Synthesis, crystal, luminescent properties and electronic structures of two copper(I) halide polymers based on Cu4I4 cubane tetramers

Two novel coordination polymers [Cu4I4(en)2]n 1 and [Cu4I4(pn)2]n 2 (en = 1,2-diaminoethane and pn = 1,3-diaminopropane) were prepared by hydrothermal methods and determined by single-crystal X-ray diffraction analysis. Compound 1 possesses a 3D zeolite-like architecture with infinite intersected channels, constructing from cubane Cu4I4 tetramers, which is simplified into a twofold interpenetrating dia network. Compound 2 with the similar Cu4I4 cores, features a 2D layer with parallelogram-shaped channels along the b axis, showing a uninodal sql net. Both exhibit luminescent emission bands at about 600 nm at room temperature when excited at 350 and 370 nm, respectively. Furthermore, thermogravimetric analyses, optical diffuse reflectance spectroscopy, and the theoretical calculations were discussed.