Just the shape of it: Tetrakaidecahedral (see picture, left) and oblique parallelepiped (right) α‐Fe2O3 polyhedra with exposed high‐index facets were obtained in high yield. Magnetic studies show that these two forms of iron oxide have distinct magnetic properties owing to their different shapes and different exposed high‐indexed facets.

The use of a single crystal gold bead electrode is demonstrated for characterization of self-assembled monolayers (SAM)s formed on the bead surface expressing a complete set of face centered cubic (fcc) surface structures represented by a stereographic projection. Simultaneous analysis of many crystallographic orientations was accomplished through the use of an in situ fluorescence microscopic imaging technique coupled with electrochemical measurements. SAMs were prepared from different classes of molecules, which were modified with a fluorescent tag enabling characterization of the influence of electrical potential and a direct comparison of the influence of surface structure on SAMs adsorbed onto low index, vicinal and chiral surfaces. The assembly of alkylthiol, Aib peptide and DNA SAMs are studied as a function of the electrical potential of the interface revealing how the organization of these SAMs depend on the surface crystallographic orientation, all in one measurement. This approach allows for a simultaneous determination of SAMs assembled onto an electrode surface onto which the whole fcc stereographic triangle can be mapped, revealing the influence of intermolecular interactions as well as the atomic arrangement of the substrate. Moreover, this method enables study of the influence of the Au surface atom arrangement on SAMs that were created and analyzed, both under identical conditions, something that can be challenging for the typical studies of this kind using individual gold single crystal electrodes. Also demonstrated is the analysis of a SAM containing two components prepared using thiol exchange. The two component SAM shows remarkable differences in the surface coverage, which strongly depends on the surface crystallography enabling estimates of the thiol exchange energetics. In addition, these electrode surfaces enable studies of molecular adsorption onto the symmetry related chiral surfaces since more than one stereographic triangle can be imaged at the same time. The ability to observe a SAM modified surface that contains many complete fcc stereographic triangles will facilitate the study of the single and multicomponent SAMs, identifying interesting surfaces for further analysis.

In this study, hierarchically complex hollow cage-like superstructures assembled by ZnO nanorods have been successfully constructed with water-soluble biopolymer sodium carboxymethyl cellulose as crystal growth modifiers. The number of the hollow cage could be adjusted from single-cage, double-cage, multi-cage to connected-cage. A possible formation mechanism of the hollow superstructures has also been proposed. The catalytic study shows that these ZnO superstructures have good abilities to enhance propellant combustion of ammonium perchlorate (an important oxidizer used in solid rocket propellants), by decreasing its decomposition temperature to as low as 285 °C. Photoluminescence studies reveal that the increase in the cage number leads to an increase in the relative photoluminescence intensity around 500 to 700 nm, which might be attributed to the increase in radiative defects at the interface of the components of the ZnO hollow structure with the growth in cage number.

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In surface-based biosensors, the nonspecific or undesired adsorption of the probe is an important characteristic that is typically difficult to measure and therefore to control or eliminate. A methodology for measuring and then minimizing or eliminating this problem on gold surfaces, readily applicable to many common surface modifications is presented. Combining electrochemical perturbation and fluorescence microscopy, we show that the potential at which the adsorbed species is removed can be used as an estimate of the strength of the adsorbate-surface interaction. This desorption potential can be easily measured through an increase in fluorescence intensity as the potential is manipulated. Furthermore, this method can be used to evaluate strategies for preventing or removing nonspecific adsorption. This is demonstrated for a wide variety of surface modifications, from strongly chemisorbed monolayers such as thiol self-assembled monolayers (SAMs) to physisorbed monolayers as well as for complex surface structures like peptide and DNA mixed-component SAMs. The use of a coadsorption strategy or small magnitude potential-step cycles was shown to significantly decrease the amount of nonspecifically or noncovalently bound probe, creating better defined surfaces.

Gut in Form: α‐Fe2O3‐Tetrakaidekaeder (siehe Bild, links) und abgeschrägte α‐Fe2O3‐Parallelepipede (rechts) mit exponierten hochindizierten Flächen wurden in hohen Ausbeuten erhalten. Die magnetischen Eigenschaften beider Proben unterscheiden sich, offenbar aufgrund ihrer unterschiedlichen Formen und hochindizierten Flächen.

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