Kinetic stabilities of double, tetra- and hexarosette hydrogen-bonded assemblies

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Prins, Leonard J. and Neuteboom, Edda E. and Paraschiv, Vasile and Crego-Calama, Mercedes and Timmerman, Peter and Reinhoudt, David N. (2002) Kinetic stabilities of double, tetra- and hexarosette hydrogen-bonded assemblies. Journal of Organic Chemistry, 67 (14). pp. 4808-4820. ISSN 0022-3263

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Abstract:A study of the kinetic stabilities of hydrogen-bonded double, tetra-, and hexarosette assemblies, comprising 36, 72, and 108 hydrogen bonds, respectively, is described. The kinetic stabilities are measured using both chiral amplification and racemization experiments. The chiral amplification studies show that solvent polarity and temperature strongly affect the kinetic stabilities of these hydrogen-bonded assemblies. For example, the activation energy for the dissociation of a tetramelamine from a tetrarosette assembly, a process that involves the breakage of 24 hydrogen bonds, was determined at 98.7 ± 16.6 kJ mol-1 in chloroform and 172.8 ± 11.3 kJ mol-1 in benzene. Moreover, racemization studies with enantiomerically enriched assemblies reveal a strong dependence of the kinetic stability on the number and strength of the hydrogen bonds involved in assembly formation. The half-lives for double, tetra-, and hexarosette assemblies were found to be 8.4 min, 5.5 h, and 150 h in chloroform at 50 °C, respectively. For higher generations of these types of assemblies, the kinetic stabilities become so high that they can no longer measured in a direct manner.
Item Type:Article
Copyright:© 2002 American Chemical Society
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Link to this item:http://purl.utwente.nl/publications/37955
Official URL:http://dx.doi.org/10.1021/jo0201023
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Metis ID: 206214