“Perfecting” pure shift HSQC: full homodecoupling for accurate and precise determination of heteronuclear couplings

Abstract

Fully homodecoupled HSQC spectra can be obtained through the use of a new pulse sequence element, "perfectBIRD". By way of illustration, we show that perfectBIRD decoupling allows one-bond residual dipolar couplings (RDCs), which provide important NMR restraints for structure elucidation, to be measured with outstanding precision, even in methylene groups.

Real-time bilinear rotation decoupling in absorptive mode J-spectroscopy: Detecting low-intensity metabolite peak close to high-intensity metabolite peak with convenience

“…Another drawback of BIRD is that geminal J-coupling between diastereotopic protons is not refocused although coupling to third partner is refocused. Perfect BIRD and constant time BIRD were developed to address this problem which can achieve full broadband decoupling even in the case of diastereotopic methylene protons [34,12]. The lower sensitivity of BIRD method demands a large number of scans.…”

Pure shift 1H NMR: what is next?

“…An important practical application of the pure shift techniques is the determination of the magnitude and sign of scalar and residual dipolar coupling constants through the highly resolved and simplified pure shift spectra. [21,22,25,[48][49][50][51][52][53][54][55] Further promising applications are currently in their initial stage of development, such as the combination of pure shift with the dynamic nuclear polarization technique [56] or the use of pure shift spectra to carry out quantitative studies in metabolomics. [57] In the future, it could also be possible to explore the application of pure shift techniques to other nuclei (such as 19 F, 31 P or 2 H), in quality control processes, drug degradation studies and to monitor fast reactions, among others.…”

Perspectives in the application of residual dipolar couplings in the structure elucidation of weakly aligned small molecules

“…The decoupled spectra are shifted in the carbon dimension for easier comparison. Reproduced from Kaltschnee et al . with permission from The Royal Society of Chemistry.…”

“…These issues become particularly apparent for pairs of diasterotopic protons, where bilinear rotation decoupling filtration fails because of the protons being attached to the same carbon and 2 D HH RDCs of large magnitude are often observed. Recently, some of the developments in the field of pure shift techniques were incorporated into these pulse sequences, giving much improved lineshapes and facilitating reliable RDC extraction, where the basic methods fail because of distorted lineshapes . Representative examples of these experiments in both isotropic and anisotropic media are shown in Figs and .…”