Structure and luminescence properties of a new Cu-Cyteamine (Cu-Cy) crystal material are provided. The crystal structure of the Cu-Cy is determined by single crystal X-ray diffraction. It is found that the compound crystallizes in the monoclinic space group C2/c and cell parameters are a=7.5510(4) Å, b=16.9848(7) Å, c=7.8364(4) Å, β=104.798(3)°. The new Cu-Cy crystal material of the invention is also useful for treatment of cancer.