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 [4-[5-[5-(dimethylamino)thiophen-2-yl]-3-pyridin-4-ylthiophen-2-yl]phenyl]-hydroxy-oxoazanium .
user
C21H18N3O2S2+
assistant