Visualization and Comprehension of Electronic and Topographic Contrasts on Cooperatively Switched Diarylethene-Bridged Ditopic Ligand

Hnid, Imen; Guan, Lihao; Chatir, Elarbi; Cobo, Saioa; Lafolet, Frédéric; Maurel, François; Lacroix, Jean; Sun, Xiaomin

doi:10.3390/nano12081318

Cited by 3 publications

(3 citation statements)

References 88 publications

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“…Scanning tunneling microscopy (STM) is a powerful tool to visualize the molecules inside nanostructures. ,,− ,− It can be employed to investigate the electronic contrasts at a submolecular level, ,, which is very challenging at the solid/liquid interface. In the present work, we focus on two comparable ditopic terpyridine-terminated molecules connected by single (-Fluo-) or double (-bisFluo-) fluorene.…”

Section: Introductionmentioning

confidence: 99%

Nanopatterning by Length-Dependent Self-Assembly from Fluorene-Terpyridine Derivatives

et al. 2022

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Nanopatterning of photoactive precursors by self-assembly is an efficient nanoscale approach to optimize materials with tailored photoluminescence properties. Ditopic ligands are designed that contain terpyridine terminals connected through one or two photoactive fluorene central units. The tpy-Fluo-tpy and tpy-bisFluo-tpy molecules are self-assembled on HOPG surfaces and are investigated by high-resolution scanning tunneling microscopy, where similar organizations are observed due to the intermolecular terpyridine-terpyridine interactions. By an increase in the number of central fluorenes (single to double), the molecular centers bridges appear as distinct “X” or “S” shapes under STM. Moreover, the adsorption spectra shift toward a longer wavelength and an obvious improvement of the quantum luminescence yield is observed. In the tpy-bisFluo-tpy molecules, the STM tip is functionalized to observe the different HOMO or LUMO electronic contrasts that are interpreted by density functional theory (DFT) calculations. Our work provides a novel nanopatterning approach to organize photoactive precursors with molecular-scale precision for designing efficient light-emitting materials.

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Section: Introductionmentioning

confidence: 99%

Nanopatterning by Length-Dependent Self-Assembly from Fluorene-Terpyridine Derivatives

et al. 2022

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“…This adsorbate adopts a normally unstable Sshaped conformation when integrated into a 2D layer, which was explained by the stabilization through a combination of hydrogen bond formation and van der Waals interactions. 32 Similar results were reported by Hnid et al 33 for a derivative of diarylethene functionalized with bipyridine ligands, which possesses two isomers in the form of a closed and open structure. It was shown that the normally metastable closed form becomes predominantly populated when adsorbed on the HOPG surface, which was attributed to the stabilization via a combination of hydrogen bonds and van der Waals interactions.…”

Section: ■ Introductionmentioning

confidence: 99%

Formation of 2D Self-Assembled Layers of Allyl Cyanide on Pd(111)

et al. 2022

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We present a mechanistic study on the interaction of allyl cyanide (AC) with Pd(111) resulting in the formation of different types of self-organized 2D layers. We employ a combination of scanning tunneling microscopy with infrared reflection absorption spectroscopy to obtain complementary information on the real space distribution of AC molecules in the self-organized 2D layers and on their chemical structure as a function of surface temperature. Specifically in the temperature range of 230−250 K, AC was found to form a self-organized 2D layer involving two different types of surface species adsorbed in trans and cis configurations. Each of these species forms identical individual (8 × 5) sublattices, which are shifted with respect to each other by three Pd atoms. Both functional groups of AC�the CN and C�C bonds�are oriented nearly parallel with respect to the metal surface. With decreasing temperature, strong changes in the layer structure were observed: the AC species agglomerate in irregular concave nonagons comprising nine molecules with the nearest AC−AC distance of three Pd atoms. These individual concave nonagons form a self-assembled 2D layer with the (13 × 10) overstructure on the extended areas of Pd(111). Below 210 K, the degree of order in the AC overlayer drastically decreases and only little structured features can be found. They comprise mainly hexagons embedded into a disordered 2D layer and some parallel rows. The nearest AC−AC distance is close to three Pd atoms in these structures. For all observed AC layers, we provide detailed atomistic-level models and accurate distances between the individual species, which were found to strongly depend on the surface temperature. With the increasing surface temperature, a noticeable increase in the characteristic distances between the interacting neighboring species was observed, which we refer to as changes in the nature of intermolecular interactions.

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“…7,8 Switching of molecules or their self-assemblies have be triggered by means of chemical, optical, thermal, electrical or electrochemical stimulation at various scales, or down to the molecular level. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Once assembled on a surface, molecules can be directly visualized by Scanning Tunneling Microscopy (STM). [24][25][26][27] Thanks to sub-molecular level STM imaging, it is possible to recognize different molecular switches or reactions which lead to long-range supramolecular reorganizations on surfaces.…”

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confidence: 99%

From Multi-Switchable Self-Assemblies towards Surface Coordination Chemistry: An STM Investigation of Bipyridine-Terminated Ditopic Ligands

Yao¹,

Hnid²,

Lafolet³

et al. 2022

ECS J. Solid State Sci. Technol.

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A series of ligands, which terminate with ditopic bipyridines connected by a variable central bridge, fluorene biEDOT or azo-benzene, have been investigated by high-resolution scanning tunneling microscopy (STM). The bipyridines can form different hydrogen bonds or can coordinate with transition metal ions at the solid/liquid interface. Their interactions allow such molecules to self-assemble on HOPG. The bridges provide redox-active, photoactive, or fluorescent functionalities. Both the bipyridine terminals and the bridges are units able to switch the molecules in terms of structure organization and electronic properties. Multi-functional switches or transitions are thus generated, for example (i) protonation generates a molecular cis-like to trans-like isomerization and switches the nanoscale organization of the molecule on the surface, (ii) Co(II) cations react with the pyridines to generate on-surface coordination complexes, and (iii) changing the central bridge induces different self-organized structures on the surface. A series of bpy-X-bpy molecules showing different molecular isomers, structural phase transitions and coordination configurations have thus been revealed by means of high-resolution STM.

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Visualization and Comprehension of Electronic and Topographic Contrasts on Cooperatively Switched Diarylethene-Bridged Ditopic Ligand

Cited by 3 publications

References 88 publications

Nanopatterning by Length-Dependent Self-Assembly from Fluorene-Terpyridine Derivatives

Nanopatterning by Length-Dependent Self-Assembly from Fluorene-Terpyridine Derivatives

Formation of 2D Self-Assembled Layers of Allyl Cyanide on Pd(111)

From Multi-Switchable Self-Assemblies towards Surface Coordination Chemistry: An STM Investigation of Bipyridine-Terminated Ditopic Ligands

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