Annulated Isomeric, Expanded, and Contracted Porphyrins

Abstract

Compared to porphyrin, its isomeric, expanded, and contracted analogues are less well explored. This contrast is found to be even more drastic in the case of their peripherally annulated counterparts. Nevertheless, the chemistry of annulated isomeric, expanded, and contracted porphyrins started flourishing recently with considerable efforts over the past few years, as evidenced by an increasing number of publications. While keeping the essence of porphyrins, these annulated versions exhibit quite unique properties that have no precedence in their nonannulated counterparts. An in-depth update of research carried out so far in this emerging area will be presented in this review.

Synthesis of Expanded Hetero 2,6‐Pyrihexaphyrins

“…Expanded porphyrins containing more than four pyrroles have received tremendous attention over the years because of their excellent optical, electrochemical and coordination properties arising from their larger π ‐conjugation frameworks than those of tetrapyrrole porphyrins . Because of the large cavity, the expanded porphyrins are highly promising as multi‐metal coordinating ligands, allowing the formation of oligo nuclear complexes with notable metal–metal interaction or catalytic activity , .…”

“…Expanded porphyrins [1][2][3][4][5][6][7][8][9][10] containing more than four pyrroles have received tremendous attention over the years because of their excellent optical, electrochemical and coordination properties arising from their larger π-conjugation frameworks than those of tetrapyrrole porphyrins. [11][12][13][14] Because of the large cavity, the expanded porphyrins are highly promising as multimetal coordinating ligands, allowing the formation of oligo nuclear complexes with notable metal-metal interaction or catalytic activity. [7,[11][12][13] Furthermore, expanded porphyrins are emerging functional molecules with potential utilities in a range of applications, such as anion receptors, [3,7,15] transition or lanthanide ion chelates, [16] photodynamic therapy sensitizers, [4,16,17] magnetic resonance imaging (MRI) contrast agents, [16] optical data storage and optical limiting agents.…”

Templating Porphyrin Anisotropy via Magnetically Aligned Carbon Nanotubes

“…[46][47][48][49][50][51][52][53] Moreover, porphyrin chemistry has become extremely rich and diverse and the electronic and optical properties can be fine-tuned by shaping their periphery. [54][55][56][57][58] While a number of efforts in constructing nanostructures through the organization of porphyrins have been achieved, their organisation over multiple scales (from the nanoscale to the microscale) remains of great interest owing to their potentials in light-harvesting applications. [59][60][61][62][63] Although one-or two-dimensional supramolecular porphyrin systems are now easily prepared, the construction of three-dimensional assemblies remains a challenge.…”

Quantum chemical studies of porphyrin‐ and expanded porphyrin‐based systems and their potential applications in nanoscience. Latin America research review

“…Expanded porphyrins are macrocycles containing more than four pyrrolic units, which retain the extended conjugation features as porphyrins. They present a core expansion that produces structures with novel spectral and electronic features …”