Turn‐on fluorogenic and chromogenic detection of cations in complete water media with poly(N‐vinyl pyrrolidone) bearing rhodamine B derivatives as polymeric chemosensor

A hydrophobic organic monomer GRBE with a polymerizable methacrylester moiety had been synthesized by reaction of rhodamine B‐ethanediamine with glycidyl methacrylate. A water‐soluble polymeric chemosensor poly(VP‐GRBE) had been prepared via copolymerization with a hydrophilic comonomer (vinylpyrrolidone) and GRBE, which was able to sense environmentally poisonous cations in completely aqueous media. The chemosensor was a derivative of rhodamine B, which behaved as a fluorescent and chromogenic sensor toward various heavy cations, particularly Cr³⁺, Fe³⁺, and Hg²⁺. Titration curves of Cr³⁺, Fe³⁺, and Hg²⁺ were constructed using rapid, cheap, and widely available technique of fluorescence spectroscopies. The detection limits for Cr³⁺, Fe³⁺, or Hg²⁺ ions were found to be 2.20 × 10^?12, 2.39 × 10^?12, and 1.11 × 10^?12 mol/l in the same medium, respectively. Moreover, a colorimetric response from the polymeric chemosensor permitted the detection of Cr³⁺, Hg²⁺, or Fe³⁺ by “naked eye” because of the development of a pink or brown yellow color when Cr³⁺, Hg²⁺, or Fe³⁺ cations interacted with the copolymer in aqueous media. Copyright © 2015 John Wiley & Sons, Ltd.     

Magnetism,optical absorbance,and 19F NMR spectra of nafion films with self‐assembling paramagnetic networks

Magnetization, optical absorbance, and ¹⁹F NMR spectra of Nafion transparent films as received and doped with Mn²⁺, Co²⁺, Fe²⁺, and Fe³⁺ ions with and without treatment in 1H‐1,2,4‐triazole (trz) have been studied. Doping of Nafion with Fe²⁺ and Co²⁺ and their bridging to nitrogen of triazole yields a hybrid self‐assembling paramagnetic system that exhibits interesting magnetic and optical properties. These include spin crossover phenomena between high‐spin (HS) and low‐spin (LS) states in Nafion‐Fe²⁺‐trz and Nafion‐Co²⁺‐trz accompanied by thermochromic effects in the visible range induced by temperature. A large shift of the magnetization curve induced by a magnetic field in the vicinity of the HS ? LS, ～220 K, observed for Nafion‐Fe²⁺‐trz has a rate of ～6 K/kOe, which is about three orders of magnitude larger than that in bulk spin crossover Fe²⁺ materials. Selective response of ¹⁹F NMR signals on doping with paramagnetic ions demonstrates that NMR can be used as spatially resolved method to study Nafion film with paramagnetic network. Both chemical shift and width of ¹⁹F NMR signals show that SO groups of Nafion, Fe or Co ions, and nitrogen of triazole are bonded whereas they form a spin crossover system. Based on a model of nanosize cylinders proposed for Nafion [K. Schmidt‐Rohr and Q. Chen, Nat Mater (2008), 75], we suggest that paramagnetic ions are located inside these cylinders, forming self‐assembling magnetically and optically active nanoscale networks. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 129–138, 2012     

A Selective Colorimetric and Fluorescent Chemodosimeter for Fe(III) Ion Based on Hydrolysis of Schiff Base

An efficient colorimetric and fluorescent chemodosimeter for Fe³⁺ ions has been developed. The visual and fluorescent behaviors of the receptor toward various metal ions were investigated. The receptor shows exclusive response toward Fe³⁺ ions and also distinguishes Fe³⁺ from other cations by color change and unusual fluorescence enhancement in aqueous solution (DMSO/H₂O = 4/1, v/v). Thus, the receptor can be used as a colorimetric and fluorescent sensor for the determination of Fe³⁺ ion. The visual color detection limit and the fluorescence detection limit of the receptor towards Fe³⁺ are (1.42 ± 0.01) × 10^‐6 M and (7.57 ± 0.04) × 10^‐8 M, respectively. The fluorescence microscopy experiments showed that the receptor is efficient for detection of Fe³⁺ in vitro, developing a good image of the biological organelles. The sensing mechanism is proven to be a hydrolysis process     

