Publications by authors named "Giuseppe Pomarico"

To be profitably exploited in medicine, nanosized systems must be endowed with biocompatibility, targeting capability, the ability to evade the immune system, and resistance to clearance. Currently, biogenic nanoparticles, such as extracellular vesicles (EVs), are intensively investigated as the platform that naturally recapitulates these highly needed characteristics. EV native targeting properties and pharmacokinetics can be further augmented by decorating the EV surface with specific target ligands as antibodies.

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Two triarylcorrole complexes, (hydroxy)[5,10,15-tritolylcorrolato]silicon- and (dihydroxy)[5,10,15-tritolylcorrolato]phosphorous- , have been investigated by magnetic circular dichroism (MCD) and magnetic circularly polarized luminescence (MCPL). The spectroscopic investigations have been combined with explicit calculation of MCD response through time-dependent density functional theory (TD-DFT) formalism. This has allowed us to better define the role of molecular orbitals in the transitions associated with the Soret and Q bands.

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Porphyrins and carbon nanomaterials are among the most widely investigated and applied compounds, both offering multiple options to modulate their optical, electronic and magnetic properties by easy and well-established synthetic manipulations. Individually, they play a leading role in the development of efficient and robust chemical sensors, where they detect a plethora of analytes of practical relevance. But even more interesting, the merging of the peculiar features of these single components into hybrid nanostructures results in novel materials with amplified sensing properties exploitable in different application fields, covering the areas of health, food, environment and so on.

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Two different copper and gallium arylcorroles have been functionalized using the Vilsmeier-Haack reaction. A further Knoevenagel reaction with cyanoacetic acid was performed on both complexes, affording the desired products with yields above 90 %. The newly synthesized compounds have been thoroughly characterized by a combination of spectroscopic methods, optical analyses, and X-ray crystallography.

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Silver corrolates are attractive compounds from both practical and theoretical points of view. Indeed, they play a key role in peripheral functionalization reactions occurring at the macrocycle, enabling high-yield and regioselective group insertions useful to further elaborate the molecular skeleton. In parallel, the Janus innocent or noninnocent behavior of the corrole ligand in these complexes makes their description particularly challenging.

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Article Synopsis
  • Corrole derivatives are being used in various applications that involve solid-liquid interfaces, making it crucial to understand how their molecular layers organize when they come into contact with liquids.
  • The study focused on a water-soluble phosphorus complex of a specific corrole and observed how these molecular layers formed on a gold surface in real-time using scanning tunneling microscopy (STM) while submerged in liquid.
  • Results showed significant differences in the structures of the organic layers formed when the substrate was in solution compared to when it was dried, indicating that the presence of liquid enhances the stability and effectiveness of the coating, while also preserving the functionality of the corrole molecules.
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Silicon complexes of corrole were obtained for the first time by reaction of the free-base corrole with hexachlorodisilane. The peripheral substituents of corrole strongly influence the nature of the reaction products: β-octaalkyl corrole was mainly isolated as the μ-oxo dimer, while a hydroxo complex was obtained in the case of 5,10,15-tris-(pentafluorophenyl)corrole. In the case of meso-tritolyl corrole, a mixture of monomer/μ-oxo dimer was obtained.

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A novel solid contact type for all-solid-state ion-selective electrodes is introduced, yielding high stability and reproducibility of potential readings between sensors as well as improved analytical performance. The transducer phase herein proposed takes advantage of the presence of porphyrinoids containing the same metal ion at different oxidation states. In contrast to the traditional approach, the compounds of choice are not a redox pair; although they have different oxidation states, they cannot be electrochemically driven one to another.

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The synthesis, spectroscopic, and optical properties of the water-soluble phosphorus complex of a 2-sulfonato-10-(4-sulfonatophenyl)-5,15-dimesitylcorrole have been investigated. The compound was prepared by adopting a novel strategy for the corrole sulfonation, leading to the regioselective isomer in an almost quantitative yield. The phosphorus coordination has a key role in determining the corrole substitution pattern, limiting the formation of poly-substituted species, which affected the reaction of the corrole free base.

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Phosphorus complexes of corrole have recently attracted increasing interest since these compounds can be easily prepared in good yields, are stable, and show unusual optical properties. For these reasons, phosphorus corroles represent a class of interesting compounds to be exploited in the field of material science or for biomedical investigations and the definition of synthetic pathways for their functionalization is an important step to optimize their properties for various applications. We report here the reactivity of the phosphorus complex of 5,10,15-tritolylcorrole in the nitration or bromination reaction.

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Complexes of 5,10,15-triferrocenylcorrole were synthesized from the crude free-base corrole product obtained by the reaction of ferrocenyl aldehyde and pyrrole. Direct formation of the complex in this manner leads to an increase of the reaction yield by protecting the corrole ring toward oxidative decomposition. The procedure was successful and gave the expected product in the case of the copper and triphenylphosphinecobalt complexes, but an unexpected result was obtained in the case of the nickel derivative, where metal insertion led to a ring opening of the macrocycle at the 5 position, giving as a final product a linear tetrapyrrole nickel complex bearing two ferrocenyl groups.

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Porphyrins provide an excellent material for chemical sensors, and they have been used for sensing species both in air and solution. In the gas phase, the broad selectivity of porphyrins is largely dependant on molecular features, such as the metal ion complexed at the core of the aromatic ring and the peripheral substituents. Although these features have been largely exploited to design gas sensor arrays, so far, little attention has been devoted to modify the sensing properties of these macrocycles by variation of the molecular aromatic ring.

