Femtosecond Pump-Probe Measurements of Solvation by Hydrogen-Bonding Interactions Academic Article uri icon

abstract

  • An additional ultrafast blue shift in the transient absorption spectra of hydrogen‐bonding complexes of a strong photoacid, 8‐hydroxypyrene 1,3,6‐trisdimethylsulfonamide (HPTA), over the solvation response of the uncomplexed HPTA and also over that of the methoxy derivative of the photoacid (MPTA) in the presence of the hydrogen‐bonding base was observed on optical excitation of the photoacid. The additional 55±10 fs solvation response was found to be about 35 % and 19 % of the total C(t) of HPTA in dichloromethane (DCM) when it was hydrogen‐bonded to dimethylsulfoxide (DMSO) and dioxane, respectively, and about 29 % of the total C(t) of HPTA in dichloroethane (DCE) when it was hydrogen‐bonded to DMSO. We have assigned this additional dynamic spectral shift to a transient change in the hydrogen bond (OH⋅⋅⋅O) that links HPTA to the complexing base, after the electronic excitation of the photoacid.

publication date

  • January 1, 2004