More than a decade after the first report of single-molecule conductance, it remains a challenging goal to prove the exact nature of the transport through single molecules, including the number of transport channels and the origin of these channels from a molecular orbital point of view. We demonstrate for the archetypical organic molecule, benzenedithiol (BDT), incorporated into a mechanically controllable break junction at low temperature, how this information can be deduced from studies of the elastic and inelastic current contributions. We are able to tune the molecular conformation and thus the transport properties by displacing the nanogap electrodes. We observe stable contacts with low conductance in the order of 10(-3) conductance quanta as well as with high conductance values above ∼0.5 quanta. Our observations show unambiguously that the conductance of BDT is carried by a single transport channel provided by the same molecular level, which is coupled to the metallic electrodes, through the whole conductance range. This makes BDT particularly interesting for applications as a broad range coherent molecular conductor with tunable conductance.

We report on the experimental analysis of the charge transport through single-molecule junctions of the open and closed isomers of photoswitching molecules. Sulfur-free diarylethene molecules are developed and studied via electrical and optical measurements as well as density functional theory calculations. The single-molecule conductance and the current-voltage characteristics are measured in a mechanically controlled break-junction system at low temperatures. Comparing the results with the single-level transport model, we find an unexpected behavior of the current-dominating molecular orbital upon isomerization. We show that both the side chains and end groups of the molecules are crucial to understand the charge transport mechanism of photoswitching molecular junctions.

This study describes synthesis and detailed characterization of 2D and 3D mesocrystalline films produced by self‐assembly of iron oxide (magnetite) truncated nanocubes. The orientational relations between nanocrystals within the superlattice are examined and atomistic models are introduced. In the 2D case, two distinct superstructures (i.e., translational order) of magnetite nanocubes can be observed with p4mm and c2mm layer symmetries while maintaining the same orientational order (with [100]magnetite perpendicular to the substrate). The 3D structure can be approximated by a slightly distorted face‐centered cubic (fcc) superlattice. The most efficient space filling within the 3D superstructure is achieved by changing the orientational order of the nanoparticles and following the “bump‐to‐hollow” packing principle. Namely orientational order is determined by the shape of the nanoparticles with the following orientational relations: [001]SL||[310]magnetite, [001]SL||[301]magnetite, [001]SL||[100]magnetite. Overall the presented data provide a fundamental understanding of a mesocrystal formation mechanism and their structural evolution. Structure, composition, and magnetic properties of the synthesised nanoparticles are also characterized.

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We developed a strategy to generate gold nanoparticles within the P4VP domains of a PS-b-P4VP diblock copolymer in solid state. An organic-inorganic lamellar structure was obtained through selective incorporation of a gold precursor to the pyridine groups in the P4VP block. Understanding how nanoparticles can affect the linear viscoelastic behavior of a block-copolymer system, could assist in defining a specific processing window for this type of hybrid materials. Herein we compared the rheology of BCPs with and without nanoparticles in order to correlate structure to macroscopic response under mechanical shear. We found that nanoparticles affect significantly the glass transition temperature (T g ) of the P4VP block in which these are sequestered, but also T ODT of the block copolymer system. After reduction and shear alignment, a homogeneous spatial distribution of metallic gold nanoparticles is found within the P4VP phase. These findings are confirmed with scattering methods and transmission electron microscopy measurements. Finally, electric force microscopy scans on the surface of these materials revealed dielectric contrast between the two domains of the hybrid lamellar structure.