Conformational control in the cyclization of hydrogen-bonded supramolecular polymers.

A.T. Cate, ten, H. Kooijman, A.L. Spek, R.P. Sijbesma, E.W. Meijer

Research output: Contribution to journalArticleAcademicpeer-review

127 Citations (Scopus)

Abstract

Bifunctional 2-ureido-4[1H]-pyrimidinone (UPy) derivatives can form small cyclic oligomers as well as long supramolecular polymers in chloroform solutions using the quadruple hydrogen-bonding motif. Ring-chain equilibria of a set of supramolecular monomers containing methyl-substituted alkyl linkers between the hydrogen-bonding UPy moieties were investigated by 1H NMR spectroscopy and viscometry. The data were characterized in terms of critical concentration (CC, denoting the onset of polymerization) and equilibrium cyclic dimer concentration (EDC, representing preorganization of the monomer toward selective formation of cyclic dimer). Methyl substituents in the monomer were found to promote conformations favorable for cyclic dimerization, leading to an increase in both the EDC and the CC with respect to unsubstituted monomer. Furthermore, we observed an odd-even effect in the CC and EDC with increasing length of the linker between the hydrogen-bonding units. The combined results allow tuning of the critical concentration over a broad range and offer detailed information on the correlation between monomer structure, conformation, and polymerizability which may provide new insights for the study and design of other ring-chain equilibria or helix-random coil transitions.
Original languageEnglish
Pages (from-to)3801-3808
JournalJournal of the American Chemical Society
Volume126
Issue number12
DOIs
Publication statusPublished - 2004

Fingerprint Dive into the research topics of 'Conformational control in the cyclization of hydrogen-bonded supramolecular polymers.'. Together they form a unique fingerprint.

Cite this