×?10^?4 mol L^?1 of Cu(II), respectively. The long-wavelength excitation and emission can substantially reduce interferences by the autofluorescence and light scattering of biological matter under UV excitation. The method was successfully applied to the determination of Cu(II) in synthetic and tea samples.

Micelles with highly branched nanoporous interior: Solution properties and binding capabilities of amphiphilic copolymers with linear dendritic architecture

This article describes the solution behavior of model amphiphilic linear‐dendritic ABA block copolymers that self‐assemble in aqueous media and form micelles with highly branched nanoporous cores. The materials investigated are constructed of poly(ethylene glycol), PEG, with molecular weight 5,000 or 11,000 as the water‐soluble B block and poly(benzyl ether) monodendrons [G] of second and third generation as the hydrophobic A fragments. The process of self‐assembly in aqueous media and the character of the micellar core are investigated by fluorescence spectroscopy using pyrene as the molecular probe. The data obtained by different methods indicate that the critical micelle concentrations (cmc) for these systems are between 1.1 × 10⁻⁵ and 2.0 × 10⁻⁵ mol/L for [G‐2]‐PEG5000‐[G‐2] and between 7.08 × 10⁻⁶ and 7.94 × 10⁻⁶ mol/L for [G‐3]‐PEG11000‐[G‐3]. It is found that the ratio of the first and third vibronic bands (I₁/I₃ ) in the fluorescence spectrum of the encapsulated pyrene changes from 1.77 to 1.32 when the concentration of [G‐2]‐PEG5000‐[G‐2] increases from 1.1 × 10⁻⁶ mol/L to 1.1 × 10⁻⁴ mol/L. For [G‐3]‐PEG11000‐[G‐3] these changes are between 1.77 and 1.17 in the same concentration range. The hybrid copolymers form host‐guest complexes with several polyaromatic compounds (phenanthrene, pyrene, perylene and fullerene, C₆₀) that are stable over extended periods of time (more than 12 months). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2711–2727, 2000     

Square Wave‐Anodic Stripping Voltammetric Determination of Copper at a Bismuth Film/Glassy Carbon Electrode Using 3‐[(2‐Mercapto‐Vinyl)‐Hydrazono]‐ 1,3‐Dihydro‐Indol‐2‐One

This study reports a highly sensitive electrochemical sensor based on Bi film modified glassy carbon electrode (BiF/GCE) for total determination and speciation trace concentrations of copper(II) ions in environmental water samples. Square wave‐adsorptive anodic stripping voltammetric (SW‐ASV) experiment was performed for monitoring selective accumulation of copper(II) with reagent 3‐[(2‐mercapto‐vinyl)‐hydrazono]‐1,3‐dihydro‐indol‐2‐one (MHDI) at pH 9–10. The mechanism of the electrode reaction of Cu²⁺‐MHDI complex was safely assigned. The sensor exhibited a wide linear range (3.22×10⁻⁹–2.0×10⁻⁷ mol L⁻¹) with lower limits of detection (LOD) and quantitation (LOQ) of 9.6×1⁻¹⁰ and 3.22×10⁻⁹ mol L⁻¹, respectively (R²=0.9993). The proposed sensor exhibited interference from active metal ions e. g. Cd, Hg. The performance of the proposed method was compared successfully with most of the reported methods and comparable efficiencies were obtained. The analytical utility of the proposed SW‐ASV method has been successfully validated for trace analysis of copper(II) in environmental water samples. The method offers a precise, accurate approach with good reproducibility, robustness, ruggedness, and cost effectiveness.     

Synthesis of a novel [60]fullerene pearl-necklace polymer,poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide)

A novel [60]fullerene pearl-necklace polymer, poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide), was synthesized by a direct polycondensation of trans-2-[60]fullerenobisacetic acid with 4,4′-diaminobenzophenone in the presence of large excesses of triphenyl phosphite and pyridine. In the present polymer, [60]fullerene pearls and diamine linkers were attached to each other by methano-carbonyl connectors. The molecular weight M_w of the polymer was determined to be 4.5 × 10⁴ on the basis of the TOF-MS, and a GPC analysis of the polymer using polystyrene standards showed a weight-average molecular weight of 5.3 × 10⁴. The UV-vis spectrum of the resultant polymer in N,N-dimethylacetamide (DMAc) exhibited a broad absorption (λ_max 310 nm, ε 2.1 × 10⁴ L · mol⁻¹ · cm⁻¹), tailing to longer wavelengths, and a fluorenscence peak centered at 550 nm was observed in DMAc. There was observed a large downfield-shift of the cyclopropane methyne proton in the ¹H-NMR spectra from 4.57 ppm of the ethyl ester to 5.78 ppm of the polyamide. These observations indicate that the present polyamide is a high-molecular-weight [60]fullerene pearl-necklace polymer and that the cyclopropane rings are efficient to make the [60]fullerene cages and the diamine components conjugatable. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3632–3637, 1999     

