Self-Assembled Supramolecular Complexes with “Rods-in-Belt” Architecture in the Light of Soft X‑rays

• Published in: Journal of physical chemistry. C 2013-06, Vol.117 (23), p.12385-12392
• Main Authors: Makarova, Anna A, Grachova, Elena V, Krupenya, Dmitry V, Vilkov, Oleg, Fedorov, Alexander, Usachov, Dmitry, Generalov, Alexander, Koshevoy, Igor O, Tunik, Sergey P, Rühl, Eckart, Laubschat, Clemens, Vyalikh, Denis V
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp404459k

One of the most important properties of the recently discovered “rods-in-belt” supramolecular complexes containing Au–Cu or Au–Ag cluster cores is the possibility of tuning their electronic and photophysical properties through modification of the ligand environment. This opens great perspectives for their applications in light-emitting devices and bioimaging. The high structural ordering and self-assembly properties of these unique objects may be used to design artificial nanostructures with complex topologies that could become ideal building blocks for next-generation electronics. Here we present a detailed experimental study of the electronic structure of “rods-in-belt” supramolecular complexes. Applying X-ray photoemission and absorption spectroscopy, we systematically unraveled the structure of their occupied and unoccupied electronic states near the Fermi level. The major contribution to the highest occupied molecular orbitals is made by the triple-bonded carbons hosted in the dialkynylgold “rods” and the copper (silver) atoms from the central cluster core of the heterometallic Au–Cu (Au–Ag) molecules. The lowest unoccupied molecular orbitals are located on the carbon skeleton of the complexes, including −CC– and −CC– aromatic orbitals. The onset of the valence band in the Au–Ag systems is ∼0.3 eV lower than that in the Au–Cu complexes, implying a slightly larger energy gap for the silver-based molecules. With increasing size, the complexes become more and more sensitive to X-ray damage.