TDO structure investigation in aqueous solution by TOF-MS, UV, Raman and quantum chemistry calculations

Time of flight-mass spectroscopy (TOF-MS), ultraviolet (UV) absorption and Raman spectroscopy, and quantum chemistry calculations were used to investigate the thiourea dioxide (TDO) structure in aqueous solution. TOF-MS with the direct injection sample method was used to get molecular weight information of TDO in solution. The two structural models, (NH₂)₂CSO₂ (I) and NH₂NHCSO₂H (II), were used for the TDO single molecule, and all the methods lead to a consistent conclusion that TDO water solution is a mixture of In-cyc clusters (cyclic structures containing n molecules of TDO) and II single molecule. This work reveals the existence state of TDO in aqueous solution and supplies systematic method to explore the molecular structure of liquid solution.