Synthesis of Meso-Diarylaminocorroles via SNAr Reactions

Development of Peripheral Functionalization Chemistry of meso-Free Corroles

In contrast to the extensive development of meso functionalization of porphyrins, that of corroles has been only rarely explored until the development of practical synthetic methods of meso -free corroles in 2015. Ready availability of meso -free corroles opened up meso -functionalization chemistry of corroles, giving rise to successful synthesis of various meso-substituted corroles such as meso -halogen, meso -nitro, meso -amino, meso -oxo, and meso iminocorroles as well as meso-meso linked corrole dimers and corrole tapes. In some cases, 2NH corroles existed as stable or transient radical species. The impacts of meso -functionalization on the structures, electronic properties, optical characteristics, and aromaticity are highlighted in this Minireview.

Synthesis of 8,12-Dibromocorrole and Its Transformation to Antiaromatic 8,10-Fused Iminoisocorrole with a Polarized Resonance Contribution

8,12-Dibromo-5,15-bis(pentafluorophenyl)corrole and its Ag(III) complex were prepared via intramolecular oxidative coupling of a 8,12-dibromobilane precursor. The Ag(III) complex was allowed for further transformation via Suzuki coupling reaction. Thus, 2-aminophenyl group was coupled at one of the β-positions, and subsequent demetalation followed by oxidation with MnO₂ afforded 8,10-fused iminoisocorrole in good yields. The iminoisocorrole exhibited weak antiaromaticity due to the C(+)-N(-) polarized resonance contribution as evidenced by ¹ H NMR spectrum, UV/vis absorption spectra, cyclic voltammetry, and theoretical calculations.

Minding our P-block and Q-bands: paving inroads into main group corrole research to help instil broader potential

Main group chemistry is often considered less "dynamic" than transition metal (TM) chemistry because of predictable VSEPR-based central atom geometries, relatively slower redox switching and lack of electronic d-d transitions. However, we delineate what has been made possible with main group chemistry to give it its proper due and up-to-date treatment. The huge untapped potential regarding photophysical properties and functioning hereby spurred us to review a range of corrole reports addressing primarily photophysical trends, synthetic aspects, and important guidelines regarding substitution and inorganic principles. We also look at Ag and Au systems and also consider substitutions such as CF3, halogens, additives and also counterions. Throughout, as well as at the end of this review, we suggest various future directions; further future industrial catalytic and health science research is encouraged.

β-Disubstituted silver(III) corroles: Facile synthesis, photophysical and electrochemical redox properties

Facile synthesis of 3,17-disubstituted Ag(III) tritolylcorroles (2-5), R2[TTC]Ag where R = methyl (2), phenyl (3), methyl acrylate (MA) (4) and phenylethynyl (PE) (5) using Pd-catalyzed reactions in good to excellent yields are reported. All synthesized corroles were characterized by various spectroscopic techniques and mass spectrometry. MA2[TTC]Ag (4) and PE2[TTC]Ag (5) exhibited highly red-shifted electronic spectral bands with considerable broadening due to extended [Formula: see text]-conjugation and electron withdrawing effect of [Formula: see text]-substituents. Geometry optimization of these corroles was performed using density functional theory (DFT). Among all, MA2[TTC]Ag (4) exhibited very high dipole moment (10.31 D) which could be the potential candidate for nonlinear optical (NLO) applications. The redox tunability was achieved by substituting electron donating and withdrawing substituents at the [Formula: see text]-positions. Particularly, corroles 4 and 5 exhibited lower HOMO–LUMO gap due to extended [Formula: see text]-conjugation and electron withdrawing [Formula: see text]-substituents.

Nucleophilic Aromatic Substitution (SNAr) and Related Reactions of Porphyrinoids: Mechanistic and Regiochemical Aspects

The nucleophilic substitution of aromatic moieties (SNAr) has been known for over 150 years and found wide use for the functionalization of (hetero)aromatic systems. Currently, several "types" of SNAr reactions have been established and notably the area of porphyrinoid macrocycles has seen many uses thereof. Herein, we detail the SNAr reactions of seven types of porphyrinoids with differing number and type of pyrrole units: subporphyrins, norcorroles, corroles, porphyrins, azuliporphyrins, N-confused porphyrins, and phthalocyanines. For each we analyze the substitution dependent upon: a) the type of nucleophile and b) the site of substitution (α, β, or meso). Along with this we evaluate this route as a synthetic strategy for the generation of unsymmetrical porphyrinoids. Distinct trends can be identified for each type of porphyrinoid discussed, regardless of nucleophile. The use of nucleophilic substitution on porphyrinoids is found to often be a cost-effective procedure with the ability to yield complex substituent patterns, which can be conducted in non-anhydrous solvents with easily accessible simple porphyrinoids.

Tetrapyrrolic Macrocycles: Synthesis, Functionalization and Applications 2018

Natural and synthetic macrocycles like porphyrins, corroles and phthalocyanines are considered strong candidates to be used in different fields, such as catalysis, sensing, medicine, materials science, or in the development of advanced biomimetic models. All these applications are strongly dependent on the availability of compounds with adequate and specific structural features. This Special Issue has collected 13 contributions which consolidate and expand our knowledge on the application of these macrocycles in different fields accompanied by innovative synthetic methodologies to afford and to functionalize this type of compounds.