Studies on elucidation of isomerization reaction of Schiff bases crystals and construction of novel proton flux. supramolecular systems

点击翻译按钮获取中文摘要

Experimantal finding of a cis-keto photoproduct derived from N-salicylideneaniline crystal.Deuterium isotope kinetic effect in the solid state was observed by using thermal fading reaction of photo-coloured species derived from N-salicylideneaniline deuterohydroxyl derivative : thus, the existence of a cis-keto form in the photocoloured Schiff base crystals was suggested experimentally along with 6-methyl-substitution effect on the stability of the photoproduct.Advantage of 2,6-dialkyl substituents of aniline for preparation of photochromic Schiff base crystals.N-(3,5-Dihalosalicylidene)-2,6-dialkylaniline derivatives were prepared and their structure and photochromic properties were investigated. From the X-ray crystallography, it was revealed that steric repulsion between the azomethine hydrogen atom and the alkyl groups at the 2,6-positions of the aniline ring lead to a non-planar molecular structure, which was effective for the crystals to exhibit photochromism. The relationship between photochromicity and crystal packing of N-(3,5-dichlorosalicylidene)-2,6-dialkylanilines series was also discussed. The 2,6-dialkylaniline method was suggested to be applicable to the preparation of photochromic Schiff bases with various substituents in the salicylidene rings.Photochromism of polymorphic 4,4'-methylenebis(N-salicylidene-2,6-diisopropylaniline) crystals.4,4'-Methylenebis(N-salicylidene-2,6-dialkylaniline) derivatives were prepared and their structures were determined by ^1H NMR,IR,DSC and X-ray crystallographic analyses. The 2,6-diisopropylaniline derivative yielded definite polymorphic crystals : the space groups of the crystals were C2/c and P2_1/n, respectively. It was found that both polymorphs were similarly photochromic but the thermal stability of the photochrome was different due to the variance of the shape of molecule and cavity in each crystal.