Investigating the electronic structure of a supported metal nanoparticle: Pd in SiCN

We investigate the electronic structure of a Palladium nanoparticle that is partially embedded in a matrix of silicon carbonitride. From classical molecular dynamics simulations we first obtain a representative atomic structure. This geometry then serves as input to density-functional theory calculations that allow us to access the electronic structure of the combined system of particle and matrix. In order to make the computations feasible, we devise a subsystem strategy for calculating the relevant electronic properties. We analyze the Kohn-Sham density of states and pay particular attention to d-states which are prone to be affected by electronic self-interaction. We find that the density of states close to the Fermi level is dominated by states that originate from the Palladium nanoparticle. The matrix has little direct effect on the electronic structure of the metal. Our results contribute to explaining why silicon carbonitride does not have detrimental effects on the catalytic properties of palladium particles and can serve positively as a stabilizing mechanical support

Polynuclear Cu4I4py4 complex loaded in mesoporous silica: Photophysics, theoretical investigation, and highly sensitive oxygen sensing application

The polynuclear Cu4I4py4 complex has been largely studied in solution and in the powder form due to its interesting luminescent properties, which are largely dependent on temperature and pressure. In this work, we present the synthesis of the complex and its wet impregnation in a mesoporous silica host obtained by sol-gel methodology. For optimized guest loadings, the well-dispersed guest molecules exhibit strong interaction with molecular oxygen, resulting in a significant quenching of the luminescence. The process is highly reversible with a Stern-Volmer constant of Ksv = 33.8, which is the largest value found in the literature for similar complexes in the solid state, suggesting that the new material is a promising candidate for high sensitivity oxygen sensing. Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations reveal a weak intermolecular interaction between two guest complexes in the excited state, suggesting the formation of an excited state complex (excimer). The assumption of triplet excimer formation is confirmed by temperature- and concentration-dependent experiments, which provides a new way to explain the giant Stokes shift observed for the guest complex in different media

The manufacture and products thereof of photo-sensitizing nanomaterials and their use in photodynamic treatments

A method for the manufacture of a photosensitizing nanoma terial (40) and the products thereof are disclosed. The method for the treatment of a biological target (50) is disclosed. The photosensitizing nanomaterial (40) comprises a metal com plex tetrapyrrole derivative (10). The metal complex tetrapy rrole derivative (10) is attached by an axial covalent bond (60) to the surface (25) of a solid nanomaterial (20). The solid nanomaterial (20) has at least one dimension in the nanometer and/ or the micrometer range

Unveilling the role of macrodipolar interactions in the properties of self-assembled supramolecular materials

Self-assembling of supramolecules composed of benzene and cyclohexanetricarboxamide derivatives can form highly organized 1D fibers exhibiting macrodipoles. The way fibers pack in the condensed phase governs the final properties of the supramolecular material, where macrodipoles can be oriented parallel or antiparallel to each other, and their magnitude can be tuned by additional intra-columnar dipole stabilization. X-ray structural elucidation of these materials remains a real challenge due to the difficulty in growing single crystals. This problem can be tackled by using atomistic molecular dynamics to simulate supramolecular materials composed of cyclohexanetricarboxamide derivatives assuming different magnitudes and orientations of macrodipoles in the condensed phase, as we show here. The results provide insight on the isotropization mechanism of the supramolecules and also reveal that the relative orientation between macrodipoles can indeed influence their stability. This work nicely complements X-ray structural characterizations of supramolecular materials, and helps understand structure-property relationships of a range of similar non-covalent materials

In Depth Insights into the Key Steps of Delamination of Charged 2D Nano Materials

Delamination is a key step to obtain individual layers from inorganic layered materials needed for fundamental studies and applications. For layered van-der-Waals materials like graphene the adhesion forces are small allowing for mechanical exfoliation, whereas for ionic layered materials like layered silicates the energy to separate adjacent layers is considerably higher. Quite counter intuitively, we show for a synthetic layered silicate (Na0.5-hectorite) that a scalable and quantitative delamination by simple hydration is possible for high and homogeneous charge density, even for aspect ratios as large as 20000. A general requirement is the separation of adjacent layers by solvation to a distance where layer interactions become repulsive (Gouy-Chapman length). Further hydration up to 34 nm leads to the formation of a highly ordered lamellar liquid crystalline phase (Wigner crystal). Up to 8 higher-order reflections indicate excellent positional order of individual layers. The Wigner crystal melts when the interlayer separation reaches the Debye length, where electrostatic interactions between adjacent layers are screened. The layers become weakly chargecorrelated. This is indicated by fulfilling the classical Hansen-Verlet and Lindeman criteria for melting. We provide insight into the requirements for layer separation and controlling the layer distances for a broad range of materials and outline an important pathway for the integration of layers into devices for advanced applications