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Chemical structures of the O-doped perylenes investigated in this study: 5,5′,8,8′,11,11′-hexa-tert-butyl-[3,3′-biperylene]-2,2′-diol (BPOL), 2,5,8,14,17,20-hexa-tert-butyldiperyleno[2,3-b:3′,2′-d]furan (BPF), and 2,5,9,12,15,19-hexa-tert-butylbenzo[5′,10′]anthra-[9′,1′,2′:7,8,1]isochromeno[5,4,3-cde]benzo[5,10]anthra[9,1,2-hij]-isochromene (BPPP). 23
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Semiconducting O-doped polycyclic aromatic hydrocarbons constitute a class of molecules whose optoelectronic properties can be tailored by acting on the π-extension of the carbon-based frameworks and on the oxygen linkages. Although much is known about their photophysical and electrochemical properties in solution, their self-assembly interfacial b...
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... particular, within the class of biperylene derivatives, we investigated the monolayer phase on the Cu(111) surface of three compounds very similar in elemental composition, but with a substantial difference in their morphological adaptation. The Esatertbutyl-Biperylenol (BPOL), Esatertbutyl-Biperyleno-Furanyl (BPF), and Esatertbutyl-Biperyleno-Pyranopyranyl (BPPP) molecules are basically the same in terms of stoichiometry, with a different linkage between the two perylene arms (see molecular schemes in Figure 1), with one carbon bridge and two OH groups in BPOL and one and two bridging oxygen atoms in BPF and BPPP, respectively. These differences make them behave very differently in terms of optical emission yield and absorption in the UV−visible spectral region. ...
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... Figure 4a, the relative intensity associated with the tertbutyl groups is not compatible with the strongly non-planar structure of the BPOL isolated molecule in the gas phase with the two perylene arms tilted by 63° with respect to each other. 24 By looking carefully at the tert-butyl protrusions (six per molecule), we see a rather small difference in the height Δz MAX = 25−30 pm (see height distribution analysis in Supporting Information, Figure S11), also suggesting that perylenes should arrange in a flatter configuration than in the isolated gas-phase molecule. This refined analysis also matches the assumption of a more planar configuration described in the ARPES simulations, discussed below. ...
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... 8 displays the LEED diffractograms of the three molecular species, taken in the energy range of 23−27 eV, after depositing 1 ML on Cu(111). The pattern visible in this energy range corresponds to the large molecular unit vectors as measured by STM and reported in Table 1, while the substrate Cu(111) pattern (unit vector a⃗ = 2.58 Å, whose spots have larger separation in the reciprocal space) can be appreciated for E > 50 eV (See Figure S10 in Supporting Information). The LEED pattern simulation with the given parameters allows comparison with the experimental data. ...
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... results summarized in Figure 10 describe the case of the BPOL molecule for which we must consider two enantiomers with their corresponding lattice domain orientations; since the long molecular axis for both enantiomers is parallel to the [110] [110] and [112], respectively). ...
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... direction, the corresponding overall HOMO map is given by summing the single oriented orbital maps with the rotated ±120° accounting for the threefold substrate's symmetry (symmetrization). The constant energy cuts are compared to the clean substrate (shown in Figure 10a). The match between the simulated and experimental maps (Figure 10b,c) is acceptable if we consider that in this case, the non-planar adsorption invalidates the assumptions of orbital tomography. ...
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... constant energy cuts are compared to the clean substrate (shown in Figure 10a). The match between the simulated and experimental maps (Figure 10b,c) is acceptable if we consider that in this case, the non-planar adsorption invalidates the assumptions of orbital tomography. ...
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... the experimental map in Figure 10b, we observe interface states, also visible on the Fermi surface (E b = 0 eV) from features of substrate photoelectrons diffracted by the molecular lattice. These features have already been described, as a result of finalstate effects, for other π-conjugated molecules assembled in ordered networks 62,63 (see Figure S2 in Supporting Information). ...
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... we consider that in both chiral herringbone domain lattices the two molecules are adsorbed with 60° angular displacements, we can construct the overall photoemission map by summing up the four single-molecule orbital maps (0−60°), two +5° and two −5°, rotated with respect to the [110] direction and then proceed with the threefold symmetrization (details in Figure S4). Also in this case, the small discrepancy between the experimental and simulated maps can be ascribed to the nonflatness of the molecules even if this aspect is not as strong as for BPOL, with a better agreement between experiment and simulation, as shown in Figure 11. ...
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... L and R enantiomers being the two pro-chiral partners, they must be oriented with their long molecular axis rotated clockwise by 20° and 40°, respectively. Inversely, if one considers anti-clockwise rotations, the comparison of the experimental and simulated patterns gives a full correspondence, as shown in Figure 12, only if L is rotated by 40° and R by 20°. A schematic for L and R orientations with details on the map reconstruction is shown in Supporting Information (Figures S5 and S6). ...
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... can be seen from Figures 10, 11, and 12, the gas-phase simulations match the main features of the measured momentum maps. It is worth noting that there is a slight geometrical deviation of the simulated maps (sixfold symmetric) with respect to the measured ones (threefold symmetric). ...
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