Meso Aryl Heptaphyrins:  The First 30π Aromatic Expanded Porphyrins with an Inverted Structure

Anand, V.; Pushpan, Simi K.; Srinivasan, A.; Narayanan, S.; Sridevi, Bashyam; Chandrashekar, Tavarekere K.; Roy, Raja; Joshi, Bhavani S.

doi:10.1021/ol000251c

Cited by 49 publications

(43 citation statements)

References 18 publications

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“…[107] As shown previously in Scheme 24, reaction of 82 a or 82 b with either 43 a or 43 c produced macrocycles 84 a-d, respectively, in yields ranging from 15 to 20 %. Curiously, despite the moderate yields obtained, the report does not comment on the formation of other macrocycles that might be expected; for example, products derived from the self-coupling of the respective precursors (see, however, Sections 5.3 and 7.5).…”

Section: Methodssupporting

confidence: 52%

“…For example, as reported in the Supporting Information of the paper, [107] the CH protons of the inverted selenophene subunit in 84 d were found to resonate as a singlet at d = À1.62 ppm, while two singlets were seen at d = 0.02 and À0.47 ppm which are ascribed to the two different NH signals. Also in accord with the proposed aromatic character, signals ascribed to the "outer" b-CH protons of 84 d were found between d = 9.07 and 10.17 ppm.…”

Section: Methodsmentioning

confidence: 58%

“…The first examples of heteroatom analogues of [30]heptaphyrin(1.1.0.1.1.0.0) were recently reported by Chandrashekar and co-workers. [107] These novel macrocycles were initially obtained as side products in the synthesis of the heterorubyrins 103 (Scheme 32). Oxidative coupling of the heterotripyrranes 102 a or 102 b was found to give rise to 103 a or 103 b in 15 % yield, while the heptaphyrins 104 a or 104 b were isolated in 2 % yield.…”

Section: Systems Containing Seven Pyrrole Ringsmentioning

confidence: 99%

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Synthetic Expanded Porphyrin Chemistry

2003

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Expanded porphyrins are synthetic analogues of the porphyrins, and differ from these and other naturally occurring tetrapyrrolic macrocycles by containing a larger central core with a minimum of 17 atoms, while retaining the extended conjugation features that are a hallmark of these quintessential biological pigments. The result of core expansion is to produce systems with novel spectral and electronic features, interesting and, often unprecedented, cation-coordination properties, and, in many cases, an ability to bind anions in certain protonation states. Also adding to the appeal of expanded porphyrins is their central role in addressing issues of aromaticity. In many cases, they also display structural features, such as decidedly nonplanar "figure-eight" motifs, that have no antecedents in the chemistry of porphyrins or related macrocyclic compounds. In this Review, the various synthetic approaches now being employed to produce expanded porphyrins as well as their various applications-related aspects are discussed.

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Section: Methodssupporting

confidence: 52%

Section: Methodsmentioning

confidence: 58%

Section: Systems Containing Seven Pyrrole Ringsmentioning

confidence: 99%

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Synthetic Expanded Porphyrin Chemistry

2003

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“…The expected rubyrins were not formed when the meso substituents were phenyl or tolyl in both the precursors, indicating the necessity of the bulkier group in at least one of the precursors, while keeping the acid concentration the same and changing the mesityl substituents for a p-methoxy substituent in the terthiophene diol resulted in the formation of [ It is well known that tripyrranes and tetrapyrranes undergo acidolysis in the presence of acid and that the extent of acidolysis depends on the concentration of acid in the reaction mixture. [9,11] Acidolysis of 11 and 12 has already been reported. [9] It has been reported that in the reaction of tripyrranes 11 or 12, with 0.3 equiv.…”

Section: Synthesesmentioning

confidence: 99%

“…In these syntheses an efficient approach involving [3 + 3] acid-catalyzed condensations of terthiophene diols [9] 7-10 and tripyrranes 11-14 was applied (Scheme 1). Mixtures of the appropriate diol and tripyrrane were stirred in the presence of p-toluenesulfonic acid (PTSA) in dry CH 2 Cl 2 in the dark at room temperature.…”

Section: Synthesesmentioning

confidence: 99%

One‐Pot Synthesis of Core‐Modified Rubyrin, Octaphyrin, and Dodecaphyrin: Characterization and Nonlinear Optical Properties

et al. 2007

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Modified 26π rubyrin, 36π octaphyrin, and 54π dodecaphyrin systems have been synthesized in moderately good yields through acid‐catalyzed condensations of terthiophene diols and tripyrranes. The product distributions are decided both by the acid catalyst concentration and by the nature of the meso substituents. For example, a new isomer of [26]hexaphyrin(1.1.1.1.0.0) (rubyrin) was obtained with 0.3 equiv. of p‐toluenesulfonic acid, when the meso substituent was mesityl in at least one of the precursors. A change of the mesityl substituent for a p‐methoxy substituent in terthiophene diol resulted in the formation of a [3 + 3 + 3 + 3] condensation product – [54]dodecaphyrin(1.1.1.1.0.0.1.1.1.1.0.0) – in addition to the expected rubyrin. Furthermore, an increase in the acid concentration to 0.6 equiv. resulted in the formation of a new [36]octaphyrin(1.1.1.1.1.1.0.0), in addition to the rubyrin and dodecaphyrin. A single‐crystal X‐ray analysis of octaphyrin represents the first example of a planar conformation of an octaphyrin with six meso links. In rubyrin 19, one thiophene ring, opposite to the terthiophene subunit, is inverted, while in octaphyrin 30 one pyrrole ring and two thiophene rings are inverted. The various conformational possibilities tested for the unsubstituted dodecaphyrin 28, at semiempirical level, suggest that the most stable conformation is a figure‐eight. The final geometry optimization of figure‐eight dodecaphyrin was done at the B3LYP/6‐31G* level of DFT. Octaphyrins and dodecaphyrins bind trifluoroacetate anion effectively in their diprotonated forms, the binding constants (K) being 638 M–1 for dodecaphyrin 28, and 415 M–1 for octaphyrin 30. Electrochemical data reveal HOMO destabilization with increasing π electron conjugation, consistently with the large red shifts of the absorption bands. Preliminary studies on the use of these expanded porphyrins as third‐order NLO materials were followed by measurements of their two‐photon absorption (TPA) cross‐sections [σ(2)]. The σ(2) values increase upon going from the 26π rubyrins to the 54π dodecaphyrins, confirming our earlier observation that increases in π‐conjugated electrons increase the TPA values.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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An Unorthodox Conformation of [18]porphyrin-(1.1.1.1) Heteroanalogue—21,23-Ditelluraporphyrin with a Flipped Tellurophene Ring

2001

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Meso Aryl Heptaphyrins: The First 30π Aromatic Expanded Porphyrins with an Inverted Structure

Abstract: [reaction: see text] Synthesis of new meso aryl 30pi heptaphyrins 2, 3, and 4 is achieved. Spectroscopic studies reveal that 2, 3, and 4 are aromatic and possess an inverted structure.

Cited by 49 publications

References 18 publications

Synthetic Expanded Porphyrin Chemistry

Synthetic Expanded Porphyrin Chemistry

One‐Pot Synthesis of Core‐Modified Rubyrin, Octaphyrin, and Dodecaphyrin: Characterization and Nonlinear Optical Properties

An Unorthodox Conformation of [18]porphyrin-(1.1.1.1) Heteroanalogue—21,23-Ditelluraporphyrin with a Flipped Tellurophene Ring

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