In this work, hydrophilic silver nanoparticles (AgNPs), bifunctionalized with citrate (Cit) and L-cysteine (L-cys), were synthesized. The typical local surface plasmon resonance (LSPR) at λ max = 400 nm together with Dynamic Light Scattering (DLS) measurements (<2RH> = 8 ± 1 nm) and TEM studies (Ø = 5 ± 2 nm) confirmed the system nanodimension and the stability in water. Molecular and electronic structures of AgNPs were investigated by FTIR, SR-XPS, and NEXAFS techniques. We tested the system as plasmonic sensor in water with 16 different metal ions, finding sensitivity to Hg2+ in the range 1–10 ppm. After this first screening, the molecular and electronic structure of the AgNPs-Hg2+ conjugated system was deeply investigated by SR-XPS. Moreover, in view of AgNPs application as sensors in real water systems, environmental safety assessment (ecosafety) was performed by using standardized ecotoxicity bioassay as algal growth inhibition tests (OECD 201, ISO 10253:2006), coupled with determination of Ag+ release from the nanoparticles in fresh and marine aqueous exposure media, by means of ICP-MS. These latest studies confirmed low toxicity and low Ag+ release. Therefore, these ecosafe AgNPs demonstrate a great potential in selective detection of environmental Hg2+, which may attract a great interest for several biological research fields.

Functionalization of the β-pyrrolic positions of the corrole macrocycle with –NO2 groups is limited at present to metallocorrolates due to of the instability exhibited by corrole free bases under oxidizing conditions. A careful choice of the oxidant can limit the transformation of corroles into decomposition products or isocorrole species, preserving the corrole aromaticity, and thus allowing the insertion of nitro groups onto the corrole framework. Here we report results obtained by reacting 5,10,15-tritolylcorrole (TTCorrH3) with the AgNO2/NaNO2 system, to give mono- and di-nitrocorrole derivatives when stoichiometry is carefully controlled. Reactions were found to be regioselective, affording the 3-NO2TTCorrH3 and 3,17-(NO2)2TTCorrH3 isomers as the main products in the case of mono- and di-substitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and di-substituted isomers were detected, which were structurally characterized by X-ray crystallography. The influence of the β-nitro substituents on the corrole properties is studied in detail by UV-visible, electrochemical, and spectroelectrochemical characterization of these functionalized corroles. Density Functional Theory (DFT) and time-dependent DFT (TDDFT) calculations of the ground and excited state properties of these β-nitrocorrole derivatives also afforded significant information, closely matching the experimental observations. It is found that the β-NO2 substituents conjugate with the π-aromatic system of the macrocycle, which initiates significant changes in both the spectroscopic and redox properties of the so functionalized corroles. This effect is more pronounced when the nitro group is introduced at the 2-position, because in this case the conjugation is, for steric reasons, more efficient than in the 3-nitro isomer.

Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding β-substituted nitrocorrole iron complexes have been developed. A two-step procedure affords three Fe(III) nitrosyl products - the unsubstituted corrole, the 3-nitrocorrole and the 3,17-dinitrocorrole. In contrast, a one-pot synthetic approach drives the reaction almost exclusively to formation of the iron nitrosyl 3,17-dinitrocorrole. Electron-releasing substituents on the meso-aryl groups of the triarylcorroles induce higher yields and longer reaction times than what is observed for the synthesis of similar triarylcorroles with electron-withdrawing functionalities, and these results can be confidently attributed to the facile formation and stabilization of an intermediate iron corrole π-cation radical. Electron-withdrawing substituents on the meso-aryl groups of triarylcorrole also seem to labilize the axial nitrosyl group which, in the case of the pentafluorophenylcorrole derivative, results in the direct formation of a disubstituted iron μ-oxo dimer complex. The influence of meso-aryl substituents on the progress and products of the nitration reaction was investigated. In addition, to elucidate the most important factors which influence the redox reactivity of these different iron nitrosyl complexes, selected compounds were examined by cyclic voltammetry and thin-layer UV-visible or FTIR spectroelectrochemistry in CH2Cl2.

Mono- and di-substituted β-nitro derivatives have been obtained from the reaction of ttcorrFeCl with sodium nitrite in refluxing DMF. This result is unprecedented for iron corrolates and further evidences the non-innocent character of the corrole ligand.

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Bromination of 3-nitro-5,10,15-triarylcorrole selectively provides two regioisomers, depending on the reaction pathway. An isocorrole species is the key intermediate to drive the reaction towards the 2-Br-17-nitro regioisomer.It is impressive to note the attention that, over the last decade, corrole has received among porphyrinoids. While this consideration certainly arises from the intriguing chemistry shown by this macrocycle, which is unusual compared with the parent porphyrin congeners, it is obvious that these developments have been made possible by progress in synthetic routes leading to triarylcorroles. [1][2][3][4][5][6] The advances achieved in the synthetic chemistry of such a macrocycle allow the preparation of a large variety of corrole derivatives, which have concomitantly opened the way for their practical applications in different fields, ranging from sensors to clinical studies. [7][8][9] For these applications it is of paramount importance to develop methodology for diverse functionalization of corroles with peripheral substituents. It is also noteworthy that the functionalization of the preformed corrole framework is a relatively under-developed area. 10,11 Different factors might explain this developmental problem in the corrole field: while from one side the instability of corrole could hamper some functionalization routes, from the other side the lower symmetry of corrole compared with porphyrin could lower the yields of the desired functionalization, because in principle a complex mixture of different regioisomers could be obtained. 10 A further obstacle to the functionalization of the macrocycle has been the lack of simple protocols for the demetallation of corrole complexes. Some of these problems have been solved in the last few years, such as the admirable regioselectivity showed by corrole for substitution, and the definition of some route for the demetallation of Cu and Mn metal derivatives. [12][13][14][15][16] The problem of corrole instability under reaction conditions for functionalization pathways usually leads to the formation of isocorrole by-products, 17,18 formed because of the facile oxidation of the corrole ring, as has been observed, for example, in the case of nitration reactions. 19 However, this feature should not be an unavoidable drawback but rather a tool to widen the possible pathways for corrole functionalization. To define synthetic routes for the introduction of different substituents on the peripheral positions of meso-triarylcorroles, we decided to use as starting material the 3-nitro-5,10,15-tris(4-methylphenyl)corrole, 3- NIH Public Access Author ManuscriptChem Commun (Camb). Author manuscript; available in PMC 2011 April 14. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript NO 2 -ttcorrH 3 , which can be obtained in good yields from 5,10,15-tris-(4-methylphenyl)corrole ttcorrH 3 20 using AgNO 2 as the nitrating agent, 21 followed by reductive demetallation with DBU; 19 bromination of corrole was selected as the test reaction...

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Germanium is considered the most suitable semiconductor for monolithic integration of near-infrared detectors on silicon photonic chips. Here we report on Ge-on-Si near-infrared photodetectors fabricated by thermal evaporation, demonstrating the use of phosphorus spin-on-dopant to compensate the acceptor states introduced by dislocations. The detectors exhibit 1.55 mu m responsivities as high as 0.1 A/W, more than two orders of magnitude larger than in undoped devices and comparing well with state-of-the-art p-i-n photodiodes. This approach enables simple and low-cost monolithic integration of near-infrared sensors with silicon photonics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747213