STM Imaging of a Heptanuclear Ruthenium(II) Dendrimer, Mono-Add Layer on Graphite

Abstract

Scanning tunneling microscopy (STM) and molecular mechanics calculations were used to investigate the long-range packing and the structure of an heptanuclear ruthenium (II) dendritic species, as a PF6- salt. STM imaging was carried out on a mono-add layer of the ruthenium dendrimer formed by physisorption from a 1,2,4-trichlorobenzene solution at the liquid-graphite interface. The packing of the molecules on the surface was visualised by the formation of ordered patterns and a distance of 27 +/- 2 A was measured between two adjacent lamellae. The comparison of this dimension with the molecular-modelling data indicates that the lamellae were formed by rows of dendrimer molecules in which the counterions (PF6-) were strongly associated with the Ru atoms. The images acquired with higher spatial resolution revealed the presence of repeating units within the lamellae. The comparison of the STM images with the modelling results allowed the attribution of the repeating units observed in the imaged pattern to the STM signature of single dendrimer molecules.

Self-ordered dendrimers based on multi-octupolar ruthenium complexes for quadratic nonlinear optics

“…Projection of the heptamer structure along its C 3 axis clearly indicates a octupolar threefold symmetry at the supramolecular level. This fairly agrees with a recent STM imaging and molecular mechanics calculations on a heptanuclear ruthenium dendrimer [32]. Such octupolar arrangement of octupolar subunits results in the optimal octupolar order and the coherent second harmonic emission of each individual building-blocks as described by Eq.…”

Aggregation-Induced Energy Transfer in a Decanuclear Os(II)/Ru(II) Polypyridine Light-Harvesting Antenna Dendrimer

“…The process is fully reversible; on concentrating and diluting the solution of 1 in acetonitrile, the emission spectrum is moved from higher to lower energies and backward indefinitely (see Supplemental Information and Figure S1), indicating that self-assembly, and as a consequence the activation and de-activation of the energy-transfer process, is reversible and can be fully controlled. It can be recalled that closely related heptanuclear Ru(II) dendrimers have been demonstrated to form organized patterns on graphite substrates 34 and that other multimetallic Ru(II) complexes have also been verified to aggregate, 35 but photophysical consequences were not reported or even predicted in any of these cases.…”

RutheniumII Complexes bearing Fused Polycyclic Ligands: From Fundamental Aspects to Potential Applications

“…This ligand has allowed the synthesis of a heptanuclear Ru II core dendrimer (Figure 41) [168,169], fully characterized by electrospray mass spectrometry and femtosecond transient absorption [170]. More interestingly, it has allowed the synthesis of the first ligand-cored nonanuclear dendrimer containing mixed polyazaaromatic bridging ligands (Figure 42) [171].…”