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'-[3-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]phenyl]spiro[fluorene-9,11'-indolo[1,2-a]benzimidazole] .
user
C53H33N5
assistant