Structural regularity and diversity in hybrids of aromatic thioethers and BiBr3: from discrete complexes to layers and 3D nets

This paper aims to explore the regular structural patterns and the associated electronic properties of a group of hybrid networks based on BiBr3 and aromatic thioethers, with emphasis on structurally correlating the organic molecules with the BiBr3 aggregates as well as the overall hybrid networks. It was found that extended BiBr3 chains tend to be associated with the slender 4-methylthiophenylalkynyl units, whereas biaryl-based molecules with 4-MeSPh groups directly linked to aromatic cores form hybrids with discrete BiBr3 clusters of variable nuclearities and connectivities. By using multidentate ligands with open geometries, this exploratory study also achieves hybrid BiBr3-aromatic thioether networks with open framework and higher dimensional (e.g., 3D) features, which are potentially amenable to further study on guest exchange experiments. Diffuse reflectance measurements on the powder samples of the hybrids and the organic molecules reveal significant electronic interactions between the inorganic and organic components, with the absorption edges of the hybrids uniformly shifted to lower energies relative to the organic samples. In systems with similar network connectivity and local bonding features, the shifts appear to be proportional to the absorption energy of the organic molecules, suggesting that, in a first order approximation, the absorption edge in the hybrids involves substantially the electronic transitions from the HOMOs of the organic molecules to the LUMOs (or conduction bands) of the inorganic components.