Zn^2＋ Recognition by Two New Bipyridine Ligands

IntroductionThehighsensitivityandselectivityofmolecularfluores cenceorluminescencehavebeenwidelyutilizedinmonitoringH+ ,Ca2 + ,Na+ ,Mg2 + ,andotherimportantcationoran ionionsinbiologicalorenvironmentalsystems.Duetothesensitiveresponseofluminescenceuponmicroenviromentalchanges (e .g .polarityofsolvent,pH ,thepresenceofions) ,bipyridinecomplexesofRe(I)andRu(II)withmetaltoligandchargetransferexcitedstatesconstitutealargefami lyofchemicalsensors.1 5Intheseprobingmolecules ,theco operationofthe…     

Organocopper‐catalyzed living radical polymerization initiated with aromatic sulfonyl chlorides

The living radical polymerization of methyl methacrylate initiated from aromatic sulfonyl chlorides and catalyzed by the new catalytic systems CuSBu/bpy CuSPh/bpy and CuCCPh/bpy (bpy = 2,2′‐bipyridine) is described. For a target degree of polymerization of 200, lowering the ratio of catalyst to sulfonyl chloride group from 1/1 to 0.25/1 mol/mol decreases the values of the experimental rate constant of polymerization from 5.12 × 10⁻², 2.4 × 10⁻², and 1.87 × 10⁻² min⁻¹ to 1.8 × 10⁻³, 4.9 × 10⁻³, and 4.2 × 10⁻³ min⁻¹ for CuSBu, CuSPh, and CuCCPh, respectively, whereas the corresponding initiator efficiency increases from 62 to 99%. The external orders of reaction in the catalyst are 0.79 for CuSPh, 0.88 for CuCCPh, and 1.64 for CuSBu. A mechanistic interpretation that involves the in situ generation of, most likely, the real catalyst CuCl, starting from combinations of CuSBu, CuSPh, and CuCCPh and sulfonyl chloride or alkyl halide growing species, is suggested. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4353–4361, 2000     

Electrochemically Generated Recognition Sites in Self‐doped Polyaniline Modified Electrodes for Voltammetric and Potentiometric Determination of Copper(II) Ion

Chemical recognition elements for copper(II) ion have been generated in electrodes modified with poly(aniline‐co‐metanilic acid), P(An‐co‐MA), membrane and the resulting electrodes were used as selective sensors for voltammetric and potentiometric determination of this ion in an extended pH range. The P(An‐co‐MA) membrane was electrodeposited from aqueous mixed monomer solutions of An and MA, without the presence of a supporting electrolyte. For generating the recognition elements, P(An‐co‐MA) modified electrodes were subjected to several consecutive reduction/oxidation potential steps in copper(II) ion solution. It seems that during these potential steps, the receptor sites of the membrane are adjusted to the size, complexing property and hard/soft nature of copper(II) ion. This electrochemically mediated templating process, provided a selective sensor for determination of copper(II) ion. The results of preconcentration/differential pulse anodic stripping voltammetry, indicated analytical relation between the peak current and concentration of copper(II) from 1.0×10⁻⁹ to 1.0×10⁻⁴ M. The interference effect of various metal ions was explored and it was found that only mercury and silver ions show a considerable interference. The sensor exhibited selective potentiometric response for copper(II) over a wide concentration range (1.0×10⁻⁸ to 1.0×10⁻³ M) with a Nernstian slope of 27.9±0.3 mV per decade of copper(II) ion activity.     

New imidazole‐functionalized polyfluorene derivatives: convenient postfunctional syntheses,sensitive probes for metal ions and cyanide,and adjustable output signals with diversified fluorescence color

Based on our previous work on the sensitive and selective conjugated fluorescent polymeric sensors toward cyanide, 2,1,3‐benzothiadiazole and 4,7‐bis(thiophen‐2‐yl)‐2,1,3‐benzothiadiazole were incorporated into the polyfluorene backbone to yield three new polymers bearing imidazole moieties in the side chains, with different fluorescence color. The fluorescence could be turned off by Cu²⁺ ions and then recovered on addition of cyanide, making them good cyanide sensors with the detection limit down to 1.9 μM. Moreover, by fully understanding this “turn off–turn on” strategy and using the cooperation of two polymers with different fluorescence color, the emission color of the mixture system of one of the imidazole‐containing polymers and one from the corresponding polymers without imidazole ones, could be adjusted by the concentrations of the added copper and cyanide ions, leading to the output fluorescent signals diversity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

