Join wedge with single bond in chemfig

Question

Is there a way to join the wedges with single bonds in chemfig in a "smooth way"?

\documentclass{article}
\usepackage{chemfig}

\begin{document}
    \setchemfig{angle increment=30, bond join = true}
    \chemfig{-[-1](-[1])<[-3]-[-1]}
\end{document}

Gives out:

Is it possible to have it trim the wedge at the single bond as:

Obviously you were able to produce the result as you want. How did you create the second picture? — pisoir, Mar 27 '18 at 20:38
Chemdraw. I would rather have my figures in chemfig rather than in chemdraw for future edits if necessary. — ralk912, Mar 27 '18 at 20:51

score 5 · Accepted Answer · answered Apr 04 '19 at 18:05

I am not really an expert on pgf and tikz but I find a (partial) solution. Modifying the chemfig default values with setchemfig produces:

\documentclass{article}
\usepackage{chemfig}
\begin{document}
    \setchemfig{
         atom sep=15pt,
         cram width=3.0pt,
         cram dash width=0.75pt,
         cram dash sep=2.0pt
         bond offset=0.75pt
         bond style={line width=0.75pt}
    }
    \chemfig{-[::-30](-[::60])<[::-60]-[::60]}
\end{document}

I use usetikzlibrary{decorations} to create a custom Cram bond, based on @pisoir answer in How to make only one part of double bond bold with chemfig?.

\documentclass{article}
\usepackage{chemfig}
\usetikzlibrary{decorations}

\pgfdeclaredecoration{crambond1side}{initial}{%
    \state{initial}[width=\pgfdecoratedpathlength]{%
        \pgfsetfillcolor{black}
        \pgfpathlineto{\pgfpoint{0pt}{0.3pt}}
        \pgfpathlineto{\pgfpoint{1.10*\pgfdecoratedpathlength}{2pt}}
        \pgfpathlineto{\pgfpoint{0.96*\pgfdecoratedpathlength}{-2pt}}
        \pgfpathlineto{\pgfpoint{0pt}{-0.3pt}}
        \pgfusepath{fill}
    }
}
\tikzset{CramRight/.style={decorate, decoration=crambond1side}}
\tikzset{CramLeft/.style={decorate, decoration={crambond1side, mirror}}}

\pgfdeclaredecoration{crambond2sides}{initial}{%
    \state{initial}[width=\pgfdecoratedpathlength]{%
        \pgfsetfillcolor{black}
        \pgfpathlineto{\pgfpoint{0pt}{0.3pt}}
        \pgfpathlineto{\pgfpoint{1.10*\pgfdecoratedpathlength}{2pt}}
        \pgfpathlineto{\pgfpoint{\pgfdecoratedpathlength}{0pt}}
        \pgfpathlineto{\pgfpoint{1.10*\pgfdecoratedpathlength}{-2pt}}
        \pgfpathlineto{\pgfpoint{0pt}{-0.3pt}}
        \pgfusepath{fill}
    }
}
\tikzset{Cram2Sides/.style={decorate, decoration=crambond2sides}}

\begin{document}
    \setchemfig{
        atom sep=15pt,
        cram width=3.0pt, cram dash width=0.75pt, cram dash sep=2.0pt,
        bond offset=0.75pt,
        bond style={line width=0.75pt}
    }
    \chemfig{-[::-30](-[::+60])-[::-60,,,,CramLeft]-[::-60]}\quad
    \chemfig{-[::-30](-[::+60])-[::-60,,,,CramRight]-[::+60]}\quad
    \chemfig{-[::-30](-[::+60])-[::-60,,,,Cram2Sides](-[::-60])-[::60]}\quad
\end{document}

The final result

score 1 · Answer 2 · answered Apr 03 '18 at 21:12

This is probably not an ideal solution, but after little bit of tweaking you might get something similar to what you want. Notice that I added the cram width, line width, and shorten parameters to your code.

\documentclass{article}
\usepackage{chemfig}

\begin{document}
    \setchemfig{angle increment=30, bond join = true, cram width = 2.4pt}
    \chemfig{-[-1](-[1])<[-3]-[-1,,,,line width=1.5pt, shorten <=-1pt]}
\end{document}

which produces this:

Join wedge with single bond in chemfig

2 Answers2