Mesoscopic Metallosupramolecular Texturing by Hierarchic Assembly

Abstract

Currently, there is a strong interest in improving the fabrication and mesoscopic integration of functional nanosystems at surfaces. In particular, new pathways need to be developed to provide methodologies for the synthesis and embedding of nanostructures across multiple length scales. [1][2][3][4] Herein, we introduce the combination of nanopatterning and controlled metal-organic assembly to process prestructured metallic templates and generate arrangements at a higher hierarchical level. We present results of scanning tunneling microscopy (STM) on the metal-directed assembly and mesoscopic organization of supramolecular architectures by using a textured metal substrate, that is, an Au(111) surface decorated with Fe or Co nanodot arrays. By tuning the local reaction conditions with co-deposited dicarboxylate linker molecules, distinct low-dimensional metallosupramolecular systems have been synthesized, which include regularly spaced iron terephthalate ribbons that form a grating whose extension is only limited by the substrate terrace morphology. These findings indicate that hierarchic assembly protocols blending physical nanopatterning [5][6][7][8][9] and supramolecular engineering [10][11][12][13] on surfaces are generally useful for fabricating nanomaterials with control of features at the mesoscopic level.Metal-directed self-assembly of functional molecules provides a versatile strategy towards highly organized supramolecular systems. [14][15][16][17] Recent findings reveal that similar processes can be conducted at surfaces, where notably a series of metal-carboxylate architectures were generated, including mononuclear arrays, ladder structures, and nanoporous 2D metal-organic coordination networks. [13,[18][19][20][21] However, until now these systems have been constructed on homogeneous substrates on which typically organic layers were exposed to a flux of metal atoms. To control the spatial distribution of surface coordination architectures, it is promising to explore prestructured surfaces, which-due to their intrinsic anisotropy, local concentration of reactants and site reactivityallow us to direct and confine the assembly. This control is not possible with homogeneous substrates. Herein we present a temperature-controlled STM investigation of the steering of metallosupramolecular reticulation by using nanopatterned templates. This approach is a model for a two-stage assembly that combines self-organized metal-on-metal growth followed by chemical processing. This methodology may allow the fabrication of low-dimensional functional nanosystems, steer the formation of (metallo-) supramolecular assemblies, enable the study and control of metal-molecule interfacing, or structure template layers in the 100 nm regime for handling nanoscale objects.Specifically, we employed regular lattices of transition metal dots by depositing small amounts of cobalt or iron on Au(111) at room temperature. Due to preferred nucleation of metal islands at the elbow sites of a reconstructed surface, [22] Fe or Co nanoarrays ...

Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation

“…Coverage and temperature dependent studies gave information about the dynamics of the two phases. To our knowledge, TPA chains with a width of a single molecule, which do not rely on a metallic linker 14 and which are stable at room temperature ͑RT͒, are reported here for the first time. Our model for the chains is supported by molecular mechanics calculations rationalizing the geometry and by extended Hückel theory ͑EHT͒ calculations mimicking the molecular appearance in STM data.…”

“…It has received considerable attention in the design of three-dimensional ͑3D͒ self-assembled porous frameworks stabilized by metal-carboxylate bonds, [5][6][7][8][9] as well as in two-dimensional ͑2D͒ supramolecular architectures at surfaces. [10][11][12][13][14][15][16][17][18] When such a building block is adsorbed on a surface, the substrate chemical activity and symmetry have an influence in the final variety of molecular architectures. Furthermore, the carboxyl functional end groups do not only exhibit H bonding by dimerization of self-complementary carboxyl groups, but other bond motifs can be supported if the species in question is deprotonated and present in its carboxylate state.…”

“…Furthermore, the carboxyl functional end groups do not only exhibit H bonding by dimerization of self-complementary carboxyl groups, but other bond motifs can be supported if the species in question is deprotonated and present in its carboxylate state. 11,12,14,15,19 Therefore, we chose a more reactive substrate than those used in previous adsorption studies. Pd͑111͒ has been intensely investigated in the context of hydrogenation catalysis, electrolysis, and hydrogen purification.…”

Two-Dimensional Nanotemplates as Surface Cues for the Controlled Assembly of Organic Molecules

“…Nearly perfect honeycomb networks were formed. A combination of metal nanopatterning and controlled metal-organic assembly was employed to mesoscopically organize supramolecular architectures on surfaces [96]. Fe or Co nanodot arrays, whose formation was enabled by the preferential nucleation of metal islands at the elbow sites of the reconstructed Au(111) surface, decorated the Au(111) surface providing for the nanopatterned surface.…”

Zwitterionic self-assembly of l -methionine nanogratings on the Ag(111) surface

“…By using this methodology, regular low-dimensional systems such as supramolecular clusters, chains, or nanoporous arrays can be fabricated (2-6). A wide variety of molecular species as well as substrate materials proved to be useful (7), exploiting noncovalent directional interactions including dipole-dipole coupling (2, 3), hydrogen bridges (4,5,(8)(9)(10)(11), and metal-ligand interactions (6,(12)(13)(14)(15). With the exception of multiple H-bonded networks or coordination networks incorporating metal centers, it remains challenging to realize robust systems, and there is a need to develop protocols exploiting stronger intermolecular bonds to realize purely organic low-dimensional architectures.…”