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After the epochal discovery of the "organic metal", namely, tetrathiafulvalene (TTF)-7,7,8,8-tetracyano-p-quinodimethane (TCNQ) dyad in 1973, scientists have made efforts to derivatize TTF for constructing various supramolecular architectures to control the charge-transfer processes by adjusting the donor-acceptor strength of the dyads for numerous applications. The interesting inherent electronic donor properties of TTFs control the overall electrochemical properties of the supramolecular structures, leading to the construction of highly efficient optoelectronic materials, photovoltaic solar cells, organic field-effect transistors, and optical sensors. Modified TTF structures thus constitute promising candidates for the development of so-called "functional materials" that could see use in modern technological applications. The versatility of the TTF unit and the pioneering synthetic strategies that have been developed over the past few decades provide opportunities to tune the architecture and function for specific purposes. This review covers the "state of the art" associated with TTF-annulated oligopyrrolic macrocyclic compounds. Points of emphasis include synthesis, properties, and potential applications.

Novel hybrid cyclo[m]pyridine[n]pyrroles have been synthesized using Suzuki coupling. Their NMR and optical spectroscopic features and solid state structural parameters provide support for the proposal that these species are best described as locally aromatic compounds devoid of long-range intersubunit conjugation. However, an extension of the π-conjugation in the macrocycles can be realized through protonation, as inferred from optical spectroscopic and X-ray diffraction-based structural studies., (© 2012 American Chemical Society)

Sapphyrin is a pentapyrrolic expanded porphyrin with a 22π aromatic character. Herein, we report the synthesis of a 20π antiaromatic sapphyrin isomer 1 by oxidative cyclization of a pentapyrrane precursor P5 with a terminal β‐linked pyrrole. The resulting isomer 1, containing a mis‐linked bipyrrole unit in the skeleton, exhibits a reactivity for further oxidation due to the distinct antiaromatic electronic structure, affording a fused macrocycle 2, possessing a spiro‐carbon‐containing [5.6.5.6]‐tetracyclic structure. Subsequent treatment with an acid afforded a weakly aromatic pyrrolone‐appended N‐confused corrole 3, and thermal fusion gave a [5.6.5.7]‐tetracyclic‐ring‐embedded 14π aromatic triphyrin(2.1.1) analog 4. The cyclization at the mis‐linked pyrrole moiety of P5 played a crucial role in synthesizing the antiaromatic porphyrinoid susceptible to facile transformation to novel porphyrinoids with variable aromaticity. [ABSTRACT FROM AUTHOR]

A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face‐to‐face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials. [ABSTRACT FROM AUTHOR]

A hybrid thia‐norhexaphyrin comprising a directly linked N‐confused pyrrole and thiophene unit (1) revealed unique macrocycle transformations to afford multiply inner‐annulated aromatic macrocycles. Oxidation with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone triggered a cleavage of the C−S bond of the thiophene unit, accompanied with skeletal rearrangement to afford unique π‐conjugated products: a thiopyrrolo‐pentaphyrin embedded with a pyrrolo[1,2]isothiazole (2), a sulfur‐free pentaphyrin incorporating an indolizine moiety (3), and a thiopyranyltriphyrinoid containing a 2H‐thiopyran unit (4). Furthermore, 2 underwent desulfurization reactions to afford a fused pentaphyrin containing a pyrrolizine moiety (5) under mild conditions. Using expanded porphyrin scaffolds, oxidative thiophene cleavage and desulfurization of the hitherto unknown N‐confused core‐modified macrocycles would be a practical approach for developing unique polypyrrolic aromatic macrocycles. Oxidation of a nonaromatic thia‐modified norhexaphyrin with directly linked N‐confused pyrrole and thiophene rings triggered cleavage of a C−S bond to afford three multiply annulated polypyrrolic aromatic macrocycles with global or local aromaticity. This approach is a path to porphyrinoids with tunable structures and aromaticity based on thiophene cleavage and desulfurization. [ABSTRACT FROM AUTHOR]

