\documentclass{article}
\usepackage{chemfig}
\begin{document}
\def\test#1{#1}
\test{\chemfig{~[:30]}}\par\medskip
\test{\chemfig{()~[:30]}}
\end{document}Gute Nacht!

\documentclass{article}
\usepackage{chemfig}
\begin{document}
\def\test#1{#1}
\test{\chemfig{~[:30]}}\par\medskip
\test{\chemfig{()~[:30]}}
\end{document}
