Paramagnetic relaxation enhancement NMR as a tool to probe guest binding and exchange in metallohosts.

Autor: Swartjes A; Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands., White PB; Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. p.white@science.ru.nl., Bruekers JPJ; Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands., Elemans JAAW; Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. j.elemans@science.ru.nl., Nolte RJM; Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. r.nolte@science.ru.nl.
Jazyk: angličtina
Zdroj: Nature communications [Nat Commun] 2022 Apr 06; Vol. 13 (1), pp. 1846. Date of Electronic Publication: 2022 Apr 06.
DOI: 10.1038/s41467-022-29406-1
Abstrakt: Paramagnetic metallohost systems can bind guest molecules and find application as biomimetic catalysts. Due to the presence of the paramagnetic metal center, rigorous characterization of these systems by NMR spectroscopy can be very difficult. We report here that metallohost-guest systems can be studied by using the paramagnetic relaxation enhancement (PRE) effect. Manganese(III) porphyrin cage compounds are shown through their PRE to thread and bind viologen guests, including a polymeric one. The binding constants and dethreading activation parameters are lower than those of the metal-free porphyrin cage compounds, which is proposed to be a result of charge repulsion of the trivalent metal center and dicationic viologen guest. The threading rate of the manganese(III) porphyrin cage onto the polymer is more than 10 times faster than that of the non-metallated one, which is ascribed to initial binding of the cage to the polymer chain prior to threading, and to an entron effect.
(© 2022. The Author(s).)
Databáze: MEDLINE
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