The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Wolfgang K Maser - One of the best experts on this subject based on the ideXlab platform.

  • simultaneous reduction of graphene oxide and polyaniline doping assisted formation of a solid state Charge Transfer Complex
    Journal of Physical Chemistry C, 2011
    Co-Authors: Cristina Valles, Pablo Jiménez, Ana M Benito, Edgar Munoz, Wolfgang K Maser
    Abstract:

    We report the formation of a solid-state Charge-Transfer Complex upon simultaneous reduction of a graphene oxide–polyaniline (GO-PANI) composite consisting of GO sheets coated by a thin layer of PANI. The reduced R(GO-PANI) material exhibits an unprecedented donor–acceptor interaction at the interface between RGO sheets and the thin PANI layer coating. A conceptual explanation is proposed in which RGO plays a dual role as electron acceptor and as large counterion stabilizing an atypical intermediate oxidation state of PANI. Moreover, the donor–acceptor interactions are responsible for superior materials characteristics, such as excellent water dispersibility, high environmental (chemical and thermal) degradation stability, and enhanced electric conductivity as high as 2600 S/m. These results may enable further opportunities for the development of novel electroactive materials based on graphene and intrinsically conducting polymers and the fabrication of corresponding flexible electronic devices through tr...

  • Simultaneous reduction of graphene oxide and polyaniline: Doping-assisted formation of a solid-state Charge-Transfer Complex
    Journal of Physical Chemistry C, 2011
    Co-Authors: Cristina Valles, Pablo Jiménez, Ana M Benito, Edgar Munoz, Wolfgang K Maser
    Abstract:

    We report the formation of a solid-state Charge-Transfer Complex upon simultaneous reduction of a graphene oxidepolyaniline (GO-PANI) composite consisting of GO sheets coated by a thin layer of PANI. The reduced R(GO-PANI) material exhibits an unprecedented donoracceptor interaction at the interface between RGO sheets and the thin PANI layer coating. A conceptual explanation is proposed in which RGO plays a dual role as electron acceptor and as large counterion stabilizing an atypical intermediate oxidation state of PANI. Moreover, the donoracceptor interactions are responsible for superior materials characteristics, such as excellent water dispersibility, high environmental (chemical and thermal) degradation stability, and enhanced electric conductivity as high as 2600 S/m. These results may enable further opportunities for the development of novel electroactive materials based on graphene and intrinsically conducting polymers and the fabrication of corresponding flexible electronic devices through traditional solution processing techniques.

Deliang Wang - One of the best experts on this subject based on the ideXlab platform.

Yoshinori Tokura - One of the best experts on this subject based on the ideXlab platform.

  • quantum ferroelectricity in Charge Transfer Complex crystals
    Nature Communications, 2015
    Co-Authors: Sachio Horiuchi, Reiji Kumai, Kensuke Kobayashi, Fumitaka Kagawa, Nao Minami, Yoshinori Tokura
    Abstract:

    Quantum phase transition achieved by fine tuning the continuous phase transition down to zero kelvin is a challenge for solid state science. Critical phenomena distinct from the effects of thermal fluctuations can materialize when the electronic, structural or magnetic long-range order is perturbed by quantum fluctuations between degenerate ground states. Here we have developed chemically pure tetrahalo-p-benzoquinones of n iodine and 4–n bromine substituents (QBr4–nIn, n=0–4) to search for ferroelectric Charge-Transfer Complexes with tetrathiafulvalene (TTF). Among them, TTF–QBr2I2 exhibits a ferroelectric neutral–ionic phase transition, which is continuously controlled over a wide temperature range from near-zero kelvin to room temperature under hydrostatic pressure. Quantum critical behaviour is accompanied by a much larger permittivity than those of other neutral–ionic transition compounds, such as well-known ferroelectric Complex of TTF–QCl4 and quantum antiferroelectric of dimethyl–TTF–QBr4. By contrast, TTF–QBr3I Complex, another member of this compound family, shows complete suppression of the ferroelectric spin-Peierls-type phase transition.

Moustafa M. Habeeb - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis, spectroscopic characterization and DFT/TD-DFT computations of a novel Charge Transfer Complex via hydrogen bonding between 3-amino-1,5-dimethylpyrazole with chloranilic acid in different solvents
    Journal of Molecular Structure, 2019
    Co-Authors: Khairia M. Al-ahmary, Moustafa M. Habeeb, Safaa H. Aljahdali
    Abstract:

