Polymerization of Bis(Pyridine)bis-(2,4,6-tribromophenoxo)copper(II) Complex (Py2Cu(TBrP)2) by Electrooxidation and Structural Characterization by 1H-NMR, 13C-NMR,and FTIR Spectroscopies

Abstract

Electroinitiated polymerization of bis(2,4,6-tribromophenoxo)- bis(pyridine)copper(II) complex was achieved in dimethylformamide-tetrabutylammonium tetrafluoroborate solvent-electrolyte couple under air or nitrogen at room temperature by constant potential electrolysis. Polymerization conditions were based on the peak potentials measured by cyclic voltammetry. The structural analyses of the polymers were done by ¹H-NMR, ¹³C-NMR, and FTIR spectral analyses along with molecular weight measurements by cryoscopy. The poly(dibromo phenylene oxide)s obtained only at oxidation potentials in either atmosphere were found to be highly linear, indicating mainly 1,4-catenation was taking place.     

Thiadiazoloquinoxaline and benzodithiophene bearing polymers for electrochromic and organic photovoltaic applications

Abstract

Two novel thiadiazoloquinoxaline and benzodithiophene (BDT) bearing copolymers were designed and synthesized. Different BDT units (alkoxy and thiophene substituted) were used as donor materials and the effect of alkoxy and thiophene substitution on the electrochemical, spectroelectrochemical and photovoltaic properties were investigated. Both polymers exhibited low oxidation potentials at around 0.90 V and low optical band gaps at around 1.00?eV due to the insertion of electron poor thiadiazoloquinoxaline unit into the polymer backbone. Both P1 (poly-6,7-bis(3,4-bis(decyloxy)phenyl)-4-(4,8-bis(nonan-3-yloxy)benzo[1,2-b:4,5-b']dithiophen-2-yl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) and P2 (poly- 4-(4,8-bis(5-(nonan-3-yl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophen-2-yl)-6,7-bis(3,4-bis(decyloxy)phenyl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) exhibited multichromic behavior with different tones of greenish yellow and gray in the neutral and fully oxidized states, respectively. In addition, both polymers revealed very high optical contrasts (～87%) in the NIR region which make these promising polymers good candidates for NIR applications. Finally, in order to explore the organic photovoltaic performances, P1 and P2 were mixed with PC₇₁BM in the active layer of organic solar cells (OSCs) by conventional device structure. As a result P1 and P2 based devices revealed power conversion efficiencies (PCEs) of 0.33% and 0.60% respectively. However, the additive treatment enhanced PCE from 0.49 to 0.73% for P2 based devices.     

Immobilization of Invertase in Copolymer of 2,5-Di(thiophen-2-yl)-1-p-Tolyl-1H-Pyrrole with Pyrrole

Immobilization of invertase in conducting copolymer matrix of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole with pyrrole (poly(DDTP-co-Py)) was achieved via electrochemical polymerization. Kinetic parameters, Michaelis-Menten constant, K_m and the maximum reaction rate, V_max were investigated. Operational stability and temperature optimization of the enzyme electrodes were also examined.

Immobilized invertase reveals maximum activity at 50°C and; pH 8 and pH 4 for two copolymer matrices. Although the same two monomers are utilized for the copolymer synthesis, the way the copolymer is produced results in quite different responses in terms of enzyme activity, optimum pH and kinetic parameters. Excellent operational stability of the enzyme electrodes enables their repetitive use in the determination of invert sugar.     

Characterization of Conducting Copolymer of Thiophene via Pyrolysis Mass Spectrometry

In this work, structural and thermal characterization of a conducting copolymer of thiophene (PTh) with 2‐methylbutyl‐2‐(3‐thienyl)acetate prepared by two different methods has been performed by pyrolysis mass spectrometry techniques. The pyrolysis mass spectrometry data of both components of the copolymer, polythiophene, PTh, poly(2‐methylbutyl‐2‐(3‐thienyl)acetate), PMBTA and PTh/PMBTA have been analyzed and compared. It has been determined that when the electrochemical polymerization of thiophene was achieved on PMBTA coated anode through the thiophene moieties of PMBTA, characteristics of both PTh and PMBTA were retained to a certin extent. However, when thiophene was polymerized in the presence of MBTA, a polymer film with lower conductivity, but more uniform structure, was produced.     

Investigation of Copolymers of Thiophene‐Functionalized Polystyrene with Pyrrole by Pyrolysis Mass Spectrometry

The thermal and structural characterization of electrochemically synthesized thiophene‐functionalized polystyrene and pyrrole (PS/PPy) and their copolymers were investigated by direct pyrolysis mass spectrometry. The pyrolysis data confirmed the growth of polypyrrole onto the pendant thiophene moiety of polystyrene. It is determined that the electrolytic film has different properties from the mechanical mixture and the related homopolymers.     

