Electron Transfer Through Bridging Molecular Structures

Abstract

Pairs of reducible pentakis(thiophenyl)benzene subunits are linked by different molecular structures as model compounds for reducible molecular-wire-type synthons showing varying electron-transfer ability as a function of the bridging structures, consisting of either para-divinylbenzene, bis-hydrazone, or diacetylene. Their electron-transfer ability from one reducible subunit to the other was investigated by electrochemical and spectroelectrochemical methods. In the case of the bis-hydrazone bridge and the diacetylene bridge, the solid-state structures support the experimental findings. While the para-divinylbenzene bridge completely isolates the reducible subunits (class I system) the diacetylene bridge electronically connects the two reducible structures (class III system), demonstrating its potential application as a "molecular wire." The bis-hydrazone linked dimer displays electronic communication only to a small extend, which was only observed in the spectroelectrochemical investigation. The diacetylene connection as active electron-transfer linker together with poly(thiophenyl)benzene as reducible subunits was used to design more complex molecular architectures. Linear rodlike struktures did allow adjustment of the length of these type of molecular wires and investigation of the extent of electron mobility. Cyclic structures addressed the possibility of moving electrons on a bent molecular wire.

Dissecting Contact Mechanics from Quantum Interference in Single-Molecule Junctions of Stilbene Derivatives

“…30 For direct experimental evidence, Daub and co-workers electrochemically quantified the charge-transport kinetics between meta-and para-(styryl)stilbenes. 31 However, this area has recently received more theoretical attention due to the possibility of studying these effects at the single-molecule level. 6−12 In summary, single-molecule junctions of stilbene derivates with para and meta-linked stilbenes have been formed using a conducting-AFM approach that allows for measurements of single-molecule mechanics through force, independent of conductance.…”

Metal–metal communication in diruthenium complexes of the bridging ligand bis(imidazo[4,5-f][1,10]phenanthroline)

“…Conjugated organic polymers and oligomers are known to be electroactive, and in some cases, polynuclear transition metal complexes that employ conjugated bridging ligands have exhibited behavior that indicates through-bridge (i.e. superexchange) electronic communication [4][5][6]. It has been demonstrated that the degree of this interaction may be tuned through several approaches.…”

Diazocine-functionalized TATA platforms

“…In compound 1 the diazocine is connected to the platform with the ethynyl group in para -position to the azo group, providing a full π-conjugation path of the N=N unit through the ethynyl spacer into the platform. Diazocine-TATA 2 is connected in meta -position and thus interrupting conjugation [24–25]. Both diazocine-TATAs are equipped with methoxy groups, which serve as “reporter units” indicating the configuration of the molecules on metal surfaces [15].…”