Visual Anatomy of an Article – Lessons Learned and Taught in Five Figures

To grow is to teach. In that spirit this article aims to teach best practice for visualizations and at the same time to highlight some of the harvest we could reap in our lab. Following figures recently published in one of our manuscripts, we demonstrate how creativity in figure making goes hand in hand with storytelling, a deepened understanding of the scientific work and an increase in lateral thinking inside the research avenue. We hope it will help to promote scientific visualizations as a useful, even if sometimes harsh, mirror to give new angles to the laboratory work

Scientific Crocheting - A Proposal

This article draws an unconventional bridge between the art of crocheting and the intricate world of chemistry. Crocheting can serve as a tactile model for understanding chemical synthesis, structure and emergent properties, with parallels between the manipulation of crochet patterns and chemical codes. The aim is to nurture what we need most in next-generation scientists: confronting the unexpected, creativity and curiosity

Chirality in curved polyaromatic systems

Carbon allotropes constituted of sp(2)-hybridised carbon atoms display a variety of properties that arise from their delocalised Pi-conjugated electronic structure. Apart from carbon's planar allotropic form graphene, bent or curved structures, such as carbon nanotubes or fullerenes, respectively, have been discovered. In this Tutorial Review, we analyse and conceptually categorise chiral synthetic molecular fragments of non-planar sp(2)-carbon allotropes, including hypothetical forms of carbon that have been proposed to exist as stable entities. Two types of molecular systems composed of equally or differently sized rings are examined: bent with zero Gaussian curvature and curved with positive or negative Gaussian curvature. To affirm that a system is chiral, two conditions must be fulfilled: (1) both reflective symmetry elements, an inversion centre and a mirror plane, must be absent and (2) the system must be stereochemically rigid. It is therefore crucial to not only consider the symmetry of a given system as if it was a rigid object but also its structural dynamics. These principles serve as guidelines for the design of molecular fragments that encode and transcribe chirality into larger systems

Tailor-Made helicity in polyaromatic systems

This thesis was, and still is, the translation of a conceptual idea that took root years before its realization. As with many ideas that eventually get transcribed into actual molecular systems, it needed two things: a molecular design –and a name. For both existed a myriad of possibilities. But how to find a working title that reflects the topological beauty and simple elegance of the molecule? And how to address the general, underlying concept of a ladder with mismatched rails as an organic synthetic chemist? Eventually both were found: a molecular design involving six interlinked phenyl rings. And a name. Evelyne. The thesis is grouped around that concept chronologically, starting with the initial conceptual publication in Angewandte Chemie and the detailed synthetic aspects in the European Journal of Organic Chemistry. Besides the resolution of the synthetic maze, the structure as obtained by X-Ray diffraction analysis as well as the dynamic behavior is described therein. The ensuing publication from Chemistry – A European Journal expands on the concept, finding ways to fine-tune the shape of the helical structures by targeted changes in the structure. In a way, describing Evelyn’s daughters. Schwefelyn. And Selenyn. The supplementary information provided in the manuscripts have been added for the reader’s convenience at the very end, also chronologically ordered. Preceding these three manuscripts, the reader will find a review entitled “Strain Induced Helical Chirality in Polyaromatic Systems” which has been published in Chemical Society Reviews. This tutorial article explains the rise of helical shapes due to steric interactions with carefully selected examples. It gives a clear systematic overview over the different concepts used to induce helical chirality in small organic molecules – including the one realized in this thesis. It connects the thesis’ topic with the wider world of polyaromatic systems that become chiral due to steric interactions. The last publication included arises from a wonderful collaboration with the group of Prof. Dr. Willem Klopper at the Karlsruhe Institute of Technology, Germany. The excellent theoretical work by Angela Bihlmeier and experimental work by Jürgen Rotzler on the atropisomerizaion of alkyl bridged biphenyls was complemented by kinetic circular dichroism studies

Determining Inversion Barriers in Atrop- isomers - A Tutorial for Organic Chemists

Dynamic behavior is a fascinating property of natural and artificial systems and its understanding has significantly impacted the transformation of molecular interchanges into controlled molecular motion. In this tutorial, the key descriptors of enantiomeric stability are examined in-depth. Enantiomerization and racemization are discussed and differentiated on a fundamental level proposing a unified and distinct nomenclature. Their mathematical meanings and relations are described and deduced cohesively in the context of atropisomerization. The calculation of inversion barriers from thermodynamic and kinetic data is demonstrated and the interdependences between the latter are explained mathematically. Using current examples from our group, the determination of rate constants and the thermodynamic parameters is shown in a step-by-step manner using the most common techniques. The tutorial is concluded with aspects and considerations concerning statistical data analysis and error determination of measurements including a practical guide to Monte-Carlo simulations

