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.