Induced axial chirality by a tight belt: naphthalene chromophores fixed in a 2,5-substituted cofacial para-phenylene-ethynylene framework

We report the design of a synthetically easy accessible axial chirality-inducing framework for a chromophore of choice. The scaffold consists of two basic para-phenylene-ethynylene backbones separated by laterally placed corner units. Substitution with an inherently achiral chromophore at the 2 and 5 positions of the central phenylene excitonically couples the chromophore associated transition and thereby results in chiroptical properties. Using 6-methoxynaphthalene as a model chromophore, we present the synthesis, structural analysis and spectroscopic investigation of the framework. The chiral framework was synthesized in three straightforward synthetic steps and fully characterized. The obtained racemic compounds were resolved using HPLC and assignment of the absolute configuration was performed using the exciton chirality method, crystallography and DFT calculations. This simple yet potent framework might prove useful to enrich the structural diversity of chiral materials

Microservice-based Architecture for the Integration of Data Backends and Dashboard Applications in the Energy and Environment Domains

This article presents a software architecture based on the onion architecture that uses the concept of application microservices in order to integrate data backends with dashboard applications. Its main goal is to reduce the complexity in the architecture\u27s frontend and therefore to increase the performance of the application for the user. The concept of the added application layer as well as its interaction with the other parts of the architecture is described in detail. Then an evaluation of its advantages is presented which shows the benefits of the concept regarding performance and simplicity using a real-world use case in the energy and environmental domains

Intense Molar Circular Dichroism in Fully Conjugated All-Carbon Macrocyclic 1,3-Butadiyne Linked pseudo-meta [2.2]Paracyclophanes

The synthetic access to macrocyclic molecular topologies with interesting photophysical properties has greatly improved thanks to the successful implementation of organic and inorganic corner units. Based on recent reports, we realized that pseudo-meta [2.2]paracyclophanes (PCPs) might serve as optimal corner units for constructing 3D functional materials, owing to their efficient electronic communication, angled substituents and planar chirality. Herein, we report the synthesis, characterization and optical properties of four novel all-carbon enantiopure macrocycles bearing three to six pseudo-meta PCPs linked by 1,3-butadiyne units. The macrocycles were obtained by a single step from enantiopure, literature-known dialkyne pseudo-meta PCP and were unambiguously identified and characterized by state of the art spectroscopic methods and in part even by x-ray crystallography. By comparing the optical properties to relevant reference compounds, it is shown that the pseudo-meta PCP subunit effectively elongates the conjugated system throughout the macrocyclic backbone, such that already the smallest macrocycle consisting of only three subunits reaches a polymer-like conjugation length. Additionally, it is shown that the chiral pseudo-meta PCPs induce a remarkable chiroptical response in the respective macrocycles, reaching unprecedented high molar circular dichroism values for all-carbon macrocycles of up to 1307 L mol-1 cm-1

Intense Molar Circular Dichroism in Fully Conjugated All‐Carbon Macrocyclic 1,3‐Butadiyne Linked pseudo‐ meta [2.2]Paracyclophanes**

The synthetic access to macrocyclic molecular topologies with interesting photophysical properties has greatly improved thanks to the successful implementation of organic and inorganic corner units. Based on recent reports, we realized that pseudo-meta [2.2]paracyclophanes (PCPs) might serve as optimal corner units for constructing 3D functional materials, owing to their efficient electronic communication, angled substituents and planar chirality. Herein, we report the synthesis, characterization and optical properties of four novel all-carbon enantiopure macrocycles bearing three to six pseudo-meta PCPs linked by 1,3-butadiyne units. The macrocycles were obtained by a single step from enantiopure, literature-known dialkyne pseudo-meta PCP and were unambiguously identified and characterized by state of the art spectroscopic methods and in part even by x-ray crystallography. By comparing the optical properties to relevant reference compounds, it is shown that the pseudo-meta PCP subunit effectively elongates the conjugated system throughout the macrocyclic backbone, such that already the smallest macrocycle consisting of only three subunits reaches a polymer-like conjugation length. Additionally, it is shown that the chiral pseudo-meta PCPs induce a remarkable chiroptical response in the respective macrocycles, reaching unprecedented high molar circular dichroism values for all-carbon macrocycles of up to 1307 L mol$^{−1}$ cm$^{−1}$

