In this study, we describe a synthetic method for incorporating arenes into closed tubes that we name capsularenes. First, we prepared vase‐shaped molecular baskets
In this study, we describe a synthetic method for incorporating arenes into closed tubes that we name capsularenes. First, we prepared vase‐shaped molecular baskets
- PAR ID:
- 10373487
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 61
- Issue:
- 41
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 4 –7 . The baskets comprise a benzene base fused to three bicycle[2.2.1]heptane rings that extend into phthalimide (4 ), naphthalimide (6 ), and anthraceneimide sides (7 ), each carrying a dimethoxyethane acetal group. In the presence of catalytic trifluoroacetic acid (TFA), the acetals at top of4 ,6 and7 change into aliphatic aldehydes followed by their intramolecular cyclization into 1,3,5‐trioxane (1H NMR spectroscopy). Such ring closure is nearly a quantitative process that furnishes differently sized capsularenes1 (0.7×0.9 nm),8 (0.7×1.1 nm;) and9 (0.7×1.4 nm;) characterized by X‐Ray crystallography, microcrystal electron diffraction, UV/Vis, fluorescence, cyclic voltammetry, and thermogravimetry. With exceptional rigidity, unique topology, great thermal stability, and perhaps tuneable optoelectronic characteristics, capsularenes hold promise for the construction of novel organic electronic devices. -
Abstract Living systems use chemical fuels to transiently assemble functional structures. As a step toward constructing abiotic mimics of such structures, we herein describe dissipative formation of covalent basket cage CBC
5 by reversible imine condensation of cup‐shaped aldehyde2 (i.e., basket) with trivalent aromatic amine4 . This nanosized [4+4] cage (V =5 nm3,M w=6150 Da) has shape of a truncated tetrahedron with four baskets at its vertices and four aromatic amines forming the faces. Importantly,tris ‐aldehyde basket2 and aliphatictris ‐amine7 undergo condensation to give small [1+1] cage6 . The imine metathesis of6 and aromatictris ‐amine4 into CBC5 was optimized to bias the equilibrium favouring6 . Addition of tribromoacetic acid (TBA) as a chemical fuel perturbs this equilibrium to result in the transient formation of CBC5 , with subsequent consumption of TBA via decarboxylation driving the system back to the starting state. -
Abstract Living systems use chemical fuels to transiently assemble functional structures. As a step toward constructing abiotic mimics of such structures, we herein describe dissipative formation of covalent basket cage CBC
5 by reversible imine condensation of cup‐shaped aldehyde2 (i.e., basket) with trivalent aromatic amine4 . This nanosized [4+4] cage (V =5 nm3,M w=6150 Da) has shape of a truncated tetrahedron with four baskets at its vertices and four aromatic amines forming the faces. Importantly,tris ‐aldehyde basket2 and aliphatictris ‐amine7 undergo condensation to give small [1+1] cage6 . The imine metathesis of6 and aromatictris ‐amine4 into CBC5 was optimized to bias the equilibrium favouring6 . Addition of tribromoacetic acid (TBA) as a chemical fuel perturbs this equilibrium to result in the transient formation of CBC5 , with subsequent consumption of TBA via decarboxylation driving the system back to the starting state. -
Abstract Covalent capsule
1 was designed to include two molecular baskets linked with three mobile pyridines tucked into its inner space. On the basis of both theory (DFT) and experiments (NMR and X‐ray crystallography), we found that the pyridine “doors” split the chamber (380 Å3) of1 so that two equally sizeable compartments (190 Å3) became joined through a conformationally flexible aromatic barrier. The compartments of such unique host could be populated with CCl4(88 Å3; PC=46 %), CBr4(106 Å3; 56 %) or their combination CCl4/CBr4(PC=51 %), with thermodynamic stabilities ΔG ° tracking the values of packing coefficients (PC). Halogen (C−X⋅⋅⋅π) and hydrogen bonding (C−H⋅⋅⋅X) contacts held the haloalkane guests in the cavities of1 . The consecutive complexations were found to occur in a negative allosteric manner, which we propose to result from the induced‐fit mode of complexation. Newly designed1 opens a way for probing the effects of inner conformational dynamics on noncovalent interactions, reactivity and intramolecular translation in confined spaces of hollow molecules. -
Abstract Supramolecular hosts bind to inorganic anions at a fast rate and select them in proportion with thermodynamic stability of the corresponding [anion⊂host] complexes, forming in a reversible manner. In this study, we describe the action of hexapodal capsule
1 and its remarkable ability to select anions based on a large span of rates by which they enter this host. The thermodynamic affinity of1 toward eighteen anions extends over eight orders of magnitude (0<K a<108 M−1;1H NMR spectroscopy). The capsule would retain CO32−(K a=107 M−1) for hours in the presence of eleven competing anions, including stronger binding SO42−, HAsO42−and HPO42−(K a=107–108 M−1). The observed selection resulted from1 possessing narrow apertures (ca. 3×6 Å) comparable in size to anions (d =3.5–7.1 Å) slowing down the encapsulation to last from seconds to days. The unorthodox mode of action of1 sets the stage for creating hosts that pick anions by their ability to access the host.