Calculated electrostatic potential in mV plotted over an electron density contour of 10 À3 e ˚ A À3 for ConA (top panels) and ConB (bottom panels). (a and d) Gas-phase CBHP. (b and e) CBHP-Pt complex. (c and f) CBHP-Pt on Pt(111).

Contexts in source publication

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... changes described previously can be analyzed in terms of the calculated electrostatic potential of the isolated CBHP molecule, isolated CBHP-Pt complex, and adsorbed CBHP-Pt complex. The results are plotted in Fig. 5 for both conformations. The plots show the evolution of the electrostatic potential along the sequential binding to the Pt adatom and then onto the Pt(111) substrate, while excluding effects due to changes in geometry. Electrostatic potential values (in mV) are projected on an isocontour of the electron density and are shown as a color ...

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... projected on an isocontour of the electron density and are shown as a color scale. 33 High values of the electrostatic potential (blue) are related to a reduced electron density. Low electrostatic potential values (red) occur in electronegative regions and correspond to accumulation of electron density. The comparison between both conformers in Fig. 5 shows a similar pattern, indicating that the differences in geometry between ConA and ConB do not play an important role in determining the electrostatic distribution upon adsorption. The electrostatic potential of the isolated CBHP molecule ( Fig. 5a and d) shows positive values near the peripheral H atoms, while negative values are ...

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... and correspond to accumulation of electron density. The comparison between both conformers in Fig. 5 shows a similar pattern, indicating that the differences in geometry between ConA and ConB do not play an important role in determining the electrostatic distribution upon adsorption. The electrostatic potential of the isolated CBHP molecule ( Fig. 5a and d) shows positive values near the peripheral H atoms, while negative values are found near the O atoms of the HP acceptor and, to a lesser extent, in the CB donor rings. Consequently, the planar carbon system forming the acceptor shows a lower electron density (green/blue) than the carbon system of the donor (yellow/green) conrming the ...

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... the HP acceptor and, to a lesser extent, in the CB donor rings. Consequently, the planar carbon system forming the acceptor shows a lower electron density (green/blue) than the carbon system of the donor (yellow/green) conrming the donor-acceptor character of CBHP for both congurations in the gas phase. Binding of the complex to the Pt adatom ( Fig. 5b and e) introduces changes in the O-Pt region but the potential in other parts of the molecule remains almost unchanged, thus the donor-acceptor character is maintained. This is consistent with the ndings shown in Fig. 4, which indicate the introduction of Pt-related states but otherwise the preservation of the character of isolated ...

Context 5

... conformers electron transfer to Pt(111) from the CB donor unit is higher than from the HP-Pt acceptor (0.10-0.13 electrons compared to 0.06 electrons, respectively). This is consistent with the high work function of 5.8 eV for the Pt (111) substrate, 36 which possesses a higher acceptor character than either CB or HP. However, the analysis of Fig. 5 shows that the donoracceptor character of the dyad does not disappear completely when adsorbed on Pt(111), although it is ...