Thin-film materials based on phthalocyanine derivatives: structure and physico-chemical properties (original) (raw)
Related papers
Monolayers and Langmuir-Blodgett films of crown-substituted phthalocyanines
Russian Chemical Bulletin, 2004
Tetra 15 crown 5 phthalocyanine ligand and its ruthenium complex with axial CO and MeOH groups were synthesized. The properties of their monolayers and Langmuir-Blodgett films were studied. In the case of the ligand, monolayer films of molecular associates are formed. The compatibility of the ligand and stearic acid in a mixed binary monolayer was established. Stearic acid improves the ligand distribution over the water surface and results in the formation of monolayer associates immobilized in its matrix. The condensation effect of Na + cations on the mixed monolayers was found. The ruthenium complex (R 4 Pc)Ru(MeOH)(CO) forms stable true monolayers. The macrocycle planes in stacking are inclined relatively to the normal to the subphase surface by an angle of 25°. The Langmuir-Blodgett films of the complex were established to have redox peaks. A high electrochemical stability of the Langmuir-Blodgett films and a high electroactivity of phthalocyanine rings were demon strated. It was shown by impedance spectroscopy that the binding of Na + and К + ions by Langmuir-Blodgett films of the (R 4 Pc)Ru(MeOH)(CO) complex results in an increase in the impedance values in a region of medium frequencies by three and five times, respectively.
Journal of Physics: Conference Series
The article presents a comprehensive study of the supramolecular organization of floating layers of the mix-substituted phthalocyanine of A3B-type (1,4,8,11,15,18-hexahexyloxy-22,23,24,25-tetrachlorophthalocyanine). Molecular packing modeling of the studied compound in monolayer structures on the water surface was simulated, and the parameters of the unit cell of the monolayer were calculated. On the base of these data, the supramolecular organization of the floating layers was proposed. Using Brewster microscopy (BAM) and grazing incidence X-ray diffraction (GID), it was shown that at the water/air interface the studied phthalocyanine forms a stable bilayer crystalline structure with an imperceptible number of 3D-aggregates. Interplanar spacing of the crystalline bilayer is 1.93 nm.
Association of some phthalocyanines: from solutions to thin films
Thin Solid Films, 1996
Three kinds of substituted phthalocyanines (Pc) were aggregated in binary solutions and via preparation of thin films. By optical absorption measurements in the visible region the aggregate structure was found to be greatly dependent on the kind of Pc and slightly dependent on the conditions under which the aggregate was formed. It was found also that LB films of substituted Pc are built up of molecular aggregates similar to those found in solutions.
Chemistry of Materials, 1989
The intermolecular interactions between trivalent metal and tetravalent metal phthalocyanines in vacuum-deposited thin films lead to at least two different crystallite types with different optical and electronic properties. UV-visible, infrared, and Raman spectroscopies, X-ray diffraction, scanning electron microscopy (SEM), and photoelectrochemical metal deposition followed by SEM have been used in combination on the same thin films to characterize these different phases and to differentiate their photoelectrochemical activity. Two distinct crystallite forms are evident from these data, which we hypothesize to be (a) a cofacially stacked linear assembly, aligned along the metal-halide or metal-oxo bond or (b) an assembly where adjacent molecules are staggered to form a slipped-stack arrangement and a unique crystallite in the thin film. This latter stacking arrangement leads to a red-shifted Q band in the visible absorbance spectrum, and these crystallites appear to be photoelectrochemically more active by a factor of at least 10.
Characteristics of Langmuir Blodgett Films Obtained from New Phthalocyanine Derivatives
Surface activities, including self-assembling properties as monolayers and multilayers at gas-liquid and solid-gas interfaces were investigated for some metallic phthalocyanines derivatives. Phthalocyanine compounds with Cu and Sm, and various substituted hydrophobic and hydrophilic groups were investigated, in order to determine the monolayer forming and deposition Langmuir Blodgett films behaviour. Particular attention was given to films containing Sm derivatives, which is described as a compound with many potential applications in sensor devices.
Structure and Electronic Properties of Phthalocyanine Films on Metal and Semiconductor Substrates
Http Www Theses Fr, 2014
The current thesis presents fundamental studies of phthalocyanines (Pcs), a group of organic macro-cycle molecules. The use of phthalocyanine molecular films in devices with a variety of possible technological applications has been the reason of the many studies dedicated to such molecules during the last decades. Core and valence photoelectron spectroscopies (PES), X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy (STM) techniques are used to study phthalocyanine molecules in gas phase and adsorbed on gold (111) and silicon Si(100)-2x1 substrates. Density functional theory (DFT) is used to obtain further insights in the electronic structure of the phthalocyanines. The aim of our studies is to get a deeper understanding into the molecule-molecule and molecule-substrate interactions, a fundamental requirement for improving the devices based on such molecular materials. Gas phase PES and XAS studies and single molecule DFT calculations are performed on the valence band (VB) of iron phthalocyanine (FePc), manganese phthalocyanine (MnPc) and metal-free phthalocyanine (H 2 Pc). The VB simulations have shown how the metal atom of the Pc influences the inner valence states of the molecules. The HOMO of the H 2 Pc and FePc is formed by mostly C2p states, whereas the HOMO of MnPc has mainly Mn3d character. PES studies of H 2 Pc on Au(111) have revealed the influence of the surface on the adsorption of the monolayer. XAS studies indicate formation of ordered monolayer with the Pc ligands parallel to the surface and the change of the molecular tilt angle with increasing thicknesses. For LuPc 2 adsorbed on Au(111), STM study demonstrates a formation of bilayer instead of a monolayer. A comparison between the results of LuPc 2 adsorbed on pristine or passivated Si(100)-2x1 confirmes the different reactivities of these surfaces: LuPc 2 retains many molecular-like characters, when adsorbed on the innert passivated Si. Instead, on the more reactive pristine Si surface, the spectroscopic results have indicated a more significant interaction, possible hybridization and charge redistribution between the molecules and the surface. Moreover, STM images show a modification of the geometrical shape of the molecules, which are proposed to adsorb in two different geometries on the pristine Si surface.
Further optical studies on Langmuir-Blodgett films of octa-substituted metal-free phthalocyanines
Supramolecular Science, 1997
Ellipsometry and optical spectroscopy in the ultraviolet-visible (UV-vis.) and infra-red ranges were used to study the correlation between structure and optical properties of Langmuir-Blodgett (LB) films of o&a-substituted metal-free phthalocyanines containing different alkyl chains. The thickness and refractive index of LB films and the orientation of phthalocyanine moieties in the monolayer were obtained from ellipsometric measurements and then data were compared with those from II/,4 isotherms of the floating layer. UV-vis. absorption spectra of LB films of the molecules show Davydov splitting of the Q band. Small changes in alkyl length lead to significant changes in the Q-band shape. The optical characteristics of monolayers are found to be different from those of multilayer films. 0 1997 Elsevier Science Ltd. All rights reserved.