Takasuka, Mamoru published the artcileSubstituent effects on the amino stretching vibration band in 4′-substituted 4-nitrodiphenylamines, Quality Control of 1821-27-8, the publication is Spectroscopy Letters (1985), 18(9), 659-64, database is CAplus.
IR spectral measurements were made to obtain the frequency (¦ÍNH) and the integrated intensity (A) of the amino stretching vibration band of 4′-substituted 4-nitrodiphenylamines in dilute CHCl3 solution The effects of substituents were examined and the maximum and min. correlations were obtained for the ¦ÍNH and A values against the substituent constants (¦Ò), resp.
Spectroscopy Letters published new progress about 1821-27-8. 1821-27-8 belongs to catalysis-chemistry, auxiliary class Nitro Compound,Amine,Benzene, name is Bis(4-nitrophenyl)amine, and the molecular formula is C44H28ClFeN4, Quality Control of 1821-27-8.
Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia