In coordination compounds, the weak interaction of guest molecules, coordination geometry distortion, and coordination number changes can effectively modulate the physical properties of magnetism, absorption, and chirality. Therefore, dynamic molecular crystals capable of crystal-to-crystal transformations, involving changes in the dimensionality, color, and physical properties, are very attractive for their potential applications in molecular devices such as switches and sensors. [1] Because it is usually difficult to obtain highquality transformed crystals after removal of the bound water or solvent due to collapsing of the framework, only a few crystal-to-crystal transformations have been reported. [2] So far, the crystal-to-crystal transformations were observed between different dimensional coordination polymers, such as 1D to 2D, 1D to 3D, and 2D to 3D. [3] The crystal-to-crystal transformations from 0D polynuclear compounds to 2D and 3D coordination polymers have also been reported. [4] Herein, we present a crystal-to-crystal transformation from 0D mononuclear compound CuCl 2 (1,4-dioxane) ) into 2D coordination polymer Cu 3 Cl 6 (1,4-dioxane) 2 (2) accompanied by changes in the crystal color, cell parameters, space group, crystal structure, coordination environments of Cu 2 + , and magnetic properties.
Blue crystal 1 was obtained from CuCl 2 β’6 H 2 O in a mixture of 3 n HCl/CH 3 OH/(1,4-dioxane) with a yield of 60 %.