Getting Hooked on Supramolecular Coordination Chemistry

The author describes the beginnings of her research in Switzerland, the inspiration she received from her senior colleagues as well as her first successful research results in the chemistry of alkaline earth metal aggregates and silver coordination polymer networks. Her current interest lies in the design of smart materials, using different building blocks from previous projects. These projects evolved in Geneva, Karlsruhe, Basel, and Fribourg, where she became a full professor in 2006

Influence of the sacrificial polystyrene removal pathway on the TiO₂ nanocapsule structure

This study demonstrates the significant influence of the polystyrene removal pathway on the TiO₂ nanocapsules obtained from PS@TiO₂ core-shell particles. In a first step, the polystyrene spheres were coated with titanium oxide via hydrolysis and condensation of the titanium precursor to form PS@TiO₂ core-shell particles. Then, the creation of the empty cavity to form TiO₂ nanocapsules was achieved by removing the polystyrene template by i) thermal decomposition of the polystyrene or ii) dissolution of the polystyrene using Soxhlet extractor followed by a thermal procedure. These pathways to remove the polystyrene were investigated by thermogravimetric studies, IR spectroscopy, transmission and scanning electron microscopy and powder X-ray diffraction. The final TiO₂ nanocapsule structure strongly depends on the sacrificial polystyrene removal pathway. The preservation of the TiO₂ nanocapsules was obtained essentially when the polystyrene was dissolved before the crystallization of the TiO₂

Nanorattles or yolk–shell nanoparticles—what are they, how are they made, and what are they good for?

The development of nanotechnology has led to the design of cutting-edge nanomaterials with increasing levels of complexity. Although “traditional” solid, uniform nanoparticles are still the most frequently reported structures, new generations of nanoparticles have been constantly emerging over the last several decades. The outcome of this nano-art extends beyond nanomaterials with alternative compositions and/or morphologies. The current state-of-the-art allows for the design of nanostructures composed of different building blocks that exhibit diverse properties. Furthermore, those properties can be a reflection of either individual features, which are characteristic of a particular building block alone, and/or synergistic effects resulting from interactions between building blocks. Therefore, the unique structures as well as the outstanding properties of nanorattles have attracted increasing attention for possible biomedical and industrial applications. Although these nanoparticles resemble core–shell particles, they have a distinctive feature, which is a presence of a void that provides a homogenous environment for the encapsulated core. In this Review, we give a comprehensive insight into the fabrication of nanorattles. A special emphasis is put on the choice of building blocks as well as the choice of preparation method, because those two aspects further influence properties and thus possible future applications, which will also be discussed

One-pot synthesis and catalytic properties of encapsulated silver nanoparticles in silica nanocontainers

The microemulsion approach constitutes a novel method for preparation of nanorattles, which are nanostructures with a preserved void between an encapsulated core and the surrounding shell of the nanocontainer. A facile one-pot synthesis and encapsulation is demonstrated for silver nanoparticles into silica nanocontainers to form Ag@SiO₂ nanorattles

Antimicrobial coatings for implant surfaces

Body-foreign materials are used more and more frequently in our lives: joint implants (hips, knees, fingers, etc.), catheters, pacemakers, dental and aesthetic implants, etc. The increasing numbers of patients requiring such implants also raises the absolute numbers of implant-related infections. Thus, it is known that body-foreign materials are prone to bacterial adhesion and subsequent biofilm formation, either via bacterial debris on implant materials, infections during implantation or, later on, via haematogenous seeding. Biofilms, once formed, are impossible to treat with antibiotics, and the immune system response leads to implant loosening, requiring total replacement. The strategy is thus to prevent bacterial adhesion to implant materials' surfaces. Different strategies have been tested in this context and will be presented here, together with our own approach, using a combination of different anti-microbial compounds

Memorial Issue Dedicated to Dr. Howard D. Flack: The Man behind the Flack Parameter

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Nonabelian Hodge theory and vector valued modular forms

We examine the relationship between nonabelian Hodge theory for Riemann surfaces and the theory of vector valued modular forms. In particular, we explain how one might use this relationship to prove a conjectural three-term inequality on the weights of free bases of vector valued modular forms associated to complex, finite dimensional, irreducible representations of the modular group. This conjecture is known for irreducible unitary representations and for all irreducible representations of dimension at most 12. We prove new instances of the three-term inequality for certain nonunitary representations, corresponding to a class of maximally-decomposed variations of Hodge structure, by considering the same inequality with respect to a new type of modular form, called a "Higgs form", that arises naturally on the Dolbeault side of nonabelian Hodge theory. The paper concludes with a discussion of a strategy for reducing the general case of nilpotent Higgs bundles to the case under consideration in our main theorem.Comment: 22 pages, 1 tabl

A structural study of copper(II) carboxylates: Crystal structure and physical characterisation of [Cu2(2-bromopropanoato)4(caffeine)2]

Based on the bond-valence sum model the continual transition between the bidentate and monodentate bonding mode of carboxylato group and minimum of Cu-O bond lengths were estimated. The dependence of Cu⋯Cu separation on Cu-N bond length in binuclear Cu(II) carboxylates with caffeine were derived and fitted to the observed data. The crystal structure of [Cu2(2-bromopropanoato)4(caffeine)2] has been determined by X-ray crystallography. The structure consists of centrosymmetric binuclear units where the two Cu atoms are coordinated by four disordered bridging 2-bromopropionates and two caffeine ligands at the apices of a bicapped square prism. Both 2-bromopropionates show disorder of their -Br and -CH3 substituents. Stacking π·π interactions between the adjacent caffeine molecules link the complex units in 1-D networks. The binuclear structure of the studied compound is consistent with magnetic data and EPR spectru

The first phospho­ramide-mercury(II) complex with a Cl₂Hg-OP[N(C)(C)]₃ segment

Mercury(II) exhibits a strong preference for linear coordination which has been attributed to relativistic effects splitting the 6p orbitals and promoting sp hybridization. If the two ligands attached to the mercury(II) ion are weak donors, the metal ion can act as a good Lewis acid and expand its coordination number. Moreover, mercury has a special affinity for softer bases, such as S and N atoms, and has much less affinity for hard bases, such as those including an O atom. The asymmetric unit of di­chlorido­[tris­(piperidin-1-yl)phos­phane oxide- ΚO]mercury(II)-di­chlorido­ mercury(II) (2/1), [HgCl₂{(C₅H₁₀N)₃PO}]₂·[HgCl₂], is composed of one HgCl₂{(C₅H₁₀N)₃PO} complex and one half of a discrete HgCl₂ entity located on an inversion centre. The coordination environment around the HgII centre in the complex component is a distorted T-shape. Bond- valence-sum calculations confirm the three-coordination mode of the HgII atom of the complex mol­ ecule. The noncovalent nature of the Hg...Cl and Hg...O inter­actions in the structure are discussed