To construct a sensing interface, in the present work, a conjugated polymer and core-shell magnetic nanoparticle containing biosensor was constructed for the pesticide analysis. The monomer 4,7-di(furan-2-yl)benzo[c][1,2,5]thiadiazole (FBThF) and core-shell magnetic nanoparticles were designed and synthesized for fabrication of the biosensing device. The magnetic nanoparticles were first treated with silica and then modified using carboxyl groups, which enabled binding of the biomolecules covalently. For the construction of the proposed sensor a two-step procedure was performed. First, the poly(FBThF) was electrochemically generated on the electrode surface. Then, carboxyl group modified magnetic nanoparticles (f-MNPs) and acetylcholinesterase (AChE), the model enzyme, were co-immobilized on the polymer-coated surface. Thereby, a robust and novel surface, conjugated polymer bearing magnetic nanoparticles with pendant carboxyl groups, was constructed, which was characterized using Fourier transform infrared spectrometer, cyclic voltammetry, scanning electron microscopy, and contact angle measurements. This novel architecture was then applied as an immobilization platform to detect pesticides. To the best of our knowledge, a sensor design that combines both conjugated polymer and magnetic nanoparticles was attempted for the first time, and this approach resulted in improved biosensor characteristics. Hence, this approach opens a new perspective in the field of enzyme immobilization and sensing applications. Paraoxon and trichlorfon were selected as the model toxicants. To obtain best biosensor performance, optimization studies were performed. Under optimized conditions, the biosensor in concern revealed a rapid response (5 s), a low detection limit (6.66 × 10(-3) mM), and high sensitivity (45.01 μA mM(-1) cm(-2)). The KM(app) value of poly(FBThF)/f-MNPs/AChE were determined as 0.73 mM. Furthermore, there was no considerable activity loss for 10 d for poly(FBThF)/f-MNPs/AChE biofilm.

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Herein, we report the synthesis of two donor-acceptor-donor polymers (P1 and P2) based on thiophene (M1) and thieno [3,2-b]thiophene (M2) as the donor and 2,5-bis(dodecyloxy)benzene as the acceptor unit. The effects of different donor units on the polymers' electrochemical and optical properties were examined by cyclic voltammetry and spectroelectrochemical analysis. Introducing thieno [3,2-b]thiophene unit as the donor unit enhances π-stacking and consequently lowering the bandgap of the resulting polymer. The electronic band gaps, defined as the onset of the π-π * transition, were found to be 2.0 eV for P1 and 1.7 eV for P2. Both P1 and P2 films revealed multi-colored electrochromism. A dual-type complementary colored electrochromic device (ECD) using P2/PEDOT in sandwich configuration was constructed. Spectroelectrochemistry, switching ability and open circuit memory of the ECD were investigated.During the past decade, the field of organic electronics has progressed enormously as a result of growing interest in materials chemistry. The first generation of conducting organic materials were composed of predominantly carbon-based molecular structures such as linear acenes, poly acetylene, and poly(p-phenylene vinylene) derivatives (PPV). 1-3 The following generation involved the widespread incorporation of heterocycles into the conjugated backbone such as thiophene, pyrrole and their derivatives. 4-6 Currently, conjugated polymers and small organic molecules have been designed using "donor-acceptor" strategy. 7-10 This method involves synthesizing monomers and polymers with a delocalized π-electron system that consists of alternating electron-rich (donor) and electron-deficient (acceptor) units. The combination of high-lying HOMO levels (residing on the donor units) and low-lying LUMO levels (residing on the acceptor units) results in a local electron density gradient along the backbone, creating a lower energy charge-transfer transition. 11,12 The presence of this lower energy transition leads to smaller optical band gaps. A low bandgap leads to absorption in the visible region. Low bandgap, stability, solubility (which is crucial for their processability), planarity (which is important for obtaining good π-orbital overlap and effective electron delocalization) are the main requirements for organic electronic materials. In an attempt to manipulate relevant parameters to fulfill these requirements through synthetic expertise, numerous organic heterocyclic and pendant groups have been incorporated into the backbones of donor-acceptor conjugated polymers and small molecules. Thiophene based materials have demonstrated great potential as donor units due to their desirable properties such as stability, ease of synthesis, and modification. In recent years, thiophene moiety was coupled with benzoselenadiazole, 13 benzotriazole, 14,15 carbazole, 16 benzothiadiazole, 17,18 ethylenedioxythiophene, 19 diketopyrrolopyrrole, 20 3-alkylthiophene, 21 quinoxaline, 22 and benzimidazole. 23 The study of the opto-electronic proper...

