title: Improved pulse sequences for measurement of small long-range couplings between heteronuclei (29Si-13C) at natural abundance.
abstract: The gradient pulse sequences for measurement of small long-range couplings between heteronuclei ((29)Si-(13)C) in natural abundance reported to date (INEPT-(Si,C)gCOSY and INEPT-(Si,C,Si)HMQC) suffer from significant signal loss when these nuclei ((29)Si, (13)C) are coupled through one-bond couplings to protons. This negative effect can be completely eliminated by using non-gradient versions (INEPT-(Si,C)COSY) or by switching proton decoupling off during gradient pulses (modified INEPT-(Si,C,Si)gHMQC pulse sequence). The beneficial effects of these two approaches on the quality of the spectra are demonstrated here.
authors.affiliation: Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135, CZ-165 02 Prague 6-Suchdol, Czech Republic. Blechta@icpf.cas.cz
authors.forename: Vratislav
authors.initials: V
authors.lastname: Blechta
authors.forename: Jan
authors.initials: J
authors.lastname: Schraml