PROTON-TRANSFER IN N-(2-HYDROXY-1-NAPHTHYLMETHYLENE)-1-PYRENAMINE AND N,N'-BIS(2-HYDROXY-1-NAPHTHYLMETHYLENE)-P-PHENYLENEDIAMINE CRYSTALS

Two kinds of N-(2-hydroxy-1-naphthylmethylene)aniline-type compounds, N-(2-hydroxy-1-naphthylmethylene)-1-pyrenamine (NPY) and N,N'-bis(2-hydroxy-1-naphthylmethylene)-p-phenylenediamine (DNP), have heen prepared as members of the N-salicylideneaniline family and subjected to structural studies in the crystalline state. In NPY, the hydrogen in the intramolecular N ... H-0 hydrogen bond has been found to locate not only at the oxygen site, but also at the nitrogen site, even at 120 K. A similar hydrogen-bond structure has also been found for DNP. This is mainly due to the pi-electron delocalization effect. The relative stabilization of the proton transferred form (NH-form) compared with ordianry N-salicylideneanilines has been clearly indicated by solid-state NMR measurements.