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Reaction between 4-hydroxy-6-methyl-2H-pyran-2-one and aldehydes with 2-methylpyridine in dioxane under catalyst-free conditions provided a simple and efficient one-pot route for the synthesis of 3...

The structure of poly aniline (PANI), poly para phenylenediamine (PpPDA), and poly benzidine (PBz) is strongly dependent on the synthesis conditions and procedure. For this reason there is an ambiguity in the proposed structure of the polymers in the literature. A density functional theory (DFT) calculation were performed to establish the structure of synthesized PANI, PpPDA, and PBz. Different structures were considered for each polymer and fully optimized. Then their electrical and optical properties were calculated. Experimental band gaps of studied polymers were obtained using cyclic voltammetry technique and compared with those calculated by DFT. Optical band gap was also obtained from UV–visible spectrum of each polymer dissolved in DMSO solvent. Optical band gap value obtained for aniline is 1.90 eV which is close to the experimental band gap value reported for emeraldine form of poly aniline. Comparing calculated and experimental HOMO–LUMO gaps decline the formation of benzoid (PPDA-a) and phenenzine (PPDA-b) structures during synthesis of PpPDA. However, the exact structure of PpPDA was recognized through comparing experimental and simulated optical properties. Calculated electronic and optical band gaps of phenanzine structure of synthesized benzidine (PBz-c) are close to those of experimental ones and are confirmed by the spectroscopic results. Obtained results show that theoretical calculations play an important role in the detection of complex polymer structures.

In this study, 3,4-dihydroxy-L-phenylalanine (L-Dopa) was solvothermally polymerized to monodisperse microspheres 1 μ " role="presentation"> μ μ \mu m in diameter. Polymerization was carried out in dimethylformamide containing appropriate amounts of urea and L-Dopa at 120 ∘ " role="presentation"> ∘ ∘ ^{\circ} C for 24 h. Synthesis of the polymer in basic aqueous solution under hydrothermal conditions or via conventional heating resulted in the formation of bulky powders including irregularly shaped particles of the polymer. The morphologies of the synthesized polymers were characterized by scanning electron microscopy (SEM). The microspheres synthesized by solvothermal method (with ∼ " role="presentation"> ∼ ∼ \sim 1 μ " role="presentation"> μ μ \mu m average diameter) were clearly observable in SEM micrographs. The thermal stability of the synthesized polymer was studied by thermogravimetry and differential scanning calorimetry techniques. It was recognized that the polymer is thermally stable at more than 200 ∘ " role="presentation"> ∘ ∘ ^{\circ} C. Applicability of the polymer microspheres was investigated for catalyzing the reaction of one-pot multicomponent synthesis of dihydrofurans. Several dihydrofuran derivatives were successfully synthesized using poly L-Dopa as a novel, environmentally friendly, and efficient catalyst with efficiency of more than 90%. Poly L-Dopa is easily separated by filtration from the reaction mixture. It can be used several times without decreasing the catalyzing activity after washing by suitable solvents.

Dye sensitized solar cells (DSSCs) are a type of photovoltaic device that have received widespread attention in recent years. In comparison with silicon photovoltaic cells, DSSCs exhibit some specific advantages including easy fabrication procedures, low manufacturing cost and compatibility with flexible substrates. In spite of the advantages mentioned, from the industrial point of view, the efficiency and the long term stability of the DSSCs system have been subject of concern during the past years of development of this technology. In order to solve these problems, numerous research efforts have been devoted to the engineering and manufacturing of devices that could meet the standards of the photovoltaic cells market for various applications, but the low efficiency and stability have remained as the major challenges in development of DSSCs over the past 25 year. This review focuses on the obstacles and restrictions in the fabrication and commercialization of DSSCs. Losses-in-potential as a limiting efficiency and degradation processes are discussed and external effective factors on the stability of DSSC such as thermal and light soaking stresses, environmental conditions and issues related to the sealing have been investigated in detail. Also, commercial photovoltaic technology of DSSCs in term of efficiency, stability and lifetime is compared to the different types of photovoltaic solar cells. Results indicate that despite the many attractive features of this technology, the transition from laboratory to industry and outdoor applications has been hampered by a number of issues.

4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline, an interesting novel monomer was successfully synthesized in which α-carbon on ethylenedioxythiophene was linked to aniline at para position. The structure of the monomer was approved by infrared (IR), gas chromatography-mass spectrometry (GC-MS) and 1H nuclear magnetic resonance (1H NMR) spectroscopies. Poly (4-(2,3-dihydrothieno[3,4-6][1,4][dioxin-5-yl) aniline) and its composite with graphene were electrochemically synthesized in aqueous solution by cyclic potential sweep method. The Polymer was characterized by IR and UV–vis spectroscopies, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. Electrochemical synthesis conditions were optimized to prepare high conducting and porous polymer so it can be efficiently used as a counter electrode in fabrication of dye sensitized solar cells. Photovoltaic experiments revealed that energy conversion efficiency of the solar cell fabricated using polymer composite (7.52%) is 21% greater than that prepared by Pt counter electrode (6.19%).

A one-pot, efficient, synthesis of six novel trans-spirocyclopropane-indanedione derivatives with high stereoselectivity has been achieved via the reaction of acetopyridinium chloride with 1,3-indandione and an araldehyde in the presence of triethylamine in acetonitrile under reflux conditions. The attractive features of the method are excellent yields and high purity, short reaction times, and easy work-up.

