TY - JOUR
T1 - Ultrafast Broadband Transient Absorption and Circular Dichroism Reveal Relaxation of a Chiral Copolymer
AU - Scholz, Mirko
AU - Morgenroth, Marius
AU - Cho, Min Ju
AU - Choi, Dong Hoon
AU - Oum, Kawon
AU - Lenzer, Thomas
N1 - Funding Information:
K.O. and T.L. acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG) through Grants OU 58/11-1 and LE 926/12-1. D.H.C. and M.J.C. thank the National Research Foundation of Korea (NRF) for supporting their research by Grant NRF 2019R1A6A1A11044070. We also thank H. Ihmels, J. Hermann, and C. Stremmel (Organic Chemistry 2, University of Siegen) for providing the steadystate CD spectrometer and technical support during the steady-state CD experiments.
Funding Information:
K.O. and T.L. acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG) through Grants OU 58/11-1 and LE 926/12-1. D.H.C. and M.J.C. thank the National Research Foundation of Korea (NRF) for supporting their research by Grant NRF 2019R1A6A1A11044070. We also thank H. Ihmels, J. Hermann, and C. Stremmel (Organic Chemistry 2, University of Siegen) for providing the steady-state CD spectrometer and technical support during the steady-state CD experiments.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/9/5
Y1 - 2019/9/5
N2 - We present a study of the photoinduced dynamics of the chiral polyfluorene-phenylene copolymer PFPh in THF and in cholesteric thin films. After photoexcitation at 370 nm in THF, ultraviolet-visible-near-infrared (UV-vis-NIR) transient absorption spectra show fast subpicosecond to picosecond intrachain migration of singlet excitons, solvation dynamics, and an exciton lifetime of 410 ps. The PFPh thin film features also interchain singlet exciton migration and exhibits shorter (2.1 and 240 ps) and longer lifetime components (2800 ps, interchain recombination). Furthermore, a setup for ultrafast UV-vis broadband transient circular dichroism (TrCD) spectroscopy has been developed. Fast supramolecular relaxation processes are observed, which are linked to changes in the anisotropic polarizability and pitch length of the cholesteric film. Such combined ultrafast transient CD and absorption experiments hold promise to reveal not only details of relaxation processes in supramolecular arrangements but also structural rearrangements of chiral molecular systems featuring CD signals in the UV-vis region.
AB - We present a study of the photoinduced dynamics of the chiral polyfluorene-phenylene copolymer PFPh in THF and in cholesteric thin films. After photoexcitation at 370 nm in THF, ultraviolet-visible-near-infrared (UV-vis-NIR) transient absorption spectra show fast subpicosecond to picosecond intrachain migration of singlet excitons, solvation dynamics, and an exciton lifetime of 410 ps. The PFPh thin film features also interchain singlet exciton migration and exhibits shorter (2.1 and 240 ps) and longer lifetime components (2800 ps, interchain recombination). Furthermore, a setup for ultrafast UV-vis broadband transient circular dichroism (TrCD) spectroscopy has been developed. Fast supramolecular relaxation processes are observed, which are linked to changes in the anisotropic polarizability and pitch length of the cholesteric film. Such combined ultrafast transient CD and absorption experiments hold promise to reveal not only details of relaxation processes in supramolecular arrangements but also structural rearrangements of chiral molecular systems featuring CD signals in the UV-vis region.
UR - http://www.scopus.com/inward/record.url?scp=85072526853&partnerID=8YFLogxK
U2 - 10.1021/acs.jpclett.9b02061
DO - 10.1021/acs.jpclett.9b02061
M3 - Article
C2 - 31436421
AN - SCOPUS:85072526853
VL - 10
SP - 5160
EP - 5166
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
SN - 1948-7185
IS - 17
ER -