5- and 10-oxocorroles from β-octaalkylcorroles.

The reaction of Zn ions with β-octaalkylcorroles leads to the air oxidation of the macrocycle, with the formation of a mixture of 5- and 10-oxocorroles. Spectroscopic characterization confirms the antiaromatic character of these macrocycles. A simple synthetic protocol opens the way for more detailed studies of oxocorrole chemistry.

Palladium Complexes of N-Methylcorroles.

Alkylation of one of the inner-core nitrogen atoms is one possible approach to obtain dianionic corrole ligands, suitable for the coordination of divalent metal ions, such as Pd . Inner-core N-methylation can be obtained by treating the corrole with CH I, but the reaction conditions should be optimized to limit the formation of the dimethylated derivative. Two regioisomers, the N-21 and the N-22 methyl derivatives are obtained from the reaction, with the first product achieved in a higher amount.

The Difficult Marriage of Triarylcorroles with Zinc and Nickel Ions.

The coordination chemistry of corrole has witnessed a great improvement in the past few years and its Periodic Table has been widened to be so large that it is compared with that of porphyrins. However, Ni and Zn ions, commonly used with porphyrins for both synthetic and theoretical purposes, are sparsely reported in the case of corroles. Here, we report synthetic protocols for preparing Ni and Zn triarylcorrole complexes.

Controlling Electronic Events Through Rational Structural Design in Subphthalocyanine-Corrole Dyads: Synthesis, Characterization, and Photophysical Properties.

Porphyrinoids are considered perfect candidates for their incorporation into electron donor-acceptor (D-A) arrays due to their remarkable optoelectronic properties and low reorganization energies. For the first time, a series of subphthalocyanine (SubPc) and corrole (Cor) were covalently connected through a short-range linkage. SubPc axial substitution strategies were employed, which allowed the synthesis of the target molecules in decent yields.

Advances in Optical Sensors for Persistent Organic Pollutant Environmental Monitoring.

Optical chemical sensors are widely applied in many fields of modern analytical practice, due to their simplicity in preparation and signal acquisition, low costs, and fast response time. Moreover, the construction of most modern optical sensors requires neither wire connections with the detector nor sophisticated and energy-consuming hardware, enabling wireless sensor development for a fast, in-field and online analysis. In this review, the last five years of progress (from 2017 to 2021) in the field of optical chemical sensors development for persistent organic pollutants (POPs) is provided.

Exploring the Association of Electron-Donating Corroles with Phthalocyanines as Electron Acceptors.

Electron-donating corroles (Cor) were integrated with electron-accepting phthalocyanines (Pc) to afford two different non-covalent Cor ⋅ Pc systems. At the forefront was the coordination between a 10-meso-pyridine Cor and a ZnPc. The complexation was corroborated in a combination of NMR, absorption, and fluorescence assays, and revealed association with binding constants as high as 10  m .

The strength in Numbers! Porphyrin hybrid nanostructured materials for chemical sensing.

The development of chemical sensors is an urgent need for both environmental and health issues. The breakthrough needed for the advancement of these devices is the development of efficient receptors. Porphyrins have been widely used as sensing layers in chemical sensors, but their integration with nanostructures can greatly boost the performance of these macrocycles, improving from one side the stability of the sensing layer, and from the other, offering additional interaction mechanisms with target analytes.

Recent Advances in Chemical Sensors Using Porphyrin-Carbon Nanostructure Hybrid Materials.

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.

A Leopard Cannot Change Its Spots: Unexpected Products from the Vilsmeier Reaction on 5,10,15-Tritolylcorrole.

The reaction of 5,10,15-tritolylcorrole with 3-dimethylaminoacrolein (3-DMA) and POCl gives a further example of the rebel reactivity of this contracted macrocycle. While no evidence was obtained for the formation of the expected β-acrolein corrole, the inner core substituted N21,N22-3-formylpropylcorrole and the 10-acrolein isocorrole were the reaction products. By increasing the temperature or the amount of the Vilsmeier reagent, the 10-isocorrole became the unique reaction product.

Panchromatic Light Harvesting and Stabilizing Charge-Separated States in Corrole-Phthalocyanine Conjugates through Coordinating a Subphthalocyanine.

Owing to the electron-donating and -accepting nature of corroles (Corr) and phthalocyanines (Pc), respectively, we designed and developed two novel covalently linked Corr-Pc conjugates. The synthetic route allows the preparation of the target conjugates in satisfying yields. Comprehensive steady-state absorption, fluorescence, and electrochemical assays enabled insights into energy and electron-transfer processes upon photoexcitation.