3D‐printed Microfluidic Device Based on Cotton Threads for Amperometric Estimation of Antioxidants in Wine Samples

The present work describes the evaluation of microfluidic electroanalytical devices constructed by a 3D printer using ABS (acrylonitrile butadiene styrene) polymer combined with cotton threads as microchannels. Screen‐printed carbon electrodes (SPCEs) were used as electrochemical detector for amperometric determination of gallic and caffeic acid in wine samples. Using optimal experimental conditions (flow rate of 0.71 μL s⁻¹, applied potential of +0.30 V and volume of injection of 2.0 μL) the proposed method presented a linear response for a concentration range of 5.0×10⁻⁶ to 1.0×10⁻³ mol L⁻¹. The detection limits for gallic and caffeic acid were found to 1.5×10⁻⁶ mol L⁻¹ and 8.0×10⁻⁷ mol L⁻¹, respectively, with a sample throughput of 43 h⁻¹. The achieved results are in agreement with those found using the official Folin‐Ciocaulteu method.     

Water‐soluble anionic conjugated polymers for metal ion sensing: Effect of interchain aggregation

Three sulfonato‐containing fluorene‐based anionic water‐soluble conjugated polymers, which are specially designed to link fluorene with alternating moieties such as bipyridine ( P1 ), pyridine ( P2 ), and benzene ( P3 ) have been synthesized via the Pd‐catalyzed Sonogashira‐coupling reaction, respectively. These polymers had good solubility in water and showed different responses for transition metal ions with different valence in aqueous environments: the fluorescence of bipyridine‐containing P1 can be completely quenched by addition of all transition metal ions selected and showed a good selectivity for Ni²⁺; the pyridine‐containing P2 had a little response for monovalent and divalent metal ions while showed good quenching with the addition of trivalent metal ions (with a special selectivity for Fe³⁺); P3 had responses only for the trivalent metal ions within the ionic concentration we studied. After investigation of the UV‐vis absorption spectra, PL emission spectra, DLS, and fluorescence lifetime of P1 – P3 in aqueous solution when adding transition metal ions, we found that the different spectrum responses of these polymers are attributed to the different coordination ability of the units linked with fluorene in the main chain. The energy or electron‐transfer reactions were the main reason for fluorescence quenching of P1 and P2 . On the other hand, interchain aggregation caused by trivalent metal ions lead to fluorescence quenching for P3 and also caused partly fluorescence quenching of P1 and P2 . These results revealed the origin of ionochromic effects of these polymers and suggested the potential application for these polymers as novel chemosensors with higher sensing sensitivity in aqueous environments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5057–5067, 2009     

Oligonucleotide‐mediated aggregation of a cationic conjugated polymer for fluorescent detection of mercury ions in an aqueous medium

A cationically charged conjugated polymer ( P2 ) functionalized with quaternary ammonium salt was newly synthesized via Suzuki cross‐coupling polymerization. The functionalized P2 features different fluorescence colors according to its phases (blue emission in solution and green emission as asolid) which is caused by intramolecular and intermolecular exciton migration, respectively. The use of P2 as a novel fluorescent sensing platform is demonstrated for mercury ion detection. The detection of mercury ions is accomplished in two steps: (1) the cationic, blue‐emitting P2 absorbs an anionic oligonucleotide, polythymidine ( PT ) via electrostatic interaction to form a complex with green emission due to aggregation between the two species; (2) the addition of mercury ions to the complex produces a new complex of PT ‐Hg²⁺ via more favorable specific interaction, resulting in the isolation of P2 and the consequent recovery of blue fluorescence of P2 . It suggests that this detection system has high selectivity and sensitivity down to the ～10^?7 M level, even in mixtures of metal ions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2393–2400     

Depyrimidination of synthetic poly(uridylic acid) analogue

A poly(uridylic acid) analogue, poly{[1′‐(β‐uracil‐1‐yl)‐5′‐deoxy‐D‐erythro‐pent‐4′‐enofuranose]‐alt‐[maleic acid]} (3), was synthesized by the alternating copolymerization of nucleoside derivative 1 and maleic anhydride and subsequent hydrolysis. N‐glycosidic bonds of the polymer were hydrolyzed spontaneously to liberate uracil from the polymer backbone in a buffer solution (pH 7.4) at room temperature. The depyrimidination rate constant of the polymer at pH 7.4 at 80 °C was 8.2 × 10⁻⁵ s⁻¹, which was 10⁴ times higher than that of the depyrimidination of DNA (1.2 × 10⁻⁹ s⁻¹) under the same condition. The activation energy for the depyrimidination was 16 kcal/mol, which was about half of that for the relevant nucleoside reactions. The increase in the depyrimidination rate was attributable to the high potential energy of the polymer caused by the crowded environment around the bases, so that the polymer was more susceptible to the hydrolysis. Because natural nucleic acids often have compact structures with a crowded environment around the bases by an intricate chain folding, the pyrimidination also may have been accelerated in a similar manner in the biological system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 423–429, 2000     

