title: Photochromism of polymorphic 4,4'-methylenebis(N-salicylidene-2,6-diisopropylaniline) crystals.
abstract: 4,4[prime or minute]-Methylenebis(N-salicylidene-2,6-dialkylaniline) derivatives were prepared and their structures were determined by (1)H 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.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560, Japan.
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Taneda
authors.forename: Kiichi
authors.initials: K
authors.lastname: Amimoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.forename: Toshio
authors.initials: T
authors.lastname: Kawato