The reaction of RhCl3·3H2O with the ligand L = 2-(2′-pyridyl)quinoxaline (pqo) in a 1:2 molar ratio formed the mononuclear complex cis-[RhL2Cl2]Cl (1), which has been characterized by elemental analysis, FT-IR, FT-Raman, 1H, 13C NMR, electronic absorption spectroscopy and by electrospray mass spectrometry. The molecular structure of 1 (needle like and prismatic polymorphs) in the crystal has been elucidated by single-crystal X-ray diffraction, revealing a bidentate behavior of L, while the geometry around the Rh(III) atom is that of a distorted octahedron.. Preliminary biological tests revealed that this compound inhibited PAF-induced rabbit platelet aggregation. © 2009 Elsevier Ltd. All rights reserved.

Self-organized porous TiO2 nanotubes (NTs) were prepared on conductive glass by galvanostatic anodizing of sputtered titanium in an NH 4F /glycerol electrolyte. DC magnetron sputtering at an elevated substrate temperature (500 °C) was used to deposit 650nm thick titanium films. After anodizing, NTs, 830nm long, with an average external diameter of 92nm, were grown; this gave a high conversion rate of oxide from titanium (1.9), with a 220nm thick layer of titanium, which was not oxidized, located at the base of the tubes. The NTs revealed a mainly amorphous structure, which transformed mostly to anatase upon thermal treatment in air at 450 °C. The tubes were sensitized by the N719 complex and the resultant photoelectrodes were incorporated into liquid dye solar cells (DSCs) and further tested under back-side illumination. High values of Voc (714mV) were obtained under 1 sun (AM 1.5), assigned to low dark current magnitude and large recombination resistance and electron lifetime. In addition, typical values of fill factors (of the order of 0.62) were attained, in agreement with the estimated ohmic resistance of the cells in combination with low electron transfer resistance at the platinum/electrolyte interface. The overall moderate power conversion efficiency (of the order of 0.3%) was mainly due to the low short-circuit photocurrents (Jsc = 0.68mAcm-2), which was confirmed further by the corresponding IPCE values (5.2% at 510nm). The magnitude of Jsc was attributed to absorbed light losses due to back-side illumination of the cells, the low dye loading (due to the limited thickness of anodic titania) and the high charge transfer resistance at the TiO2 /conductive substrate due to the presence of barrier layer(s) underneath the tubes. These preliminary results encourage the DSC community to explore further the galvanostatic anodizing of titanium in order to produce highly efficient porous TiO2 NTs directly on conductive glass. Current work is focusing on achieving complete anodizing of the metal substrate and full transparency for the photoelectrode in order to increase and optimize the resultant cell efficiencies. © 2009 IOP Publishing Ltd.

Micro-Raman spectroscopy is applied to investigate the long-term stability of industrial dye-sensitized solar cells under prolonged light soaking and thermal stress following continuous illumination over 6450 h at 55-60 °C. The Raman spectral characteristics of the individual cell components have been investigated using two excitation wavelengths in the visible and near-infrared range allowing us to assess the microstructure of the TiO2/conducting glass photoelectrode, the chemical bonding of the hydrophobic Ru(II)-polypyridyl dye complex on the mesoporous TiO2 film, and the electrolyte composition. Comparative ex situ resonance Raman measurements on fresh and aged cells indicate minor differences in the vibrational characteristics of the triiodide, dye molecules, and the triiodide/dye charge transfer adduct at the electrode/electrolyte interface upon aging, confirming the absence of any distinct chemical modification that could create instability. In situ Raman experiments implemented via the application of a polarization bias reveal a less pronounced potential dependence of both the electrolyte and the dye Raman response for the aged cells. These features together with the intensity reduction and broadening of the anatase Raman modes imply that the chemical stability of the cell interfaces is accompanied by a modification of the interfacial electric field on the TiO2/dye/electrolyte junction after long-term light and thermal stress.© 2009 American Chemical Society.

Surface functionalization of self-organized Ti02 nanotube (NT) arrays produced by electrochemical anodization is implemented by dextrin-coated iron-oxide nanoparticles leading to a composite semiconductor nanostructure. The morphological and structural properties are studied by electron and atomic force microscopy, X-ray diffraction, X-ray photoelectron, and resonance micro-Raman spectroscopies revealing successful deposition of maghemite (γ-Fe2o3) nanoparticles on the nanotube walls. The nanocomposite surface simultaneously exhibits high photocatalytic activity for the degradation of model pollutants under UV irradiation at relatively low loading levels of the γ-Fe2o3 nanoparticles and light-independent wetting properties, as the initially superhydrophilic surface is converted to a moderately hydrophilic substrate, while obtaining an additional functionality through the magnetic field response of the iron-oxide component that shows appreciable magnetization anisotropy. Electrochemical impedance investigation including Mott-Schottky analysis attests to a significant improvement of the interfacial electron-transfer kinetics together with a modification of the surface chemistry for the functionalized Ti0 2 nanotubes, promoting electron-hole separation through the polyhydroxyl dextrin shell that mediates charge transfer between the constituent semiconductor oxides and validating their improved photocatalytic performance. These composite nanotubular materials offer the opportunity of advanced applications, where the unique photoinduced reactivity, the controlled wetting behavior, and the magnetic field response can be effectively combined. © 2009 American Chemical Society.

Self-organized TiO2 nanotubes with packed, vertically aligned morphology and different lateral characteristics were grown on Ti metal substrates by controlled electrochemical anodization in phosphate/HF and ethylene glycol/HF electrolytes. The wetting, photo-induced superhydrophilicity, and photocatalytic activity of the nanotubular materials were investigated under ultraviolet irradiation. The photoactivity of the TiO2 nanotube arrays was analysed in terms of their morphological characteristics that were determined by means of scanning electron microscopy and atomic force microscopy in conjunction with geometrical modelling. The wetting and the UV-induced superhydrophilicity could be accordingly modelled by the Cassie-Baxter mode arising from the large scale roughness of the nanotubular arrays in combination with the Wenzel mode due to the small scale roughness induced by ridges at the outer tube surface. The photocatalytic activity of the TiO2 nanotube arrays was further found to correlate quantitatively with the variation of the geometric roughness factor, verifying the strong impact of morphology on the photo-induced properties of the vertically oriented TiO2 tubular architecture. © IOP Publishing Ltd.

{cis-[Ru(bpy)2(Ln)]Cl2 (n = 1, L 1 = 4-carboxy-2-(2′-pyridyl)quinoline (2); n = 2