You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2-[4-[4-(1-oxo-4-phenylphthalazin-2-yl)phenyl]sulfonylphenyl]-4-phenylphthalazin-1-one .
user
C40H26N4O4S
assistant