Multiplicity-edited HSQC spectrum of 200 mM sample of ibuprofen. F 1 and F 2 spectral widths were 2500 Hz and 2000 Hz, respectively, giving an overall acquisition time of 68 minutes. 128 t 1 increments, each comprising 8 scans and 1024 complex points, were recorded using a recycle time of 2 s. 1 below shows an HSQC spectrum of a sample of 200 mM ibuprofen in CDCl 3, collected on a Spinsolve Carbon NMR spectrometer. To illustrate the usefulness of the multiplicity-edited HSQC experiment, Fig. There are many instances where you can obtain a nice HSQC spectrum quite easily, whereas to get acceptable signal-to-noise with DEPT can take significantly longer. It tells you how many protons are attached to each carbon, and you also get the correlations between the chemical shifts.Īnother important advantage of multiplicity-edited HSQC experiment: you can often get the chemical shift correlation and multiplicity information in significantly less time than you can in running a carbon-detected experiment such as DEPT. With the HSQC experiment you can get the same-or very similar- information obtained by DEPT, but you can also get a whole load of additional information as well. So in the 2D spectrum you might have your CH and CH 3s denoted by certain colours and your CH 2s denoted by others. To those of you who are familiar with the DEPT experiment this might sound rather familiar, because this “multiplicity” information is exactly what DEPT provides you with and, just like in a DEPT-135 spectrum, in a multiplicity-edited HSQC spectrum the CH and CH 3 signals point one way (say, “up”), while CH 2s point the other way (“down”). For example, one such version of the experiment provides information about how many hydrogen atoms are attached to a given carbon atom. However, there are variants of this basic HSQC sequence that go further than “just” providing chemical shift correlations. This information on its own is extremely useful to chemists in many different ways. In the world of “small molecule” NMR, HSQC is most frequently used to correlate protons and carbons over one chemical bond.Ī peak in a 2D HSQC spectrum says, “ this hydrogen is attached to this carbon”, and so on. One of the most widely-used 2D techniques these days is the HSQC ( Heteronuclear Single Quantum Correlation) experiment.