Synthesis of salicylideneamines-inclusion compounds and elucidation of their chromotropism

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Chiral N-salicylidene-1-phenylethylamine derivatives and achiral N-salicylidenebenzylamine derivatives were prepared by the condensation of 1-phenylethylamine and benzylamine derivatives with salicylaldehyde or 3,5-di-tert-butylsalicylaldehyde. From the chiral salicylideneamines (R)-and (S)-enantiomers, racemic compounds, and racemic mixtures were obtained. Photo-colored species were obtained by irradiating the crystalline salicylidencamines powder with 365 nm light. The thermal fading reaction of the photochrome was followed by reflectance spectrophotometry by measuring the optical density at the wavelength at which a maximal decrease occurred in the dark. The photochromicity of the (R)-and (S)-enantiomers and the racemic mixture was identical and differed from that of the racemic compound. Introduction of bulky t-butyl substituents to salicylideneamines was effective to prepare photosensitive Schiff base crystals.Each (R)-and (S)-isomer of the salicylidencamines without tert-butyl substituent was incroporated in the crystal lattice cavities formed by chiral deoxycholic acid (DCA) to give diastereomeric crystals.Most of the obtained definite clathrate compounds were photosensitive but the rate constants of the diastereomeric crystals were different each other. These results clearly show that the photoinduced framework alteration is not entirely independent from nonbonding interaction with the neighboring chiral molecules and that unimolecular asymmetric motion in the crystals is influenced by the neighboring asymmetric crystal environments.Trying to develop a new series of functional ligands, we introduced steroidal subunits derived from 3beta-cholesterol and 3beta-cholestanol to a pyridine ring at the 2- and 6-positions. The Pd (II) complexes of the resultant ligands were recrystallized from ordinary organic solvents with some Schiff bases to fail to include the Schiff bases between the steroidal substituents to prepare clathrate compounds.