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Ion Sensing (ion + sensing)
Selected AbstractsAmperometric Ion Sensing Using Polypyrrole MembranesELECTROANALYSIS, Issue 5-6 2003Agata Michalska Abstract Oxidation/reduction of conducting polymers, coupled with ion exchange between the polymer and electrolyte solution can be utilized for amperometric ion sensing. Electrochemically deposited "model" polypyrrole membranes doped by chloride (PPyCl) and hexacyanoferrate (PPyFeCN) anions were studied from the point of view of their advantages and limits for amperometric determination of electroinactive anions and cations, respectively. Monotonous dependences of the current on electrolyte concentration were obtained for short reading times after potential step application (in the range of ms). The experimental conditions were optimized to obtain linear dependences: log (current) vs. log (KCl concentration) within the range 10,6,1,M. The advantages of the amperometric method over the potentiometric one are highlighted: much lower effect of redox and pH interferences, wider concentration range, elimination of long conditioning procedure. [source] Water-soluble anionic conjugated polymers for metal ion sensing: Effect of interchain aggregationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2009Yi Chen Abstract 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 [source] Synthesis and photophysical behavior of a water-soluble coumarin-bearing polymer for proton and Ni2+ ion sensingPOLYMER INTERNATIONAL, Issue 6 2009Bao-Yan Wang Abstract BACKGROUND: In recent years, many fluorescent chemosensors with various macromolecular structures have been prepared for the detection of protons or metal cations in the environment. Most of this research is focused on polymer sensors with fluorescent recognition sites in the main chain. In this case, the fluorescent recognition sites are covalently bonded to the polymer chain, and thus the polymer shows photophysical properties as a chemosensor for protons and metal ions. RESULTS: An acrylic monomer bearing coumarin moieties, 7-hydroxy-4-methyl-8-(4,-acryloylpiperazin-1,-yl)methylcoumarin, was synthesized. This was then copolymerized with N -vinylpyrrolidone to obtain a blue fluorescent material. The fluorescent copolymer has good solubility in aqueous solution. Its main photophysical properties were determined in relation to its use as a sensor for protons and metal cations. It is an efficient ,off-on' switcher for pH between 3.02 and 12.08. Additionally, the polymer sensor is selective to Ni2+ ions, with the increase in the fluorescence intensity depending on Ni2+ ion concentrations in the range 0.33 × 10,5,7.67 × 10,5 mol L,1. CONCLUSION: The results suggest that this copolymer may offer potential as a reusable polymer sensor for protons and Ni2+ ions in aqueous solution. Copyright © 2009 Society of Chemical Industry [source] New Polyalkynyl Dendrons and Dendrimers: "Click" Chemistry with Azidomethylferrocene and Specific Anion and Cation Electrochemical Sensing Properties of the 1,2,3-Triazole-Containing DendrimersCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2009Jérémy Camponovo Abstract Dendrimers for ion sensing: The synthesis and use of new tris-alkynyl dendrons are reported. So-called "click" reactions of the dendrimers described with azidomethylferrocene give 27-ferrocenyl, 81-ferrocenyl, and 243-ferrocenyl dendrimers. Electrochemical recognition of oxo-anions and Pd2+ cations has been compared using the three polyferrocenyl dendrimers. The synthesis and use of the new tris-alkynyl dendrons 2 to 5 are reported, including the Williamson reaction of 5 with 9-iodo (9), 27-iodo (11), and 81-iodo (12) dendritic cores to yield 27-alkynyl (13), 81-alkynyl (14), and 243-alkynyl (15) dendrimers. So-called "click" reactions of these three dendrimers with azidomethylferrocene (20) give 27-ferrocenyl (16), 81-ferrocenyl (17), and 243-ferrocenyl (18) dendrimers. Electrochemical recognition of oxo-anions (H2PO4, and ATP2,) and Pd2+ cation has been compared using the three polyferrocenyl dendrimers. Derivatization of Pt electrodes with the dendrimers for recognition becomes more facile with increasing size of the dendrimer. This first "click" dendrimer bearing 243-ferrocenyl groups is the best one in the series to obtain robust, recyclable modified Pt electrodes, whereas previous "click" ferrocenyl dendrimers have not been suitable for this purpose. Nous reportons ici la synthèse et l'utilisation de nouveaux dendrons tris-alcynes (composés 2 à 5). La réaction de Williamson entre 5 et les c,urs dendritiques polyiodés comportant 9, 27 ou 81 branches (composés 9, 11 et 12) conduit aux dendrimères poly-alcynes à 27, 81 et 243 branches respectivement (composés 13 à 15). La réaction "click" de ces dendrimères avec l'azidométhylferrocène (20) permet d'obtenir des dendrimères polyferrocéniques à 27, 81 et 243 branches (composés 16 à 18). La reconnaissance électrochimique d'oxo-anions (H2PO4,et ATP2,) et du cation Pd2+est comparée avec trois dendrimères polyferrocéniques, et l'obtention d'électrodes de Pt modifiées à l'aide de ces dendrimères pour cette reconnaissance est de plus en plus facile lorsque la taille du dendrimère augmente. Le premier dendrimère "click" comportant 243 ferrocènes est le meilleur de la série pour la modification d'électrodes de Pt. Ces électrodes sont robustes et recyclables avec ce dendrimère, alors que les dendrimères "click" précédemment publiés n'étaient pas utilisables pour cette fonction. [source] | |||||||||||||