Grafting Copper and Gallium Corroles onto Zinc Oxide Nanoparticles.

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.

β-Acrolein-Substituted Corroles: A Route to the Preparation of Functionalized Polyacrolein Microspheres for Chemical Sensor Applications.

An efficient β-functionalization of [5,10,15-tris-(4-methylphenyl)corrolato]cobalt derivatives through a Vilsmeier-type reaction allows the introduction of an acrolein substituent, which is subsequently copolymerized with pure acrolein. The obtained hybrid microspheres are exploited as nanogravimetric chemical sensors. The sensing properties of the developed sensors are tested through exposure to different volatile organic compounds chosen as model analytes.

Porphyrinoids for Chemical Sensor Applications.

Porphyrins and related macrocycles have been intensively exploited as sensing materials in chemical sensors, since in these devices they mimic most of their biological functions, such as reversible binding, catalytic activation, and optical changes. Such a magnificent bouquet of properties allows applying porphyrin derivatives to different transducers, ranging from nanogravimetric to optical devices, also enabling the realization of multifunctional chemical sensors, in which multiple transduction mechanisms are applied to the same sensing layer. Potential applications are further expanded through sensor arrays, where cross-selective sensing layers can be applied for the analysis of complex chemical matrices.

A Highly Emissive Water-Soluble Phosphorus Corrole.

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.

β-Pyrrolopyrazino Annulated Corroles via a Pictet-Spengler Approach.

Reaction of 2-amino-3-(pyrrol-1-yl)-5,10,15-tris(4-tert-butylphenyl)corrolato copper(II) with arylaldehydes affords novel π-extended β,β'-pyrrolo(1,2-a)pyrazino-fused corroles via a Pictet-Spengler reaction. Corrole shows an unprecedented reaction pathway, leading to a mixture of phenyl-substituted and nonsubstituted pyrrolopyrazino annulated species as reaction products.

Extending the corrole ring conjugation: preparation of β,β'-fused 2,3-[1',2'-b]pyrazinocorroles.

A novel method for the preparation of corroles with β-fused pyrazino rings was developed, exploiting a one-pot reaction of 2,3-diaminocorroles (or 2,3,17,18-tetraaminocorroles) with different diones; a variety of π-extended corroles were obtained in moderate yields as copper complexes, which can then be demetallated to give the corresponding free base in good yields.

5,10,15-Triferrocenylcorrole Complexes.

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.

Investigation of VOCs associated with different characteristics of breast cancer cells.

The efficacy of breath volatile organic compounds (VOCs) analysis for the screening of patients bearing breast cancer lesions has been demonstrated by using gas chromatography and artificial olfactory systems. On the other hand, in-vitro studies suggest that VOCs detection could also give important indications regarding molecular and tumorigenic characteristics of tumor cells. Aim of this study was to analyze VOCs in the headspace of breast cancer cell lines in order to ascertain the potentiality of VOCs signatures in giving information about these cells and set-up a new sensor system able to detect breast tumor-associated VOCs.

New example of hemiporphycene formation from the corrole ring expansion.

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.

Phenyl derivative of iron 5,10,15-tritolylcorrole.

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.

β-Pyrazino-fused tetrarylporphyrins.

A novel method for the preparation of β-fused porphyrin dyads was developed that exploits a one-pot reaction of 2,3-diaminoporphyrins with diethyl oxalate. This approach provides good yields of the zinc β-fused dyad and the corresponding free-base, opening the way for preparation of several metal derivatives to permit modulation of optoelectronic characteristics for commercial applications.

Copper β-trinitrocorrolates.

The β-nitration reaction carried out on the corrole macrocycle has been shown to be extremely regioselective, although the reduced symmetry of the macrocycle could potentially lead to a huge number of possible regioisomers. We recently reported that the careful use of AgNO/NaNO as a nitrating system enabled the achievement in good yields of mono- and dinitro-derivatives on both corrole free base and its copper complex, proving to be an efficient and cost-effective method. In this work, we present a detailed study of the scope of this method using TtBuCorrH as a model corrole.

Synthesis and characterization of functionalized meso-triaryltetrabenzocorroles.

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.

Interaction of tricationic corroles with single/double helix of homopolymeric nucleic acids and DNA.

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).

Aluminum, gallium, germanium, copper, and phosphorus complexes of meso-triaryltetrabenzocorrole.

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.