Recently p-d conjugated coordination polymers have received alot of attention owing to their unique material properties,although synthesis of long and defect-free polymers remains challenging. Herein we introduce an ovel on-surface synthesis of coordination polymers with quinoidal ligands under ultra-high vacuum conditions,whiche nables formation of flexible coordination polymers with lengths up to hundreds of nanometers.M oreover,t his procedure allows the incorporation of different transition-metal atoms with four-ortwo-fold coordination. Remarkably,t he twofold coordination mode revealed the formation of wires constituted by (electronically) independent 12-membered antiaromatic macrocycles linked together through two CÀCs ingle bonds.

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.

We investigate electroluminescence of single molecular emitters on NaCl on Ag (111) and Au(111) with submolecular resolution in a low-temperature scanning probe microscope with tunneling current, atomic force and light detection capabilities. Role of the tip state is studied in the photon maps of a prototypical emitter, zinc phthalocyanine (ZnPc), using metal and CO-metal tips. CO-functionalization is found to have a dramatic impact on the resolution and contrast of the photon maps due to the localized overlap of the p-orbitals on the tip with the molecular orbitals of the emitter. The possibility of using the same CO-functionalized tip for tip-enhanced photon detection and high resolution atomic force is demonstrated. We study the electroluminescence of ZnPc, induced by charge carrier injection at sufficiently high bias voltages. We propose that the distinct level alignment of the ZnPc frontier orbital with the Au(111) and Ag(111) Fermi levels governs the primary excitation mechanisms as the injection of electrons and holes from the tip into the molecule, respectively. These findings put forward the importance of the tip status in the photon maps and contribute to a better understanding of the photophysics of organic molecules on surfaces.

Functionalization of surfaces with derivatives of Buckminsterfullerene fragment molecules seems a promising approach towards bottom up fabrication of carbon nanotube modified electrode surfaces. The modification of a Cu(100) surface with molecules of the buckybowl pentaindenocorannulene has been studied by means of scanning tunneling microscopy, carbon monoxide-modified non-contact atomic force microscopy, time-of-flight secondary mass spectrometry and quantum chemical calculations. Two different adsorbate modes are identified, in which the majority is oriented such that the bowl cavity points away from the surface and the convex side is partially immersed into a fouratom vacancy in the Cu(100) surface. A minority is oriented such that the convex side points away from the surface with the five benzo tabs oriented basically parallel to the surface. Thermal annealing leads to hydrogenation and planarization of the molecules in two steps under specific C-C bond cleavage. The benzo tabs of the convex side up species serve as hydrogen source. The final product has an open shell electron structure that is quenched on the surface.

In hydrogen bonded systems, nuclear quantum effects such as zero-point motion and tunneling can significantly affect their material properties through underlying physical and chemical processes. Presently, direct observation of the influence of nuclear quantum effects on the strength of hydrogen bonds with resulting structural and electronic implications remains elusive, leaving opportunities for deeper understanding to harness their fascinating properties.We studied hydrogen-bonded one-dimensional quinonediimine molecular networks which may adopt two isomeric electronic configurations via proton transfer. Herein, we demonstrate that concerted proton transfer promotes a delocalization of π-electrons along the molecular chain, which enhances the cohesive energy between molecular units, increasing the mechanical stability of the chain and giving rise to new electronic in-gap states localized at the ends.

One-dimensional metal–organic chains often possess a complex magnetic structure susceptible to modification by alteration of their chemical composition. The possibility to tune their magnetic properties provides an interesting playground to explore quasi-particle interactions in low-dimensional systems. Despite the great effort invested so far, a detailed understanding of the interactions governing the electronic and magnetic properties of the low-dimensional systems is still incomplete. One of the reasons is the limited ability to characterize their magnetic properties at the atomic scale. Here, we provide a comprehensive study of the magnetic properties of metal–organic one-dimensional (1D) coordination polymers consisting of 2,5-diamino-1,4-benzoquinonediimine ligands coordinated with Co or Cr atoms synthesized under ultrahigh-vacuum conditions on a Au(111) surface. A combination of integral X-ray spectroscopy with local-probe inelastic electron tunneling spectroscopy corroborated by multiplet analysis, density functional theory, and inelastic electron tunneling simulations enables us to obtain essential information about their magnetic structures, including the spin magnitude and orientation at the magnetic atoms, as well as the magnetic anisotropy.

