reversible c-c bond formation in a surface reaction catalysed by...

Reversible C-C bond formation in a surface reaction catalysed by graphene on Ru(0001) J.J. Navarro 1,4 , M. Pisarra 2 , B. Nieto-Ortega 4 , J. Villalva 4 , C. Díaz 2,3 , F. Calleja 4 , R. Miranda 1,3,4 , F. Martín 2,3,4 , E.M. Pérez 4 , A.L. Vázquez de Parga 1,3,4 1 Dep. Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain 2 Dep. Química C-13, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid Spain 3 Condensed Matter Physics Center IFIMAC, Cantoblanco 28049, Madrid, Spain 4 IMDEA-Nanociencia, Calle Faraday 9, Cantoblanco 28049, Madrid, Spain [email protected] When working on transition metals, graphitic carbon structures usually are a major obstacle for catalytic processes: Carbon deposits physically block the surface active sites, poisoning the catalytic reaction due to its chemical inertness. However, we demonstrated in a previous work that nanostructured graphene on Ru(0001) can be covalently functionalized employing CH2CN • radicals, resulting in an extremely high yield and site-selectivity [1][2]. On the other hand, TCNQ molecules become radicals upon adsorption on gr/Ru(0001) due to a charge transfer process [3]. Now, we found that TCNQ molecules react with the previously attached -CH2CN groups forming a new C-C bond promoted by graphene, as demonstrated by means of scanning tunnelling microscopy (STM) and density functional theory (DFT). Furthermore, this newly formed C-C bond can be reversed using STM manipulation techniques, recovering the bond between the -CH2CN group and graphene, while the TCNQ moiety remains pristine. Fig 1. a) STM image (-1.5 V, 5 pA) showing the product molecules, resulting from the C-C bond formation between -CH2CN and TCNQ, adsorbed on gr/Ru(0001). b) and c) STM images (-2 V, 20 pA) taken on a certain area before and after tip manipulation on the encircled molecule. References: [1] J.J. Navarro, S. Leret, F. Calleja, D. Stradi, A. Black, R. Bernardo-Gavito, M. Garnica, D. Granados, A.L. Vázquez de Parga, E.M. Pérez and R. Miranda. Nano Lett. 16, 355-361 (2016) [2] J.J. Navarro, F. Calleja, R. Miranda, E.M. Pérez and A.L. Vázquez de Parga. Chem. Commun. 53, 1041-10452 (2017) [3] M. Garnica, D. Stradi, S. Barja, F. Calleja, C. Díaz, M. Alcamí, N. Martín, A.L. Vázquez de Parga, F. Martín and R. Miranda. Nat. Phys. 9, 368 (2013)

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Page 1: Reversible C-C bond formation in a surface reaction catalysed by ...conferences.au.dk/fileadmin/conferences/2018/ecoss2018/MOL/MOL-CT... · Reversible C-C bond formation in a surface

Reversible C-C bond formation in a surface reaction catalysed by graphene on Ru(0001)

J.J. Navarro1,4, M. Pisarra2, B. Nieto-Ortega4, J. Villalva4, C. Díaz2,3, F. Calleja4, R. Miranda1,3,4, F. Martín2,3,4, E.M. Pérez4, A.L. Vázquez de Parga1,3,4

1Dep. Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain

2Dep. Química C-13, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid Spain 3Condensed Matter Physics Center IFIMAC, Cantoblanco 28049, Madrid, Spain

4IMDEA-Nanociencia, Calle Faraday 9, Cantoblanco 28049, Madrid, Spain [email protected]

When working on transition metals, graphitic carbon structures usually are a major obstacle for catalytic processes: Carbon deposits physically block the surface active sites, poisoning the catalytic reaction due to its chemical inertness. However, we demonstrated in a previous work that nanostructured graphene on Ru(0001) can be covalently functionalized employing CH2CN•

radicals, resulting in an extremely high yield and site-selectivity [1][2].

On the other hand, TCNQ molecules become radicals upon adsorption on gr/Ru(0001) due to a charge transfer process [3]. Now, we found that TCNQ molecules react with the previously attached -CH2CN groups forming a new C-C bond promoted by graphene, as demonstrated by means of scanning tunnelling microscopy (STM) and density functional theory (DFT). Furthermore, this newly formed C-C bond can be reversed using STM manipulation techniques, recovering the bond between the -CH2CN group and graphene, while the TCNQ moiety remains pristine.

Fig 1. a) STM image (-1.5 V, 5 pA) showing the product molecules, resulting from the C-C bond formation between -CH2CN and TCNQ, adsorbed on gr/Ru(0001). b) and c) STM images (-2 V, 20 pA) taken on a certain area before and after tip manipulation on the encircled molecule.

References:

[1] J.J. Navarro, S. Leret, F. Calleja, D. Stradi, A. Black, R. Bernardo-Gavito, M. Garnica, D. Granados, A.L. Vázquez de Parga, E.M. Pérez and R. Miranda. Nano Lett. 16, 355-361 (2016)

[2] J.J. Navarro, F. Calleja, R. Miranda, E.M. Pérez and A.L. Vázquez de Parga. Chem. Commun. 53, 1041-10452 (2017)

[3] M. Garnica, D. Stradi, S. Barja, F. Calleja, C. Díaz, M. Alcamí, N. Martín, A.L. Vázquez de Parga, F. Martín and R. Miranda. Nat. Phys. 9, 368 (2013)

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