3D to 2D reorganization of silver–thiol nanostructures, triggered by solvent vapor annealing

Metal–organic composites are of great interest for a wide range of applications. The control of their struc-ture remains a challenge, one of the problems being a complex interplay of covalent and supramolecularinteractions. This paper describes the self-assembly, thermal stability and phase transitions of orderedstructures of silver atoms and thiol molecules spanning from the molecular to the mesoscopic scale.Building blocks of molecularly defined clusters formed from 44 silver atoms, each particle coated by amonolayer of 30 thiol ligands, are used as ideal building blocks. By changing solvent and temperature it ispossible to tune the self-assembled 3D crystals of pristine nanoparticles or, conversely, 2D layered structures, with alternated stacks of Ag atoms and thiol monolayers. The study investigates morphological,chemical and structural stability of these materials between 25 and 300 °Cin situandex situat the nano-scale by combining optical and electronic spectroscopic and scattering techniques, scanning probemicroscopies and density-functional theory (DFT) calculations. The proposed wet-chemistry approach isrelatively cheap, easy to implement, and scalable, allowing the fabricated materials with tuned propertiesusing the same building blocks

3D to 2D reorganization of silver-thiol nanostructures, triggered by solvent vapor annealing

Metal-organic composites are of great interest for a wide range of applications. The control of their structure remains a challenge, one of the problems being a complex interplay of covalent and supramolecular interactions. This paper describes the self-assembly, thermal stability and phase transitions of ordered structures of silver atoms and thiol molecules spanning from the molecular to the mesoscopic scale. Building blocks of molecularly defined clusters formed from 44 silver atoms, each particle coated by a monolayer of 30 thiol ligands, are used as ideal building blocks. By changing solvent and temperature it is possible to tune the self-assembled 3D crystals of pristine nanoparticles or, conversely, 2D layered structures, with alternated stacks of Ag atoms and thiol monolayers. The study investigates morphological, chemical and structural stability of these materials between 25 and 300 \ub0C in situ and ex situ at the nanoscale by combining optical and electronic spectroscopic and scattering techniques, scanning probe microscopies and density-functional theory (DFT) calculations. The proposed wet-chemistry approach is relatively cheap, easy to implement, and scalable, allowing the fabricated materials with tuned properties using the same building blocks

Architecturing Nanospace via Thermal Rearrangement for Highly Efficient Gas Separations

The ability to monitor free volume formation during space-making treatments is critical for the ultrafine tuning of nanospace for efficient gas separation. Here, investigating the polymer thermal rearrangement using synchrotron in situ small-angle X-ray scattering for the first time and combining this information with transport theory, we elucidate the evolution of nanospace features in polymer-based gas separation membranes. The proposed nanospace monitoring technique encompasses the structure–property relationships, therefore offering a powerful tool for tuning the polymer properties for particular gas-related clean energy applications. These results demonstrate that the fine control of the nanospace dimension and magnitude leads to a drastic improvement in gas separation performance above any material to date

Factors Determining the Superior Performance of Lipid/DNA/Protammine Nanoparticles over Lipoplexes

The utility of using a protammine/DNA complex coated with a lipid envelope made of cationic 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) for transfecting CHO (Chinese hamster ovary cells), HEK293 (human embryonic kidney cells), NIH 3T3 (mouse embryonal cells), and A17 (murine cancer cells) cells was examined. The widely used DOTAP/DNA lipoplex was employed as a reference. In all the tested cell lines lipid/protamine/DNA (LPD) nanoparticles were more efficient in transfecting cells than lipoplexes even though the lipid composition of the lipid envelope was the same in both devices. Physical-chemical properties were found to control the ability of nanocarriers to release DNA upon interaction with cellular membranes. LPD complexes easily release their DNA payload, while lipoplexes remain largely intact and accumulate at the cell nucleus. Collectively, these data explain why LPD nanoparticles often exhibit superior performances compared to lipoplexes in trasfecting cells and represent a promising class of nanocarriers for gene delivery