Paper SS+NS-ThA10
The Effect of S to Se Substitution in SAMs: Odd-Even Polymorphism of Biphenyl-Substituted Alkaneselenolate on Au(111)

Thursday, November 1, 2012, 5:00 pm, Room 21

To fabricate aromatic self-assembled monolayers (SAMs) of practical importance for molecular electronics and other applications, high level of control over the SAMs properties should be achieved. In particular, besides monitoring the electronic properties, the control of structure and stability, is an issue of equal importance. As demonstrated previously one way to improve structure and stability of these systems can be achieved by the substitution of the headgroup atom (S versus Se, which binds SAMs constituent to the substrate) [1-3]. In the present study [4], to elucidate how the S to Se substitution influences SAMs structure and stability, we investigate influence of the BPnSe/Au(111) (BPnSe, CH₃-(C₆H₄)₂-(CH₂)_n-Se-, n =2-6) formation temperature and compare obtained results with the corresponding data obtained for their thiol analogues i.e. for BPnS/Au(111) SAMs. Obtained STM data are discussed and analysed in view of the spectroscopic [2] and spectrometric [3] results reported by us recently for these systems, as well as compared to the previously reported STM data [1]. Observed odd-even effect in polimorfizm for BPnSe/Au(111) indicates that bonding configuration at the molecule-substrate interface contributes significantly to the energetics of the SAM. We conclude that S to Se substitution increases strength of the molecule-substrate bonding at the expense of reducing strength of the Au_surface-Au_bulk and Se-C bonding.

References

(1) P. Cyganik, K. Szelagowska-Kunstman, et al. J. Phys. Chem. C 2008, 112, 15466.

(2) K. Szelagowska-Kunstman, P. Cyganik, et al. Phys. Chem. Chem. Phys.2010, 12, 4400.

(3) S. Wyczawska, P. Cyganik, A. Terfort, P. Lievens, ChemPhysChem 2011, 12, 2554.

(4) M. Dendzik, A. Terfort, and P. Cyganik in preparation