Construction of amperometric biosensor modified with conducting polymer/carbon dots for the analysis of catechol

Phenolic compounds used in food industries and pesticide industry, are environmentally toxic and pollute the rivers and ground water. For that reason, detection of phenolic compounds such as catechol by using simple, efficient and cost‐effective devices have been becoming increasingly popular. In this study, a suitable and a novel matrix was composed using a novel conjugated polymer, namely poly[1‐(5‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b']dithiophen‐2‐yl)furan‐2‐yl)‐5‐(2‐ethylhexyl)‐3‐(furan‐2‐yl)‐4H thieno[3,4‐c]pyrrole‐4,6(5H)‐dione] (PFTBDT) and carbon dots (CDs) to detect catechol. PFTBDT and CDs were synthesized and the optoelectronic properties of PFTBDT were investigated via electrochemical and spectroelectrochemical studies. Laccase enzyme was immobilized onto the constructed film matrix on the graphite electrode. The proposed biosensor was found to have a low detection limit (1.23 μM) and a high sensitivity (737.44 μA/mM.cm−2) with a linear range of 1.25–175 μM. Finally, the applicability of the proposed enzymatic biosensor was evaluated in a tap water sample and a satisfactory recovery (96–104%) was obtained for catechol determination.Publisher's Versio

Synthesis and Characterization of Thiophene and Thieno[3,2-b]thiophene Containing Conjugated Polymers

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 pi-stacking and consequently lowering the bandgap of the resulting polymer. The electronic band gaps, defined as the onset of the pi-pi 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. (C) 2015 The Electrochemical Society. All rights reserved

Molecular architecture: Another plausible pathway toward a low band gap polymer

A donor-acceptor-donor pi-conjugated monomer (10,13-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)dibenzo[a,c]phenazine (PHED)) composed of bi-EDOT and dibenzo[a,c]phenazine repeat units was synthesized to examine the role of acceptor structure on the electronic and optoelectronic properties of the polymer. The spectroelectrochemical analysis showed that the introduction of electron-accepting unit results in a shift in the onset of the pi-pi* transition towards longer wavelengths. The optical band gap (Eg) for PPHED was found to be 1.10 eV and lambda(max) was 790 nm. Switching ability of PPHED was evaluated by kinetic studies via measuring the percent transmittance as 80% at 1600 nm. The high optical contrast within the NIR region makes this material a good candidate for NIR device applications. Dual-type complementary colored electrochromic devices (ECD) using PPHED/PEDOT in sandwich configuration were constructed. Spectroelectrochemistry, switching ability and open circuit memory of the ECDs were investigated

Tailoring the optoelectronic properties of donor-acceptor-donor type pi-conjugated polymers via incorporating different electron-acceptor moieties

Syntheses of donor-acceptor-donor type of pi-conjugated monomers were performed to examine the effect of the acceptor units' strength on the electrochemical and optoelectrochemical properties of the resulting monomer and polymer. Palladium catalyzed Stille cross-coupling reaction of an organotin reagent with an organic electrophile was used for the synthesis of target monomers, 5,8-bis(4-hexylthiophen-2-yl)-2-(2,3-dihydrobenzo[b][1,4]clioxin-6-y1)-3-(2,3-dihydrobenzo[b][1,41dioxin-7-yl)quinoxaline (DBQHT) and 10,13-bis(4-hexylthiophen-2-yl)dibenzo[a,c]phenazine (PHEHT)

Tuning of the neutral state color of the pi-conjugated donor-acceptor-donor type polymer from blue to green via changing the donor strength on the polymer

Two donor-acceptor-donor types of T-conjugated monomers were synthesized using Stille coupling reaction. Both monomers were found to produce electroactive polymers upon electrochemical oxidation. The effects of different donor substituents on the polymers' electrochemical and spectroelectrochemical properties were examined. Optical characterization revealed that the band gaps of poly(2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b][1,4]dioxin-7-yl)-5,8-di(thiophen-2-yl)quinoxaline) (PDBQTh) and poly(2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b][1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7- yl)quinoxaline) (PDBQEd) were 1.5 eV and 1.3 eV, respectively. PDBQEd reveals two distinct absorption bands as expected for this type of donor-acceptor-donor polymer at 423 and 738 nm, while PDBQTh has a single absorption band at 630 nm. The colorimetry analysis revealed that while PDBQTh has a blue color, PDBQEd showed a green color in the neutral state. PDBQEd revealed reversible n-doping

Multichromic and soluble conjugated polymers containing thiazolothiazole unit for electrochromic applications

