The aromatic character of porphyrins, which has significant chemical and biological consequences, can be substantially altered by judicious modifications the parent ring system. Expansion macrocycle, is achieved introducing additional subunits, usually increases so-called free curvature ring, leading to larger angular strain. This strain reduced a variety conformational changes, most notably subunit inversion p surface twisting. latter effect creates particularly convenient access Möbius...

Dual identity: It takes a single phenylene twist to reveal the dichotomous nature of di-para-benzihexaphyrin (see picture; rings highlighted in red). This expanded porphyrinoid switches between Hückel and Möbius topologies an unusual solvent- temperature-dependent equilibrium. Each two incarnations macrocycle has its own unmistakable spectral signature. aromaticity1, 2 is intriguing rarely encountered type electron delocalization, so called because formal relationship famous band, classical...

A cycloparaphenylene-based molecular lemniscate (CPPL) was obtained in a short synthesis involving masked p-phenylene equivalents. The strained figure-eight geometry of CPPL is sustained by the incorporated 9,9′-bicarbazole subunit, which also acts as stereogenic element. shape distorted [16]cycloparaphenylene nanohoop embedded accurately approximated with Booth lemniscate. structure CPPL, investigated using NMR and Raman spectroscopic methods, revealed strain-dependent features, consistent...

Abstract 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 erhöhen seine Ringkrümmung, was zu einer höheren Winkelspannung führt. Diese Ring eine Reihe Konformationsänderungen wieder abbauen, insbesondere Invertieren Verdrillen (twisting) π‐Oberfläche. Letzterer Effekt bietet einen Zugang...

Möbius pi-conjugation in cyclic molecules leads to the reversal of Huckel aromaticity rules and affects electronic magnetic properties these systems. We found first example a medium-sized macrocyclic structure that is sufficiently flexible switch between three distinct topologies, planar (T0), (T1), twisted (T2), without changing its oxidation level. The switching under thermodynamic kinetic control can be realized three- or four-step cycle. On titration with trifluoroacetic acid (TFAH)...

Abstract Dieser Aufsatz fast die jüngsten Fortschritte in der Chemie gekrümmter aromatischer Moleküle zusammen. Mit dem Schwerpunkt auf den wesentlichen Erfolgen des vergangenen Jahrzehnts stellen wir einen allgemeinen Überblick über Synthesemethoden zur Verfügung, eine effiziente Induktion von interner Spannung π‐konjugierten Strukturen ermöglichen. ist gemäß am spannungsinduzierenden Reaktionsschritt (Cyclisierungen, Eliminierungen, Ringexpansionen und –kontraktionen) beteiligten...

Molecular jellyfish: A new family of bowl-shaped aromatic compounds swims into view (see picture). Quite unlike true jellyfish, chrysaoroles possess a rigid skeleton, which is assembled from fused carbazole units. Their synthesis involves fold-in step to convert macrocyclic precursor the target molecule. As service our authors and readers, this journal provides supporting information supplied by authors. Such materials are peer reviewed may be re-organized for online delivery, but not...

Abstract Octulene, the higher homologue of kekulene and septulene, was synthesized using fold‐in method. This new hydrocarbon macrocycle contains a large 24‐membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion π‐conjugated surface. The consequences in octulene were explored photophysical methods, revealed reduced electronic band gap greater flexibility π system. Octulene functional cavity with diameter larger...

Chiral heteroaromatic propellers based on radially π-extended hexapyrrolohexaazacoronenes were obtained in a concise synthesis from suitably functionalized donor-acceptor monopyrroles. To overcome steric hindrance, new cyclodehydrogenation method was developed, and it uses bromine electrophiles as oxidative coupling agents instead of the commonly employed high-potential oxidants. The reaction offers high yields propeller-shaped targets, even for electron-deficient precursors, shows...

Weak metal-arene interactions have been investigated in Zn, Cd, Hg, and Ni complexes of meso-tetraaryl m- p-benziporphyrin (1 2) the new compound, m-benziporphodimethene (3). Compounds 1-3 incorporate phenylene moiety into a macrocyclic structure so as to facilitate interaction between arene coordinated metal ion. X-ray studies performed on Cd(II) Ni(II) show that fragment approaches ion at distance much shorter than sum van der Waals radii. In chloronickel(II) m-benziporphyrin, weak agostic...

As a valuable ligand for organometallic investigations of benzene reactivity, tetraphenylbenziporphyrin undergoes number interesting reactions with palladium(II) and platinum(II) complexes, example PtCl2 (see scheme), in which the metal ion becomes bound macrocyclic cavity. In contrast reaction silver(I) acetate leads to selective acetoxylation at internal carbon atom ring. 6,11,16,21-Tetraphenylbenziporphyrin (TPBPH)H, an analogue tetraphenylporphyrin one pyrrole groups replaced by ring, is...

