Chemical Way to Tune Spin Excitation of Magnetic Atoms in Sierpiński Triangles

Abstract

Various Sierpinśki triangles (STs) have been constructed on surfaces, but minimal research efforts focus on their properties. In this work, three different types of STs are prepared with iron atoms as metal centers, and 4,4″-dicyano-1,1′:3′,1″-terphenyl, 1,3-bis(4pyridyl)-benzene, and 4,4″-dihydroxy-1,1′:3′,1″-terphenyl as organic ligands, respectively. The spin excitation of magnetic Fe atoms in STs is investigated by low-temperature scanning tunneling microscopy. In the STs consisting of Fe atoms and 4,4″-dihydroxy-1,1′:3′,1″terphenyl molecules, spin excitation of Fe atoms is observed in the spectra measured by scanning tunneling spectroscopy. For the other two ligands, the related spin excitation has not been found in spectra. Density functional theory calculations explain the excitation mechanism of Fe atoms in STs. The results pave the way for tuning spin excitation of magnetic atoms using ligand molecules with various functional groups.

Lattice-Directed Stabilization of Different Spin-State Phases in Metallo-Supramolecular Chains on Au Surfaces

“…Both the spectral features and their response to the magnetic field of the bright Ni atoms in the chains on Au(100) are similar to those of the HS-Ni ( S = 1) atoms on Au(111) (Figure S2b, also see ref ), suggesting that the bright Ni defects in the chains on Au(100) are at the HS ( S = 1) state. Moreover, both the line shape and the magnetic-field evolution of the d I /d V spectra of the bright Ni atoms are similar to those reported for the absorbed iron phthalocyanine molecules exhibiting the Kondo effect − but distinct from those induced by spin excitation at B = 0 probed at the molecules whose spin degeneracy is lifted by magnetic anisotropy. − Given that the spectra of the bright HS-Ni atoms on Au(100) can be fitted by two Fano functions (dark red dashed curve in Figure b), we propose them to be originated from two independent Kondo channels screening the molecular spins, presumably contributed by two spin-polarized d orbitals of the Ni atom, as had been concluded for the HS-Ni atoms on Au(111) in our previous work . The emergence of the HS-Ni defects in the coordination chains on Au(100) is ascribed to the distortion of the coordination geometry of the Ni atoms caused by the corrugation of the reconstructed substrate surface, including the variations in the Ni–O bond length, the O–Ni–O bond angle, the Ni-substrate distance, and the dihedral angle of the fourfold Ni–O coordination center, which results in the stabilization of the HS sites.…”

Assembling Surface Molecular Sierpiński Triangle Fractals via K+-Invoked Electrostatic Interaction

“…Assembling functional molecules into desired molecular structures in a controlled manner is one of the key issues in surface chemistry. , Recently, molecular fractal Sierpiński triangles (STs), an attractive family of ordered yet nonperiodic surface molecular architectures, have drawn great attention due to their structural elegance and aesthetics. − Moreover, the capabilities of the surface-confined ST structures to regulate the assembly of biomolecules, modulate the electronic properties of the substrate surfaces, , and tune intermolecular magnetic interactions make the molecular fractals an appealing candidate for functional devices. It is been testified that once the threefold nodal motif and heterotactic trimer configuration are satisfied, a variety of molecular interactions ranging from the weak and directional halogen and hydrogen bonds , to strong coordination and covalent bonds − can be employed to assemble 120° V-shaped molecular precursors into the STs.…”

Identification of the Physicochemical Factors Involved in the Dye Separation via Methionine‐Functionalized Mesoporous Carbons

“…Overall, the effectiveness of the process is determined by the quality and properties of the adsorbent. Many of the hitherto used adsorbents, including silica gels, [27] alumina, [28] and zeolite molecular sieves [29,30] are rather ineffective in the removal of dyes. Actual studies propose the direction of using other types of porous materials that exhibit better performance, such as activated carbons (ACs), [31,32] ordered mesoporous carbons (OMCs), [33,34] or even metal-organic frameworks (MOFs).…”