Chimie minérale

thumb|150px|Les composés inorganiques sont très variés : A : le borane est déficient en électrons ; B : le chlorure de césium a une structure cristalline archétypique ; C : les ferrocènes sont des complexes organométalliques ; D : le silicone a de nombreuses utilisations dont les implants mammaires ; E : le catalyseur de Grubbs a valu le prix Nobel de chimie à son découvreur ; F : les zéolithes ont des structures poreuses et servent de tamis moléculaires ; G : l'acétate de cuivre (II) a surpris les théoriciens avec son diamagnétisme. La chimie minérale, aussi appelée chimie inorganique (par traduction littérale de l'anglais), est la branche la plus ancienne de la chimie. Elle comporte l'étude des divers corps simples existant dans la nature ou obtenus artificiellement et celle des composés qu'ils engendrent en réagissant les uns sur les autres, à l'exception des combinaisons avec le carbone qui sont étudiées à part et font l'objet de la chi

Characterization and prediction of peptide structures on inorganic surfaces

Dmitrii Maksimov

Interfaces between peptides and metallic surfaces are the subject of great interest for possible use in technological and medicinal applications, mainly since organic systems present an extensive range of functionalities, are abundant, cheap, and exhibit low toxicity. Exemplary applications are biosensors that may be sensitive to specific metabolites or harmful compounds. However, these hybrid interfaces pose a challenge to computational modelling, particularly regarding predicting the most relevant configurations at the surface, which determines the electronic properties of the system as a whole. From a theoretical point of view, predicting the most stable interface configuration requires searching through the enormous structure space of flexible biomolecules with respect to the surface for different configurations and performing computational calculations of their properties. However, it is impossible to investigate those parts separately due to complex interactions during adsorption. In order to capture these complex interactions, one has to employ accurate theoretical methods, which are very computationally expensive. In this thesis, we provide a comprehensive description of the complex nature of the interaction of selected amino acids with metallic surfaces using state-of-the-art dimensionality reduction techniques and accurate ab initio theoretical methods and creation of tools tailored for the high-throughput investigations of interface systems. The theoretical methods used in the thesis are described in the first part of the thesis. The second section looks into the conformational space changes of Arginine (Arg) and its protonated counterpart after adsorption on three noble metallic surfaces. Arg is an excellent testbed because it is tiny enough to be treated using density functional theory, which is considered the best compromise between accuracy and computational efficiency. At the same time, Arg is complex enough due to a highly flexible side-chain that allows for hundreds of different configurations in the gas phase alone. The examination of adsorption behavior requires creating a database by performing a large number of geometry optimizations of various conformations and orientations. The investigation of that database includes creating a low-dimensional representation of the conformational spaces using recent dimensionality reduction techniques, followed by examining various bonding and charge transfer patterns and how they affect the available conformational spaces.The third section of the thesis is concerned with developing tools for the automated structure search of interface systems and the modelling of self-assembly patterns formed after adsorption. Different geometry optimization algorithms and a flexible method of preconditioning the quasi-Newton optimization algorithms are implemented in the GenSec package that was developed. Together, these enable a more straightforward interface with a wide range of quantum chemistry packages for sampling the conformational spaces of flexible molecules in 1D (ions), 2D (surfaces), and 3D (cavities and molecules) systems. Structure search of the conformational space of a flexible molecule using GenSec provided satisfactory results for di-L-alanine adsorbed on Cu(110) surface.

EPFL2022

Half-clathrochelate Complexes as Versatile Links in Supramolecular Chemistry

Erica Giraldi

Clathrochelate complexes have been widely investigated with different size and shape and used as building blocks for the obtainment of discrete supramolecular architectures. These clathrochelate complexes are very stable and kinetically inert complexes. A new link, described as a 'half-clathrochelate complex' with one boronate ester-cap and one 'open' side can be used as novel structural motifs in supramolecular chemistry. Since the metal ion is not completely encapsulated, these complexes are more labile than standard clathrochelate complexes with two boronate ester caps. The half-clathrochelate complexes are obtained by metal-templated condensation reactions of 2-pyridylaldoximes with boronic acids. For applications in supramolecular chemistry, half-clathrochelate complexes are very intriguing compounds for several reasons: the central metal ion can be varied to obtain diamagnetic or paramagnetic complexes and substituents at the pyridyl group of the oxime ligand can be used to fuse half-clathrochelate complexes into defined supramolecular assemblies such as dinuclear triple-stranded helicates or tetrahedral cages.

EPFL2021

Characterization and prediction of peptide structures on inorganic surfaces

Dmitrii Maksimov

EPFL2022

Characterization and prediction of peptide structures on inorganic surfaces

Dense and narrowly distributed silica-supported rhodium and iridium nanoparticles: Preparation via surface organometallic chemistry and chemisorption stoichiometry

Half-clathrochelate Complexes as Versatile Links in Supramolecular Chemistry

Characterization and prediction of peptide structures on inorganic surfaces

Dense and narrowly distributed silica-supported rhodium and iridium nanoparticles: Preparation via surface organometallic chemistry and chemisorption stoichiometry

Half-clathrochelate Complexes as Versatile Links in Supramolecular Chemistry