Search results for " Phthalocyanine"
showing 10 items of 21 documents
Humidity effect on ammonia sensing properties of substituted and unsubstituted cobalt phthalocyanines
2012
In this paper, we studied the effect of humidity on the response of cobalt phthalocyanine-containing resistors to ammonia, in the ppm range. We pointed out the fact that, when alternating exposure periods with recovery periods, the humidity effect had to be carefully studied, in correlation with the flow variation. Thus, for a sulfonated cobalt phthalocyanine, the effect of NH(3) was totally screened as soon as the relative humidity (RH) was above 10%. On the contrary, when using unsubstituted cobalt phthalocyanine (CoPc) as sensing material, the sensors' response to NH(3) appears to be quite stable in a wide RH range, allowing a discrimination between 12, 25 and 50 ppm of NH(3) over the 10…
Microwave signature for gas sensing: 2005 to present
2015
Abstract We present here the development and the implementation of a technique of gas detection involving a microwave transduction method. The use of low-cost sensors based on microstrip or coplanar structures, adapted to the microwaves domain, allows the sensitive materials deposition under various forms. The purpose of the study is to assess the interest of microwave transduction for gas detection. The choice of the sensitive materials concerns materials widely used in the field of gas sensing: the metal oxides (SnO2 and TiO2) as well as molecular materials like cobalt phthalocyanine (CoPc). In this article we shall apply to explain the principles of the microwave transduction before appr…
Phthalocyanine/TiO2 and Porphyrin /TiO2 Photocatalysts Used in Processes under Mild Conditions
2015
Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II) and metal-free phthalocyanines or porphyrins, have been used as photocatalysts to promote photo degradative processes as well as the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid.
Differential study of substituted and unsubstituted cobalt phthalocyanines for gas sensor applications
2011
Abstract The conductivity of CoPc (cobalt phthalocyanine) and Co[(SO3Na)2,3Pc] was measured under a flow of two different gases (NH3 and O3), during exposure/recovery cycles. It appears that the relative responses are linearly related to the concentration, in the 20–200 ppb range for O3 and in the 20–200 ppm range for NH3. Observed during time, the sensing parameters allow a qualitative understanding of the kinetics. The comparative study of those products under both different gases gave interesting results for sensor applications. Whereas CoPc is sensitive to both gases, its sulfonated counterpart is only sensitive to NH3.
Microwave-based gas sensor with phthalocyanine film at room temperature
2013
Abstract This work presents the development of a microwave gas sensor at room temperature. The design of the sensor includes a coplanar grounded wave guide where is deposited a molecular gas sensing material. In this study, the sensitive material is a thin layer of cobalt phthalocyanine (CoPc), sensitive to ammonia and toluene. Submitted to an electromagnetic incident wave in the microwave range, the sensor response is a reflected wave. In the presence of pollutant, the reflected wave shape is specific to the species concentrations. The results interpretation is led at each frequency by the evaluation of the reflected coefficient, which traduces the ratio between the reflected wave over the…
High sensing potentialities of tetra-tert-butyl-metallophthalocyaninesbased acoustic microsensors for xylenes measurement in air at room temperature
2022
International audience; Xylenes, classified as Volatil Organic Compounds, is a very harmful pollutant for human health that can be absorbed into the body via all exposures routes: inhalation, ingestion, or dermal. As defined by the US Environmental Protection Agency, the occupational exposure limi-tes are set to 100 ppm while the guidelines in non-occupational context are fixed to 50 ppm. For the concentration measurements in the at-mosphere, authorities commonly used sampling methods with post-exposure chemical titration or chromatography. A strong interest remains on the development of low cost, low power consumption and easy implemented microsensors able to deliver real-time indicative m…
Aggregation of Free-Base Octacarboxyphthalocyanine in Aqueous Solutions
1999
Results of spectral (UV-VIS) investigations on the aggregation phenomena of the freebase 2,3,9,10,16,17,23,24-octacarboxypthalocyanine are reported. Phthalocyanine exists mainly in associated (aggregated) froms in water. The aggregates are present even in very diluted (10-7 -10-6 mol/dm-3) solutions. The hydrogen bonding between the carboxyl groups of the adjacent molecules in considered. The increase in pH and temperature, as well as the presence of the cationic surfactant and alcohols (in an appropriate quantity) cause a prtial or full disaggregation. The spectrum of the monomeric phthalocyanine from has been observed. The increase in H2Pc(COOH)8 concentration, the decrease in pH, as well…
Effect of air-absorbed oxygen and moisture on the chemical stability of photoexcitedMg,ZnandEuphthalocyanines in dimethylformamide
2006
Absorption of oxygen and moisture from air by MPc-DMF systems was studied and related to the molecular stability demonstrated by phthalocyanine complexes (unsubstituted MPc's : MgPc , ZnPc and EuPc2; Pc = phthalocyanine ligand, C32H16N8) subjected to UV irradiation. A lower stability of air-exposed dimethylformamide solutions is observed and is due to a specific affinity for molecular oxygen revealed by the Pc macrocycle. SEM results proved oxygen molecules fixed to the phthalocyanine solids by forces strong enough to sustain desorption under vacuum. Absorption curves determined for MPc-DMF systems also indicate oxygen accommodated by the phthalocyanine moiety. This explains the predominant…
When the Grafting of Double Decker Phthalocyanines on Si(100)-2 × 1 Partly Affects the Molecular Electronic Structure
2016
International audience; A combined X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and density functional theory (DFT) study has been performed to characterize the adsorbate interaction of lutetium biphthalocyanine (LuPc2) molecules on the Si(100)-2 × 1 surface. Large molecule–substrate adsorption energies are computed and are found to compete with the molecule–molecule interactions of the double decker molecules. A particularly good matching between STM images and computed ones confirms the deformation of the molecule upon the absorption process. The comparison between DFT calculations and XP spectra reveals that the electronic distribution in the two plateaus …
Synteza i właściwości fizykochemiczne ftalocyjaniny manganu
2017
Ftalocyjaniny to organiczne związki chemiczne, które uzyskuje się jedynie na drodze syntezy chemicznej. Stanowią one jednak analogi strukturalne porfiryn, które naturalnie występują w przyrodzie, m.in. w takich cząsteczkach jak witamina B12 czy chlorofil. Obszerne badania dotyczące kompleksów ftalocyjanin wynikają z budowy tych związków, ponieważ cząsteczkę ftalocyjaniny można modyfikować na bardzo wiele sposobów. Wpływa to na różnorodność zastosowań ftalocyjanin, m.in. w urządzeniach elektronicznych, fotowoltaicznych, jako fotosensiblilizatory, barwniki i pigmenty. Kompleksy ftalocyjanin z takimi metalami jak mangan czy kobalt są intensywnie badane ze względu na ich interesujące właściwośc…