Highly insulating alkane rings with destructive σ-interference

Science China Chemistry - Destructive quantum interference (DQI) provides a unique approach to controlling the leakage current in the OFF state of molecular devices. However, the DQI in...     

Optimised power harvesting by controlling the pressure applied to molecular junctions

A major potential advantage of creating thermoelectric devices using self-assembled molecular layers is their mechanical flexibility. Previous reports have discussed the advantage of this flexibility from the perspective of facile skin attachment and the ability to avoid mechanical deformation. In this work, we demonstrate that the thermoelectric properties of such molecular devices can be controlled by taking advantage of their mechanical flexibility. The thermoelectric properties of self-assembled monolayers (SAMs) fabricated from thiol terminated molecules were measured with a modified AFM system, and the conformation of the SAMs was controlled by regulating the loading force between the organic thin film and the probe, which changes the tilt angle at the metal-molecule interface. We tracked the thermopower shift vs. the tilt angle of the SAM and showed that changes in both the electrical conductivity and Seebeck coefficient combine to optimize the power factor at a specific angle. This optimization of thermoelectric performance via applied pressure is confirmed through the use of theoretical calculations and is expected to be a general method for optimising the power factor of SAMs.

A major potential advantage of creating thermoelectric devices using self-assembled molecular layers is their mechanical flexibility.     

Pyridine analogues of the antimetastatic Ru(III) complex NAMI-A targeting non-covalent interactions with albumin

A series of pyridine-based derivatives of the antimetastatic Ru(III) complex imidazolium [trans-RuCl(4)(1H-imidazole)(DMSO-S)] (NAMI-A) have been synthesized along with their sodium-ion compensated analogues. These compounds have been characterized by X-ray crystallography, electron paramagnetic resonance (EPR), NMR, and electrochemistry, with the goal of probing their noncovalent interactions with human serum albumin (hsA). EPR studies show that the choice of imidazolium ligands and compensating ions does not strongly influence the rates of ligand exchange processes in aqueous buffer solutions. By contrast, the rate of formation and persistence of interactions of the complexes with hsA is found to be strongly dependent on the properties of the axial ligands. The stability of noncovalent binding is shown to correlate with the anticipated ability of the various pyridine ligands to interact with the hydrophobic binding domains of hsA. These interactions prevent the oligomerization of the complexes in solution and limit the rate of covalent binding to albumin amino acid side chains. Electrochemical studies demonstrate relatively high reduction potentials for these complexes, leading to the formation of Ru(II) species in aqueous solutions containing biological reducing agents, such as ascorbate. However, EPR measurements indicate that while noncovalent interactions with hsA do not prevent reduction, covalent binding produces persistent mononuclear Ru(III) species under these conditions.