Polymer brackets with chemfig

Question

I am trying to do the mechanism shown in the image. I am stuck in the second molecule. I don't know how to use brackets properly. I also need to put the asterisk as an exponent.

Answer 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}