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Title: Butterfly deformation modes in a photoexcited pyrazolate-bridged Pt complex measured by time-resolved x-ray scattering in solution

Pyrazolate-bridged di-nuclear Pt complexes represent a series of molecules with tunable absorption and emission properties that can be directly modulated by structural factors, such as the Pt-Pt distance. However, direct experimental information regarding the structure of the emissive triplet excited state has remained scarce. Using time-resolved wide angle X-ray scattering (WAXS), the molecular structure of the triplet excited state for one of the complexes [Pt(ppy)(μ-tBu 2pz)] 2 was obtained in a dilute (0.5 mM) toluene solution utilizing the monochromatic X-ray beamline 11IDD of the Advanced Photon Source. The excited state structural analysis was carried out based on the results from both transient WAXS measurements and DFT calculations to shed light on the primary structural changes, in particular the Pt-Pt distance and ligand rotation taking place following the photo-excitation of [Pt(ppy)(μ-tBu 2pz)] 2 in toluene solution. We find that in the triplet excited state a pronounced contraction along the Pt-Pt axis has taken place accompanied by rotational motions of ppy ligands toward one another. Our results suggest that the contraction is larger than what has previously been reported, but are in good agreement with recent theoretical efforts and suggest the ppy moieties as targets for rational synthesis aimed at tuning themore » excited-state structure and properties« less
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [1] ;  [4] ;  [4] ;  [3] ;  [5]
  1. Technical Univ. of Denmark, Lyngby (Denmark)
  2. Northwestern Univ., Evanston, IL (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States)
  4. North Carolina State Univ., Raleigh, NC (United States)
  5. Northwestern Univ., Evanston, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 120; Journal Issue: 38; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
OSTI Identifier:
1363790