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@ARTICLE{Basuroy:626302,
      author       = {Basuroy, Krishnayan and Velazquez-Garcia, J. and Techert,
                      Simone},
      title        = {{C}apturing photo-induced structural changes in a
                      donor–bridge–acceptor dyad crystal, that also exhibits
                      elastic bending under mechanical pressure, using
                      pump–probe photocrystallography},
      journal      = {Acta crystallographica / Section A},
      volume       = {80},
      number       = {a1},
      issn         = {0108-7673},
      address      = {Oxford [u.a.]},
      publisher    = {Blackwell},
      reportid     = {PUBDB-2025-01375},
      pages        = {e425},
      year         = {2024},
      abstract     = {Controlling different external stimuli to tune the
                      photophysical properties of purely organic molecular
                      crystals toward designing multifunctional materials remains
                      a challenge. Over the years, pyrene-based fluorophores owing
                      to their high charge carrier mobility, complex
                      photoelectronic characteristics in the excited state, and
                      high fluorescence quantum yield, have come up as an
                      attractive choice for researchers while designing
                      luminescent molecular crystals. Recently, we have employed a
                      pair of polymorphic D-B-A dyad crystals where electron-rich
                      N,N ¢-dimethylaniline (DMA) acts as an electron donor (D)
                      is attached to pyrene (Py) that acts as an acceptor (A),
                      through -CH2-CH2- group, to study photo-induced charge
                      transfer (PCT) mechanism by time-resolved pump-probe
                      photocrystallography [1]. These D-B-A dyads sometimes behave
                      like semiconductors and if designed properly can be useful
                      as an efficient means of charge transfer and the creation of
                      long-lived charge-separated states necessary for designing
                      smart optoelectronic materials. The light-driven processes
                      are mostly investigated in the D-B-A dyads due to the
                      obvious reason of the matching of UV-Vis radiation
                      wavelength with the electronic excitations and the need to
                      investigate the excited state electron/hole transfer akin to
                      the one observed in the naturalphotosynthesis process. For
                      the present study, one such D-B-A molecule with an aromatic
                      ring as the bridging (B) group has been employed (Fig. 1a).
                      Since, the aromatic ring in the bridging group has the
                      potential to play the role of a hopping station during
                      electron transfer from DMA moiety to pyrene, measurements at
                      different pump-probe delays were employed. The
                      TCSPCmeasurements show that the photoinduced transient
                      excited state is decaying bi-exponentially with a ~22ns long
                      intramolecular charge transfer (ICT) state and a long-lived
                      excimer state (~85ns) (Fig. 1b). The TDDFT calculations show
                      a spatially separated HOMO and LUMO with a HOMO-LUMO gap of
                      3.46 eV, suggesting the CT nature of the HOMO-LUMO
                      transition (Fig. 1c). The needle-shaped single crystals were
                      also exhibiting elastic bending up to ~49° upon pressing
                      with a needle (Fig. 1d). These single crystals were employed
                      for time-resolved photocrystallography measurements at the
                      BioCARS beamline at the APS using different pump-probe
                      delays, where a short 35ps laser pump pulse was followed by
                      a ~100ps X-ray probe pulse on the single crystals (Fig.
                      1e-f). The pump-probe photocrystallography datasets
                      collected at different pump-probe delays show very
                      interesting structural changes directly correlating the
                      photo-chemical processes in solid-state. The
                      photo-difference map from an 18ns pump-probe
                      photocrytallography dataset shows how atomic shifts take
                      place in a photo-induced, intramolecular charge-separated
                      state (Fig. 1g). The results will be also useful in
                      accessing the changes in the intermolecular interactions at
                      different pump-probe delays which in turn will help design
                      solid-state, smart materials.},
      month         = {Aug},
      date          = {2024-08-26},
      organization  = {34th Crystallographic Meeting, Padova
                       (Italy), 26 Aug 2024 - 30 Aug 2024},
      cin          = {FS-SCS},
      ddc          = {530},
      cid          = {I:(DE-H253)FS-SCS-20131031},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G2 - FLASH (DESY) (POF4-6G2) / 6G3 -
                      PETRA III (DESY) (POF4-6G3)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G2 /
                      G:(DE-HGF)POF4-6G3},
      experiment   = {EXP:(DE-H253)P-P11-20150101},
      typ          = {PUB:(DE-HGF)8 / PUB:(DE-HGF)16},
      UT           = {WOS:001397789000405},
      doi          = {10.1107/S2053273324095743},
      url          = {https://bib-pubdb1.desy.de/record/626302},
}