Dipartimento di Fisica dell'Università di Genova, Italy.
Langmuir. 2010 May 18;26(10):7208-15. doi: 10.1021/la904331d.
Self-assembly of organic molecules at metal surfaces is of greatest importance in nanoscience; in fact, it opens new perspectives in the field of molecular electronics and in the study of biocompatible materials. Combining an experimental low-temperature scanning tunneling microscopy investigation with ab initio calculations, we succeeded to describe in detail (S)-glutamic acid adsorption on Ag(100) at T = 350 K. We find that (S)-glutamic acid organizes in a squared structure and, at variance with the majority of cases reported in literature, it adsorbs in the neutral form, 4.6 A above the surface plane. The interaction with the poorly reactive Ag substrate is only due to weak van der Waals forces, while H-bonds between carboxyl groups and the formation of a OCOH-OCOH-OCOH-OCOH cycle at the vertex of the squares are the main responsible for the self-assembly.
有机分子在金属表面的自组装在纳米科学中至关重要；事实上，它为分子电子学领域和生物相容性材料的研究开辟了新的前景。通过结合低温扫描隧道显微镜实验和从头算计算，我们成功地详细描述了（S）-谷氨酸在 T = 350 K 时在 Ag(100)上的吸附。我们发现（S）-谷氨酸以正方形结构组织，与文献中报道的大多数情况不同，它以中性形式吸附，距离表面平面 4.6Å。与反应性差的 Ag 衬底的相互作用仅归因于较弱的范德华力，而羧酸基团之间的氢键和正方形顶点处的 OCOH-OCOH-OCOH-OCOH 环的形成是自组装的主要原因。
