Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 105: Nanostructures at surfaces: 1D and 2D structures and networks III

O 105.4: Talk

Thursday, March 15, 2018, 18:00–18:15, MA 141

Antiaromaticity as p-doping of the aromatic electronic structure. — •Narendra Prabhakar Arasu and Héctor Vázquez — Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10/112, Prague, Czech Republic

Hückel's rule states that cyclic and planar π-system is aromatic when it shares 4n + 2 π-electrons and antiaromatic when it possesses 4n electrons. Electrochemical studies had predicted antiaromatic molecules to have excellent conducting properties [1,2] but their instability limited their study. Recently, the single molecule conductance of a genuinely antiaromatic molecule was measured for the first time [3].

In this talk, I will describe our study on the electronic structure and conductance of aromatic and antiaromatic molecular junctions using first-principle calculations. First, I will compare the conductance of an aromatic porphyrin backbone with that of a norcorrole antiaromatic unit. We found that the conductance of the antiaromatic molecule was much higher than that of the aromatic counterpart [3]. I will then generalize this analysis to a series of aromatic-antiaromatic pairs of molecules. From a quantitative analysis of the similarity in their electronic structure, antiaromaticity is found to correspond to p-doping of the aromatic electronic structure. We generalize this analysis to explain the higher conductance of quinones [2] and discuss the implications for single molecule transport.

[1] R. Breslow et al., J. Am. Chem. Soc, 95 (20), 6688 (1973). [2] R. Breslow et al., J. Phys.: Condens. Matter, 20, 374104 (2008). [3] S. Fujii et al., Nat. Commun, 8, 15984 (2017).