Synthesis and characterization of some novel polythiophene derivatives containing pyrazoline

Eight polythiophene derivatives containing pyrazoline side groups were synthesized by a chemical oxidative coupling polymerization using FeCl₃. The crystal structures of four monomers were determined which confirm the almost perpendicular orientation of the thiophene and pyrazoline rings, while the other substituents are more coplanar. Analyses of IR, ¹H-NMR, Raman and UV-Vis spectra demonstrated that the suggested polymerization was successful to generate the synthesized polythiophenes with the expected structures. The morphology of the synthesized polythiophenes was studied by SEM. The different substituents attached to the 1- and 3-positions of the pyrazoline side chain led to differences in optical properties, electrical conductivity, and thermal stability of the synthesized polythiophenes. By adding a pyrazoline side chain to polythiophenes, some polymers achieve good solubility, electrical conductivity of about 1.3 × 10^–6 S/cm, high fluorescence intensity (above 40,000 a.u.) at 505–550 nm and thermal stability up to 590°C in the air.

Synthesis and Characterization of Novel Polythiophenes Containing Pyrene Chromophores: Thermal, Optical and Electrochemical Properties

A novel series of pyrene containing thiophene monomers TPM1-5 were synthesized and fully characterized by FTIR, MS, ¹H- and (13)C-NMR spectroscopy; their thermal properties were determined by TGA and DSC. These monomers were chemically polymerized using FeCl3 as oxidizing agent to give the corresponding oligomers TPO1-5) and they were electrochemically polymerized to obtain the corresponding polymer films deposited onto ITO. All oligomers exhibited good thermal stability, with T10 values between 255 and 299 °C, and Tg values varying from 36 to 39 °C. The monomers showed an absorption band at 345 nm due to the S0 → S2 transition of the pyrene group, whereas the fluorescence spectra showed a broad emission band arising from the "monomer" emission at 375-420 nm. The obtained polymers exhibited two absorption bands at 244 and 354 nm, due to the polythiophene and the pyrene moieties, respectively. The fluorescence spectra of polymers showed a broad "monomer" emission at 380-420 nm followed by an intense excimer emission band at 570 nm, due to the presence of intramolecular pyrene-pyrene interactions in these compounds.

Developments in the Field of Conducting and Non-conducting Polymer Based Potentiometric Membrane Sensors for Ions Over the Past Decade

Many research studies have been conducted on the use of conjugated polymers in the construction of chemical sensors including potentiometric, conductometric and amperometric sensors or biosensors over the last decade. The induction of conductivity on conjugated polymers by treating them with suitable oxidizing agents won Heeger, MacDiarmid and Shirakawa the 2000 Nobel Prize in Chemistry. Common conjugated polymers are poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(terthiophene)s, poly(aniline)s, poly(fluorine)s, poly(3-alkylthiophene)s, polytetrathiafulvalenes, polynapthalenes, poly(p-phenylene sulfide), poly(p-phenylenevinylene)s, poly(3,4-ethylenedioxythiophene), polyparaphenylene, polyazulene, polyparaphenylene sulfide, polycarbazole and polydiaminonaphthalene. More than 60 sensors for inorganic cations and anions with different characteristics based on conducting polymers have been reported. There have also been reports on the application of non-conducting polymers (nCPs), i.e. PVC, in the construction of potentiometric membrane sensors for determination of more than 60 inorganic cations and anions. However, the leakage of ionophores from the membranes based on these polymers leads to relatively lower life times. In this article, we try to give an overview of Solid-Contact ISE (SCISE), Single-Piece ISE (SPISE), Conducting Polymer (CP)-Based, and also non-conducting polymer PVC-based ISEs for various ions which their difference is in the way of the polymer used with selective membrane. In SCISEs and SPISEs, the plasticized PVC containing the ionophore and ionic additives govern the selectivity behavior of the electrode and the conducting polymer is responsible of ion-to-electron transducer. However, in CPISEs, the conducting polymer layer is doped with a suitable ionophore which enhances the ion selectivity of the CP while its redox response has to be suppressed.

Conducting polymers in chemical sensors and arrays

The review covers main applications of conducting polymers in chemical sensors and biosensors. The first part is focused on intrinsic and induced receptor properties of conducting polymers, such as pH sensitivity, sensitivity to inorganic ions and organic molecules as well as sensitivity to gases. Induced receptor properties can be also formed by molecularly imprinted polymerization or by immobilization of biological receptors. Immobilization strategies are reviewed in the second part. The third part is focused on applications of conducting polymers as transducers and includes usual optical (fluorescence, SPR, etc.) and electrical (conductometric, amperometric, potentiometric, etc.) transducing techniques as well as organic chemosensitive semiconductor devices. An assembly of stable sensing structures requires strong binding of conducting polymers to solid supports. These aspects are discussed in the next part. Finally, an application of combinatorial synthesis and high-throughput analysis to the development and optimization of sensing materials is described.

Electrochemical Sensors Based on Organic Conjugated Polymers

Organic conjugated polymers (conducting polymers) have emerged as potentialcandidates for electrochemical sensors. Due to their straightforward preparation methods,unique properties, and stability in air, conducting polymers have been applied to energystorage, electrochemical devices, memory devices, chemical sensors, and electrocatalysts.Conducting polymers are also known to be compatible with biological molecules in aneutral aqueous solution. Thus, these are extensively used in the fabrication of accurate,fast, and inexpensive devices, such as biosensors and chemical sensors in the medicaldiagnostic laboratories. Conducting polymer-based electrochemical sensors and biosensorsplay an important role in the improvement of public health and environment because rapiddetection, high sensitivity, small size, and specificity are achievable for environmentalmonitoring and clinical diagnostics. In this review, we summarized the recent advances inconducting polymer-based electrochemical sensors, which covers chemical sensors(potentiometric, voltammetric, amperometric) and biosensors (enzyme based biosensors,immunosensors, DNA sensors).

Electrochemical determination of Ag-ions in environment waters and their action on plant embryos

We utilized liquid chromatography coupled with electrochemical detector (HPLC-ED) for analyzing of silver ions. The optimization of basic chromatographic parameters has been done. The detection limit (3 S/N) obtained were 20 nmol/dm(3). Influence of different interferences (anions and cations) on current response of silver ions has been described. Moreover, we used HPLC-ED to analyze waters of different purity including photographic emulsion, which naturally contained silver ions. We found out that content of silver ions in the emulsion was 1.57 x 0.03 mmol/dm(3). Moreover, we investigated influence of silver ions on early somatic embryos of Blue Spruce. We were interested in the issue how much silver ions can embryos uptake during four days long treatment. For this purpose, we used optimized HPLC-ED technique. The content increased with increasing treatment time and applied concentration. We also studied how silver ions can influence thiols content in the treated embryos. For these purposes we used adsorptive transfer stripping voltammetry in connection with differential pulse voltammetry--Brdicka reaction. It clearly follows from the obtained results that content of thiols increased with increasing treatment time and applied concentration.