Carboxylate Based Nanoworires – A DFT Study of the Mechanical and Electronic Properties.

MARTIN E. ZOLOFF MICHOFF; E. P.M. LEIVA

Niza

Congreso; 61th Annual Meeting of the International Society of Electrochemistry; 2010

Molecular electronics is an emerging field which has the ultimate objective of using individual molecules as constituting parts of electronic circuits. This developing technology has the potential of replacing the actual semiconductor devices. Using molecules as building blocks is appealing, since it allows tailoring the properties of the contact either by modifying the nature of the anchoring group or by introducing different substituents on the molecule. Benzene provides a simple model for studying not only the effects of different functional groups as anchoring points to the metallic electrodes, but also how substituents on the aromatic ring could affect the electronic properties of the nanojuntion created. In fact, many experimental, as well as theoretical studies have been carried out using substituted benzenes to bridge the gap between gold and platinum electrodes. In this work we explore, from a theoretical point of view, terephthalic acid (benzene-1,4-dicarboxylic acid) as a molecular junction formed between Au and Pt electrodes. There are no experimental antecedents on this system, although aliphatic carboxylic acids have been successfully probed as molecular nanowires. Most of the theoretical studies performed on these types of systems deal with conductance calculations. Here we focus our study not only on the electronic property of the nanojuntion, but also on its mechanical properties, such as the rupture force, obtained by the adiabatic stretching of the nanojuntion. The effect of the protonation level, the identity of the metallic electrodes and their structure is assessed. The results indicate that a very strong bond (~2 eV) can be formed when the molecule is fully deprotonated, and that this bond is mainly of an electrostatic nature. In general, Pt electrodes are more reactive, giving stronger nanojuntions.