Preparation and ion conductivities of the plasticized polymer electrolytes based on the poly(acrylonitrile‐ co‐lithium methacrylate)

The polymer electrolytes composed of poly(acrylonitrile‐co‐lithium methacrylate) [P(AN‐co‐LiMA)], ethylene carbonate (EC), and LiClO₄ salts have been prepared. The ion groups in the P(AN‐co‐LiMA) were found to prevent EC from crystallization through their ion–dipole interactions with the polar groups in the EC. This suppression of the EC crystallization could lead to the enhancement of the ion conductivity at subambient temperature. The polymer electrolytes based on the PAN ionomer with 4 mol % ion content exhibited ion conductivities of 2.4 × 10⁻⁴ S/cm at −10°C and 1.9 × 10⁻³ S/cm at 25°C by simply using EC as a plasticizer. In the polymer electrolytes based on the PAN ionomer, ion motions seemed to be coupled with the segmental motions of the polymer chain due to the presence of the ion–dipole interaction between the ion groups in the ionomer and the polar groups in the EC, while the ion transport in the PAN‐based polymer electrolytes was similar to that of the liquid electrolytes. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 247–252, 1999     

The mechanisms of removal of heavy metals from water by ionizing radiation

The removal of heavy metal ions from water using electron beam and gamma irradiation has been investigated for the cases of Pb²⁺ and Hg²⁺ ions. These metal ions are reduced by hydrated electrons and hydrogen atoms to lower or zero valence state and eventually precipitate out of solution. Ethanol is applied as a relatively non-toxic additive to scavenge ^·OH radicals, to enhance reduction and inhibit oxidation. Mercury can be completely (>99.9%) removed from aqueous solution of 1×10⁻³ mol L⁻¹ mercury (II) chloride by using a 3 kGy dose. However, a 40 kGy dose is required to remove 96% of lead ions from a 1×10⁻³ mol L⁻¹ of PbCl₂ solution. The effect of dissolved oxygen and carbonate were also investigated. E-beam irradiation of 1×10⁻³ mol L⁻¹ lead ions complexed with ethylenediamine tetraacetic acid (EDTA) in deoxygenated as well as air-saturated solutions in the absence of ethanol resulted in removal of about 97% of the lead.     

A Turn‐On Fluorescence Chemosensor for Cyanide in Aqueous Media Based on a Nucleophilic Addition Reaction

We synthesized a new cyanide (CN ⁻) chemosensor CX based on a nucleophilic addition reaction prompted by cyanide ion, which could be used for highly selective and sensitive fluorescence turn‐on detection of cyanide in aqueous media. The CX showed selective fluorescence recognition for CN ⁻, the miscellaneous competitive anions (F⁻, Cl⁻, Br⁻, I⁻, AcO ⁻, H₂PO₄⁻, HSO₄⁻, ClO₄⁻, S^{2 −}, PO₄³⁻, CO₃²⁻ and SCN ⁻) did not lead to any significant interference. The detection limit of the sensor towards CN ⁻ is 1.15 × 10⁻⁷ mol•L⁻¹. The sensor has been successfully applied to estimate the cyanide ion in seeds of cherries. Test strips based on CX were fabricated, which could be used as a convenient and efficient CN ⁻ test kit to detect CN ⁻ in aqueous solution for “in‐the‐field” measurement.     

Bithiophene triarylborane dyad: An efficient material for the selective detection of CN− and F− ions

A new fluorescent chemosensor based on bithiophene coupled dimesitylborane (BMB-1) was synthesized and characterized. BMB-1 was used for colorimetric and turn-on fluorescent sensing of cyanide (CN⁻) and fluoride (F⁻) ions, in the presence of other competitive anions in an aqueous (CH₃CN–H₂O) medium. BMB-1 showed a hypsochromic shift (blue shift) with addition of CN⁻ and F⁻ ions in absorption studies. The lower detection level of CN⁻ and F⁻ ions is 1.37 × 10⁻⁹ and 1.75 × 10⁻⁹ M, respectively. The BMB-1 binding mechanism is based on the nucleophilic addition of CN⁻ and F⁻ ions in the internal charge transfer transition of bithio moiety to the boranylmesitylene unit, and the color changes were observed under UV light. This result is further confirmed by Fourier transform infrared spectroscopy, mass spectrometry and density functional theory calculations. Also, the BMB-1 probe is found to be a good adsorbent for the removal of F⁻ ions in real water samples using the adsorption technique.