The importance of hydrogen bonded clusters in the stabilization of the intramolecular charge transfer state of 4,4'-diaminophenyl sulphone in alcohols and alcohol:acetonitrile mixtures

The formation of the twisted intramolecular charge transfer (TICT) state of 4,4'-diaminophenyl sulphone (APS) has been examined in hexanol/acetonitrile mixtures. The TICT emission reveals wavelength dependent rise times which are sensitive to the alcohol concentration. Discernible wavelength-dependent rise times are observed for hexanol:acetonitrile mixtures above 1:2. Examination of the infrared O-H stretch for these solutions shows that above this ratio, hydrogen-bonded aggregates are formed. In addition, the emission dynamics of APS in neat hexanol are compared with those observed for 4,4'-dimethylaminophenyl sulphone (DMAPS) and 3,3'-diaminophenylsulphone (3,3'-APS).