Von Templat-gesteuerten metallorganischen Rotaxansynthesen und Darstellung molekularer Shuttle zu massenspektrometrischen Untersuchungen supramolekularer Systeme in der hochverdünnten Gasphase

Im Rahmen dieser Arbeit sind Rotaxansynthesen mit modernen katalytischen metallorganischen Reaktionen entwickelt worden. Hierbei wurde die Kupfer-katalysierte Glaser-Kupplung erfolgreich mit einer Templatsynthese kombiniert, wodurch [2]Rotaxane mit symmetrischen und unsymmetrischen Achsen hergestellt werden konnten. Somit war es erstmals möglich, mit Hilfe der Glaser-Kupplung Rotaxane mit unsymmetrischen Achsen zu erzeugen. Das Ziel dieser Rotaxansynthesen war die Entwicklung schaltbarer molekularer Funktionseinheiten (Shuttle). So konnte im Rahmen dieser Arbeit die Lösungsmittel-abhängige Säure/Base-Schaltung eines [2]Rotaxans mit Hilfe der NMR-Spektroskopie aufgeklärt werden. Weiterhin wurde ein [2]Rotaxan mit einer unsymmetrischen Achse synthetisiert, welches die Möglichkeit bietet, eine Schaltung der molekularen Bewegung sowohl durch den pH-Wert als auch durch eine Metallkomplexierung zu ermöglichen. Ziel dieser Arbeit war ebenso die massenspektrometrische Untersuchung von nicht-kovalent gebundenen supramolekularen Systemen mit einem ESI-FT-ICR-Massenspektrometer. Neben der analytischen Charakterisierung der Proben konnten erweiterte massenspektrometrische Experimente (unter anderem Tandem-MS-Experimente) durchgeführt werden, die zusätzliche Einblicke in Struktur und Reaktivität der zu untersuchenden Systemen lieferten. Hiermit wurden Informationen erhalten, die mit anderen analytischen Methoden nicht zugänglich waren. So konnten mit diesen Experimenten neben der Strukturaufklärung eines metallosupramolekularen Wirt/Gast-Komplexes auch Reaktivitäten von Metallkomplexen in der hochverdünnten Gasphase untersucht werden, die sich auf die Eigenschaften der zu untersuchenden Systeme in der Lösungsphase übertragen ließen. In dieser Arbeit konnte gezeigt werden, daß die Massenspektrometrie eine hervorragende Untersuchungsmethode für schwach gebundene supramolekulare Systeme ist.From Template-Controlled Organometallic Rotaxane Syntheses And Development Of Molecular Shuttle To Mass Spectrometric Investigations Of Supramolecular Systems In The Highly Diluted Gas Phase In the scope of this work modern catalytic organometallic reactions for rotaxane syntheses have been developed. Therefore, the copper catalyzed Glaser coupling reaction has successfully been combined with template synthesis and results in the creation of [2]rotaxanes with symmetric and unsymmetric axles. For the first time, the Glaser coupling reaction was used to synthesize rotaxanes with unsymmetric axles. The main goal of the rotaxane syntheses was the development of switchable functional units (molecular shuttle). One functional unit, a so-called molecular brake, has been analyzed with NMR techniques in the scope of this work. Furthermore, another [2]rotaxane with unsymmetric axle has been synthesized. It offers the possibility of switching the molecular motion via pH change or metal complexation. The second focus of this work was the mass spectrometric investigation of non-covalent bonded supramolecular systems with an ESI-FT-ICR mass spectrometer. Beyond analytical characterization, special experiments (e.g. tandem MS experiments) revealed a deep insight in structure and reactivity of the analytes. These experiments were used to elucidate the structure of a metallosupramolecular host/guest complex in the highly diluted gas phase. Furthermore, they also revealed reactivities of metal complexes in the gas phase. The obtained information could successfully be transferred to the condensed phase to investigate ligand exchange kinetics in metal complexes. The achieved results clearly show that mass spectrometry is a highly valuable tool in the investigation of supramolecular systems

Ресурсосберегающий метод синтеза нитрида ниобия

Разработка новых методов синтеза нитридов в настоящее время актуальна, поскольку эти нитриды, нитриды и другие металлы широко используются в промышленности.Development of new methods for synthesis of nitrides is currently relevant because these nitrides, and nitrides of other metals are commonly used in industry

Open Babel: An open chemical toolbox

Background: A frequent problem in computational modeling is the interconversion of chemical structures between different formats. While standard interchange formats exist (for example, Chemical Markup Language) and de facto standards have arisen (for example, SMILES format), the need to interconvert formats is a continuing problem due to the multitude of different application areas for chemistry data, differences in the data stored by different formats (0D versus 3D, for example), and competition between software along with a lack of vendorneutral formats. Results: We discuss, for the first time, Open Babel, an open-source chemical toolbox that speaks the many languages of chemical data. Open Babel version 2.3 interconverts over 110 formats. The need to represent such a wide variety of chemical and molecular data requires a library that implements a wide range of cheminformatics algorithms, from partial charge assignment and aromaticity detection, to bond order perception and canonicalization. We detail the implementation of Open Babel, describe key advances in the 2.3 release, and outline a variety of uses both in terms of software products and scientific research, including applications far beyond simple format interconversion. Conclusions: Open Babel presents a solution to the proliferation of multiple chemical file formats. In addition, it provides a variety of useful utilities from conformer searching and 2D depiction, to filtering, batch conversion, and substructure and similarity searching. For developers, it can be used as a programming library to handle chemical data in areas such as organic chemistry, drug design, materials science, and computational chemistry. It is freely available under an open-source license fro

Design of Organic Molecules with Large Two-Photon Absorption Cross Sections

A strategy for the design of molecules with large two-photon absorption cross sections, δ, was developed, on the basis of the concept that symmetric charge transfer, from the ends of a conjugated system to the middle, or vice versa, upon excitation is correlated to enhanced values of δ. Synthesized bis(styryl)benzene derivatives with donor-π-donor, donor-acceptor-donor, and acceptor-donor-acceptor structural motifs exhibit exceptionally large values of δ, up to about 400 times that of trans-stilbene. Quantum chemical calculations performed on these molecules indicate that substantial symmetric charge redistribution occurs upon excitation and provide δ values in good agreement with experimental values. The combination of large δ and high fluorescence quantum yield or triplet yield exhibited by molecules developed here offers potential for unprecedented brightness in two-photon fluorescent imaging or enhanced photosensitivity in two-photon sensitization, respectively

Theoretical Design of Organic Chromophores with Large Two-Photon Absorption Cross-Sections

Design strategies and structure-property relationships for two-photon absorption in conjugated molecules are described on the basis of correlated quantum-chemical calculations. We first focus on stilbene derivatives with centrosymmetric structures. We found that derivatization of the conjugated molecule with electroactive groups in a quadrupolarlike arrangement leads to a large increase in the two-photon absorption cross section, δ. Quantum-chemical description provides rich insight into the mechanisms for the two-photon absorption phenomenon