Studying the photophysical properties of a polymerizable 1,8‐naphthalimide dye and its copolymer with styrene as potential fluorescent sensors for metal cations

The photophysical characteristics of a polymerizable 1,8‐naphthalimide dye and its copolymer with styrene have been investigated. The functional properties of both low and high molecular weight fluorophores in the presence of different metal cations have been discussed with regard to their potential application as fluorosensors for the metal cations and protons. In acetonitrile solution the monomeric 1,8‐naphthalimide enhances its fluorescence emission in the presence of metal cations (Zn²⁺, Fe³⁺, Co²⁺, Pb²⁺, Cu²⁺, Ni²⁺, and Mn²⁺). In aqueous media the poly(St‐co‐MD) exhibits a selective response to Fe³⁺ cations. The monomeric and polymeric fluorophores also exhibit a considerable increase in their fluorescence intensity at acidic pH values (pH < 6) which suggest that they could be used as ON–OFF probes in analytical devices for signaling the presence of protons. Copyright © 2008 John Wiley & Sons, Ltd.     

Polymer‐based colorimetric and “turn off” fluorescence sensor incorporating benzo[2,1,3]thiadiazole moiety for Hg2+ Detection

A conjugated polymer was synthesized by the polymerization of 4,7‐dibromobenzo[2,1,3]thiadiazole ( M‐1 ) with tri{1,4‐diethynyl‐2,5‐bis(2‐(2‐methoxyethoxy)‐ethoxy)}‐benzene ( M‐2 ) via Pd‐catalyzed Sonogashira reaction. The polymer shows strong orange fluorescence. The responsive optical properties of the polymer on various metal ions were investigated through photoluminescence and UV–vis absorption measurements. The polymer displays highly sensitive and selective on‐off Hg²⁺ fluorescence quenching property in tetrahydrofuran solution in comparison with the other cations including Mg²⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, and Pb²⁺. More importantly, the fluorescent color of the polymer sensor disappears after addition of Hg²⁺, which could be easily detected by naked eyes. The results indicate that this kind of polymer sensor incorporating benzo[2,1,3]thiadiazole moiety as a ligand can be used as a novel colorimetric and fluorometric sensor for Hg²⁺ detection. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Hyperbranch‐polyethyleniminated functional polymers. I. Synthesis,characterization of novel ABA type of dumbbell‐like polyethyleniminated polyoxypropylenediamines,and their complexing properties with copper(II) ions in aqueous solution

Novel ABA‐type dumbbell‐like water‐soluble copolymers [D230(EI)₄, D400(EI)₄, and D400(EI)₈] were synthesized by introducing ethylenimine (EI) groups into both sides of polyoxypropylenediamines via a simple in situ ethylamination of polyoxypropylenediamine with 2‐chloroethylamine hydrochloride. The structures of the resultant polymers were identified by Fourier transform infrared spectroscopy and ¹H NMR. The percentages of primary, secondary, and tertiary amine present were determined by the potentiometric titration method after treatments with the appropriate chemicals of salicylaldehyde and acetic anhydride. The surface tension and solubilizing behavior of pyrene in the presence of these polymers in aqueous medium were also investigated, and the efficiency to reduce the surface tension and solubilizing behavior of pyrene depends on the attachments of EI to polymer backbone. The chelating properties of these polymers were examined quantitatively by ultraviolet–visible (UV–vis) spectroscopy in the presence of Cu²⁺ ions in aqueous solution, and continuous variation analysis revealed that the most stable complex is formed at the normality ratio of [N]/[Cu²⁺] = 3.0. UV–vis spectroscopy and transmission electron microscopy were used to evaluate the dumbbell‐like water‐soluble copolymer, D400(EI)₈, as a stabilizer for preparing colloidal noble metal nanoparticles (Au and Pt) in aqueous solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1360–1370, 2003     

Synthesis of polyacrylonitrile by single‐electron transfer‐living radical polymerization using Fe(0) as catalyst and its adsorption properties after modification

