Metalloceneincorporated Hybrid Singly N-Methyl N-Confused Calixphyrins: Synthesis, Characterization, Protonation and Deprotonation Studies

Rational design and isolation of two hitherto unknown highly stable single conformer of ferrocene incorporated meso-aryl substituted singly N-methyl N-confused-calixphyrins have been achieved in quantitative yields. The solid-state crystal structure reveals the obvious trans-geometry for the meso-protons with the possibility for both the macrocycles to exist either racemic or enantiomer forms. However, thorough solution-state spectroscopic characterization strongly concludes the experimental isolation of a single isomer for both the macrocycles. The drastic modification of UV-vis spectral patterns upon imine pyrrole N protonation and amine pyrrole NH deprotonation of both the calixphyrins could pave way for these macrocycles to act as opto-electronic materials. The conformational preorganization and protonation and deprotonation induced conformational reorganization have been extensively studied by solution state spectroscopic techniques, solid state X-ray crystal structure and in depth DFT level theoretical calculations.

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.

A Stable Antiaromatic 5,20-Dibenzoyl [28]Hexaphyrin(1.1.1.1.1.1): Core AuIII Metalation and Subsequent Peripheral BIII Metalation

5,20-Dibenzoyl [28]hexaphyrin(1.1.1.1.1.1) was synthesized as the first hexaphyrin bearing meso-aroyl substituents. The meso-dibenzoyl substituents are hydrogen-bonded with the pyrrolic protons to stabilize an antiaromatic dumbbell conformer. Core metalation of this hexaphyrin with Au^III afforded rectangular and aromatic [26]hexaphyrin bis-Au^III complexes, the major isomer of which was reduced with NaBH₄ to give its antiaromatic 28π bis-Au^III complex. This complex allowed facile peripheral metalation with B^III owing to the peripheral benzoyl substituents.

Fusing Porphyrins and Phospholes: Synthesis and Analysis of a Phosphorus-Containing Porphyrin

A phosphole-fused porphyrin dimer, as a representative of a new class of porphyrins with a phosphorus atom, was synthesized for the first time. The porphyrin dimer exhibits remarkably broadened absorption, indicating effective π-conjugation over the two porphyrins through the phosphole moiety. The porphyrin dimer possesses excellent electron-accepting character, which is comparable to that of a representative electron-accepting material, [60]PCBM. These results provide access to a new class of phosphorus-containing porphyrins with unique optoelectronic properties.