    Abstract A novel Charge Transfer Complex including hydrogen bonding between the e-donor (H-acceptor) 3-amino-1,5-dimethylpyrazole (3-ADMP) with the e-acceptor (H-donor) chloranilic acid (CLA) has been synthesized and characterized experimentally and theoretically. The experimental work was carried out in different solvents including chloroform (CHL), ethanol (EtOH), methanol (MeOH) and acetonitrile (AN). The solution characterizations included the determining of the molecular composition of the formed CT Complex where it recorded 1:1 (donor:acceptor) in all solvent. Also, estimating its formation constant by Benesie-Hildebrand equation where it recorded high values in all solvents, suggesting its high stability. Thermodynamic and some spectroscopic physical parameters were introduced and interpreted where they confirmed the presence of Charge Transfer besides hydrogen bonding in the formed Complex. The solid Complex was prepared and characterized by elemental analysis, infrared and NMR (1H and 13C) spectroscopies, the Complex was formed in 1:1 ratio, with good evidences for existing both Charge Transfer and hydrogen bonding in its molecular structure. Density functional theory B3LYP-DFT at the basis set 6-31G (d,p) has been running out in gas phase and solution using chloroform and acetonitrile as solvents to compliment the measured results. The Complex optimized structure included two hydrogen bonds between OH and C O of chloranilic acid with the adjacent ring nitrogen and amino group of pyrazole ring. The optimization energy, Complexation energy, geometrical parameters, Mullikan atomic Charges as well as molecular electrostatic potential maps (MEP) were calculated and interpreted; they consisted with the experimental results where the Complex stability is attributed to the presence of H-bond beside e-Transfer. The electronic spectra were computed using TD-DFT through adding polarizable continuum solvation method PCM, PCM-TD-DFT to compare with the experimental results. It has been found that, the measured and computed λmax are coming close to each other. The allowed singlet transitions are located and their HOMO and LUMO contributions are presented. The pictures of the frontier HOMO and LUMO molecular orbitals, participating in the first six singlet transitions were presented. A good consistency between experimental and DFT computations has been found.

  • spectral and solvation effect studies on Charge Transfer Complex of 2 6 diaminopyridine with chloranilic acid
    Journal of Molecular Liquids, 2013
    Co-Authors: Reem M Alghanmi, Moustafa M. Habeeb
    Abstract:

    Abstract Charge Transfer Complex formation between 2,6-diaminopyridine (2,6-DAP) as the electron donor, proton acceptor, with chloranilic acid (CLA) as the π-electron acceptor, proton donor, has been investigated spectrophotometrically in ethanol (EtOH), acetonitrile (AN) and binary mixture composed of 50% ethanol + 50% acetonitrile (v/v), (ANET). The stoichiometry of the Complex has been identified by Job's, photometric and conductometric titration methods to be 1:1. Benesi–Hildebrand equation has been applied to estimate the formation constant (K CT ) and molecular extinction coefficient (e), they recorded high values confirming high stability of the produced Complex. Oscillator strength (f), transition dipole moment (μ), ionization potential (I P ) and dissociation energy (W) of the formed CT-Complex were also determined and evaluated, they showed solvent dependency. Based on the simple composition and fast production of the CT-Complex in solution, a rapid, simple and accurate spectrophotometric method for donor determination is suggested. The solid CT-Complex between 2,6-DAP and CLA has been isolated and characterized using elemental analysis, FTIR and 1 H NMR measurements, it has been found that its molecular composition is 3:2 (electron donor: electron acceptor). Also, molecular modeling utilizing MM2 method including in ChemBio3D Ultra 12.0 software confirmed this molecular composition. Moreover, the present work showed the existence of proton Transfer beside Charge Transfer in the obtained Complex.

  • spectroscopic studies of the hydrogen bonded Charge Transfer Complex of 2 aminopyridine with π acceptor chloranilic acid in different polar solvents
    Journal of Molecular Liquids, 2011
    Co-Authors: Khairia M Alahmary, Moustafa M. Habeeb, Eman A Alsolmy
    Abstract:

    Abstract Hydrogen bonded Charge Transfer Complex (HBCT) between 2-aminopyridine (2AP) as electron donor, hydrogen bond acceptor, with chloranilic acid (CHA) as the π-electron acceptor, hydrogen bond donor, has been studied spectrophotometrically in the polar solvents acetonitrile (AN), methanol (MeOH) and ethanol (EtOH). The stoichiometry of the Complex has been identified by Job's and photometric titration methods to be 1:1. The Benesi–Hildebrand equation has been applied to estimate the formation constant (KCT) and molar extinction coefficient (e). It was found that the value of KCT is larger in methanol than those in acetonitrile or ethanol. The results were interpreted in terms of Kamlet–Taft α and β solvent parameters. Furthermore, the data were analyzed in terms of standard free energy change (ΔG°), oscillator strength (f), dissociation energy (W), transition dipole moment (μ) and ionization potential (IP). Also, the solid HBCT-Complex was synthesized and characterized by using elemental analysis and FTIR spectroscopy.

Wonyong Choi - One of the best experts on this subject based on the ideXlab platform.

  • glucose tio2 Charge Transfer Complex mediated photocatalysis under visible light
    Applied Catalysis B-environmental, 2015
    Co-Authors: Wonyong Choi
    Abstract:

    Abstract Glucose adsorbed-TiO2 nanoparticles show photoactivity under visible light (λ > 420 nm) through the ligand-to-metal Charge Transfer (LMCT) mechanism. Although glucose has been often utilized as a hole scavenger in TiO2-based photocatalytic systems, the fact that TiO2–glucose can form a LMCT Complex that absorbs visible light has not been recognized. The TiO2–glucose LMCT Complex induced a marked red-shift in the absorption spectrum which extended to 600 nm, and the visible light absorption gradually decreased with decreasing the concentration of glucose. The TiO2–glucose Complex exhibited remarkable visible light activities for the reduction of Cr(VI) to Cr(III) and the reduction of O2 to H2O2. The observed visible light activities were significantly inhibited when the TiO2 surface was fluorinated, because the surface fluorides inhibited the formation of LMCT Complex of glucose. The electrode coated with TiO2–glucose Complex generated a significant level of photocurrent under visible light. The ATR-FTIR spectra showed that glucose forms a surface Complex on TiO2 through the hydroxyl linkages. The evidences for the formation of the TiO2–glucose Complex and the experimental parameters affecting the visible light-induced activities are discussed in detail.