Soluble Congeners of Prior Insoluble Shape‐Persistent Imine Cages

Abstract

One of the most applied reaction types to synthesize shape-persistent organic cage compounds is the imine condensation reaction and it is assumed that the formed cages are thermodynamically controlled products due to the reversibility of the imine condensation. However, most of the synthesized imine cages reported are formed as precipitate from the reaction mixture and therefore rather may be kinetically controlled products. There are even examples in literature, where resulting cages are not soluble at all in common organic solvents to characterize or study their formation by NMR spectroscopy in solution. Here, a triptycene triamine containing three solubilizing n-hexyloxy chains has been used to synthesize soluble congeners of prior insoluble cages. This allowed us to study the formation as well as the reversibility of cage formation in solution by investigating exchange of building blocks between the cages and deuterated derivatives thereof.

Dimeric and trimeric catenation of giant chiral [8 + 12] imine cubes driven by weak supramolecular interactions

“…Due to the triply interlocked catenation of dimer (OMe-cube)≡(OMe-cube) in favour of a possible singly interlocked dimer (OMe-cube)-(OMe-cube), the aforementioned π-π-stacking as driving force-found for almost all the interlocked organic cages previously described in the literature-was excluded (see above), Article https://doi.org/10.1038/s41557-022-01094-w otherwise singly interlocked catenation should have been formed preferably. In addition for OH-cube a higher tendency of dimerization would have been expected than for OMe-cube, because intramolecular hydrogen-bonding of the hydroxyl imine stiffens the π-backbone and strongly enhances intermolecular π-π-stacking 40 41 . Since π-stacking was ruled out as a driving force, we first hypothesized that dipole-dipole interactions (so-called Keesom interactions) 42 of the methoxy groups may be responsible for the catenation, as found, for example, in single crystals of methoxy-substituted π-systems (d(MeO⋯CH 3 O) = 3.1 Å) 43 .…”

Template-Free Synthesis of an Interlocked Covalent Organic Molecular Cage

“…44 We further speculate on the cause of the formation of the interlocked cages of Cage-1. 33,43,45 As shown in Figure 2a, two partner cages consisting of triphenylbenzene units intertwine and form interlocked Cage-1 with almost no space. As nature abhors a vacuum, the cages are interpenetrated to minimize space.…”

Purely Covalent Molecular Cages and Containers for Guest Encapsulation

“…The [4 + 6] endo cages 45 and 46 showed only significant exchange with p-toluidine and TFA and slow exchange in the presence of TFA and water (Figure 13). 49 Another key aspect that defines the success or failure in the synthesis of organic cages is the geometry and rigidity of building blocks, which must have the appropriate conformation and preorganization. Mastalerz and co-workers studied the influence of building block conformational rigidity on the formation of a [4 + 4] imine cage with a truncated tetrahedral geometry over time (Figure 14).…”