Self-Organized Overlayers Formed by Alanine on Cu{311} Surfaces

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• 作者：David C. Madden ; Israel Temprano ; Marco Sacchi ; Maria Blanco-Rey ; Stephen J. Jenkins ; Stephen M. Driver
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：August 14, 2014
• 年：2014
• 卷：118
• 期：32
• 页码：18589-18603
• 全文大小：776K
• ISSN：1932-7455

文摘

Chirality can manifest itself in diverse ways when a molecule adsorbs on a metal surface. A clear understanding of the interplay between molecular chirality, 鈥渇ootprint chirality鈥? and chirality in the long-range self-organization is crucial if metal surfaces are to be exploited for enantioselective heterogeneous catalysis or enantio-discriminating sensors. We have investigated the self-organization of l-alanine adsorbed as alaninate on Cu{311}, using reflection鈥揳bsorption infrared spectroscopy in conjunction with first-principles calculations to determine bonding configurations, and low-energy electron diffraction and scanning tunnelling microscopy to elucidate structural features. Three ordered structures are seen. One has a symmetric lattice and 3-point adsorbate bonding (the 鈥渟ymmetric lattice鈥?or SL phase); the others, occurring at higher coverage, have chiral lattices and also involve 2-point bonding (the 鈥渃hiral lattice鈥?or CL phase). Possible models for these structures are discussed, together with the roles of footprint chirality and of long-range chirality in the self-organization. These results set the forms of chirality seen in alaninate overlayers on Cu{110} and {100} surfaces into a wider context. The common underlying principles should help in establishing a general framework for understanding the behavior of chiral adsorbates on low-symmetry metal surfaces.