2013
DOI: 10.1021/ja410396g
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Abstract: To date, only metal-containing hydrogenation catalysts have been utilized for producing substantial NMR signal enhancements by means of parahydrogen-induced polarization (PHIP). Herein, we show that metal-free compounds known as molecular tweezers are useful in this respect. It is shown that ansa-aminoborane tweezers QCAT provided (20-30)-fold signal enhancements of parahydrogen-originating hydrogens in (1)H NMR spectra. Nuclear polarization transfer from the polarized hydrogens to (11)B nuclei leads to a 10-f… Show more

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Cited by 37 publications
(57 citation statements)
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“…Unusual distortions of o-H 2 signals released from transient dihydrides had been observed previously also by other groups,[20][21][22] but the origin of the PNL formation has not been discussed or remains unclear. During the preparation of this manuscript the Koptyug group23 reported in a beautiful PHIP study PNL shapes of o-H 2 in the presence of a metal-free ansa-aminoborane catalysts (BorylCat).…”
mentioning
confidence: 83%
“…Unusual distortions of o-H 2 signals released from transient dihydrides had been observed previously also by other groups,[20][21][22] but the origin of the PNL formation has not been discussed or remains unclear. During the preparation of this manuscript the Koptyug group23 reported in a beautiful PHIP study PNL shapes of o-H 2 in the presence of a metal-free ansa-aminoborane catalysts (BorylCat).…”
mentioning
confidence: 83%
“…In the conventional PHIP experiments the pure singlet state can be kept after hydrogenation only under the action of a strong RF-field, 12 but in photo-PHIP experiments the singlet state is generated after a single laser shot with high purity. 8 Current applications of pure singlet states are mainly optimization of generation of hyperpolarization in PHIP related experiments, [13][14][15] and storage of hyperpolarization in long-lived spin states (LLS) 16,17 and in long-lived coherences (LLC). 18 In this contribution we are (1) giving an amendment to the interpretation of photo-PHIP experiments as it was given in the original paper, 8 as well as (2) a generalization of the theoretical description of spin evolution of photo-PHIP in weakly coupled multi-spin systems 19 that is confirmed by experimental observation.…”
Section: Introductionmentioning
confidence: 99%
“…663 Activation of parahydrogen with these`molecular tweezers' results in enhancement of the NMR signals of not only the exchanging but also other hydrogen atoms in a molecule, as well as of 11 B NMR signals, which demonstrates the applicability of the method to study the H 2 activation mechanism by systems containing no metal atoms.…”
Section: Studies Of the Mechanisms Of Catalytic Reactions By Thmentioning
confidence: 89%