Spinus and nmrdb.org
I don't remember how many years ago I discovered the web. I was excited by how many things were available for free. There were a lot of curious and interesting things but, I was the first to admit, nothing really serious that could substitute a true book, or a true CD or a true computer program. The great thing about the internet was that I could easily read the opinions of other people around the world. I mean: ordinary people just like me.
Things began to change with the appearance of SDBS 14 years ago. It was the first really useful thing I found on the web.
The last discoveries are Spinus and nmrdb.org.
SPINUS (Structure-based Predictions In NUclear magnetic resonance Spectroscopy) is an on-going project for the development of structure-based tools for fast prediction of NMR spectra. SPINUS - WEB currently accepts molecular structures via a Java molecular editor, and estimates 1H NMR chemical shifts. The predictions are obtained from ensembles of previously trained feed-forward neural networks, and corrected with data from an additional memory.
SPINUS - WEB predictions are restricted to:
CHn protons (no predictions for hydrogen atoms bonded to heteroatoms are made),
compounds containing elements C, H, N, O, S (some oxidation states), F, Cl, Br, or I.
For a data set of 100 independent structures representing a wide variety of structural features, SPINUS gave the following average errors for chemical shifts: 0.16 ppm for aliphatic class, 0.23 ppm for aromatic class, 0.35 ppm for non-aromatic pi class, and 0.29 ppm for rigid aliphatic class. A global average error of 0.23 ppm was obtained for the 952 predictions. A global error of ca. 0.6 Hz was observed for coupling constants.
This service depends on a number of Java applets that apparently do not work on my computer. Who cares, an alternative interface is available at nmrdb.org. In practice you can forget about Spinus and just connect to the latter. Spinus will be called in the background.
When you arrive at the home page of nmrdb.org, you find 4 applications: Simulator, Resurrector, Assigner, Predictor. The latter lets you draw a formula, from which a H-1 spectrum is generated. No alternative is given: if you already have the ChemDraw formula, it's of no use. You have to draw the formula again, which is easy and funny, I have to say.
The Simulator allows to simulate a second-order H-1 spectrum, so it's nothing really new. The required input are the values of chemical shifts and Js. Every time you change a value, a new FID is generated and FTed. Too slow for running it on the web, in my opinion.
The Resurrector transforms a list of peaks (copied from a PDF paper, for example) into the picture of the corresponding H-1 spectrum. How many formats are recognized? As you know, different journals may require different styles for reporting the NMR values. The ACS style is of course recognized. They have described nmrdb.org on a scientific paper, which probably contains all the details; I have not found them on the web page for the Resurrector.
The Assigner is something that does not work but suggests you to move to another site, called mylims.org:
The principe of mylims.org is very simple:
You upload a jcamp file
You process your spectrum
You save the result of the processing
You retrieve the ACS assignment for publication
Using mylims.org you will be able to make fourier transform, phase correction, baseline correction, “smart” peak picking, auto peak picking and even be able to assign 2D nmr !
The NMR Predictor brings us back to our starting point. This picture gives you an idea of how it works:
You hover the mouse over an atom in the formula or over a peak in the spectrum. Two yellow squares appear, that hilights the correponding spots into the formula and into the spectrum. Just what you expect, because the similar programs all work in this way.