Prospective Design, Rapid Prototyping, and Testing of Smart Dressings, Drug Delivery Patches, and Replacement Body Parts Using Microscopy Aided Design and ManufacturE (MADAME)

Natural materials exhibit smart properties including gradients in biophysical properties that engender higher order functions, as well as stimuli-responsive properties which integrate sensor and/or actuator capacities. Elucidation of mechanisms underpinning such smart material properties (i), and translation of that understanding (ii), represent two of the biggest challenges in emulating natural design paradigms for design and manufacture of disruptive materials, parts, and products. Microscopy Aided Design And ManufacturE (MADAME) stands for a computer-aided additive manufacturing platform that incorporates multidimensional (multi-D) printing and computer-controlled weaving. MADAME enables the creation of composite design motifs emulating e.g., patterns of woven protein fibers as well as gradients in different caliber porosities, mechanical, and molecular properties, found in natural tissues, from the skin on bones (periosteum) to tree bark. Insodoing, MADAME provides a means to manufacture a new genre of smart materials, products and replacement body parts that exhibit advantageous properties both under the influence of as well as harnessing dynamic mechanical loads to activate material properties (mechanoactive properties). This Technical Report introduces the MADAME technology platform and its associated machine-based workflow (pipeline), provides basic technical background of the novel technology and its applications, and discusses advantages and disadvantages of the approach in context of current 3 and 4D printing platforms

The Power of Macrocyclic Chemistry: Delving into Unexplored Structures of Conjugated Rings

The following PhD thesis covers the research inquiries that I performed in the group of Prof. Dr. Marcel Mayor at the University of Basel from 2018 to 2022. During the course of the recent past years, various organic chemistry projects were investigated, involving multistep synthesis, structural characterization and in-depth spectroscopic analysis of functional organic molecules. While the individual chapters of the thesis might seem unrelated at a first glance, they share a core structural feature of organic chemistry: Macrocycles. The fundamental base of the explored structures involves radially and planarly pi-conjugated carbon-based macrocycles, which are known to exhibit remarkable optoelectronic properties. Conjugated macrocycles are thus attractive candidates to study fundamental questions and represent attractive molecules for the application in various technological fields, making the exploration of novel ring structures an intriguing and exciting research field. In an initial introductory part (Introduction), the history of the discovery and structural investigation of benzene will be elucidated, elaborating how it eventually lead to the huge and fascinating research topic of conjugated macrocycles. After covering the pioneering work on various (anti)aromatic [n]annulenes, the story will move towards more complex planarly conjugated macrocycles, followed by recently published radially conjugated macrocycles. Thereby the focus will be laid on the unique optoelectronic properties of selected examples. In a final part, the potential applications of various macrocyclic structures will be illuminated, highlighting the importance of future research inquiries regarding macrocyclic chemistry. This section by no means envisions lying out a comprehensive overview of the state-of-the-art, but aims at providing a historical and chemical context, in which the three main chapters reside. In the first chapter (Chapter I: Inducing Axial Chirality by a Tight Macrocycle), the chemistry of chromophores will be unraveled and the importance of developing functional molecules with chiroptical properties will be highlighted. Subsequently, our novel macrocyclic rigid framework bearing four mounting points for achiral chromophores of choice will be discussed. The structural constraints of a narrow macrocycle fixes four chromophores in space and places them within a chiral environment. Thus, achiral chromophores can be equipped with chiroptical properties, owing to the optical stability provided by the tight macrocycle. Additionally, the non parallel arrangement of the chromophores enables exciton coupling, which not only allows to determine the absolute configuration but also massively enhances the Cotton effects in the circular dichroism of the chromophore’s transition. Using 6-methoxynaphthalene as a model chromophore, we synthesized and fully characterized the designed framework and demonstrate the effectiveness of the scaffold. In collaboration with Prof. Dr. Stefan Bernhard, we also demonstrate that the chromophore’s fluorescence gains significant luminescence dissymmetry, despite the inherent lack of chirality of the chromophore. We thus believe this framework to be a viable option to diversify chiral materials, which certainly incentivizes its application for various chromophores. In the second chapter (Chapter II: Macrocyclic pseudo-meta Substituted [2.2]Paracyclophanes), [2.2]paracyclophanes (PCPs) will be introduced as versatile building blocks for incorporation in functional molecules. The main focus will be laid upon twofold substituted pseudo-ortho, pseudo-para and pseudo-meta PCPs and their implementation into conjugated macrocycles. Based on recent experimental evidence by our research group, demonstrating constructive quantum interference in pseudo-meta PCPs, we figured they might be the ideal candidates for embedding into macrocycles. Given the angle between its substituents, its inherent planar chirality and efficient conjugation, pseudo-meta PCPs should be the ideal corner unit for macrocyclization reactions, equip the macrocycle with chiroptical properties and enable thorough through-space conjugation. We thus synthesized and fully characterized four enantiopure polygon-shaped macrocyclic 1,3-butadiyne linked pseudo-meta PCPs. The obtained structures display unprecedented high molar circular dichroism values for all carbon macrocycles, which partially increases non-linearly with regards of the number of PCP subunits. By analysis of key reference compounds, we also demonstrate that the structures are fully conjugated and display polymer-like conjugation lengths. In a concluding part, we further show that the 1,3-butadiynes can be transformed into thiophenes using heterocyclization conditions and highlight the potential of studying global (anti)aromatic ring currents in these thoroughly conjugated systems. The remarkable properties of the studied macrocycles surely motivate future chemists to incorporate pseudo-meta PCPs within various conjugated structures. In the third chapter (Chapter III: Novel Approach Towards Armchair Carbon Nanotubes), the discovery of carbon nanotubes (CNTs) bearing astonishing mechanical and electrical properties will be presented. With the inherent disadvantages of typical top-down strategies for their synthesis, the necessity for novel bottom-up approaches for the production of CNTs with defined lengths and diameters will be further introduced. Although segments of zigzag and armchair CNTs are nowadays known and accessible reliably using novel synthetic methodologies, their elongation into actual tubes has proven to be troublesome. Based on a recently developed strategy to synthesize graphene sheets through benzannulations and Scholl oxidations on a poly(p-phenylene ethynylene) intermediate, we envisioned to adapt the same synthesis for the production of armchair CNTs. By developing a six-step reaction sequence benefiting from a key Sonogashira coupling as macrocyclization strategy, we were able to access the final CNT precursor in a reliable fashion. The final Scholl reaction involving the formation of 72 carbon-carbon bonds was so far unsuccessful. However, we hereby show that this strategy is a viable option for the successful bottom-up synthesis of armchair CNTs. In a final summarizing and concluding chapter (Summary and Conclusion), the main findings of the thesis will be recapitulated and brought into the context of potential future opportunities with the hope to inspire future organic chemists

Toward a Scalable Synthesis and Process for EMA401. Part II: Development and Scale-up of a Pyridine- and Piperidine-free Knoevenagel-Doebner Condensation

During the route scouting of EMA401 (1), a angiotensin II type 2 antagonist, we identified the synthesis of key amino acid intermediate 2 via its cinnamic acid derivative 3 as a streamlined option. In general, cinnamic acids can be synthesized from the corresponding aldehyde in a Knoevenagel-Doebner condensation in pyridine with piperidine as an organocatalyst. We aimed at replacing both of these reagents and found novel conditions in toluene as the solvent and morpholine as the organocatalyst. Scale-up of the process allowed production of 25 kg of the cinnamic acid 3, which was of required quality for process development on the subsequent phenylalanine ammonia lyase-catalyzed step. The modified conditions were found to be widely applicable to alternative aldehydes, and so of relevance to practitioners of chemical scale-up

Toward a Scalable Synthesis and Process for EMA401 Part II: Development and Scale-Up of a Pyridine- and Piperidine-Free KnoevenagelDoebner Condensation

During the route scouting of EMA401 (1), a angiotensin II type 2 antagonist, we identified the synthesis of key amino acid intermediate 2 via its cinnamic acid derivative 3 as a streamlined option. In general, cinnamic acids can be synthesized from the corresponding aldehyde in a Knoevenagel-Doebner condensation in pyridine with piperidine as an organocatalyst. We aimed at replacing both of these reagents and found novel conditions in toluene as the solvent and morpholine as the organocatalyst. Scale-up of the process allowed production of 25 kg of the cinnamic acid 3, which was of required quality for process development on the subsequent phenylalanine ammonia lyase-catalyzed step. The modified conditions were found to be widely applicable to alternative aldehydes, and so of relevance to practitioners of chemical scale-up

Helical Threads: Enantiomerically Pure Carbo[6]Helicene Oligomers

ISSN:0947-6539ISSN:1521-376