Aza-Triangulene: On-Surface Synthesis and Electronic and Magnetic Properties
journal contributionposted on 2022-03-07, 14:12 authored by Tao Wang, Alejandro Berdonces-Layunta, Niklas Friedrich, Manuel Vilas-Varela, Jan Patrick Calupitan, Jose Ignacio Pascual, Diego Peña, David Casanova, Martina Corso, Dimas G. de Oteyza
Nitrogen heteroatom doping into a triangulene molecule allows tuning its magnetic state. However, the synthesis of the nitrogen-doped triangulene (aza-triangulene) has been challenging. Herein, we report the successful synthesis of aza-triangulene on the Au(111) and Ag(111) surfaces, along with their characterizations by scanning tunneling microscopy and spectroscopy in combination with density functional theory (DFT) calculations. Aza-triangulenes were obtained by reducing ketone-substituted precursors. Exposure to atomic hydrogen followed by thermal annealing and, when necessary, manipulations with the scanning probe afforded the target product. We demonstrate that on Au(111), aza-triangulene donates an electron to the substrate and exhibits an open-shell triplet ground state. This is derived from the different Kondo resonances of the final aza-triangulene product and a series of intermediates on Au(111). Experimentally mapped molecular orbitals match with DFT-calculated counterparts for a positively charged aza-triangulene. In contrast, aza-triangulene on Ag(111) receives an extra electron from the substrate and displays a closed-shell character. Our study reveals the electronic properties of aza-triangulene on different metal surfaces and offers an approach for the fabrication of new hydrocarbon structures, including reactive open-shell molecules.
scanning tunneling microscopyscanning probe affordednew hydrocarbon structuresdifferent kondo resonancesdensity functional theoryatomic hydrogen followedpositively charged azaincluding reactive opendifferent metal surfaces111 ), azafinal azathermal annealingtarget productsubstituted precursorsstudy revealsshell moleculesshell characterreducing ketonemagnetic statecalculated counterparts111 ).