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@INPROCEEDINGS{Wiegand:849924,
      author       = {Wiegand, Simone},
      title        = {{H}ow does the hydration layer influence the
                      thermodiffusion of aqueous systems?},
      reportid     = {FZJ-2018-04020},
      year         = {2018},
      abstract     = {Thermodiffusion, also called the Ludwig-Soret effect, has
                      gained popularity in recent years as an analytical approach
                      (Microscale Thermophoresis (MST)) to monitor binding
                      reactions in biological molecules that are relevant in
                      pharmaceutical applications. The success of this technique
                      relies on the superb sensitivity of thermodiffusion to
                      changes in the hydration layer around a solute. While for
                      non-polar systems the « heat of transfer » concept has
                      been successfully applied, the mechanism in aqueous systems
                      is more complicated due to charge effects and strong
                      specific cross interactions. On the other hand a detailed
                      understanding of aqueous systems would be valuable due to
                      important applications in biotechnology. To get a better
                      comprehension of the underlying processes we systematically
                      investigated various small molecules and charged colloids by
                      a holographic grating method called infrared Thermal
                      Diffusion Forced Rayleigh Scattering (IR-TDFRS). We
                      elucidate the often found typical temperature dependence of
                      the Soret coefficient of solute molecules in water. From a
                      literature survey and measurements of hydrogen bond formers
                      like amides in water we claim that this simple empirical
                      approach to describe the temperature dependence breaks down
                      at higher solute concentrations, when interactions between
                      different solute molecules start to play a role.
                      Additionally the concept also requires a hydrogen bond
                      network without micro-heterogeneities or cage structures.
                      Performing temperature and concentration dependent
                      measurements, we observe a clear correlation of the
                      temperature and concentration dependence of the Soret
                      coefficient with the hydrophilicity, which can be
                      quantitatively described by the logarithm of the
                      1-octanol/water partition coefficient P, which is a measure
                      for the hydrophilicity/hydrophobicity balance of a solute.
                      This coefficient is often used to model the transport of a
                      compound in the environment or to screen for potential
                      pharmaceutical compounds. The clear correlation between log
                      P and the temperature sensitivity of the Soret coefficient
                      open a route for a more sophisticated hydrophilicity scale.},
      month         = {Jun},
      date          = {2018-06-24},
      organization  = {Twentieth Symposium on Thermophysical
                       Properties, Boulder (USA), 24 Jun 2018
                       - 29 Jun 2018},
      subtyp        = {Invited},
      cin          = {ICS-3},
      cid          = {I:(DE-Juel1)ICS-3-20110106},
      pnm          = {551 - Functional Macromolecules and Complexes (POF3-551)},
      pid          = {G:(DE-HGF)POF3-551},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/849924},
}