All psyched up: A flexible and general pure shift experiment (PSYCHE) has been developed that offers superior sensitivity, spectral purity, and tolerance of strong coupling over existing methods for broadband homonuclear decoupling. The partial spectra of estradiol in [D6]DMSO obtained by normal 1H NMR spectroscopy and PSYCHE are shown for comparison

BIRD's eye view: Adding periodic BIRD J‐refocusing (BIRD=bilinear rotation decoupling) to data acquisition in an HSQC experiment causes broadband homonuclear decoupling, giving a single signal for each proton chemical shift. This pure shift method improves both resolution and signal‐to‐noise ratio, without the need for special data processing.

Resolution and sensitivity are paramount for extracting detailed structural information using NMR spectroscopy. Recently developed "pure shift" techniques have greatly improved the resolution attainable in one- and two-dimensional NMR, but at a considerable cost in sensitivity. A newly introduced method, PSYCHE, greatly reduces this loss. It produces pure shift spectra with significantly improved sensitivity, spectral purity, and tolerance of strong coupling compared to previous methods. Here PSYCHE is applied to the TOCSY experiment. In combination with covariance processing, the result is a high-quality, high-resolution TOCSY spectrum with singlets in both dimensions: a pure chemical shift correlation map. Such spectra should greatly simplify both manual spectral analysis and automated structure elucidation.

The PSYCHE method for pure shift NMR is exploited to generate 2D J spectra with full decoupling in one dimension and multiplet structure in the other, allowing spin-spin coupling constants to be measured even in very crowded spectra. Significant improvements over existing techniques are demonstrated for the hormones estradiol and androstenedione.

Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks, including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced.