J-Edited Pure Shift NMR for the Facile Measurement of n J HH for Specific Protons Sachin Rama Chaudhari and N. Suryaprakash* [a] Dedicated to Prof. K. V. Ramanathan on his 65 th Birthday 1. Introduction In recent years, slice-selection-based experiments have proven to be one of the most exciting advancements in NMR spectro- scopy. [1] In this direction, 1 H-homodecoupled spectra, which are obtained by suppressing the coupled multiplet pattern and are known as “pure shift” spectra, have been utilized to enhance spectral resolution. [2] Pure shift spectra, which provide information on chemical shifts, have wide applications, such as, unraveling the overlapped peaks, thereby giving access to diastereomeric ratio determination, [3] measurement of hetero- nuclear couplings, [4] and so forth. The biggest drawback of pure shift spectra is the loss of information on homonuclear scalar couplings; it is well known that homonuclear scalar cou- plings are important for obtaining the relative configurations and conformations of small molecules, according to Karplus. [5] 3 J HH values and nuclear Overhauser effect (NOE) restraints, combined with a range of computational approaches have ac- celerated the structure elucidation of molecules, for example, in the J-based configurational analysis of acyclic systems. [6] A similar approach has also been explored to gain an insight into the molecular dynamics and different mechanistic pathways in modern chemistry, [7] and researchers have been inspired to ex- plore newer experimental techniques for the accurate determi- nation of scalar couplings. The measurement of n J HH is usually carried out by the well-known exclusive correlation spectrosco- py (E-COSY) [8] and 2D J-resolved type techniques. [9] Although such experiments are invaluable, the analysis is tedious when the spectrum contains complex splitting patterns, together with signal overlap. Such problems are partially overcome by using the gradient-encoded selective refocusing (G-SERF) tech- nique, in which the homonuclear couplings of a selected proton to all its coupled network of protons are measured in a single 2D experiment. [10] However, deriving this information from the 1D 1 H spectrum would obviously be a highly advan- tageous, simple, and attractive option. Few such experiments, such as, multifrequency homonuclear decoupling (MDEC) [11] and the window-acquired spin-tailoring experiment (WASTE) [12] are available. Each of these experiments yields, from a single experiment, a unique value of coupling between any two pro- tons in a coupled network of spins. Thus, to measure all J HH of a particular proton, one is required to carry out multiple ex- periments, rendering it a cumbersome and time-consuming approach. To resolve some of these constraints and to derive all the homonuclear couplings of a specific proton from a 1D experiment, in the present study we introduce a J-edited pure shift (J-PSHIFT) experiment, which is a pseudo 2D approach. The method reintroduces the scalar interactions of a selected proton in the pure shift experiment, and the entire spectrum is completely broadband decoupled by using the well-known Zangger–Sterk (ZS) technique. [2] The experiment provides infor- mation on multiple couplings analogous to the G-SERF tech- nique, [10] and has an added advantage that it yields the infor- mation on the chemical shifts of the remaining protons. As a result, a single experiment gives dual information, thus dem- onstrating the importance of the present method. Further- more, by using the newly designed sequence we are able to exclusively generate the coupled correlated spectrum of a spe- cific proton, while completely suppressing the remaining part of the spectrum. This permits direct, accurate, and error-free measurement of the couplings; this is another interesting fea- ture and is a unique characteristic, which is not found in the current library of available NMR experiments. Recently, real- time SERF experiments have also been reported for the deter- mination of n J HH values, where the time domain data is inter- We report a novel 1D J-edited pure shift NMR experiment (J- PSHIFT) that was constructed from a pseudo 2D experiment for the direct measurement of proton–proton scalar couplings. The experiment gives homonuclear broad-band 1 H-decoupled 1 H NMR spectra, which provide a single peak for chemically distinct protons, and only retain the homonuclear-scalar-cou- pled doublet pattern at the chemical-shift positions of the pro- tons in the coupled network of a specific proton. This permits the direct and unambiguous measurement of the magnitudes of the couplings. The incorporation of a 1D selective correla- tion spectroscopy (COSY)/ total correlation spectroscopy (TOCSY) block in lieu of the initial selective pulse, results in the exclusive detection of the correlated spectrum of a specific proton. [a] Dr. S. R. Chaudhari, Prof. N. Suryaprakash NMR Research Centre and Solid State Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India) Fax: (+ 81) 8023601550 E-mail : nsp@sif.iisc.ernet.in Supporting Information for this article is available on the WWW under http://dx.doi.org/10.1002/cphc.201402792. ChemPhysChem 0000, 00,0–0  0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1 & These are not the final page numbers! ÞÞ These are not the final page numbers! ÞÞ Articles DOI: 10.1002/cphc.201402792