Toward single-shot pure-shift solution 1H NMR by trains of BIRD-based homonuclear decoupling

Achieving homonuclear 1H decoupling remains one of the key challenges in liquid-state NMR. Such spectra would endow a variety of organic and analytical applications with an increased resolution, and would ideally do so even in a one-dimensional format. A number of parallel efforts aimed at achieving this goal using two-dimensional acquisitions have been proposed; approaches demonstrated over recent years include, among others, new modes for achieving purely-absorptive integral spectroscopy, the use of spatially-selective manipulations, and exploiting the natural spin dilution afforded by heteronuclei. The present study relies on the latter approach, and explores the use of BIRD pulses distinguishing between protons bonded to C-13 from those bonded to C-12, to achieve homonuclear decoupling in a continuous 1D scan. Studies on several representative compounds demonstrate that this goal can be implemented in a robust format, provided that suitable care is also taken to suppress unwanted coherences, of making all manipulations sufficiently broad-banded, and to provide adequate heteronuclear decoupling of the targeted protons. Dependable homonuclear decoupling performance can then be achieved, with minimal line width, fine-tuning, and sensitivity penalties. (C) 2012 Elsevier Inc. All rights reserved.