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Dual-Cavity Basket Promotes Encapsulation in Water in an Allosteric Fashion
- Source :
- Journal of the American Chemical Society. 137:12276-12281
- Publication Year :
- 2015
- Publisher :
- American Chemical Society (ACS), 2015.
-
Abstract
- We prepared dual-cavity basket 1 to carry six (S)-alanine residues at the entrance of its two juxtaposed cavities (289 Å(3)). With the assistance of (1)H NMR spectroscopy and calorimetry, we found that 1 could trap a single molecule of 4 (K1 = 1.45 ± 0.40 × 10(4) M(-1), ITC), akin in size (241 Å(3)) and polar characteristics to nerve agent VX (289 Å(3)). The results of density functional theory calculations (DFT, M06-2X/6-31G*) and experiments ((1)H NMR spectroscopy) suggest that the negative homotropic allosterism arises from the guest forming C-H···π contacts with all three of the aromatic walls of the occupied basket's cavity. In response, the other cavity increases its size and turns rigid to prevent the formation of the ternary complex. A smaller guest 6 (180 Å(3)), akin in size and polar characteristics to soman (186 Å(3)), was also found to bind to dual-cavity 1, although giving both binary [1⊂6] and ternary [1⊂62] complexes (K1 = 7910 M(-1) and K2 = 2374 M(-1), (1)H NMR spectroscopy). In this case, the computational and experimental ((1)H NMR spectroscopy) results suggest that only two aromatic walls of the occupied basket's cavity form C-H···π contacts with the guest to render the singly occupied host flexible enough to undergo additional structural changes necessary for receiving another guest molecule. The structural adaptivity of dual-cavity baskets of type 1 is unique and important for designing multivalent hosts capable of effectively sequestering targeted guests in an allosteric manner to give stable supramolecular polymers.
- Subjects :
- Models, Molecular
Alanine
Magnetic Resonance Spectroscopy
Stereochemistry
Chemistry
Allosteric regulation
Molecular Conformation
Water
General Chemistry
Nuclear magnetic resonance spectroscopy
Calorimetry
Biochemistry
Catalysis
Crystallography
Colloid and Surface Chemistry
Allosteric Regulation
Quantum Theory
Polar
Molecule
Density functional theory
Protons
Ternary operation
Ternary complex
Subjects
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 137
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi.dedup.....b64982d9f5fee0f337a08c42ed2aa34e