Version 2.0 of MoleculeViewer has been released. The package now uses the new API system for ChemSpider, so users of previous versions will need to register for a new API key on the RSC page.

Additionally, the PubChem API is now also used to obtain structural information. For example:

MoleculeViewer[GetPubChem["fexofenadine"]]

Support for files and URLs has also been implemented:

MoleculeViewer["http://exampledata.wolfram.com/aspirin.mol"]

as well as chemical Entity[] objects:

Download the paclet from GitHub.

When you have a ChemSpider (actually, RSC) account, go to your ChemSpider profile page. The API key is listed under the "Security Token" field. Copy that, and assign the string to $ChemSpiderAPIToken, which should look like this:

$ChemSpiderAPIToken = "ef739634-61c8-3c6c-6ff5-6d3a8a12f5d1"

(not my actual API key!)

You might wish to edit the notebook or the package itself so that $ChemSpiderAPIToken is permanently assigned to your API key.

I'll need to think of an easier way to let people enter their API keys.

Next issue: how to tell RunOpenBabel the path on which to find the openbabel binary obabel. The program is in my macOS system path (at /opt/local/bin/obabel).

I ask because I tried in your notebook molviewer.nb to execute the code:

MoleculeViewer[RunOpenBabel[GetChemSpider["ixabepilone", "InChI"]], 
 PlotLegends -> True]

But that gave an error:

RunProcess: Program babel not found. Check Environment'"PATH"]

I agree with your assessment; I have been using it for a while (and its predecessor functions for a while more), so I do have blind spots with respect to usability. (Feedback like yours is a good thing!)

I believe I did something like that for $ChemSpiderAPIToken in one of the initialization cells for molviewer.nb, but did not add one for gallery.nb. I'll commit that, along with fixes for some bug reports that have been sent in, in my next point (i.e., 1.1) release.

But why is Mathematica not picking up the path from /etc/paths (really /private/etc/paths) and /etc/paths.d (really, /private/etc/paths.d) files?

As I indicated in a previous reply, one of the paths in /etc/paths is not being picked up by Mathematica as shown in the output from evaluating Environment["PATH"].

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Why I ask: Mathematica has chemical modeling built-in and also downloadable data (ie, molecules)

• Right, this augments the built-in functionality. I've already noted the bit about depicting multiple bonds (which the default renderer does not do) in the very first post. Additionally, I do use ChemicalData[] as one possible source of info, but it does not have everything. (Try looking up the first and last examples in ChemicalData[] yourself and report back.)

And I imagine Mathematica store has one or a few extenders of that.

• If indeed there are, they did not show up in my searching efforts. Feel free to post links to anything you've seen. ;)

P. S. I am a chemist, FWIW.