Structure of molecules (a) PyH, which has a pyrene core and hexyl side chains, and (b) PyTMS, which has branched chains with a silicon core atom.
(a) POM view of PyH crystals drop-casted on a glass slide from an acetone solution (0.3 mg/mL), (b) profilometry image of PyH crystals.
Crystalline structure view along the a-axis is shown for (a) PyH and (b) PyTMS. Silicon atoms are shown in yellow. The dotted lines represent the primitive cells.
Absorption and emission spectra of (a) PyH and (b) PyTMS in chloroform at room temperature. Absorption, emission, and photoluminescence excitation (grey) spectra of (c) PyH and (d) PyTMS of solution-casted films. The measurements were carried out at room temperature.
(a) HOMO and (b) LUMO orbitals for pyrene derivative PyTMS obtained by DFT calculations. The corresponding orbitals for PyH are identical. We note that the orbitals are located on the pyrene core and on the first carbon atoms of the side chains.
Brillouin zone (top) and band structure (bottom) of PyH and PyTMS crystals. Symbols refer to the following points of the PyH Brillouin zone: Γ = (000); ; ; ; ; ; ; X = (0.396749, 0.370929, 0.174518); Y = (0.478292, −0.458278, −0.613158); Z = (0.54012, −0.516068, −0.40455); and to the following points of the PyTMS Brillouin zone: Γ = (000); ; ; ; ; ; ; ; X = (0.477149, 0.365506, −0.564731); Y = (0.457726, 0.434971, −0.319374); Z = (0.551163, −0.319709, −0.235124); Y′ = (0.542274, −0.434971, 0.319374). The coordinates are given in the primitive vectors basis. The Fermi energy has been set to 0 eV.
Absorption spectrum of PyTMS in chloroform solution (see Fig. 4), with the vibrational replicas calculated as described in the Appendix.
Experimental Raman spectrum of PyTMS solution in chloroform (black line), and of the chloroform solvent only (grey line).
Unit cell parameters for PyH and PyTMS triclinic crystals determined by x-ray diffraction measurements at 77 K. Both crystals contain only one molecule in the primitive cell.
Energy levels of PyH and PyTMS molecules obtained from DFT/B3LYP calculations.
Normal modes that contribute to the molecular reorganization associated with the ground-state absorption spectrum in isolated PyTMS molecules. The mode number refers to its ordering amongst the 240 vibrational modes. The vibrational frequency is , E is the mode energy, and S is the Huang-Rhys parameter.
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