title: Bisthienylethene Th2im and its complex (Th2imH)2[ReCl6]: crystalline-phase photochromism, and photochemical regulation of luminescence and magnetic properties.
abstract: Molecular assembly of bisthienylethene Th2im (1) and [ReCl6]2− anions leads to the complex (Th2imH)2[ReCl6] (2), in which a [ReCl6]2(-) anion connects two equivalent Th2imH+ cations through Cl⋯N/C hydrogen bonds. Crystal structures of 1 and 2 indicate that two thiophene groups of each Th2im/Th2imH+ molecule adopt a photoactive antiparallel conformation. Thus, two compounds show crystalline-phase photochromism (CPP), i.e. reversible structural transformation between the open form and the closed form upon alternately irradiating the sample with UV light (365 nm) and visible light (574 nm for 1, 624 nm for 2). It was found that the CPP behaviors of 1 and 2 could regulate their luminescence and/or magnetic properties. Their solid-state emissions (433, 448, 482, 531 and 570 nm for 1, and 460, 489, 535 and 593 nm for 2) exhibited weaker intensities after UV irradiation with 365 nm light. Besides CPP and luminescence, compound 2 shows field-induced slow magnetic relaxation. Before and after UV irradiation, this compound revealed different magnetic behaviors, including the differences in the shape of the χMT vs. T plot, D parameter, and the values of the relaxation barrier Ueff and the preexponential factor τ0.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China. dkcao@nju.edu.cn.
authors.forename: Dan-Ping
authors.initials: DP
authors.lastname: Gong
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China. dkcao@nju.edu.cn.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China. dkcao@nju.edu.cn.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China. dkcao@nju.edu.cn.
authors.forename: Deng-Ke
authors.initials: DK
authors.lastname: Cao