TY - JOUR
T1 - Electronic transitions of tetrathiafulvalene oriented in polyethylene film
T2 - Near and vacuum UV synchrotron radiation polarization spectroscopy
AU - Thulstrup, Peter Waaben
AU - Hoffmann, Søren Vrønning
AU - Jones, Nykola Clare
AU - Spanget-Larsen, Jens
PY - 2021/6
Y1 - 2021/6
N2 - The electronic spectrum of tetrathiafulvalene (TTF) oriented in a polyethylene film is characterized experimentally using synchrotron radiation linear dichroism from the near-UV to the vacuum-UV region to 56,500 cm–1 (177 nm). The non-planar TTF molecule is shown to have electronic transitions of significant intensity polarized along all three molecular symmetry axes. A procedure for processing linear dichroic data to obtain partial absorbance curves representing different polarization directions is exemplified. The overlapping contributions to eight individual spectral features are furthermore interpreted by the aid of time-dependent density functional theory using CAM-B3LYP / 6-311++G(3df,3pd) with geometry optimized at the B3LYP / 6-311++G(3df,3pd) level within the C2v point group. Additional calculations using larger basis sets as well as other long-range corrected functionals (LC-ωPBE and ωB97XD) yielded similar results. The planar conformer with D2h symmetry is also considered and it is discussed that rapid equilibration via this transition state may contribute to the diffuse nature of some features of the electronic spectrum. The TTF molecule is a dynamic and 3-dimensional chromophore, and these characteristics may serve as a basis for understanding the optical properties of the numerous TTF-based materials finding applications in supramolecular chemistry, molecular electronics and beyond.
AB - The electronic spectrum of tetrathiafulvalene (TTF) oriented in a polyethylene film is characterized experimentally using synchrotron radiation linear dichroism from the near-UV to the vacuum-UV region to 56,500 cm–1 (177 nm). The non-planar TTF molecule is shown to have electronic transitions of significant intensity polarized along all three molecular symmetry axes. A procedure for processing linear dichroic data to obtain partial absorbance curves representing different polarization directions is exemplified. The overlapping contributions to eight individual spectral features are furthermore interpreted by the aid of time-dependent density functional theory using CAM-B3LYP / 6-311++G(3df,3pd) with geometry optimized at the B3LYP / 6-311++G(3df,3pd) level within the C2v point group. Additional calculations using larger basis sets as well as other long-range corrected functionals (LC-ωPBE and ωB97XD) yielded similar results. The planar conformer with D2h symmetry is also considered and it is discussed that rapid equilibration via this transition state may contribute to the diffuse nature of some features of the electronic spectrum. The TTF molecule is a dynamic and 3-dimensional chromophore, and these characteristics may serve as a basis for understanding the optical properties of the numerous TTF-based materials finding applications in supramolecular chemistry, molecular electronics and beyond.
KW - Tetrathiafulvalene
KW - Linear dichroism (LD)
KW - Polarization directions
KW - Electronic transitions
KW - Synchrotron radiation
KW - UV spectroscopy
U2 - 10.1016/j.chphi.2020.100009
DO - 10.1016/j.chphi.2020.100009
M3 - Journal article
VL - 2
JO - Chemical Physics Impact
JF - Chemical Physics Impact
SN - 2667-0224
IS - June 2021
M1 - 100009
ER -