Liquid Scattering
Determining the spatial structure of a molecule by X-ray methods is not
new and to do so in solution is only slightly new – but it is new to do
both at the same time while simultaneously observing the formation and
structure of a new chemical species.
At the CMM we have, in close collaboration with our colleagues at the
ESRF, succeeded in developing an experimental know-how and an analysis
methodology that has allowed us to determine key structural parameters
for the lowest electronically excited state of the photo-active platinum
compound PtPOP (Pt_2 [H_2 P_2 O_5 ]_4 ^4- , see figure) in solution.
This new knowledge regarding the excited state (PtPOP*) has subsequently
allowed us to directly determine the structure of PtPOP*´s short-lived
thallium compound TlPtPOP*, which is a textbook example of a type of
excited-state complexes, exciplexes, that has important implications for
the understanding of photo-catalysed reactions. As exciplexes are almost
exclusively found in liquid solution and usually have very short
lifetimes, it has not been possible to determine their structural
parameters by direct methods, until the work reported here. This
investigation has been made possible by the CMM's cross-disciplinary
capabilities within both chemical synthesis and the analysis of X-ray
data, but also by the strong ties to the research environment at the
time-resolved beamline ID09 at the ESRF synchrotron facility.
