答案1
\documentclass[border=5mm]{standalone}
\usepackage{chemfig}
\begin{document}
\schemestart
\chemfig{[:-30]*6(=-=(-C(=[6]O)(=[2,,,,draw=none]\phantom{O})-*6(=-=-=-))-=-)}
\arrow{->[$h\nu$]}[,1.5]
\chemleft[\chemfig{[:-30]*6(=-=(-C(=[6]O)(=[2,,,,draw=none]\phantom{O})-*6(=-=-=-))-=-)}\chemright]
\schemestop
\chemmove{
\node at ([shift={(3pt,-2pt)}]c2.north east) {$\ast$};
}
\end{document}