Structure and Optical Properties of Thermochromic Schiff Bases. Charge Transfer Interaction and Proton Transfer in the N-Tetrachlorosalicylideneaniline and N-Tetrachlorosalicylidene-1-pyrenylamine Crystals

Article abstract of DOI:10.1246/bcsj.64.801

Two kinds of N-salicylideneaniline derivatives, N-tetrachlorosalicylideneaniline (CL4SA) and N-tetrachlorosalicylidene-1-pyrenylamine (CL4SPY), have been prepared and subjected to structural and optical studies in the crystalline state.A thermochromic-type behavior of the former crystal has been observed as a shift of the absorption edge, while that of the latter crystal is much less pronounced.Fairly short O-H...N hydrogen bonds have been found in both compounds through crystallographic studies, which may be mainly due to a steric effect of chlorine substituents.The difference in the proton transfer behavior of CL4SA and CL4SPY should presumably be caused by an intermolecular charge-transfer interaction in the latter crystal.