A low band gap donor-acceptor (D-A) copolymer PTBTBDT, namely, poly(2-dodecyl-4,7-di(thiophen-2yl)-2H-benzo [d][1,2,3]triazole-alt-4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b 0 ]dithiophene), was designed and synthesized via a Pd-catalyzed Stille polycondensation reaction. The polymer was characterized using 1 H NMR spectroscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC). PTBTBDT has good solubility in common organic solvents, good thermal stability, broad absorption, low band gap and exhibits not only high hole mobility but also moderate photovoltaic properties. PTBTBDT displays broad absorption in the wavelength range from 300 nm to 630 nm, and its HOMO and LUMO energy levels were calculated to be À4.98 eV and À3.34 eV, respectively.Bulk heterojunction solar cells were fabricated using PTBTBDT as the electron donor and PC 70 BM as the acceptor. The device exhibits a power conversion efficiency of 2.12% with a current density of 5.45 mA cm À2 , an open-circuit voltage of 0.72 V, and a fill factor of 54% under the illumination of AM 1.5 G, 100 mW cm À2 .Under similar device fabrication conditions, the PTBTBDT based device showed considerably improved efficiency among its previously synthesized counterparts, i.e. PBDTDTBTz and PBDTBTz based devices, which have 1.7% and 1.4% efficiencies, respectively. The hole mobility of the PTBTBDT : PC 70 BM (1 : 2 w/w) blend reached up to 1.47 Â 10 À3 cm 2 V À1 s À1 as calculated by the space-charge-limited current (SCLC) method. By side-chain engineering, this study demonstrates a good example of tuning the absorption range, energy level, charge transport, and photovoltaic properties of polymers.

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Two low band gap triphenylamine based random copolymers are synthesized via Pd-catalyzed Stille polycondensation reaction to investigate the role of molecular weight on device performance and optoelectronic properties. 1 H NMR spectroscopy, UV−vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC) are used for characterization of polymers. The polymerization conditions are optimized to achieve high molecular weight polymers with enhanced optoelectronic properties. PBTP1 reveals broad absorption in the wavelength range of 300-670 nm whereas PBTP2 has absorption in the wavelength range of 300-660 nm. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are calculated as −5.43 and −3.20 eV for PBTP1 and −5.33 and −3.02 eV for PBTP2. The photovoltaic device containing donor PBTP1 and acceptor PCBM [70] in 1:3 weight ratio reveals the highest power conversion efficiency of 2.27%, with V oc of 0.63 V, J sc of 8.19 mA cm −2 , and fill factor of 44% under illumination of AM 1.5 G, 100 mW cm −2 . Organic photovoltaics (OPV) cells fabricated with PBTP2 demonstrate improved photo voltaic results due to higher molecular weight and enhanced optoelectronic properties. Photon-tocurrent efficiency of 3.65% with a current density of 14.73 mA cm −2 , V oc of 0.69 V, and fill factor of 36% are obtained.

Four new 2,1,3‐benzooxadiazole‐based donor–acceptor conjugated polymers, namely poly{9‐(9‐heptadecanyl)‐9H‐carbazole‐alt‐5,6‐bis(octyloxy)‐4,7‐di(selenophen‐2‐yl)benzo[c][1,2,5]oxadiazole)}(PSBSC), poly{9‐(9‐heptadecanyl)‐9H‐carbazole‐alt‐5,6‐bis(octyloxy)‐4,7‐di(furan‐2‐yl)benzo[c][1,2,5]oxadiazole)}(PFBFC), poly{9,9‐dioctyl‐9H‐fluorene‐alt‐5,6‐bis(octyloxy)‐4,7‐di(selenophen‐2‐yl)benzo[c][1,2,5]oxadiazole)}(PSBSFL), and poly{9,9‐dioctyl‐9H‐fluorene‐alt‐5,6‐bis(octyloxy)‐4,7‐di(furan‐2‐yl)benzo[c][1,2,5]oxadiazole)}(PFBFFL), were synthesized via Stille polycondensation reaction. All polymers were found to be soluble in common organic solvents such as chloroform, tetrahydrofuran, and chlorobenzene. Their structures were verified by 1H‐NMR and the molecular weights were determined by gel permeation chromatography (GPC). The polymer films exhibited broad absorption bands. Among all polymers, photovoltaic cells based on the device structure of ITO/PEDOT:PSS/PSBSC:PC71BM(1:3, w/w)/LiF/Al revealed an open‐circuit voltage of 0.62 V, a short circuit current of 7.63 mA cm−2 and a power conversion efficiency of 1.89%. This work demonstrates a good example for tuning absorption range, energy level, and photovoltaic properties of the polymers with different spacers and donor units can offer a simple and effective method to improve the efficiency of PSCs. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2459–2467