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Filtering the NMR Spectra of Complex Mixtures through Polymer‐Mediated Paramagnetic Spin Relaxation
Author(s) -
Correa Juan,
Pinto Luiz F.,
Zhao Libo,
Riguera Ricardo,
FernandezMegia Eduardo
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803519
Subject(s) - paramagnetism , polymer , relaxation (psychology) , ionic bonding , spectral line , diffusion , acrylic acid , nmr spectra database , chemical physics , chemistry , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , materials science , polymer chemistry , analytical chemistry (journal) , ion , organic chemistry , physics , thermodynamics , copolymer , condensed matter physics , psychology , social psychology , astronomy
A polymer‐mediated paramagnetic spin relaxation (PSR) filter is presented for the selective suppression of signals from polymer‐interacting species in the 1D and 2D NMR spectra of mixtures. The combined use of Gd 3+ and a polymer with a high transverse relaxation enhancement ( R 2p , which gives a measure of the Gd 3+ ‐complexing ability) results in the suppression of signals from any polymer‐interacting component in mixtures, irrespective of their R 2p . By using poly(acrylic acid) (PAA) as a model system, we demonstrate selective filtering of the signals of typical low‐ R 2p species (insensitive to Gd 3+ ), such as molecular/polymeric cations and non‐ionic polymers, which, through PAA recognition (electrostatic/hydrogen‐bonding interactions), become exposed to the paramagnetic effect of Gd 3+ , while leaving non‐PAA‐interacting species unaffected. Typical suppression conditions involve PAA (approximately equimolar amount with respect to the species to be filtered) accompanied by sub‐m m concentrations of Gd 3+ and T 2 ‐filters ≤100 ms. Overall, by exploiting the PSR principles and the recognition properties of polymers, selective NMR filtrations that are not attainable by diffusion, relaxation, or direct PSR filters, can be achieved.