Synthesis and characterization of a novel three-dimensional oligopyrrole: tris(bipyrro)methane

Abstract

The synthesis, characterization and X-ray structure of the novel three dimensional tris(bipyrr0)methane 3 is reported; this species is predisposed to self-assemble into a cryptandlike dimer in both organic solution and the solid state.Compounds containing three pyrrole units bonded via the aposition to an sp3 hybridized carbon have been known for at least 80 years.] Dubbed tripyrrylmethanes (e.g. 1) Corwin and co-workers2 proposed these species as intermediates in the formation of dipyrromethenes after the initial work of Piloty, Krannich and Will. la They found that the condensation of an. afree pyrrole with a 2-formylpyrrole could give rise to several different dipyrromethanes, presumably through an intermediary tripyrrylmethane, which was never characterized beyond its elemental composition and melting point. The finding that the bacterial pigment prodigiosin,3 originally proposed as being a

Konjugierte Makrocyclen: Konzepte und Anwendungen

“…[113] Später berichteten Sessler et al über eine Serie von b-substituierten Sapphyrinen mit einem oder mehreren Heteroatomen, von denen das Monooxasapphyrin stabile aromatische Komplexe (151) bildete, in denen eine Uranyleinheit in der Porphyrinebene liegt (Abbildung 33). [114] Das Schwefelanalogon 152 des 22p-Pentaphyrins wurde von Vogel und Mitarbeitern beschrieben. [115] Da die Synthesemethoden und die bemerkenswerten Eigenschaften bereits in anderen Übersichten erläutert wurden, [100,101,116] fassen wir hier nur die aktuellsten Ergebnisse zu kernmodifizierten expandierten Porphyrinen zusammen.…”

Hexaphyrin(1.0.1.0.0.0): An Expanded Porphyrin Ligand for the Actinide Cations Uranyl (UO22+) and Neptunyl (NpO2+)

“…Porphyrins are also macrocycles that are recognized as excellent cation complexation agents, particularly for cations of the late transition series 16. While structurally characterized U IV and Th IV porphyrin complexes have been reported,17 the expanded porphyrins appear more attractive as ligands18 for the specific purpose of actinyl cation coordination, and a select few, such as alaskaphyrin ( 2 ), oxasapphyrin ( 3 ), and pentaphyrin ( 4 ), have been shown to complex uranyl cations effectively 19–21. A uranyl complex of so‐called “super phthalocyanine” was also reported early on 22…”

“…The uranyl center is shifted towards the quaterpyrrolic subunit; as such, the coordination environment of the uranium ion is best described in terms of a distorted hexagonal bipyramid. The U−O bond length of 1.760(2) Å is typical for a UO 2 2+ unit,19–21 which indicates that no reduction of the metal center occurred. The average U−N bond length of 2.63(1) Å is comparable to that found in the hexacoordinate uranyl complex of alaskaphyrin (2.63(3) Å) 20.…”

Oligopyrrole Macrocycles: Receptors and Chemosensors for Potentially Hazardous Materials

“…These latter complexes typically exploit the larger cavity size and greater number of nitrogen donor atoms present in expanded porphyins (relative to the porphyrins). In early studies, uranyl complexation was observed in the case of Alaskaphyrin, [19] oxasaphyrrin, [20] pentaphyrrin, [21] and amethyrin. [22] In 2001, the Sessler group reported the synthesis and characterization of hexaphyrin(1.0.1.0.0.0) (isoamethyrin; 1 ; Scheme 1) and its ability to complex the actinide ions uranyl (UO 2 2+ ) and neptunyl (NpO 2 + ).…”