A1 Journal article (refereed)
Dynamic Refolding of Ion-Pair Catalysts in Response to Different Anions (2019)

Neuvonen, A. J., Noutsias, D., Topić, F., Rissanen, K., Földes, T., Pápai, I., & Pihko, P. M. (2019). Dynamic Refolding of Ion-Pair Catalysts in Response to Different Anions. Journal of Organic Chemistry, 84(23), 15009-15019. https://doi.org/10.1021/acs.joc.9b01980

JYU authors or editors

Neuvonen, Antti
Noutsias, Dimitris
Topic, Filip
Rissanen, Kari
Pihko, Petri

Publication details

All authors or editors: Neuvonen, Antti J.; Noutsias, Dimitris; Topić, Filip; Rissanen, Kari; Földes, Tamás; Pápai, Imre; Pihko, Petri M.

Journal or series: Journal of Organic Chemistry

ISSN: 0022-3263

eISSN: 1520-6904

Publication year: 2019

Volume: 84

Issue number: 23

Pages range: 15009-15019

Publisher: American Chemical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1021/acs.joc.9b01980

Publication open access: Not open

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/65607

Abstract

Four distinct folding patterns were identified in two foldamer-type urea-thiourea catalysts bearing a basic dimethylamino unit by a combination of X-ray crystallography, solution NMR studies, and computational studies (DFT). These patterns are characterized by different intramolecular hydrogen bonding schemes that arise largely from different thiourea conformers. The free base forms of the catalysts are characterized by folds where the intramolecular hydrogen bonds between the urea and the thiourea units remain intact. In contrast, the catalytically relevant salt forms of the catalyst, where the catalyst forms an ion pair with the substrate or substrate analogues, appear in two entirely different folding patterns. With larger anions that mimic the dialkyl malonate substrates, the catalysts maintain its native fold both in the solid state and in solution, but with smaller halide anions (fluoride, chloride and bromide), the catalysts fold around the halide anion (anion receptor fold) and the intramolecular hydrogen bonds are disrupted. Titration of catalyst hexafluoroacetylacetonate salt with tetra-n-butylammonium chloride results in dynamic refolding of the catalyst from the native fold to the anion receptor fold.

Keywords: anions; catalysis; crystallography; x-ray crystallography

Free keywords: catalysis; folding, anion binding; X-ray; solution structures; conformational change

Fields of science: