-
Manuela Stefanelli,
Giuseppe Pomarico,
Luca Tortora,
Sara Nardis,
Frank R. Fronczek,
Gregory T. McCandless,
Kevin M. Smith, Machima Manowong,
Yuanyuan Fang,
Ping Chen,
Karl M. Kadish,
Angela Rosa,
Giampaolo Ricciardi,
Roberto Paolesse
[show abstract]
[hide abstract]
ABSTRACT: Functionalization of the β-pyrrolic positions of the corrole
macrocycle with −NO2
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
(TTCorrH3
) with the AgNO2
/NaNO2
system, to give mono- and dinitrocorrole
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 disubstitution, in 53 and
20% yields, respectively. In both cases, traces of other mono- and disubstituted
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.
Inorganic Chemistry 06/2012; · 4.60 Impact Factor
-
Manuela Stefanelli,
Giuseppe Pomarico,
Luca Tortora,
Sara Nardis,
Frank R Fronczek,
Gregory T McCandless,
Kevin M Smith, Machima Manowong,
Yuanyuan Fang,
Ping Chen,
Karl M Kadish,
Angela Rosa,
Giampaolo Ricciardi,
Roberto Paolesse
[show abstract]
[hide abstract]
ABSTRACT: 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. Reactions were found to be regioselective, affording the 3-NO(2)TTCorrH(3) and 3,17-(NO(2))(2)TTCorrH(3) isomers as the main products in the case of mono- and disubstitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and disubstituted 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-NO(2) 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.
Inorganic Chemistry 06/2012; 51(12):6928-42. · 4.60 Impact Factor
-
Sara Nardis,
Manuela Stefanelli,
Pruthviraj Mohite,
Giuseppe Pomarico,
Luca Tortora, Machima Manowong,
Ping Chen,
Karl M Kadish,
Frank R Fronczek,
Gregory T McCandless,
Kevin M Smith,
Roberto Paolesse
[show abstract]
[hide abstract]
ABSTRACT: 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 CH(2)Cl(2).
Inorganic Chemistry 03/2012; 51(6):3910-20. · 4.60 Impact Factor
-
Sara Nardis,
Manuela Stefanelli,
Pruthviraj Mohite,
Giuseppe Pomarico,
Luca Tortora, Machima Manowong,
Ping Chen,
Karl M Kadish,
Frank R Fronczek,
Gregory T McCandless,
Kevin M Smith,
Roberto Paolesse
[show abstract]
[hide abstract]
ABSTRACT: Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding beta-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 pi-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 mu-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 CH(2)Cl(2).
Inorganic chemistry. 51(6):3910-20.
