<i>meso</i>-Aryl Smaragdyrins:  Novel Anion and Metal Receptors

Sridevi, Bashyam; Narayanan, S.; Rao, R. P.; Chandrashekar, Tavarekere K.; Englich, Ulrich; Ruhlandt‐Senge, Karin

doi:10.1021/ic000031v

Cited by 68 publications

(71 citation statements)

References 37 publications

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“…The two systems of primary interest are sapphyrin (19-H 3 ) and pentaphyrin(1.1.1.1.1) (26-H 2 ), whose rich chemistry will be discussed in some detail below. Orangarin (16 a-H 3 ), [55] smaragdyrin (17 a-H 4 ), [56,182,183] and isosmaragdyrin (18 a-H 4 ), [49] are characterized by t F values smaller than that of porphyrin and consequently yield only convex conformations that are essentially planar. Orangarin, a [20]annulenoid antiaromatic macrocycle, [55] is markedly paratropic, as evidenced by its center NICS value of 43 ppm.…”

Section: Pentaphyrinsmentioning

confidence: 99%

“…[102] In spite of their aromatic character, smaragdyrins and their oxa analogues are unstable towards acids and light, [56,182] but they can be made more robust by appropriate peripheral substitution. [183][184][185][186][187][188] Interestingly, no pentaphyrins containing less than two meso carbons have yet been reported. Hypothetical pentaphyrins (1.0.0.0.0) and (0.0.0.0.0) yield t F values of 0.83 and 0.66, respectively.…”

Section: Pentaphyrinsmentioning

confidence: 99%

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Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

2011

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The aromatic character of porphyrins, which has significant chemical and biological consequences, can be substantially altered by judicious modifications of the parent ring system. Expansion of the macrocycle, which is achieved by introducing additional subunits, usually increases the so-called free curvature of the ring, leading to larger angular strain. This strain is reduced by a variety of conformational changes, most notably by subunit inversion and p surface twisting. The latter effect creates a particularly convenient access to Möbius aromatic molecules, whose properties, predicted over 40 years ago, are of considerable theoretical importance. The conformational processes occurring in porphyrin analogues are often coupled to other chemical phenomena, and can thus be exploited as a means of constructing functional molecular devices. In this Review, the structural chemistry of porphyrinoids is discussed in the context of their conformational dynamics and p-electron conjugation.

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Section: Pentaphyrinsmentioning

confidence: 99%

Section: Pentaphyrinsmentioning

confidence: 99%

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

2011

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“…[63] Specifically, a Ni II complex as well as a [Rh(CO) 2 ] complex of this formally trianionic ligand were described; the X-ray structure of the latter species is shown in Scheme 5. Catalytic decomposition of peroxynitrite by a manganesetexaphyrin complex.…”

Section: Heteroatom-containing Smaragdyrinsmentioning

confidence: 99%

“…Front (top) and side (bottom) views of the solid-state structure of complex 44 b·HCl. [63] Scheme 7. Synthesis of partially meso-substituted isosmaragdyrins 47.…”

Section: Heterosapphyrinsmentioning

confidence: 99%

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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“…[102] Trotz ihres aromatischen Charakters sind Smaragdyrin und seine Oxa-Analoga gegenüber Säure und Licht instabil, [56,182] können jedoch durch geeignete periphere Substitution robuster gemacht werden. [183][184][185][186][187][188] Interessanterweise wurden bis jetzt noch keine Pentaphyrine beschrieben, die weniger als zwei Mesokohlenstoffatome …”

Section: Pentaphyrineunclassified

Figure‐Eight‐Strukturen, Möbius‐Bänder und mehr: Konformation und Aromatizität von Porphyrinoiden

2011

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Der aromatische Charakter von Porphyrinen, der signifikante chemische und biologische Auswirkungen hat, kann durch gezielte Modifikationen des Stammringsystems beträchtlich verändert werden. Zusätzliche Untereinheiten expandieren den Makrocyclus und erhöhen seine Ringkrümmung, was zu einer höheren Winkelspannung führt. Diese Winkelspannung kann der Ring durch eine Reihe von Konformationsänderungen wieder abbauen, insbesondere durch Invertieren von Untereinheiten und Verdrillen (twisting) der π‐Oberfläche. Letzterer Effekt bietet einen Zugang zu Möbius‐aromatischen Molekülen, deren Eigenschaften, gleichwohl vor über 40 Jahren vorausgesagt, unter theoretischen Aspekten von großer Bedeutung sind. Häufig gehen Konformationsprozesse in den Porphyrinanaloga mit anderen chemischen Phänomenen einher, sodass sie für den Aufbau von molekularen Funktionseinheiten verwendet werden können. In diesem Aufsatz wird die Strukturchemie der Porphyrinoide im Zusammenhang mit ihrer Konformationsdynamik und elektronischen π‐Konjugation diskutiert.

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meso-Aryl Smaragdyrins: Novel Anion and Metal Receptors

Cited by 68 publications

References 37 publications

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

Figure Eights, Möbius Bands, and More: Conformation and Aromaticity of Porphyrinoids

Synthetic Expanded Porphyrin Chemistry

Figure‐Eight‐Strukturen, Möbius‐Bänder und mehr: Konformation und Aromatizität von Porphyrinoiden

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