The thermodynamic data for the interaction between diphenylketimine and phenols are determined in carbontetrachloride solution by infrared spectroscopy. Complex formation brings about a frequency increase of the nu(NH) vibration. From a pK(a) value of the proton donor of 6, proton transfer takes place.
Leunens, V., Migchels, P., Peeters, D., & Zeegershuyskens, T. (1992). Infrared Investigation of the Interaction Between Diphenylketimine and Proton Donors. Societes Chimiques Belges. Bulletin, 101(2), 165-166. https://doi.org/10.1002/bscb.19921010212 (Original work published 1992)