748 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
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
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
First direct synthesis of a corrole ring from a monopyrrolic precursor. Crystal and molecular structure of (triphenylphosphine)-(5,10,15-triphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato) cobalt(III)-dichloromethane
No full textThe first synthesis of the corrole ring by self-condensation of a monopyrrolic unit is reported. The reaction occurs only in the presence of cobalt ions; it leads to the formation of (triphenylphosphine)(5,10,15-triphenyl-2,3,7,8,12, 13,17,18-octamethylcorrolato)cobalt(III), [Co(OMTPC)PPh3] and represents the first example of interconversion between a porphyrinoid and a corrole structure. Crystals of [Co(OMTPC)PPh3].CH2Cl2 have been obtained by slow diffusion of methanol into a dichloromethane solution of the complex and have been characterized by single-crystal X-ray analysis. They crystallize in the triclinic system, space group P1BAR, with a = 10.628 (2) angstrom, b = 11.585(2) angstrom, c = 22.352(4) angstrom, alpha = 84.93(2)-degrees, beta = 78.56(2)-degrees, gamma = 72.93(2)-degrees, and Z = 2. The structure was solved by heavy-atom methods and refined by least-square techniques to R = 0.051 for 6377 unique data [F(o) > 4 sigma(F(o))]. The analysis reveals the substantial planarity of the macrocyclic ring. In the 23-atom core of the corrole moiety each atom shows an average displacement from the plane of best fit of 0.14 angstrom, with the largest deviations being +0.33 and -0.33 angstrom for C(2) and C(12), respectively. The synthesis of diphenyl derivatives of corrole: (triphenylphosphine) (5,10-diphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III), [Co(5,10-OMDPC)PPh3], and (triphenylphosphine) (5,15-diphenyl-2,3,7,8,12,13,17,18-octamethylcorrolato)cobalt(III), [Co(5,15-OMDPC)PPh3], is also reported. Plausible reaction pathways leading to the formation of the two isomers are discussed together with the spectral properties of the complexes
Naked-eye detection of morphine by Au@Ag nanoparticles-based colorimetric chemosensors
No full textIn 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
Novel NMR aspects of tertiary phosphine complexes of Ru(II) etioporphyrin I
No full textThe synthesis and characterization of hexacoordinated ruthenium complexes of etioporphyrin I (EP) of general formula [(EP)RuL2] (L = teriary phosphine) and of the pentacoordinated complex [(EP)Ru(PPh3)] are reported. The multiplicity observed in the 1H NMR spectra of complexes is discussed on the basis of the steric interactions between the axial ligands and the macrocycle
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
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