Abdiaziz A. Farah

Conductivity enhancement of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) films post-spincasting

Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films on indium tin oxide and glass substrates have been fabricated and subjected to a non-adiabatic annealing process. The films showed subtle changes in their structure and optical properties as well as an increase in conductivity due to the effects of rapid thermal annealing. Through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy studies in conjunction with electrical characterization, and four-point probe measurements, material enrichment of conductive PEDOT domains at the polymer-metal interface have been demonstrated, which well explains the surface conductivity improvement of a thin film of PEDOT:PSS after annealing.

Influence of Nonadiabatic Annealing on the Morphology and Molecular Structure of PEDOT−PSS Films

The effect of nonadiabatic annealing on poly(3,4-ethylendioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) thin films prepared on silicon substrate has been investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The analysis indicates the formation of an annealing-induced doping in PEDOT structure, suggesting a modification of the polymer electronic structure and the formation of a PEDOT-rich film surface.

Synthesis and Characterization of Ruthenium bis-Bipyridine Mono- and Disulfinato Complexes

Reaction of cis-Ru(bpy)(2)Cl(2) with 1,2-benzenedithiol afforded a monosulfhydryl-monosulfinate complex, [Ru(bpy)(2)(S.SO(2))] (1). Complex 1 readily undergoes oxidation when treated with 30% H(2)O(2) and also upon exposure to atmospheric O(2) (rapidly in bright light) to afford the disulfinate complex, [Ru(bpy)(2)(SO(2.)SO(2))] (2). Complexes 1 and 2 were studied using various analytical techniques including elemental analysis, UV-vis, mass spectroscopy, NMR, IR spectroscopy, cyclic voltammetry, X-ray crystallography (for 2). Density functional theory computation was employed with extended charge decomposition and natural population analyses. The agreement between the observed electronic spectrum and that predicted by time dependent DFT, and between the observed infrared spectrum and that predicted by DFT, is truly exceptional. These molecules are relevant to the very unusual active site in the metalloenzyme nitrile hydratase.

REDOX ACTIVE, MULTI-CHROMOPHORE RU(II) POLYPYRIDYL-CARBAZOLE COPOLYMERS: SYNTHESIS AND CHARACTERIZATION

A novel diimine ligand, 2-(2-pyridyl) 4-carboxyquinoline (pcq) and its corresponding polypyridyl Ru(II) complex were synthesized, characterized, and covalently attached to a carbazole based copolymer via post polymer modification. The resulting modified electroactive and multi-chromophoric polymer was readily characterized by UV-visible, FT-IR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and elemental and electrochemical analysis. Results from cyclic voltammetry and FT-IR analysis both confirmed the covalent attachment of redox active Ru(II) center into the polymer. The emission spectrum of the copolymer, in comparison to that of Ru(II) complex, demonstrated that the excited-state properties of the metal complex is maintained, in contrast to the electronic absorption spectrum, which is sensitive to the hydrophobic polymeric chain surrounding the redox sites. The thermal analysis suggested that this metallopolymer also possesses high thermal stability. The ruthenium content was also found to be 7%, which corresponds to 80% of the maximum loading, by elemental analysis.

Surface functionalization of cadmium sulfide quantum confined nanoclusters6: Evidence of facile electronic communication between remote surface sites

Abstract The preparation and derivatization of a series of surface functionalized ∼30 A cadmium sulfide nanoclusters possessing surfaces of varied electron demand, tethered covalently to an electroactive fluorescent ruthenium polypyridyl complex, are described. Electrochemical analyses of these nanoclusters bearing ruthenium moieties yield a monotonic relationship between the Ru(II/III) oxidation potential and the electron withdrawing nature of the cluster surface, indicating that the electron density at the electroactive ruthenium center is indeed influenced by remote electropositive and electronegative substituents attached to the nanocluster. Further evidence of cluster mediated electronic interactions between remote surface moieties presents itself in the form of a dependence of the integrated ruthenium based MLCT emission intensity on the mole per cent of attached thiolate capping agent possessing an electron withdrawing substituent in the position para to the point of cluster attachment.

Synthesis, structure and electrochemical properties of tris (2-(2-pyridyl)-4-methylcarbonylquinoline) ruthenium(II) hexafluorophosphate

Abstract A novel ruthenium complex with 2-(2-pyridyl)-4-methylcarbonylquinoline ligand has been prepared and characterized: the first crystal structure of such complex along with its physical and chemical properties are also described.

Syntheses, characterization and structures of 2-(2-pyridyl)-4-methylcarboxyquinoline ligand and bis(2,2′-bipyridine)-2-(2-pyridyl)-4-methylcarboxyquinoline ruthenium (II) hexafluorophosphate

Abstract The synthesis, characterization and X-ray single crystal structure of a 2-(2-pyridyl)-4-methylcarboxyquinoline diimine ligand (pqme) and its corresponding bis(2,2′-bipyridine)-2-(2-pyridyl)-4-methylcarboxyquinoline ruthenium (II) hexafluorophosphate Ru(bpy)2(pqme)(PF6)2 complex is described. 1H, 1H–1H COSY, 1H–1H TOCSY, 13C NMR, FT-IR, elemental and mass spectrometric analyses were used to characterize the products and fully ascertain their structures. The complex exhibited two well-resolved MLCT transitions in the visible region and a ligand-based transition in the UV region. The cyclic voltammogram of the complex showed a reversible Ru(III)/Ru(II) couple and three well-defined ligand-based reductions. X-ray diffraction analyses provided further insight as to the conformations and geometry of both products. A trans conformation is shown in the solid state as expected for the 2-(2-pyridyl)-4-methylcarboxyquinoline ligand, and a distorted octahedral geometry for the bis(2,2′-bipyridyl)-2-(2-pyridyl)-4-methylcarboxyquinoline ruthenium (II) hexafluorophosphate complex due to α hydrogens of the opposing N–N ligands have been revealed.

Binuclear trans-μ-pyrazine-bis­[bromo­tetra­pyridine­ruthenium(II)] dihexa­fluoro­phosphate di­methyl­form­amide disolvate

The Ru atoms of the title compound, [Ru2Br2(C4H4N2)(C5H5N)8](PF6)2.2C3H7NO, are coordinated by the four N atoms of the pyridine (py) ligands and a bromide. Two such units are bridged by a pyrazine (pz) unit, which is disposed about a centre of inversion, so as to form a trans pseudo-octahedral geometry about Ru. The py units are in an eclipsed conformation when viewed down the internuclear axis. The Ru—N(pz) distance is 2.079 (3) A, while the Ru—Br distance is 2.5524 (4) A.

Cis-dichloro-bis-2-(2-pyridyl)-4-(methylcarboxy)quinoline ruthenium (II): a novel ruthenium (II) tris-chelated building precursor

Abstract Synthesis, characterization and single crystal X-ray structure of cis-dichloro-bis-2-(2-pyridyl)-4-(methylcarboxy)quinoline ruthenium (II), a versatile polypyridyl ruthenium (II) building precursor with additional two peripherally functionalizable sites will be described.