Lumo coronado1/1/2023 ![]() However, advanced supramolecular architectures, such as organic porous networks, have not been reported on either hBN/Cu(111) or other metal-supported hBN monolayers so far, in contrast to graphene or bulk hBN. Studies focusing on the preparation of coordination networks, wires of polycyclic aromatic hydrocarbons, and graphene patches were also performed on hBN/Cu(111). In recent years, our group and others used hBN/Cu(111) to guide the self-assembly of porphyrins, decouple perylenetetracarboxylic dianhydride (PTCDA) aggregates, study interfacial charge transfer in binary phthalocyanine arrays, probe vibronic conductance in oligophenylenes, and control the charge state of F 16CoPc. For instance, hBN/Cu(111) features a work function template with a moiré superstructure: Depending on the registry of the layer and substrate atoms, the surface is divided in areas of low and high local work function, denoted as “pores” and “wires”, respectively. Atomically-thin hBN sheets attracted considerable interest as such spacer layers and can promote site-dependent decoupling and adsorption, yielding access to optical transitions as well as allowing for orbital-resolved STM imaging. As a promising alternative to bulk insulators, ultrathin dielectric films can act as decoupling layers but maintain the possibility to perform STM and STS measurements. Consequently, recent studies aiming to characterize the relation of adsorption, supramolecular organization, and electronic and optical properties in organic layers relied on bulk insulator supports. In many cases, molecule–metal interactions can adversely affect the intrinsic electronic characteristics of molecular adsorbates and quench the optical properties. Diverse self-assembly protocols have been extensively explored on metal substrates, and organic–metal interfaces have been analyzed in great detail. Specifically, the effects of adsorption, conformation, and supramolecular organization on the resulting electronic and optical properties of molecular tectons and the respective assemblies must be comprehensively characterized. ![]() Keywords: electronic structure hexagonal boron nitride optical properties pyrene self-assemblyĪtomic-level control of molecular materials at interfaces is crucial to fully exploit the materials’ potential in electronic, optoelectronic, spintronic, and sensing applications. ![]() The selection of the number and positioning of the pyridyl termini in tetrasubstituted, trans- and cis-like-disubstituted derivatives governed the self-assembly of the pyrenyl core on the nanostructured hBN support, affording dense-packed arrays and intricate porous networks featuring a kagome lattice. Furthermore, we discuss the influence of template-induced gating and supramolecular organization on the energies of distinct molecular orbitals. We demonstrate that the pyrene electronic gap is reduced with an increasing number of substituents. Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of the pyrene derivatives adsorbed on a Cu(111)-supported hexagonal boron nitride ( hBN) decoupling layer provided access to spatially and energetically resolved molecular electronic states. UV–vis measurements in toluene solutions revealed absorption at wavelengths consistent with density functional theory (DFT) calculations, while emission experiments showed a high fluorescence quantum yield. Here, we present a multimethod study comprehensively characterizing a family of pyridin-4-ylethynyl-functionalized pyrene derivatives in different environments. ![]() The controlled modification of electronic and photophysical properties of polycyclic aromatic hydrocarbons by chemical functionalization, adsorption on solid supports, and supramolecular organization is the key to optimize the application of these compounds in (opto)electronic devices. ![]()
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