Here we report the preparation of two solution processible polymers; poly(2-(5-(2-(2-octyldodecyl)-2H-benzo[d][1,2,3]triazol-4-yl)thiophen-2-yl)-5-(thiophen-2-yl)thiazolo[5,4-d]thiazole) (PBTTz) and poly(2-(5-(9,9-dioctyl-9H-fluoren-2-yl)thiophen-2-yl)-5-(thiophen-2-yl)thiazolo[5,4-d]thiazole) (PFTTz) which are multichromic electroactive polymers. PBTTz was synthesized via Stille coupling polymerization whereas PFTTz was synthesized via Suzuki coupling polymerization. Both polymers were coated on ITO slides and their electrochromic properties were investigated. The results of the PBTTz were also compared with a previously published polymer to investigate the linear and branched alkyl chain effect. The polymers were compared through their optical properties and UV-Vis spectroelectrochemistry

Electrodeposition of Poly(4-methyl carbazole-3-carboxylic acid) on Steel Surfaces and Corrosion Protection of Steel

The electropolymerization of 4-methyl carbazole-3-carboxylic acid was successfully performed on a stainless steel (316L) surface with lithium perchlorate/acetonitrile as the supporting electrolyte. The corrosion resistance of the new coating, poly(4-methyl carbazole-3-carboxylic acid) (PCz), was investigated. To this end, potentiodynamic polarization curves, open circuit potentials, and electrochemical impedance spectroscopy were used to evaluate the capacity of the PCz coating to protect the steel surface. The corrosion tests indicated that PCz exhibited effective anodic protection in a corrosive test solution. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1496-1500, 200

Electrochemical and optical properties of novel terthienyl based azobenzene, coumarine and fluorescein containing polymers: Multicolored electrochromic polymers

Three electroactive terthienyl based monomers, namely 1-phenyl-2-[4-(2,2':5',2 ''-terthien-3'-ylmethoxy)phenyl]diazene (TTAz), 4-(2,2':5',2 ''-terthien-3'-ylmethoxy)-2H-chromen-2-one (TTCo) and methyl 2-[3-oxo-6-(2,2':5',2 ''-terthien-3'-ylmethoxy)-3H-xanthen-9-yl] benzoate (TTFlo), were synthesized with good yields and their conducting polymers were electrochemically prepared on ITO electrode surfaces. The effect of chromophore type on electrochemical and optical properties of the polymers was investigated using cyclic voltammetry and spectroelectrochemical techniques in detail. Results revealed that type of chromophore group greatly influences the electronic and optoelectronic behaviors of electrochromic materials. It was observed that PTTAz, PTTCo and PTTFlo also exhibited multicolored electrochromism at their neutral and oxidized states. Electrochromic switching studies indicated that PTTAz (28% at 500 nm, 25% at 770 nm and 64% at 1220 nm) and PTTCo (25% at 475 nm, 32% at 740 nm and 63% at 1200 nm) have higher optical contrasts (Delta T%) with longer switching times than those of PTTFlo (16% at 496 nm and 50% at 1280 nm) in both visible and NIR regions. Comparing with PTTFlo film, PTTAz and PTTCo polymer films showed more reasonable switching stabilities. Besides, the optical band gaps were calculated from the onset of pi-pi* transition in polymer's neutral states, as 1.65 eV, 1.80 eV and 1.78 eV for PTTAz, PTTCo and PTTFlo, respectively

Synthesis and optical properties of fused aromatic thienopyrazine based pi-conjugated polymers

Two new polythieno[3,4-b]pyrazine derivatives, poly-10,12-bis(4-hexylthiophen-2-yl)dibenzo[f,h]thieno[3,4-b]quinoxaline (PDBTQ) and poly-8,10-bis(4-hexylthiophen-2-yl)acenaphtho[1,2-b]thieno[3,4-e]pyrazine (PATP) were synthesized by electrochemical polymerization and their electrochemical properties reported. Electroactivity of the monomer and electrochemical redox behavior of its polymers were investigated by cyclic voltammetry. Spectroelectrochemical analysis was performed and the band gaps of the polymers were determined as 2.0 eV and 1.2 eV from the onset of the pi-pi* transitions of PDBTQ and PATP, respectively. The polymer PDBTQ shows multicolored electrochromic behavior with five distinct states-orange (0.0 V), yellow (+0.30 V), brown (+0.50 V), green (+0.65 V), blue-gray (0.80 V); PATP has two distinct colors-transmissive gray (0.0 V) and green (+0.80 V). The polymers revealed superior optical contrast in the near-infrared (NIR) region with fast switching times of less than 1 s