Fe(0) was firstly used as single‐electron transfer‐living radical polymerization catalyst for acrylonitrile polymerization using carbon tetrachloride as initiator, hexamethylenetetramine as N‐ligand, and N,N‐dimethylformamide as the solvent at 65 °C. First‐order kinetic studies indicated that this polymerization proceeded in a “living”/controlled manner. The living nature of the polymerization was also confirmed by chain extension of methyl methacrylate with polyacrylonitrile (PAN) as macroinitiator. Furthermore, PAN was modified with NH₂OH·HCl to generate amidoxime groups for extraction of heavy metal ions (Hg²⁺) from aqueous solutions. Fourier transformed infrared spectroscopy was performed to characterize chemical composition and structure. The adsorption property of Hg²⁺ was investigated at different pH values of aqueous solutions and distilled water. The maximal saturated adsorption capacity of Hg²⁺ was 4.8 mmol g^?1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Highly soluble conducting poly(ethylene oxide) grafted at two sites of poly(o‐aminobenzyl alcohol)

Poly(o‐aminobenzyl alcohol) (POABA) was grafted with poly(ethylene oxide)s (PEOs) through the reaction of tosylated PEO with both the hydroxide and amine moieties of reduced POABA. Reduced POABA was prepared through the acid‐mediated polymerization of o‐aminobenzyl alcohol, followed by neutralization with an aqueous ammonium hydroxide solution and reduction with hydrazine. The grafted copolymers were very soluble in common polar solvents, such as chloroform, tetrahydrofuran, and dimethylformamide, and the copolymers with longer PEO side chains (number‐average molecular weight > 164) were even water‐soluble. The conductivities of the doped grafted copolymers decreased with increasing PEO side‐chain length because of the nonconducting PEO and its torsional effect on the POABA backbone. The conductivity of highly water‐soluble POABA‐g‐PEO‐350 was 0.689 × 10^?3 S/cm, that is, in the semiconducting range. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4756–4764, 2004     

New green fluorescent polyvinylcarbazole copolymer with 1,8‐naphthalimide side chains as chemosensor for iron cations

The synthesis and basic photophysical characteristics of a novel green fluorescent polyvinylcarbazole polymer containing 4‐N,N‐dimethylaminoethyleneamino‐1,8‐naphthalimide side chains has been described. The ability to sense metal cations has been monitored by fluorescence emission spectroscopy. It is shown that the fluorescent intensity is very sensitive to the Fe²⁺ cations and the copolymer can be used as an homogeneous and heterogeneous fluorescent sensor for Fe²⁺ cations. Copyright © 2004 John Wiley & Sons, Ltd.     

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     

A Simple Colorimetric Sensor with High Selectivity for Mercury Cation in Aqueous Solution

Abstract

A simple and sensitive mercapto thiadiazole Schiff-base colorimetric chemosensor 2 was synthesized. It exhibits good selectivity and sensitivity for the mercury cation over other metal cations such as Zn²⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, Ag⁺, Ca²⁺, Mg²⁺, and Cr³⁺ in both aqueous solution and on paper-made test kits. The change in color is very easily observed by the naked eye for the presence of Hg²⁺ cation, whereas other metal cations do not induce such a change. The chemosensor 2 showed remarkably anti-interference ability toward other metal cations and the detection limit toward Hg²⁺ was 1.5 × 10^?5 M.

GRAPHICAL ABSTRACT      

Water‐soluble conjugated polymers: Synthesis and optical properties

Two sets of water‐soluble poly(phenylene vinylene)s were synthesized and their optical properties were studied. The aqueous solubility of all these polymers is rendered by pendant sulfonate groups. One set of polymers (polymer I series) contains, in addition to the sulfonate pendants, dimethoxy substituents, while the other (polymer II series) contains oligo(ethylene oxide) side chains. Within each set, polymers containing lithium (Ia and IIa), sodium (Ib and IIb), and potassium (Ic and IIc) counter ions were prepared. The two sets of polymers showed different properties from physical appearance (fiber vs film) to thermal properties and to optical properties. It was found that set I polymers, with shorter side chains, exhibit stronger aggregation in aqueous solutions than set II polymers, which led to their lower fluorescence quantum yields and lower polymer‐to‐MV²⁺ quenching efficiencies. Within each set, the effect of counter ions on optical properties was noted. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5123–5135, 2007     

Fourier transform infrared spectroscopy study of the effect of pH on anion and cation adsorption onto poly(acrylo‐amidino diethylenediamine)