Recent Concepts for Supramolecular 2D Materials

Bottom-up approaches are one strategy geared towards designing novel two-dimensional materials. Supramolecular polymerization has proven to be an effective way of obtaining these architectures due to the increasing control and tunability offered by different functional groups, which are not afforded by conventional polymerization. In this short review, we highlight examples of supramolecular assemblies held together by well-known non-covalent interactions, as well as new approaches that are becoming more relevant in recent years

Synthesizing Strained Azatriseptane Frameworks

Embedding seven-membered rings into polycyclic aromatic molecules is attractive as they can exert an influence on molecular conformation that ultimately changes the solubility and π-electronics. The considerations in designing and synthesizing a highly strained azatriseptane framework is discussed herein. We employ a twofold macrocyclization strategy to form the [7,7,7]-system and through scoping various strategies identify a Friedel–Crafts approach is key. The synthetic limitations we have identified, in addition to the successes presented here, highlights the key challenges in forming triseptane frameworks and paves the way for second-generation analogues that may have various applications in optical as well as electronic organic materials

Spin-Delocalization in a Helical Open-Shell Hydrocarbon

Neutral open-shell molecules, in which spin density is delocalized through a helical conjugated backbone, hold promise as models for investigating phenomena arising from the interplay of magnetism and chirality. Apart from a handful of examples, however, the chemistry of these compounds remains largely unexplored. Here, we examine the prospect of extending spin-delocalization over a helical backbone in a model compound naphtho[3,2,1- no ]tetraphene, the first helically chiral open-shell hydrocarbon, in which one benzene ring is fused to [5]helicene, forming a phenalenyl subunit. The unpaired electron in this molecule is delocalized over the entire helical core composed of six rings, albeit in a nonuniform fashion, unlike in phenalenyl. In the case of a monosubstituted derivative, the uneven spin-distribution results in a selective σ-dimer formation in solution, as confirmed by 2D NMR spectroscopy. In contrast, the dimerization process is suppressed entirely when four substituents are installed to sterically hinder all reactive positions. The persistent nature of the tetrasubstituted derivative allowed its characterization by EPR, UV–vis, and CD spectroscopies, validating spin-delocalization through a chiral backbone, in accord with DFT calculations. The nonuniform spin-distribution, which dictates the selectivity of the σ-dimer formation, is rationalized by evaluating the aromaticity of the resonance structures that contribute to spin-delocalization

Shape-assisted self-assembly

Self-assembly and molecular recognition are critical processes both in life and material sciences. They usually depend on strong, directional non-covalent interactions to gain specificity and to make long-range organization possible. Most supramolecular constructs are also at least partially governed by topography, whose role is hard to disentangle. This makes it nearly impossible to discern the potential of shape and motion in the creation of complexity. Here, we demonstrate that long-range order in supramolecular constructs can be assisted by the topography of the individual units even in the absence of highly directional interactions. Molecular units of remarkable simplicity self-assemble in solution to give single-molecule thin two-dimensional supramolecular polymers of defined boundaries. This dramatic example spotlights the critical function that topography can have in molecular assembly and paves the path to rationally designed systems of increasing sophistication

Bicyclic Phenyl-Ethynyl Architectures: Synthesis of a 1,4-Bis(phenylbuta-1,3-diyn-1-yl) Benzene Banister

The novel diacetylene bridged terphenylic macrocycle 1 is presented and discussed in the context of rotationally restricted "Gelander" oligomers. The 1,4-bis(phenylbuta-1,3-diyn-1-yl) benzene bridge of diacetylene 1 is significantly longer than its terphenyl backbone, forcing the bridge to bend around the central pylon. The synthesis of molecule 1 is based to a large extent on acetylene scaffolding strategies, profiting from orthogonal alkyne protection groups to close both macrocyclic subunits by oxidative acetylene coupling sequentially. The spatial arrangement and the dynamic enantiomerization process of the bicyclic target structure 1 are analyzed. In-depth NMR investigations not only reveal an unexpected spatial arrangement with both oligomer strands bent alongside the backbone, but also display the limited stability of the model compound in the presence of molecular oxygen