4-(2-Thienyl)benzenamine (TBA) was successfully synthesized by a simple method including substitution of thiophene on p -nitroaniline followed by reduction of nitro group. Structure of the synthesized monomer was verified using IR, 1 H NMR, GC–MS and elemental analysis techniques. Corresponding poly 4-(2-thienyl)benzenamine) (PTBA) was electrochemically synthesized in acidic aqueous solution by cyclic potential sweep method for the first time. Characterization of the resulting polymer was performed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), UV–vis and IR spectroscopies, and scanning electron microscopy (SEM). Effects of pH and temperature on the electroactivity of the polymer modified electrode were investigated. The corrosion behavior of PTBA in 3.5 wt% NaCl solution was studied by potentiodynamic polarization test and electrochemical impedance spectroscopy. The PTBA was found to exhibit enhanced corrosion protection effect on stainless steel electrode in comparison with polyaniline (PANI) and polythiophene (PTh) homopolymers.

3,4-Dihydroxy-L-phenylalanine and ethylenedioxythiophene were chemically copolymerized via an oxidative process in aqueous solution. The copolymer was used as a novel mussel-inspired electroactive binder in conjunction with a nickel-based metal organic frame work for fabrication of environmentally friendly supercapacitors. The binder, in addition to the sticking effect, contributes to electric charge storing via the redox process of catechol moieties of poly(3,4-dihydroxy-L-phenylalanine) and also the formation of a high charge-storing double layer due to the presence of poly(ethylenedioxythiophene). Cyclic voltammetry, charge/discharge measurements, and electrochemical impedance spectrometry showed that the hybrid supercapacitors based on Ni-benzidine MOF with the new electroactive binder exhibit very high specific capacitance (770 F g − 1 " role="presentation"> − 1 − 1 ^{-1} at 1 A/g) and remarkable capacitance retention of more than 94% after 1000 cycles and 86% after 5000 cycles at high current density of 5 A g − 1 " role="presentation"> − 1 − 1 ^{-1} .

The structural and electronic properties of polyaniline, polypyrrole, and poly(aniline-co-pyrrole) (Ani-co-Py) in periodic form were investigated using calculations based on density functional theory (DFT). One to three monomers of aniline and pyrrole were placed in a supercell, and the effects of dihedral angles between the monomers on the electronic properties of the polymers were explored. All polymer configurations were optimized, and the band structures and densities of states (DOSs) were calculated and compared. The band gap of each polymer was calculated as the smallest energy difference between the HOMO and LUMO bands. The results showed that both sets of homopolymers exhibit semiconducting behavior which becomes less prominent after copolymerization. A comparison of the band structures of the homopolymers and the copolymer indicated that the pyrrole in the copolymer acts as an acceptor. The projected density of states (PDOS) was examined to obtain additional insight into orbital interactions and to identify the atoms that are most influential in the electronic properties of the studied polymers.

A new magnetic nanocomposite called MIL-100(Fe) @Fe3O4@AC was synthesized by the hydrothermal method as a stable adsorbent for the removal of Rhodamine B (RhB) dye from aqueous medium. In this work, in order to increase the carbon uptake capacity, magnetic carbon was first synthesized and then the Fe3O4 was used as the iron (III) supplier to synthesize MIL-100(Fe). The size of these nanocomposite is about 30&ndash, 50 nm. Compared with activated charcoal (AC) and magnetic activated charcoal (Fe3O4@AC) nanoparticles, the surface area of MIL-100(Fe) @Fe3O4@AC were eminently increased while the magnetic property of this adsorbent was decreased. The surface area of AC, Fe3O4@AC, and MIL-100(Fe) @Fe3O4@AC was 121, 351, and 620 m2/g, respectively. The magnetic and thermal property, chemical structure, and morphology of the MIL-100(Fe) @Fe3O4@AC were considered by vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunner-Emmet-Teller (BET), and transmission electron microscopy (TEM) analyses. The relatively high adsorption capacity was obtained at about 769.23 mg/g compared to other adsorbents to eliminate RhB dye from the aqueous solution within 40 min. Studies of adsorption kinetics and isotherms showed that RhB adsorption conformed the Langmuir isotherm model and the pseudo second-order kinetic model. Thermodynamic amounts depicted that the RhB adsorption was spontaneous and exothermic process. In addition, the obtained nanocomposite exhibited good reusability after several cycles. All experimental results showed that MIL-100(Fe) @Fe3O4@AC could be a prospective sorbent for the treatment of dye wastewater.

A magnetic metal-organic framework (MOF) composite, MIL-101(Fe)@PDopa@Fe3O4, was synthesized as the stable adsorbent for removal of methyl red (MR) and malachite green (MG) from wastewaters. A very thin film of 3,4-dihydroxy-L-phenylalanine (L-Dopa) was used as an efficient and environmentally friendly binder between Fe3O4 particles and MIL-101(Fe). Characterization of MIL-101(Fe)@PDopa@Fe3O4 was accomplished by various spectroscopic, microscopic and thermal analysis techniques. Magnetic properties of the composite were studied by vibrating sample magnetometer (VSM). Influencing factors such as pH, ionic strength, contact time, adsorbent dosage, temperature, and initial dye concentration on the adsorption ability of the MIL-101(Fe)@PDopa@Fe3O4 were investigated. The very excellent adsorption capacities (833.33 and 1250 mg/g for MG and MR, respectively) were achieved. Adsorption kinetics, thermodynamics and isotherms studies indicated that MG and MR adsorption followed Langmuir isotherm model and pseudo second-order kinetic model. The Adsorbent was successfully used to remove industrial colors from real textile wastewater. The MIL-101(Fe)@ PDopa@Fe3O4 was found to be recyclable for removal of MR and MG.