The role of hydrogen bonding in the chemistry of transition‐metal complexes remains a topic of intense scientific and technological interest. Poly(acrylo‐amidino diethylenediamine) was synthesized to study the effects of hydrogen bonding on complexes at different pHs. The polymer was synthesized through the coupling of diethylene triamine with polyacrylonitrile fiber in the presence of AlCl₃ · 6H₂O addition. The adsorption capacity of this polymer was 11.4 mequiv/g. The ions used for the adsorption test were CrO, PO, Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺. All experiments were confirmed with Fourier transform infrared. In the study of anion adsorption, at low pHs, only ionic bonds existed, whereas at high pHs, no bonds existed. However, in the middle pH region, both ionic bonds and hydrogen bonds formed between poly(acrylo‐amidino diethylenediamine) and the chromate ion or phosphate ion. When poly(acrylo‐amidino diethylenediamine) and metal ions (Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺) formed complexes, a hydrogen‐bonding effect was not observed with Fourier transform infrared. The quantity of metal ions adsorbed onto poly(acrylo‐amidino diethylenediamine) followed the order Ag⁺ > Cu²⁺ > Fe²⁺ > Ni²⁺. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2010–2018, 2004     

Water‐soluble,biocompatible polyphosphazenes with controllable and pH‐promoted degradation behavior

The synthesis of a series of novel, water‐soluble poly(organophosphazenes) prepared via living cationic polymerization is presented. The degradation profiles of the polyphosphazenes prepared are analyzed by GPC, ³¹P NMR spectroscopy, and UV–Vis spectroscopy in aqueous media and show tunable degradation rates ranging from days to months, adjusted by subtle changes to the chemical structure of the polyphosphazene. Furthermore, it is observed that these polymers demonstrate a pH‐promoted hydrolytic degradation behavior, with a remarkably faster rate of degradation at lower pH values. These degradable, water soluble polymers with controlled molecular weights and structures could be of significant interest for use in aqueous biomedical applications, such as polymer therapeutics, in which biological clearance is a requirement and in this context cell viability tests are described which show the non‐toxic nature of the polymers as well as their degradation intermediates and products. © 2013 The Authors Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 287–294     

Linear poly(amide triazole)s derived from d‐glucose

The click reaction between azides and alkynes is been increasingly employed in the preparation of polymers. In this article, we describe the synthesis and click polyaddition reaction of a new A‐B‐type amide monomer—prepared from d ‐glucose as renewable resource—containing the alkyne and azide functions. Both Cu(I)‐catalyzed and metal‐free click polymerization methods were used to prepare glucose‐derived poly(amide triazole)s. The resulting polymers had weight‐average molecular weights in the 45,000–129,000 range and were characterized by GPC, IR, and NMR spectroscopies. Thermal and X‐ray diffraction studies revealed them to be amorphous. Their qualitative solubilities in various solvents and their water sorption have been studied. The poly(amide triazole)s having the alcohol functions protected as methyl ether were water‐soluble. The presence of the amide functions along the polymer chain made these polytriazoles degradable in the presence of sodium deuteroxide. The degradation was monitored by NMR analysis, and the degradation product was characterized by HRMS. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 629–638     

Controlled synthesis of hydrophilic concentrated polymer brushes and their friction/lubrication properties in aqueous solutions

Polymer brushes of water‐soluble polymers, poly(2‐hydroxyethyl acrylate) (PHEA) and poly(poly(oxyethyleneglycol)methylether acrylate) (PPEGA), were synthesized on a silicon wafer and a silica particle by applying photo‐induced organotellurium‐mediated radical polymerization to surface‐initiated graft polymerization. High graft densities were obtained, corresponding to reduced graft densities of about 0.32 and 0.42 for the PHEA and PPEGA brushes, respectively. These values were high enough to be categorized in the regime of “concentrated” polymer brushes (CPBs). Atomic force microscopic (AFM) study revealed that the CPB of PPEGA was allowed to be highly swollen in water but the CPB of PHEA did not. This means that water is reasonably good for PPEGA but not for PHEA. The AFM microtribological study between swollen brushes revealed two lubrication regimes, namely, boundary‐ and hydrodynamic‐lubrication regimes, with different shear‐velocity dependencies. Reflecting insufficient quality of water as a solvent, the CPB of PHEA showed adhesive interaction and thereby a higher frictional coefficient μ in the boundary lubrication. More interestingly, super lubrication was achieved for the CPB of PPEGA with a μ value in the order of 10^?4 in water and in 0.1 M aqueous NaCl solution (without the help of electrostatic repulsion). Super lubrication was concluded to be a characteristic feature of the CPB, even in an aqueous system. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Cobalt Ion‐Mediated Cysteine Detection With a Hyperbranched Conjugated Polyelectrolyte as a New Sensing Platform