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High sensitivity and cross-selectivity are mandatory properties for sensor arrays. Although metalloporphyrins and pH indicators are among the most common and appropriate choices for the preparation of optical sensor arrays, the sensitivity spectrum of these dyes is limited to those analytes able to induce an optical response. To extend the receptive field of optical sensors, we explore the design of composite materials, where the molecular interaction among the subunits enriches their sensing working mechanisms.

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The reaction of 5,10,15-tris(4-tert-butylphenyl)corrole with 2,3-bis(bromomethyl)-5,6-dicyanopyrazine provides a new example of corrole ring expansion to a hemiporphycene derivative. The ring expansion is regioselective, with insertion of the pyrazine derivative at the 5-position of the corrole ring, affording the corresponding 5-hemiporphycene. Different macrocyclic products accompany formation of the 5-hemiporphycene, depending on the reaction experimental conditions.

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The phenyl-iron complex of 5,10,15-tritolylcorrole was prepared by reaction of the starting chloro-iron complex with phenylmagnesium bromide in dichloromethane. The organometallic complex was fully characterized by a combination of spectroscopic methods, X-ray crystallography, and density functional theory (DFT) calculations. All of these techniques support the description of the electronic structure of this phenyl-iron derivative as a low-spin iron(IV) coordinated to a closed-shell corrolate trianion and to a phenyl monoanion.

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Two synthetic routes have been defined for the preparation of a 5,10,15-triferrocenylcorrole Cu derivative. This complex has been characterized and the preliminary electrochemical investigation shows a strong interaction among the corrole and meso ferrocenyl substituents. The results obtained suggest that peculiar properties are gained by combining the eccentric characteristics of ferrocenyl substitution with the corrole macrocycle.

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ZnO and porphyrins have complementary properties that make their combination attractive for diverse applications such as photovoltaic and chemical sensing. Among the other features, the organic layer morphology is supposed to influence both the chemical sensitivity and the charge transfer processes. In this paper, we studied the influence of the film morphology on the sensing properties by comparing porphyrins coated ZnO nanorods obtained with two different methods.

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5,10,15-Triaryltetrabenzocorroles functionalized with different electron-withdrawing groups on the β,β'-fused rings have been prepared by a cross-coupling Heck procedure between octabrominated copper corrole and a terminal alkene bearing electron-withdrawing moieties. The spectroscopic characterization of these complexes showed red-shifted UV-vis absorption bands characterized by a significant band broadening. The same feature was observed in the case of NMR spectra, where low-resolution groups of signals were observed.

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In this manuscript a multitechnique approach is proposed to characterize the interaction between new tri-N-methylpyridyl corrole (TMPC) and its germanium(IV) derivative (GeTMPC), with single- and double-stranded nucleic acid homopolymers and calf thymus DNA. The specificity of each spectroscopic technique has been exploited to analyze the different aspects of corrole binding. Noteworthy, this approach allows us to distinguish between H aggregation of TMPC in the presence of polyriboadenilic acid (poly(rA)) and J aggregates in the presence of polyribocytidinic acid (poly(rC)) as well as to identify the formation of GeTMPC dimers in the presence of single-stranded poly(rA) and pseudointercalation with single-stranded poly(rC).

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5,10,15-Triaryltetrabenzocorrole complexes of aluminum, gallium, germanium, and phosphorus were synthesized by coordination of these metal ions in the preformed triaryltetrabenzocorrole macrocycle, opening a way to the investigation of different metal complexes. The UV-vis spectra of these derivatives exhibit a red shift and broadening of all absorption bands because of the π-extended aromatic system and distortion of the molecular framework. The electrochemical and photophysical behaviors of the free base and the metal complexes of meso-triaryltetrabenzocorrole were investigated and characterized.

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Functionalization of the β-pyrrolic positions of the corrole macrocycle with -NO(2) groups is limited at present to metallocorrolates due to 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 (TTCorrH(3)) with the AgNO(2)/NaNO(2) system, to give mono- and dinitrocorrole derivatives when stoichiometry is carefully controlled.

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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.

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The modification of peripheral positions of corroles by introduction of nitro groups is an important functionalization of this macrocycle. The nitro substituent strongly influences the corrole behavior leading to the preparation of macrocycles with different properties, which can be of interest for their exploitation as catalysts, sensing layers in chemical sensors or in the field of supramolecular chemistry. In the last few years we have developed different routes for the β-nitration of the corrole ring, and we report here novel synthetic protocols which can allow the formation of tri- and tetranitro derivatives, as demonstrated by X-ray analysis.

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Two different synthetic routes for the preparation of 5,10,15-triaryl-tetrabenzocorroles have been developed. The first approach is based on the condensation of a tetrahydroisoindole with aryl-aldehydes, and the second pathway involves a cross-coupling reaction between a bromo-substituted corrole and a suitable substrate to form the four β-fused aryl rings. These routes are successful to lead to the target tetrabenzocorroles, obtained in both cases as the corresponding Cu complex and with the highest yield obtained via the one-step cross-coupling methodology.

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The reaction of 5,10,15-tritolylcorrole with EtMgBr opens the way for novel functionalizations of the corrole ring. DDQ oxidation of the macrocycle, followed by addition of the Grignard reagent, led to the formation of 5- and 10-alkyl substituted isocorroles in satisfying yields. Together with the one-pot formation of these isocorrole isomers, the use of such a nucleophile evidenced the competitive reactivity of the macrocycle β-positions, leading to the formation of 2-bromo- and 3-bromo-5,10,15-tritolylcorrole.

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