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Phthalocyanine monolayer films

LB films of 1,4,8,11,15,18-hexaoctyl-22,25-bis-(carboxypropyl)-phthalocyanine (2), an asymmetrically substituted phthalocyanine, were stable monolayers formed at the water—air interface that could be transferred onto hydrophilic siUca substrates (32—34). When a monolayer film of the phthalocyanine derivative was heated, there was a remarkable change in the optical spectmm. This, by comparison to the spectmm of the bulk material, indicated a phase transition from the low temperature herringbone packing, to a high temperature hexagonal packing. [Pg.533]

Monolayer Films of Phthalocyanine Derivatives. A series of organic derivatives of phthalocyanines were prepared that have two important characteristics of materials to be deposited by the Langmuir-Blodgett technique (1) they are soluble in volatile organic solvents, and (2) they form monomolecular films on the surface of water. Further study of deposited films of these phthalocyanine derivatives will be necessary in order to determine the exact orientations on the surface, but regardless of their orientations, they offer interesting possibilities for construction of thin films of ordered arrays of molecules on the surface of gas sensors. [Pg.161]

Molecular films, ordered thin organic films in a thickness range from a few nanometers (a monolayer) to several hundred nanometers, show considerable technological promise [205, 206]. Phthalocyanine thin films have been of particular interest because of their photo and electrical responses [207-210]. However, unsubstituted phthalocyanines generally have some limitations as far as arranging and organizing phthalocyanine moieties into a desired crystal... [Pg.131]

In 1988, the distance dependence of surface-enhanced fluorescence was studied for Langmuir-Blodgett monolayers deposited on silver island films. This study was inspired in part by two earlier reports that examined the distance dependence of SERS of LB films on metal surfaces. Varying numbers of spacer layers of arachidic acid were employed in order to probe the competition between EM enhancement and radiationless energy transfer for a phthalocyanine monolayer. In direct contact with the metal surface, a broadened, enhanced, and red-shifted fluorescence spectrum was observed. These spectral changes can be attributed to a drastic decrease in the fluorescence lifetime of the molecule when it is placed in contact with the metal surface. However, an enhanced version of the unperturbed spectrum was observed when intervening spacer layers were introduced. It was found at enhancements on the order of about 400 could be realized when S monolayers were placed between the Ag island film and the phthalocyanine monolayer. [Pg.239]

Akinbulu A, Nyokong T (2010) Fabrication and characterization of single walled carbon nanotubes-iron phthalocyanine nano-composite surface properties and electron transport dynamics of its self assembled monolayer film. New J Chem 34 2875-2886... [Pg.267]

Monolayer structures and epitaxial growth of vapor-deposited crystalline phthalocyanine films on single crystal copper substrates were studied using low energy electron diffraction Ordered monolayers of three different phthalocyanines, copper, iron, and metal-free, were seen on two different faces of copper, the (111) and (100). The monolayer structures formed were different on the two crystal faces and the several phthalocyanines yield nonidentical monolayer structures. [Pg.105]

Extremely robust monolayer assemblies can be constructed by using dye molecules such as the porphyrins and phthalocyanines. In general, their quality is relatively imperfect compared with those of the classic film-forming materials, but their significant advantages lie in their thermal and mechanical stabilities. An example of a substituted phthalocyanine molecule (J5), which can be deposited in monolayer form, is shown in Chart 4.1. [Pg.231]

Figure 4.14. Top (not to scale) An Au-LB film-GaP structure. The semiconductor-organic film interface is common to all four devices. Bottom A plot of the electroluminescent efficiency versus the number of monolayers of substituted phthalocyanine (see reference 55). Figure 4.14. Top (not to scale) An Au-LB film-GaP structure. The semiconductor-organic film interface is common to all four devices. Bottom A plot of the electroluminescent efficiency versus the number of monolayers of substituted phthalocyanine (see reference 55).
Figure 4. Various semiconductor electrodes, modified with monolayers (covalently attached) of phthalocyanine tethered to the electrode surface (a) or multilayers (adsorbed or sublimed) which aggregate to leave a semiporous surface layer (b) and a uniform phthalocyanine film leading to a p-type semiconductor layer adjacent to the n-type semiconductor substrate (c). Figure 4. Various semiconductor electrodes, modified with monolayers (covalently attached) of phthalocyanine tethered to the electrode surface (a) or multilayers (adsorbed or sublimed) which aggregate to leave a semiporous surface layer (b) and a uniform phthalocyanine film leading to a p-type semiconductor layer adjacent to the n-type semiconductor substrate (c).
The phthalocyanines are still of some interest, and Ayers has interpreted the photoelectrochemistry of copper phthalocyanine in terms of the band-model for semiconductors. Menzel et alf have studied the photoconductivity and electrical field-induced fluorescence quenching in metal-free phthalocyanine films. Doping of the film increases charge-carrier photogeneration, and it seems likely that the mechanism is extrinsic, involving field-assisted exciplex dissociation. These are complicated materials, which are difficult to purify, and the mechanisms of carrier generation in polycrystalline and amorphous films are still obscure. The porphyrins and monolayer assemblies of chlorophyll on SnOj electrodes 2 72,273 ijggjj studied. [Pg.599]

BW Gregory, D Vaknin, TM Cotton, WS Struve. Interfacial complexation of phospholipid Langmuir monolayers with water-soluble porphyrins and phthalocyanines an X-ray reflectivity study. Proceedings of Seventh International Conference on Organized Molecular Films, Numana, Italy, 1996, pp 849-853. [Pg.658]


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