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Shaping two-dimensional (2D) materials in arbitrarily complex geometries is a key to designing their unique physical properties in a controlled fashion. This is an elegant solution, taking benefit from the extreme flexibility of the 2D layers but requiring the ability to force their spatial arrangement from flat to curved geometries in a delicate balance among free-energy contributions from strain, slip-and-shear mechanisms, and adhesion to the substrate. Here, we report on a chemical vapor deposition approach, which takes advantage of the surfactant effects of organic molecules, namely the tetrapotassium salt of perylene-3,4,9,10-tetracarboxylic acid (PTAS), to conformally grow atomically thin layers of molybdenum disulphide (MoS2) on arbitrarily nanopatterned substrates. Using atomically resolved transmission electron microscope images and density functional theory calculations, we show that the most energetically favorable condition for the MoS2 layers consists of its adaptation to the local curvature of the patterned substrate through a shear-and-slip mechanism rather than strain accumulation. This conclusion also reveals that the perylene-based molecules have a role in promoting the adhesion of the layers onto the substrate, no matter the local-scale geometry.

Polymeric nanoparticles obtained by co-aggregation of a polybenzofulvene derivative with bulky substituted perylene diimide dyes in tetrahydrofuran/water mixtures display emission color tunable from blue to red, or deep-red, thanks to energy transfer processes from the polymer to the emissive dyes activated by nanoparticle shrinking. At high water concentrations the presence of well emissive perylene diimide dye micro-aggregates within the polymer nanoparticles limits the FRET efficiency leading to a combined emission from both the polymer (blue) and the dyes (red and deep-red). The optical properties of the NPs are retained also in the solid state where a weak blue contribution of the polymer emission is observed providing multicolor emission in the films obtained by NPs deposition

A flavin-modified gold electrode was developed in order to catalyze the electrochemical oxidoreduction of flavoproteins. Surface modification was carried out by a two-step procedure. In the first step a mixed self-assembled monolayer obtained by adsorption of activated and nonactivated 3,3'-dithiopropionic acid (free acid and N-succinimidyl ester) was formed, followed by the covalent attachment of a N(10)-hexylamino-alkylated flavin derivative via an amide bond in the second step. The electrochemical properties of the flavin-modified electrode are presented and discussed. The redox potential of the attached flavin was measured at various pH values and the electron-transfer rate constant between electrode and flavin was determined as k0 = 5 s(-1) independent of pH. The flavin-modified electrode was successfully applied to the electrochemical and spectroelectrochemical investigation of the flavoprotein WrbA from Escherichia coli that shows some structural similarities to flavodoxins. It is concluded that the electron transfer "electrode --> flavin --> flavoprotein" occurs by a two-step hopping mechanism where the first step is rate determining. Kinetic details are discussed. Furthermore, it turned out that, in contrast to flavodoxins, where the semiquinone state is stabilized, WrbA rapidly takes up two electrons, directly leading to the fully reduced form. The presented electrode surface modification may generally lend itself for spectroelectrochemical investigations of flavoproteins.

The tryptophan (W)-repressor binding protein A(WrbA ) identified as an Escherichia coli stationary-phase protein was proposed as the founding member of a new family of multimeric flavodoxin-like proteins implicated in oxidativestress defense. Since WrbAis largely uncharacterized with respect to both molecular and physiological functions, the present effort is aimed at structural characterization. WrbAapoprotein was purified and used for crystallization trials at room temperature. Multicrystals of WrbAapoprotein were obtained using standard and advanced crystallization techniques. Application of additives and gelling protein for crystallization in single capillaries yielded diffractionquality single crystals. The crystals diffracted to a resolution of 2.2A ¿ at synchrotrons DESY (X13) in Hamburg (Germany), and Elletra (XRD1) in Trieste (Italy).