Bis‐4,4′‐biphenyl Ring Embedded Octaphyrin with Three Distinct Conformational Structures

Abstract

Three distinct conformational structures of carbaoctaphyrins were prepared by incorporating bis‐4,4'‐biphenyl units in the macrocyclic core. The free‐base form adopts a figure‐eight conformation, whereas the protonation triggers a conformational change with a pyrrole ring inversion and acquires an open‐framework structure. The insertion of bis‐RhI metal ion in the macrocyclic core affords a singly twisted conformational structure. Furthermore, the local aromaticity in the bis‐4,4'‐biphenyl ring dominates the overall macrocyclic aromaticity in all three forms, and thus adopts nonaromatic characteristics. These results are supported by spectral as well as theoretical studies, and they are unambiguously confirmed by X‐ray crystal analyses.

Conformation‐Dependent Response to the Protonation of Diphenanthrioctaphyrin(1.1.1.0.1.1.1.0): A Route to Pseudorotaxane‐Like Structures

“…The rotationo ft he heterocyclic subunit forced the concerted movement of 21,42meso-Ph, whose ortho-protons demonstrated dipolar coupling with the H (43,49) of the phenanthrene. The inversion of the pyrrole was further supported by the NOE cross-peaks linking the b-positions of the heterocycle, that is, H (19,40) with o-Ph (21,42), and H (18,39) with H (47,53). In addition, the crosspeak between H(2,23)a nd o-Ph (21,42) suggested ac lose distance between these two protons.…”

“…The inversion of the pyrrole was further supported by the NOE cross-peaks linking the b-positions of the heterocycle, that is, H (19,40) with o-Ph (21,42), and H (18,39) with H (47,53). In addition, the crosspeak between H(2,23)a nd o-Ph (21,42) suggested ac lose distance between these two protons. This aromatic ring likely causes the remarkable shielding effect detected for NH (48,54).…”

“…[40,41] Adaptation of three distinct geometries was demonstrated for octaphyrin incorporating a4 ,4'-biphenyl moiety upon acidification and rhodium(I) insertion. [42] Herein, we wish to report on complex conformational rearrangements of diphenanthrioctaphyrins upon protonation. Significantly,t he response of 1-A and 1-B to acidification differs strikingly, leadinge ventually to protonated speciesw hich adopt diversem olecular shapes.…”

Kinetic versus Thermodynamic Control Over Multiple Conformations of Di‐2,7‐naphthihexaphyrin(1.1.1.1.1.1)

“…[8][9][10] Some of them were demonstrated to act as macrocycles able to create host-guest complexes with alkali metals, [11] and organic compounds. [12,13] Themost recent examples of the compounds fulfilling the structural criteria of expanded carbaporphyrinoids,i nclude biphenylene-incorporated hexaphyrin [14] and octaphyrins,w hich demonstrate interesting conformational variety, [14,15] or the isosmaragdyrin incorporating 2,6-di-mphenylpirydine,p rone to bind transition metals with two different coordination modes. [16] As ignificant number of expanded carbaporphyrinoids were created with the use of phenanthrene-based building blocks, [17][18][19][20] for example,3 2heterophenanthrisapphyrins, [21] helicenophyrins, [22] and diphenanthrioctaphyrin.…”

Expandierte Carbaporphyrinoide

“…Durch den Austausch der beiden p-Phenylen-Einheiten von A,d-Di-p-benzihexaphyrin 145 gegen 4,4'-Biphenylene wurde das Octaphyrin(1.1.1.0.1.1.1.0) 162 generiert (Schema 28). [139] Im Unterschied zu 145 ist 162 nichtaroma- Srinivasan und Mitarbeiter berichteten über die Synthese der beiden expandierten Carbaporphyrinoide 165 und 166 mit p-o-p-beziehungsweise m-o-m-Te rphenyl-Einheiten, die in das formale Homoporphyrin-Gerüst [140] 20 eingebunden sind (Schema 28). [141] Beide Makrocyclen zeigten im 1 H-NMR-Spektrum nichtaromatische Eigenschaften, die nach der Protonierung mit TFAo der der Koordination von Rh(CO) 2 beibehalten wurden (Abbildung 9).…”