Assembled molecular face-rotating polyhedra to transfer chirality from two to three dimensions

Abstract

In nature, protein subunits on the capsids of many icosahedral viruses form rotational patterns, and mathematicians also incorporate asymmetric patterns into faces of polyhedra. Chemists have constructed molecular polyhedra with vacant or highly symmetric faces, but very little is known about constructing polyhedra with asymmetric faces. Here we report a strategy to embellish a C3h truxene unit with rotational patterns into the faces of an octahedron, forming chiral octahedra that exhibit the largest molar ellipticity ever reported, to the best of our knowledge. The directionalities of the facial rotations can be controlled by vertices to achieve identical rotational directionality on each face, resembling the homo-directionality of virus capsids. Investigations of the kinetics and mechanism reveal that non-covalent interaction among the faces is essential to the facial homo-directionality.

Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds

“…[186] On the other hand, chirality can be directly induced in the backbone by using enantiomerically pure bis(salicylidene)ethylenediamine (salen) [187] or TADDOL [181] units.Beaudoin et al reported the chiral self-sort-ing of [2+ +3] salicyliminecages derived from inherently chiral trisamino TBTQs. [188] Whereas narcissistic self-sorting is usually preferred by entropy,social self-sorting was achieved in this case due to the lower solubility of the heterochiral assemblies.T ransfer of chirality from the 2D to the 3D structures was achieved by the enantiopure assembly of facerotating polyhedra [189] (Figure 12), and ar acemization mechanism involving inside-out turning was proposed. [190]…”

Kovalente organische Netzwerke und Käfigverbindungen: Design und Anwendungen von polymeren und diskreten organischen Gerüsten

“…Wang et al berichteten über die Synthese von catenierten Käfigen durch Alkinmetathese. Ein Chiralitätstransfer von 2D zu 3D wurde fürd ie enantiomerenreine Organisation von flächenrotierenden Polyederstrukturen beobachtet (Abbildung 12), [189] fürd ie ein Racemisierungsmechanismus durch Umstülpen postuliert wurde. In einer Folgestudie konnten die Autoren zeigen, dass die Grçße der Bausteine eine wichtige Rolle fürd en Wettbewerb zwischen verzahnten Käfigen und monomeren Strukturen mit unterschiedlichen Topologien spielt.…”

“…[188] Während eine narzisstische Selbstsortierung normalerweise entropisch begünstigt ist, konnte in diesem Fall eine soziale Selbstsortierung wegen der geringeren Lçslichkeit der heterochiralen Strukturen erreicht werden. Ein Chiralitätstransfer von 2D zu 3D wurde fürd ie enantiomerenreine Organisation von flächenrotierenden Polyederstrukturen beobachtet (Abbildung 12), [189] fürd ie ein Racemisierungsmechanismus durch Umstülpen postuliert wurde. [190]…”

Shadow Mask Templates for Site‐Selective Metal Exchange in Magnesium Porphyrin Nanorings

“…The formation of (H 2 ) 6 -P6 as aside product during the reaction of Mg 6 -P6·T3 a with acetic acid reflects the weaker association constant of this tridentate template compared with T6, T5, and T4 a-T4 c. [11] Disappointingly,treatment of Mg 6 -P6 with the symmetric three-legged template T3 b [12] (1:1 molar ratio) followed by acetic acid addition did not result in site-selective demetalation. [13] Te mplate T3 c has as imilar coordination geometry to T3 b,b ut the bulky n-butyl chains in the truxene were expected to hinder stacking. 1 HNMR titrations revealed the reason for this result:W heno ne equivalent of T3 b is added to Mg 6 -P6,the main product is the 1:2complex Mg 6 -P6·(T3 b) 2 ,t ogether with as mall amount of the 1:1 complex Mg 6 -P6·T3 b and some uncomplexed Mg 6 -P6 nanorings.I ta ppears that the formation of the 1:2c omplex with T3 b is too favorable,m aking this ligand ineffective as am asking template.T os olve this problem, we designed at hree-legged template with bulky groups to prevent the stacking, T3 c,w hich is based on at ruxene core.…”

“…1 HNMR titrations revealed the reason for this result:W heno ne equivalent of T3 b is added to Mg 6 -P6,the main product is the 1:2complex Mg 6 -P6·(T3 b) 2 ,t ogether with as mall amount of the 1:1 complex Mg 6 -P6·T3 b and some uncomplexed Mg 6 -P6 nanorings.I ta ppears that the formation of the 1:2c omplex with T3 b is too favorable,m aking this ligand ineffective as am asking template.T os olve this problem, we designed at hree-legged template with bulky groups to prevent the stacking, T3 c,w hich is based on at ruxene core. [13] Te mplate T3 c has as imilar coordination geometry to T3 b,b ut the bulky n-butyl chains in the truxene were expected to hinder stacking. 1 HNMR spectroscopy showed that addition of T3 c to the nanoring only led to formation of a1:1 complex, Mg 6 -P6·T3 c.A ddition of acetic acid to this complex resulted in site-selective demetalation, together with formation of the fully demetalated nanoring (H 2 ) 6 -P6.…”