The Lewis acid catalyzed self‐condensation of hybrid diheterole (furan‐pyrrole and thiophene‐pyrrole) precursors has afforded novel Hückel antiaromatic 24π hexaphyrin(1.0.1.0.1.0) and 32π octaphyrin(1.0.1.0.1.0.1.0) structures without β‐annulated bridges. Single‐crystal X‐ray diffraction analysis of the hybrid porphyrinoids (S3N3‐ox and O4N4‐ox) revealed a nearly planar conformation and the 1H NMR spectra suggest the presence of paratropic ring currents. These antiaromatic macrocycles show characteristic optical features and underwent reversible two‐electron reduction to Hückel aromatic 26π‐ and 34π‐electron species, respectively, as is evident from the results of spectroscopic and theoretical studies (nucleus‐independent chemical shift (NICS) and anisotropy of the current‐induced density (ACID) calculations). The incorporation of hybrid diheteroles alternately into expanded porphyrin skeletons provides a novel approach to the fine‐tuning of the electronic structures of planar antiaromatic macrocycles. Antiaromatic macrocycles: The Lewis acid catalyzed self‐condensation of hybrid diheterole precursors has afforded Hückel antiaromatic 24π hexaphyrin and 32π octaphyrin structures that have been structurally characterized. The incorporation of hybrid diheteroles alternately into the expanded porphyrin skeletons could provide a novel approach to the fine‐tuning of the electronic structures of planar antiaromatic macrocycles. [ABSTRACT FROM AUTHOR]

A novel [36]octaphyrin analogue embedding two N-confused pyrrole units demonstrated unique prototropy-coupled isomerization between the Figure-of-eight and dumbbell conformers. Upon bis-metal coordination, fixation of fully π-conjugated Figure-of-eight structures was achieved as referred from the X-ray crystal structure. Chirogenesis of the helical enantiomers was proved by intense circular dichroism (CD) response in the near infrared (NIR) region. [ABSTRACT FROM AUTHOR]

A rational and effective approach for synthesizing linear π-conjugated hexa-, hepta- and octapyrrins through the regioselective oxidative coupling of monoacylated tripyrrane and bilane is described. Depending upon the numbers of pyrrolic units, the geometry and properties of bis-copper(ii) complexes could be systematically modulated. [ABSTRACT FROM AUTHOR]

Three kinds of fused porphyrinoids, L2- L4, possessing different types of corrole-based frameworks were synthesized from a pyrrole-substituted corrole isomer (norrole L1). Oxidation of L1 afforded a unique N-Cmeso-fused pyrrolyl isonorrole L2, involving the fusion of an auxiliary pyrrolic NH moiety with a meso-sp3-hybridized carbon atom. Subsequently, L2 underwent macrocycle transformations to give singly and doubly N-CAr-fused N-confused corroles, L3 and L4, respectively. L3 and L4 contain fused [5.7.6.5]-tetra- and [5.6.7.7.6.5]-hexacyclic structures, respectively, prepared through lateral annulation. These skeletal transformation reactions from norrole to its isomer isonorrole and finally to N-confused corrole indicate that multiply fused porphyrinoids could be readily synthesized from pyrrole-appended confused porphyrinoids. [ABSTRACT FROM AUTHOR]

Title compounds (IV) and (VI) are prepared in low yields via a three component condensation of benzimidazole (I), trifluoroacetic acid (III), and either pyrrole (II) or indole (V), respectively. [ABSTRACT FROM AUTHOR]

Novel hybrid cyclo[m]pyridine[n]pyrroles have been synthesized using Suzuki coupling. Their NMR and optical spectroscopic features and solid state structural parameters provide support for the proposal that these species are best described as locally aromatic compounds devoid of long-range intersubunit conjugation. However, an extension of the π-conjugation in the macrocycles can be realized through protonation, as inferred from optical spectroscopic and X-ray diffraction-based structural studies. [ABSTRACT FROM AUTHOR]