Replacement of one the pyrrole rings with a p-phenylene unit transforms porphyrin into p-benziporphyrin (1), an aromatic carbaporphyrinoid that locates two connected carbon atoms in coordination core. p-Benziporphyrin forms complex cadmium(II) (2) unprecedented η2 Cd(II)-arene interaction.

The diprotonated form of an organic-solubilized cyclo[8]pyrrole derivative, bearing eight undecyl chains on the β-pyrrolic positions, was found to extract sulfate anion effectively from neutral aqueous media into a toluene organic phase. kinetics exchange between two phases were be exceedingly slow in absence phase-transfer catalyst, Aliquat 336-nitrate (A336N), but appreciable its presence. bisnitrate bound this could generated situ by subjecting phase containing initially 0.5 mM and 0.1...

Doppelidentität: Es braucht eine einzige Phenylenverdrillung, um den dichotomen Charakter eines Di-para-benzihexaphyrins offenkundig zu machen (siehe Bild; Phenylenringe in Rot). Dieses expandierte Porphyrinoid schaltet einem ungewöhnlichen lösungsmittel- und temperaturabhängigen Gleichgewicht zwischen Hückel- Möbius-Topologien. Jede der beiden Ausprägungen des Makrocyclus hat ihre eigene unverwechselbare spektrale Signatur. Supporting information for this article is available on the WWW...

It stacks up nicely: Exposure of dihydrogen sulfate salts appropriately substituted cyclo[8]pyrroles to electron-deficient acceptor molecules gives discotic liquid crystals. The columnar mesophase structures are stabilized by electron-donor/electron-acceptor interactions (see picture; red: trinitrobenzene, green: cyclo[8]pyrrole cores, yellow: ions, gray: volume occupied the substituents). Supporting information for this article is available on WWW under...

Oxidative coupling of activated aryl groups attached to β-positions the porphyrin ring provides convenient access derivatives containing peripherally fused phenanthrene and benzo[g]chrysene units. Tetra(benzochryseno)porphyrin, reported here for first time, contains a nonplanar, sterically locked π system shows very intense electronic absorptions in Q range spectrum. Tetraphenanthroporphyrins show tendency aggregate solution. In one case, discrete dimer is formed, whose structure was...

Nonclassical nanotube end-caps have been constructed from strain-free heterocyclic precursors using a one-step synthetic procedure, involving multiple nickel-mediated Ullmann couplings. These systems consist of tubular macrocyclic sections that are tightly capped on one side with bridging benzene ring, forming deep, chemically accessible cavities. The characterized by exceptionally high internal strain energies reaching 144 kcal/mol. optical absorption and emission properties these molecules...

Abstract The four expanded p ‐benziporphyrins A,C‐di‐ ‐benzi[24]pentaphyrin(1.1.1.1.1), N‐fused A‐ ‐benzi[24]pentaphyrin, A, D ‐di‐ ‐benzi[28]hexaphyrin(1.1.1.1.1.1), and ‐benzi[28]hexaphyrin(1.1.1.1.1.1) were obtained in three‐component Lindsey‐type macrocyclizations. These compounds explored as macrocyclic ligands potential aromaticity switches. A BODIPY‐like difluoroboron complex was from the whereas ‐benzi[28]hexaphyrin yielded a Möbius‐aromatic Pd II containing fused pyrrole phenylene...

Reversible homolytic dissociation of the bis(pyrimidinenorcorrole) σ-dimer was elucidated by means variable temperature ESR and 1 H NMR spectroscopy, mass spectrometry, optical spectrocopy. Dehydrogenation yielded another dimer displaying a singlet-triplet equilibrium in solution, strong NIR absorption (1570 nm), narrow electrochemical HOMO-LUMO gap (0.74 V).

Abstract A hexapyrrolohexaazacoronene derivative containing 37 fused rings, the largest such system to date, was obtained from a naphthalenomonoimide–pyrrole hybrid in concise and efficient synthesis. This large heterocycle is electron‐deficient shows extended redox activity, spanning at least 13 oxidation levels, but otherwise chemically stable. Radial expansion of π creates chromophore characterized by strong fluorescence solvatochromism neutral state, near‐infrared absorption charged...

A family of azacoronenes containing up to two saturated bridges at the periphery was synthesized from substituted hexapyrrolylbenzenes using a two-step condensation–aromatization procedure. The introduction peripheral provides access nonplanar, sterically crowded systems that display complex reactivity patterns, involving stereospecific aromatization and nucleophile additions. Despite interrupted conjugation on periphery, new have easily accessible higher oxidation levels, quadruply charged...