Oxidative Transformation of a Tetrathia S-Confused Isophlorin into Porphyrin Cation

Tetra S-confused porphyrinoids

Maximum confusion in porphyrinoids can be achieved by inter-linking heterocycles only through 2,4-connectivity. 20π confused porphycene and 30π expanded porphycene represent examples with the highest number of confused heterocyclic units in a given macrocycle. They significantly differ from the parent 20π porphycene and 30π hexaphyrin in their structural, electronic and redox properties due to the cross conjugation arising from the 2,4-connectivity of the heterocycle. They have been characterized by single crystal X-ray diffraction studies and their aromatic features have been substantiated by quantum chemical calculations.

Synthesis and Properties of Stable 20π Porphyrinoids

The 20π porphyrinoids are immediate higher homologues of 18π porphyrins and differ from porphyrins in aromaticity which in turn affects the structure, properties and chemical reactivities. Research over the years indicated that the 20π porphyrinoids can be stabilized as non-aromatic/anti-aromatic or Mobius aromatic macrocycles using different strategies such as core-modification of porphyrins, non-metal/metal complexation of porphyrins, peripheral modification of porphyrins and expanded porphyrinoids. The structural properties such as aromaticity of the macrocycle can be controlled by choosing the right synthetic strategy. This review will provide an overview of the development in the chemistry of 20π porphyrinoids giving emphasize on the synthesis, structure and electronic properties of these macrocycles which have huge potential for various applications.

Reversible redox switching between local and global aromaticity for core-modified expanded carbaisophlorinoids

Two dithienothiophene based 28π antiaromatic macrocycles with benzene and azulene units and their effects on local and global (anti)aromaticity have been described. Experimental and computational studies confirmed the presence of weak paratropic and strong diatropic ring current effects in neutral and dicationic states, respectively.

Creation from Confusion and Fusion in the Porphyrin World─The Last Three Decades of N-Confused Porphyrinoid Chemistry

Confusion is a novel concept of isomerism in porphyrin chemistry, delivering a steady stream of new chemistry since the discovery of N-confused porphyrin, a porphyrin mutant, in 1994. These days, the number of confused porphyrinoids is increasing, and confusion and associated fusion are found in various fields such as supramolecular chemistry, materials chemistry, biological chemistry, and catalysts. In this review, the birth and growth of confused porphyrinoids in the last three decades are described.

Chemical transformation of Doubly N-Confused Porphodimethene to variants of (anti)Aromatic Doubly N-Confused Porphyrinoids and σ aromatic Doubly N-Confused Isophlorinoid

Chemical conversion of non-aromatic trans-doubly N-confused porphodimethene to hitherto unknown variants of doubly N-confused porphyrinoids/isophlorinoid have been unravelled by precise interplay between the types of oxidants, the types of meso-aryl...

Lewis acid-catalyzed formation of triply S-confused hexaphyrin (1.0.1.0.1.0) and its structure-property correlations

A simple rigid precursor termed as a “diheterole” bearing thiophene linked to [Formula: see text]-pyrrole at 4-position was prepared using a three-step synthetic strategy. This functionalized diheterole was allowed to undergo acid-catalyzed condensation in the presence of Lewis acid (BF3 [Formula: see text] Et2O) to produce the [2+2+2] cyclotrimer 1 as a major product with trace formation of 2and higher homologues.Various 1D and 2D NMR analyses along with theoretical investigations indicate that the molecule 1 exhibits nonaromaticity due to its non-conjugated annulenic structure. The optical properties and electronic structures were analyzed using UV-vis absorption spectroscopy and time-dependent density functional theory calculations. Detailed structural analyses revealed that the conformationally rigid triply S-confused hexaphyrin 1 adopts nearly planar geometry with three thiophene rings inverted. Upon protonation, the individual rings are tilted largely due to the steric congestion by both [Formula: see text]-CH’s and pyrrolic NH’s inside the core. The calculated NICS(0) values of +1.73 ppm for the protonated species, 1 [Formula: see text] 3H[Formula: see text] indicates the distinct non-aromatic feature as observed in 1 (NICS value of +2.34 ppm).