title: The Role of Weak Interactions in the Mechano-induced Single-Crystal-to-Single-Crystal Phase Transition of 8-Hydroxyquinoline-Based Co-crystals.
abstract: Mechano-induced single-crystal-to-single-crystal (SCSC) phase transitions in crystalline materials that change their properties have received more and more attention. However, there are still too few examples to study molecular-level mechanisms in the mechano-induced SCSC phase transitions, making the systematic and in-depth understanding very difficult. We report that bis-(8-hydroxyquinolinato) palladium(II)-tetracyanoquinodimethane (PdQ2 -TCNQ) and bis-(8-hydroxyquinolinato) copper(II)-tetracyanoquinodimethane (CuQ2 -TCNQ) show very different mechano-response behaviors during the SCSC phase transition. Phase transition in CuQ2 -TCNQ can be triggered by pricking on the crystal surface, while in PdQ2 -TCNQ it can only be induced by applying pressure uniformly over the whole crystal face. The crystallography data and Hirshfeld surface analysis indicate that the weak intra-layer C-H⋅⋅⋅O, C-H⋅⋅⋅N hydrogen bonds and inter-layer stacking interactions determine the feasibility of the SCSC phase transition by mechanical stimuli. Weaker intra-layer interactions and looser inter-layer stacking make the SCSC phase transition occur much more easily in the CuQ2 -TCNQ.
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China.
authors.forename: Guangfeng
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China. txt@sdu.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China.
authors.forename: Xiaoxin
authors.initials: X
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China.
authors.forename: Quanxiang
authors.initials: Q
authors.lastname: Han
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, No. 27 Shanda South Road, Jinan, 250100, P. R. China. liuyangicm@sdu.edu.cn.
authors.forename: Xutang
authors.initials: X
authors.lastname: Tao
keywords: 8-hydroxyquinoline; co-crystals; mechano-response; phase transition; single-crystal-to-single-crystal