A highly efficient colorimetric and fluorescence turn‐off probe for the sensitive and selective detection of the biologically important amino acid, cysteine (Cys), is demonstrated using a newly synthesized water‐soluble hyperbranched polymer (HP) containing sulfonic acid groups. The detection mechanism involves two steps: (i) the slight quenching of HP in the presence of Co²⁺ in advance; and (ii) the gradual quenching of the HP–Co²⁺ complex according to the concentration of Cys due to the absorption screening effect of the formation of the Cys‐Co²⁺ complex, which prevents HP from absorbing excitation energy.     

Energy transfer from fluorene‐based conjugated polyelectrolytes to on‐chain and self‐assembled porphyrin units

A new water soluble fluorene‐based polyelectrolyte containing on‐chain porphyrin units has been synthesized via Suzuki coupling, for use in optoelectronic devices. The material consist of a random copolymer of poly{1,4‐phenylene‐[9,9‐bis(4‐phenoxy butylsulfonate)]fluorene‐2,7‐diyl} (PBS‐PFP) and a 5,15‐diphenylporphyrin (DPP). The energy transfer process between the PBS‐PFP units and the porphyrin has been investigated through steady state and time‐resolved measurements. The copolymer PBS‐PFP‐DPP displays two different emissions one located in the blue region of the spectra, corresponding to the fluorene part and another in the red due to fluorescent DPP units either formed directly or by exciton transfer. However, relatively inefficient energy transfer from the PFP to the on‐chain porphyrin units was observed. We compare this with a system involving an anionic blue light‐emitting donor PBS‐PFP and a anionic red light‐emitting energy acceptor meso‐tetrakisphenylporphyrinsulfonate (TPPS), self‐assembled by electrostatic attraction induced by Ca²⁺. Based on previous studies related to chain aggregation of the anionic copolymer PBS‐PFP, two different solvent media were chosen to further explore the possibilities of the self‐assembled system: dioxane–water and aqueous nonionic surfactant n‐dodecylpentaoxyethylene glycol ether (C₁₂E₅). In contrast, with the on‐chain PBS‐PFP‐DPP system the strong overlap of the 0‐0 emission peak of the PBS‐PFP and the Soret absorption band of the TPPS results in an efficient Förster transfer. This is strongly dependent on the solvent medium used. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Metal‐ and solvent‐free,clickable synthesis and postpolymerization functionalization of poly(triazole)s

In this study, a series of linear poly(triazole)s (PTAs) were successfully synthesized by the metal‐ and solvent‐free, thermal click polymerization of diazide and dialkyne (A₂ + B₂) monomers. All click polymerizations proceeded smoothly at 80 °C in an open atmosphere without protection from oxygen and moisture. After being polymerized for 36 h, the crude polymer was further fractionated into three fractions using a multistep precipitation method. By selectively choosing precipitating agents, this process produced poly(triazole) fractions with low polydispersity index (<1.30). The resulting PTAs are soluble in common organic solvents and stable at a temperature up to 320 °C. Furthermore, the methyl benzoate moieties in the main chain can serve as useful building blocks for further postpolymerization functionalization, yielding 1,2,4‐triazole derivatives. This functionalization strategy offers potential for the development of novel triazole‐based materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of Silver Nanoparticles Reduced by Formamidinesulfinic Acid and Its Application in Colorimetric Sensor

A rapid one-step preparation approach of silver nanoparticles (AgNPs) was reported by employing formamidinesulfinic acid as reducing agent and soluble starch as stabilizing agent. The formation of AgNPs was further confirmed by using UV–Vis absorption spectroscopy, X-ray diffraction spectroscopy and transmission electron microscopy techniques. The resultant AgNPs could be directly used for the colorimetric reaction with metal ions. The results showed that Al³⁺, Cr³⁺, Fe³⁺ and Hg²⁺ ions could induce the color change of AgNPs from yellow to pink (Al³⁺), orange (Cr³⁺) and colorless (Fe³⁺ and Hg²⁺), respectively, which can be observed by the naked eye. Based on these, a sensitive colorimetric sensor for Al³⁺, Fe³⁺, Cr³⁺ and Hg²⁺ ions detection was developed.