A Molecular Transformer: A π‐Conjugated Macrocycle as an Adaptable Host

Abstract

Here, we report a facile method to synthesize a series of macrocycles with different conformations. The planar macrocycle dimer (1), twisted macrocycle trimer (2) and “figure‐eight” tetramer (3) are clearly elucidated by X‐ray single‐crystal analysis, in which the electron‐rich phenanthrene units offer the possibility of supramolecular assembly. As expected, in the solid state, 1 and 3 assemble into a columnar stack and an interlocking dimer, respectively, via π–π interactions between the phenanthrene units. Compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its enlarged ring size. 3 can deform from a figure‐eight into a boat‐shaped geometry to host a planar electron‐deficient guest using its electron‐rich phenanthrene units. When assembled with spherical electron‐deficient C60, interestingly, 3 further undergoes a conformational transformation from a figure‐eight to a belt shape in order to host C60. These supramolecular assembly behaviors of 3 demonstrate that it is an adaptable macrocyclic host for both planar molecules and fullerenes.

Corralarenes: A Family of Conjugated Tubular Hosts

“…Among them, macrocyclic arenes incorporating aromatic units in the walls of their cavities have attracted particular attention since these units endow the macrocycles not only with appealing molecular recognition features but also with potential optical and electronic properties. More recently, a number of new macrocyclic hosts, including corona­[ n ]­arenes, naphthotubes, biphen­[ n ]­arenes, tiara[5]­arene, prism­[ n ]­arenes, pagoda­[ n ]­arenes, saucer­[ n ]­arenes, and many others with host–guest properties, have appeared on the scene. Clearly, the development of new kinds of hosts with well-defined structures and properties has been one of the most popular research topics in recent years, as well as also being an indispensable source and foundation of innovation in the field of host–guest chemistry …”

A Fourfold Gold(I)−Aryl Macrocycle with Hyperbolic Geometry and its Reductive Elimination to a Carbon Nanoring Host

“…One‐pot macrocyclization of diboronic ester 5 and 1,3‐dibromobenzene led to the formation of bisacetal interphenylene‐bridged [6]CMP derivative 4 (Figure 1; roman numeral I; see also Figure S1 Section S2). Due to the reduced symmetry of 4 , the one‐pot macrocyclization of the unequal building blocks 5 and 1,3‐dibromobenzene is impeded compared to parental [6]CMP [57] . We also explored an alternative step‐wise synthetic route and different substitution patterns of 4 , which resulted in similar overall yields toward 3 (Section S2).…”

Ein vierfacher Gold(I)−Aryl‐Makrozyklus mit hyperbolischer Geometrie und dessen reduktive Eliminierung zu einem Kohlenstoffnanoring‐Wirt

“…Eine Eintopf‐Makrozyklisierung von Diboronsäureester 5 und 1,3‐Dibrombenzol führte zur Bildung des Bisacetalphenylen‐verbrückten [6]CMP‐Derivat 4 (Abbildung 1; römische Ziffer I; siehe auch Abbildung S1, Abschnitt S2). Wegen der geringeren Symmetrie in 4 ist die Ausbeute der Eintopf‐Makrozyklisierung zwischen den ungleichen Bausteinen 5 und 1,3‐Dibrombenzol im Vergleich zum ursprünglichen [6]CMP verringert (7 %) [57] . Aufgrund der geringen Ausbeute haben wir eine alternative stufenweise Route mit verschiedenen Substituenten am Gerüst 4 untersucht.…”