In a typical thionation reaction of S0, dichloromethane (DCM) used as solvent. Different molar ratio of LR and S0 were mixed in a two-neck round bottom flask at room temperature in DCM under argon blanket in an oil bath. Then the flask attached to a reflux condenser with a bleach trap, and oil bath temperature was increased to 50 °C. The reaction mixture was allowed to react under reflux for 18 to 90 hours. Subsequently, the solution was cooled down to room temperature and precipitated by adding it dropwise into a 10-fold excess of toluene. Infrared spectroscopy (IR) was performed with freeze dried samples using a IRTracer-100 (Shimadzu, Kyoto, Japan) instrument, equipped with a Specac ATR unit (London, UK). For each spectrum, 64 scans were accumulated with a spectral resolution of 4 cm -1 .