1,721,541 research outputs found
Corrole: The little big porphyrinoid
No full textIn this account, the author describes the synthetic efforts of his group on the preparation and functionalization of corrole derivatives. The work started with beta-alkylcorroles and continued with the preparation of 5,10,15-triarylcorroles. The peripheral functionalization of both the beta-alkyl- and meso-triarylcorroles is described, together with several examples of the intriguing and unexpected reactivity of this deceptive macrocycle in these reactions
Corroles at work: a small macrocycle for great applications
No full textCorrole chemistry has witnessed an impressive boost in studies in the last 20 years, thanks to the possibility of preparing corrole derivatives by simple synthetic procedures. The investigation of a large number of corroles has highlighted some peculiar characteristics of these macrocycles, having features different from those of the parent porphyrins. With this progress in the elucidation of corrole properties, attention has been focused on the potential for the exploitation of corrole derivatives in different important application fields. In some areas, the potential of corroles has been studied in certain detail, for example, the use of corrole metal complexes as electrocatalysts for energy conversion. In some other areas, the field is still in its infancy, such as in the exploitation of corroles in solar cells. Herein, we report an overview of the different applications of corroles, focusing on the studies reported in the last five years
Naked-eye detection of morphine by Au@Ag nanoparticles-based colorimetric chemosensors
Get PDFIn this study, we report a novel and facile colorimetric assay based on silver citrate-coated Au@Ag nanoparticles (Au@AgNPs) as a chemosensor for the naked-eye detection of morphine (MOR). The developed optical sensing approach relied on the aggregation of Au@Ag NPs upon exposure to morphine, which led to an evident color variation from light-yellow to brown. Au@Ag NPs have been prepared by two different protocols, using high- and low-power ultrasonic irradiation. The sonochemical method was essential for the sensing properties of the resulting nanoparticles. This facile sensing method has several advantages including excellent stability, selectivity, prompt detection, and cost-effectiveness
Iron corrolates: Unambiguous chloroiron(III) (corrolate)2-radical dot π-cation radicals
No full textThe structures, electron configurations, magnetic susceptibilities, spectroscopic properties, molecular orbital energies and spin density distributions, redox properties and reactivities of iron corrolates having chloride, phenyl, pyridine, NO and other ligands are reviewed. It is shown that with one very strong donor ligand such as phenyl anion the electron configuration of the metal is d4 S = 1 Fe(IV) coordinated to a (corrolate)3- anion, while with one weaker donor ligand such as chloride or other halide, the electron configuration is d5 S = 3/2 Fe(III) coordinated to a (corrolate)2-radical dot π-cation radical, with antiferromagnetic coupling between the metal and corrolate radical electron. Many of these complexes have been studied by electrochemical techniques and have rich redox reactivity, in most cases involving two 1-electron oxidations and two 1-electron reductions, and it is not possible to tell, from the shapes of cyclic voltammetric waves, whether the electron is added or removed from the metal or the macrocycle; often infrared, UV-Vis, or EPR spectroscopy can provide this information. 1H and 13C NMR spectroscopic methods are most useful in delineating the spin state and pattern of spin density distribution of the complexes listed above, as would also be expected to be the case for the recently-reported formal Fe(V)double bond, longO corrolate, if this complex were stable enough for characterization by NMR spectroscopy. Iron, manganese and chromium corrolates can be oxidized by iodosylbenzene and other common oxidants used previously with metalloporphyrinates to effect efficient oxidation of substrates. Whether the "resting state" form of these complexes, most generally in the case of iron [FeCl(Corr)], actually has the electron configuration Fe(IV)(Corr)3- or Fe(III)(Corr)2-radical dot is not relevant to the high-valent reactivity of the complex. © 2006 Elsevier Inc. All rights reserved
The long-lasting story of one sensor development: from novel ionophore design toward the sensor selectivity modeling and lifetime improvement
Get PDFThe metalloporphyrin ligand bearing incorporated anion-exchanger fragment, 5-[4-(3-trimethylammonium)propyloxyphenyl]-10,15,20-triphenylporphyrinate of Co(II) chloride, CoTPP-N, has been tested as anion-selective ionophore in PVC-based solvent polymeric membrane sensors. A plausible sensor working mechanism includes the axial coordination of the target anion on ionophore metal center followed by the formed complex aggregation with the second ionophore molecule through positively charged anion-exchanger fragment. The UV-visible spectroscopic studies in solution have revealed that the analyte concentration increase induces the J-type porphyrin aggregation. Polymeric membranes doped with CoTPP-N showed close to the theoretical Nernstian response toward nitrite ion, preferably coordinated by the ionophore, and were dependent on the presence of additional membrane-active components (lipophilic ionic sites and ionophore) in the membrane phase. The resulting selectivity was a subject of specific interaction and/or steric factors. Moreover, it was demonstrated theoretically and confirmed experimentally that the selection of a proper ratio of ionophore and anionic additive can optimize the sensor selectivity and lifetime
A COMPUTER EMBEDDED CAPACITIVE SENSORS ARRAY
No full textInterdigitate capacitive sensors are promising devices for gas sensing in terms of fabrication costs and ease of integration. The aim of this study was to investigate a novel arrangement of interdigitate capacitors for air quality monitoring with high sensitivity and resolution, using low cost devices at room temperature. The system is fully controlled (through audio device board) by a personal computer which feature represent a great advantage in terms of cost, versatility and ease of use. The paper will describe the characteristics of the interdigitate capacitors, the electronic system and experimental results
Fabrication of Langmuir-Blodgett chiral films from cationic (L)-proline-porphyrin derivatives
No full textStable porphyrin films expressing specific chirality at a supramolecular level have been achieved by Langmuir-Blodgett (LB) deposition of two inherently chiral (L)-proline porphyrin derivatives. Spectroscopic measurements (UV-vis, CD and fluorescence) evidenced that the stereogenic center stored on the peripheral proline residue dictates the specific supramolecular organization of the macrocycles at the air/water interface, which is found to be significantly different from that observed in solution (i.e. EtOH/H2O 25/75, v/v solvent mixture). In the case of free-base porphyrin, the firmness as well as the homogeneity of the corresponding chiral LB films are not optimal for a number of layers below 10. For the zinc derivative, thermal annealing helps to make the films more oriented and produces an amplification of the chirality of the treated films. The results described are of relevance, for example, for the development of stereoselective sensors, where the fabrication of chiral surfaces with specific and reproducible stereochemistry represents a crucial issue
Sensors for lung cancer diagnosis
No full textThe positive outcome of lung cancer treatment is strongly related to the earliness of the diagnosis. Thus, there is a strong requirement for technologies that could provide an early detection of cancer. The concept of early diagnosis is immediately extended to large population screening, and then, it is strongly related to non-invasiveness and low cost. Sensor technology takes advantage of the microelectronics revolution, and then, it promises to develop devices sufficiently sensitive to detect lung cancer biomarkers. A number of biosensors for the detection of cancer-related proteins have been demonstrated in recent years. At the same time, the interest is growing towards the analysis of volatile metabolites that could be measured directly from the breath. In this paper, a review of the state-of-the-art of biosensors and volatile compound sensors is presented
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