NCAFM2023 Programme Booklet

Wednesday 1000-1020

ON-SURFACE SYNTHESIS OF 2D SUPRAMOLECULAR ORGANIC RADICAL FRAMEWORKS

Ana Sánchez-Grande, 1 Federico Frezza, 1 Adam Matěj, 1 Pingo Mutombo, 1 David Curiel, 2 Pavel Jelínek 1

1 Institute of Physics, The Czech Academy of Sciences, Cukrovarnická 10, 162 00, Prague 6, Czech Republic. 2 Department of Organic Chemistry, University of Murcia Campus of Espinardo, 30100 Murcia, Spain. Email: ana.sanchez@fzu.cz

Supramolecular organic radical frameworks (SORF) are advanced functional materials formed by organic free radicals ordered in two- or three-dimensions through non-covalent interactions. 1 They show interesting properties and promising applications in (photo)redox catalysis, sensors or host-guest spin-spin interactions. 2 However, the intrinsic high reactivity of organic radicals make the design of SORF challenging. In the last decade, the field of on-surface synthesis under ultra-high vacuum conditions (UHV) emerged providing versatile routes to synthesize stable molecules with open-shell character. 3 Here, we propose to combine the fields of supramolecular chemistry and on-surface synthesis to design two-dimensional SORF on a Au(111) surface. The sublimation of a truxene-based precursor equipped with 7-azaindole groups on a Au(111) substrate and subsequent annealing at 320 °C leads to the formation of fluoradene-based molecular building blocks with inherent ½ spin state ordered in a Kagome phase through hydrogen bonds. This work demonstrates the on-surface synthesis of a SORF extended throughout tens of nm with a purely organic 2D magnetic order. The structural and electronic characterization of the SORF was performed by scanning tunneling microscopy/spectroscopy (STM/STS) and non-contact atomic force microscopy, and supported by density functional theory (DFT) calculations.

Fig. a) STM overview image (V b = 100 mV, I t = 200 pA), b) nc-AFM image (V b = 1 mV), and c) chemical sketch of SORF on Au(111). References

[1] B. Tang, J. Zhao, J.-F. Xu, X. Zhang. Chem. Sci. 2020, 11 (5), 1192–1204. [2] B.Huang, L. Mao, X. Shi, H.-B. Yang. Chem. Sci. 2021, 12 (41), 13648–13663. [3] D. G. de Oteyza, T. Frederiksen. J. Phys.: Condens. Matter 2022, 34 (44), 443001.

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