Graphics, Figures & Tables ⇒ Baseline of a chemical Structure

[MatthiasN]

Hi everyone,

Recently I had some problems with captions that won't align when I use subfigure. I found out that this is because I am using pictures made with chemfig. The baseline is not where it is expected to be. So my question is: how can I move the baseline of the molecule to the bottom without drawing it in another way.

For example: I've drawn this chemical structure of diazinon

Code: Select all

\documentclass{article}

\usepackage{graphicx}
\usepackage{subfigure}
\usepackage{chemfig}
\begin{document}
\chemfig{[2]N*6(-(-O-P(=[::90]S)(-[::30]OCH_2CH_3)-[::-30]OCH_2CH_3)=-(-CH_3)=N-(-CH(-[::30]CH_3)-[::-60]CH_3)=)}
\end{document}

The output is attached. The tertiary butyl on the benzene ring is underneath the baseline. Is there a way to put the baseline at the bottom of this molecule?

Thanks for reading.
Matthias

[cgnieder]

As you can see in a slightly modified version of your MWE the baseline of the molecule is determined by the first atom that is written by the corresponding \chemfig command:

Code: Select all

\documentclass{article}
\usepackage{chemfig}
\begin{document}

x\hrulefill \chemfig{[2]N*6(-(-O-P(=[::90]S)(-[::30]OCH_2CH_3)-[::-30]OCH_2CH_3)=-(-CH_3)=N-(-[,,,1]CH(-[::30]CH_3)-[::-60]CH_3)=)} \hrulefill x

\end{document}

The relevant part in the documentation (=> chemfig) is section 2 (»Presenting ChemFig«) where it reads:

ChemFig always places the first atom of the molecule on the baseline of the preceding code.

So the solution is basically: start the molecule with what you called tBu but actually seems to be iPr.

Regards

[MatthiasN]

My mistake, it's isopropyl indeed. My question was if there's a way to move the baseline without rewriting the molecule. But nevermind, I'll just redo it.

[cgnieder]

My question was if there's a way to move the baseline without rewriting the molecule.

Oh, yes, I missed that one. I only read

The baseline is not where it is expected to be.

and thought: that's wrong. It's exactly where it's supposed to be.

The answer to your actual question is: yes. Since you can insert labels to nodes inside \chemfig using its @{<nodename>} syntax and since you can pass TikZ options to the tikzpicture within which the molecule is drawn it is quite easy, actually:

Code: Select all

\documentclass{article}
\usepackage{chemfig}
\begin{document}

x\hrulefill \chemfig[baseline=(mybase.south)]{
  [2]N*6(
    -(
      -O-P(=[::90]S)(-[::30]OCH_2CH_3)-[::-30]OCH_2CH_3
    )
    =-(-CH_3)=N-(
      -[,,,1]CH(-[::30]@{mybase}CH_3)-[::-60]CH_3
    )=
  )
} \hrulefill x

\end{document}

Regards

[MatthiasN]

I meant that it is not where subfig would expect it to be. That was the reason why my captions didn't align. Thanks for the help.