The single molecule magnet (SMM) bis(phthalocyaninato)terbium(iii) (TbPc2) has received significant and increasing attention as an exemplar system for realizing molecule-based spin electronics. Attaining higher nuclearity via multi-decker TbPc systems has remained an outstanding challenge, as known examples of Tb2Pc3 systems are only those containing Pc rings with substituents (e.g. alkyl, alkoxyl). Here we report on the spontaneous formation of Tb2Pc3 species from TbPc2 precursors via sublimation in ultrahigh vacuum (UHV) onto an Ag(111) surface. The presence of Tb2Pc3 molecules on the surface are inspected using scanning probe microscopy with submolecular resolution supported by density functional theory (DFT) calculations and additional chemical analysis. We observe the selective presence of a Kondo resonance (30 K) in the Tb2Pc3 species, that we attribute to differences in the orientation of the internal molecular ligands. Formation of triple-decker complexes offers new possibilities to study and control magnetic interactions not accessible with standard TbPc2 molecules.

Iron oxides are among the most abundant compounds on Earth and have consequently been studied and used extensively in industrial processes. Despite these efforts, concrete understanding of some of their surface phase structures has remained elusive, in particular the oxidized α-Fe2O3(0001) hematite surface. We detail an optimized recipe to produce this phase over the entire hematite surface and study the geometrical parameters and composition of its complex structure by means of atomically resolved microscopy, electron diffraction and surface-sensitive spectroscopies. We conclude that the oxidized α-Fe2O3(0001) surface is terminated by a two-dimensional iron oxide with structure, lattice parameters, and orientation different from the bulk substrate. Using total-energy density functional theory for simulation of a large-scale atomic model, we identify the structure of the surface layer as antiferromagnetic, conductive 1T-FeO2 attached on half-metal terminated bulk. The model succeeds in reproducing the characteristic modulations observed in the atomically resolved images and electron diffraction patterns.Mineral iron oxide is known to be available in many stoichiometries, polymorphs, and even mixtures. Hematite (ɑ-Fe2O3), maghemite (γ-Fe2O3), magnetite (Fe3O4), and wüstite (Fe1-XO) are prominent representatives of this class, possessing a wide range of electronic, magnetic and catalytic properties, due to their different oxygen content and characteristic crystal structures 1 .Currently, a significant amount of research is focused on the catalytic processes that occur on the surfaces of iron oxides, such as CO oxidation, wastewater purification, liquid fuel synthesis via Fischer-Tropsch reactions, styrene production or water splitting 2 .The research on iron oxides has turned its focus to nanoparticles 3 and thin films, 4 which are economically advantageous and show versatility beyond that of bulk materials. The critical limit -2D iron oxide films have been achieved in a form of a monolayer of FeO(111) on Pt(111) 5 , Ag (111) 6 , Ru(0001) 7 and Pd(111) 8 . Nevertheless, stability of this monolayer is inherently linked to its strong hybridization with the metal substrate; it remains an open question whether it can exist independently or as termination of an iron oxide crystal 9,10 , in analogy with the recently revisited V2O3(0001) system 11,12 . Another recent survey on new possible candidates for 2D materials suggests that some trilayer structures of metal oxides (e.g. MnO2, CoO2, GeO2) may be stable after exfoliation from a layered bulk 13 .The atomic structures of bulk Fe3O4 and ɑ-Fe2O3 are well-known, but their surface terminations remain elusive 2,14 , owing to their complexity and the fact that their surface stoichiometry can be varied depending on the preparation. Specifically, by removing oxygen from the surface of ɑ-Fe2O3(0001) by selective sputtering, a stoichiometry and structure resembling Fe3O4(111) can be attained 15,16 . Conversely, the surfaces can be partially or fully reoxidized by increasing t...