bǔ fēn
porphin C20H14N4 (loanword)
卟
bǔ
used in the transliteration of the names of organic compounds porphyrin 卟啉[bu3 lin2] and porphin 卟吩[bu3 fen1]
吩
fēn
used in 吩咐[fen1 fu5]