Preparation and application of a polythiophene solid‐phase microextraction fiber for the determination of endocrine‐disruptor pesticides in well waters

A robust solid‐phase microextraction fiber was fabricated by electropolymerization of thiophene on a stainless steel wire. This fiber was applied for the determination of endocrine‐disruptor pesticides, namely, chlorpyrifos, penconazole, procymidone, bromopropylate, and λ‐cyhalothrin in well waters by a headspace solid‐phase microextraction procedure. Operational parameters, namely, pH, sample volume, adsorption temperature and time, desorption temperature, stirring rate, and salt amount were optimized as 7.0, 8 mL, 70°C and 20 min, 250°C, 600 rpm, and 0.3 g/mL, respectively. The separation power of GC was coupled with the excellent sensitivity of the developed fiber enabling us to determine pesticide mixtures simultaneously in a ng/mL range. The LOD was in the range of 0.02–0.64 ng/mL. The method was successfully applied for the selective and sensitive determination of target pesticides in well water samples with acceptable recovery values (92–110%). The polythiophene fiber gives satisfactory results compared with commercial fibers. Commonly used pesticides with different polarities were chosen as representative compounds to search the applicability of the fiber for well water analysis collected from vineyards.     

Preparation of conductive polybenzoxazines by oxidative polymerization

Soluble and thermally curable conducting high molecular weight polybenzoxazine precursors were prepared by oxidative polymerization 3‐phenyl‐3,4‐dihydro‐2H‐benzo[e][1,3] oxazine (P‐a) alone and in the presence of thiophene (Th) with ceric ammonium nitrate in acetonitrile. The structure of the precursors was confirmed by FTIR, ¹H NMR, and DSC measurements, indicating the presence of a cyclic benzoxazine structure, together with small but varying amount of a ring opened phenolic structure. The resulting polymers exhibit conductivities around 10^?2 S cm^?1 and undergo thermal curing at various temperatures. Attempts to copolymerize P‐a with another electroactive monomer, pyrrole (Py), by a similar redox process were unsuccessful, which was attributed to the unfavourable oxidation potential of Py. The cured products exhibited high thermal stability but lower conductivity, than those of the precursors. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 999–1006, 2007     

A disposable planar peristaltic pump for lab-on-a-chip

We demonstrate a simple planar peristaltic pump fabricated in poly(dimethylsiloxane) (PDMS) via soft lithography and suitable for microfluidic integration.     

The impact of socio-technical communication styles on the diversity and innovation potential of global science collaboratories

Emerging cyber-infrastructure tools are enabling scientists to transparently co-develop, share, and communicate about real-time diverse forms of knowledge artifacts. In these environments, communication preferences of scientists are posited as an important factor affecting innovation capacity and robustness of social and knowledge network structures. Scientific knowledge creation in such communities is called global participatory science (GPS). Recently, using agent-based modeling and collective action theory as a basis, a complex adaptive social communication network model (CollectiveInnoSim) is implemented. This work leverages CollectiveInnoSim implementing communication preferences of scientists. Social network metrics and knowledge production patterns are used as proxy metrics to infer innovation potential of emergent knowledge and collaboration networks. The objective is to present the underlying communication dynamics of GPS in a form of computational model and delineate the impacts of various communication preferences of scientists on innovation potential of the collaboration network. Gained insight can ultimately help policy-makers to design GPS environments and promote innovation.     

Phenothiazine-based chalcones as potential dual-target inhibitors toward cholinesterases (AChE,BuChE) and monoamine oxidases (MAO-A,MAO-B)

Chalcones targeting neurodegenerative diseases have been known as attractive structures in drug design and discovery. In this study, phenothiazine-based chalcones as ChEs and MAOs inhibitors were designed and synthesized via base-catalyzed Claisen-Schmidt condensation, and chemical structures of the compounds were elucidated by NMRs and HRMS. Compounds 3 and 9 showed promising inhibition potency against AChE enzyme with IC₅₀ values of 0.221 μM and 0.053 μM while compound 9 displayed remarkable inhibition potency toward MAO-B enzyme with IC₅₀ value of 0.048 μM. Compound 9 , as a dual-target inhibitor, selectively inhibited AChE and MAO-B enzymes. This promising behavior is an advantage for the compound since MAO-B and AChE inhibition have a role in Alzheimer's disease. Fused tricyclic ring systems such as phenothiazine incorporated with chalcone moiety being multitargeting ligands may help scientists for the rational design of novel lead compounds targeting neurodegenerative illnesses.