Diradical Organic One‐Dimensional Polymers Synthesized on a Metallic Surface

Abstract

We report on the synthesis and characterization of atomically precise one‐dimensional diradical peripentacene polymers on a Au(111) surface. By means of high‐resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon‐based optoelectronics and spintronics.

Back Cover: Site‐Specific Reduction‐Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation (Angew. Chem. Int. Ed. 10/2022)

“…[2] Despite the variety of amazing properties exhibited by graphene, [3] the zero band-gap prevents its use in the search for optoelectronic properties. [4] A variety of chemical and physical methods has been developed for opening the gap with great success, namely chemical modification and/or quantum confinement, thus affording graphene derivatives and the so-called carbon nanoribbons, [5] nanographenes (NGs) [6] and graphene quantum dots (GQDs), [7] respectively.…”

Precise Control of π-Electron Magnetism in Metal-Free Porphyrins

“…Recent advances of on-surface synthesis allow for tailoring -electron topologies at the single chemical bond level, and thus provide the ability to precisely engineer -electron magnetism in low-dimensional graphene nanostructures by introducing sublattice imbalance, topological frustration and topological defects [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] . Examples like triangulenes 41,43,48,51 , bowtie-shape nanographenes 47 , chiral graphene nanoribbons 45 , polymers 52 and nanographenes with topological defects 46,49 have been recently synthesized and characterized on surfaces. Similar as nanographenes, the porphyrin macrocycle is aromatic and can be interpreted as a multiple-bridged aromatic diaza [18]annulene system 53,54 .…”

Engineering the magnetism of nanographene via co-depositing hetero precursors

“…However, as an alternative method, on surface synthesis under ultra-high vacuum has emerged as a powerful flexible synthetic toolkit in recent years 14,15 . The current issues of carbon magnetism involve around three aspects: NG or graphene nanoribbons (GNR) with spin-polarized zigzag edges states [16][17][18][19] , sublattice imbalance as guided by Lerb's theorem for bipartite latices [20][21][22][23][24] and NGs with non-Kekulé structure which is formed via Coulomb repulsion between valence electrons [25][26][27][28][29][30][31][32] .…”