N,N'-diphenyl-1,4-phenylenediamine1,4-bis(phenylamino)benzene1,4-dianilinobenzene4,4'-diphenyl-p-phenylenediamine4-phenylaminodiphenylamineDPPDN,N'-diphenyl-1,4-benzenediamineN,N'-diphenyl-1,4-diaminobenzeneN,N'-diphenyl-p-phenylenediaminediphenyl-p-phenylenediaminep-bis(phenylamino)benzenep-phenylaminodiphenylamine