Patterning Porous Networks through Self-Assembly of Programmed Biomacromolecules

Single polyoxometalate-based nanoclusters characterized by infrared absorption nanospectroscopy

Bottom-up engineering is a very attractive field. However, the periodic organization of molecules on a solid substrate is challenging, particularly in the selection of the appropriate characterization technique which is suitable for both large area and accurate analysis at the nanoscale. Here, this study demonstrates the unambiguous identification of complex molecular layers by infrared absorption microscopy at the nanometric scale. This technique allowed for the direct observation of the presence of isolated polyoxometalate-based nanoclusters dispersed all over a substrate.

Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111)

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. Here, we present a multimethod study comprehensively characterizing a family of pyridin-4-ylethynyl-functionalized pyrene derivatives in different environments. 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. 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. We demonstrate that the pyrene electronic gap is reduced with an increasing number of substituents. Furthermore, we discuss the influence of template-induced gating and supramolecular organization on the energies of distinct molecular orbitals. 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.