The Difficult Marriage of Triarylcorroles with Zinc and Nickel Ions

Abstract

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. In the case of Zn, the preliminary oxidation of the free base corrole in DMSO to the neutral corrole radical is a necessary step to obtain the coordination of the metal ion, because the direct reaction led to the formation of an open-chain tetrapyrrole. The Ni complex could be directly obtained by heating the free base corrole and Ni(II) salt to 100 °C in a DMSO solution containing FeCl 3 . The non-innocent nature of the corrole ligand for both complexes has been elucidated by EPR, and in the case of the Zn derivative the first spectroelectrochemical characterization is presented.

Panchromatic and Perturbed Absorption Spectral Features and Multiredox Properties of Dicyanovinyl- and Dicyanobutadienyl-Appended Cobalt Corroles

“…Corroles are less explored in the areas of photonics and photocatalysis and have shown promising properties. − Kar and co-workers developed NIR-emissive β-tetrathiocyano functionalized corrole-based dyes via a photocatalytic pathway in good yields. − Our strategy is to synthesize a novel β-functionalized corrole with strong π-acceptor groups such as dicyanovinyl (DCV) and dicyanobutadienyl (DCBD), resulting in perturbation of the Soret and Q bands in the absorption spectrum. The recent literature on corroles revealed that π-extended corroles exhibit tunable photophysical and electrochemical redox properties. − For example, copper corroles demonstrate hypercorrole spectra, and the Soret band contains more than one electronic transition with significant phenyl-Cu­(d x 2 –y 2 ) charge-transfer characteristics. , Gros et al have shown ligand-to-ligand charge transfer interactions in biscyano cobalt corroles to meso -NO 2 Ph groups .…”

Palladium Complexes of N‐Methylcorroles

“…[6] A possible solution is to prepare neutral complexes by oxidation of corrole to the corresponding radical, making it a dianionic ligand. In this way it is possible to obtain a stable Ni complex and a less stable Zn derivative, [7] forming however paramagnetic species.…”

Molecular Engineering of Corrole Radicals by Polycyclic Aromatic Fusion: Towards Open‐Shell Near‐Infrared Materials for Efficient Photothermal Therapy

“…[25] Corrole is a 18π one-carbon-short ring-contracted porphyrin that easily undergoes one-electron oxidation to form 17π radical when coordinating with divalent ions, such as Ni(II), Cu(II) and Zn(II). [26][27][28][29][30][31] Recently, we reported a neutral Ni(II) tetrabenzocorrole radical 1 a with a [4n + 1] π system that exhibited high stability. [29] The Q α band of 1 a originated from the transition between the singly highest occupied molecular orbital (SOMO) and singly lowest unoccupied molecular orbital (SUMO) in α-spin located at 693 nm, which exhibited nearly a � 60 nm redshift corresponding to the Q band of its closed-shell aromatic anion with the [4n + 2] π system.…”

“…Additionally, porphyrins have shown promise in stabilizing π‐radicals on their conjugative structures [25] . Corrole is a 18π one‐carbon‐short ring‐contracted porphyrin that easily undergoes one‐electron oxidation to form 17π radical when coordinating with divalent ions, such as Ni(II), Cu(II) and Zn(II) [26–31] . Recently, we reported a neutral Ni(II) tetrabenzocorrole radical 1 a with a [4n+1] π system that exhibited high stability [29] .…”