Sascha Jähnigen

Dr. Sascha Jähnigen

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 July 2018 in Angewandte Chemie International Edition
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SJSascha Jähnigen
Sascha Jähnigen
ASArne Scherrer
Arne Scherrer
RVRodolphe Vuilleumier
Rodolphe Vuilleumier
DSDaniel Sebastiani
Daniel Sebastiani

3 July 2023 in Angewandte Chemie International Edition
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SJSascha Jähnigen
Sascha Jähnigen
Chirality is a curious phenomenon that appears in various forms. While the concept of molecular (RS‐)chirality is ubiquitous in chemistry, there are also more intricate forms of structural chirality. One of them is the enantiomorphism of crystals, especially molecular crystals, that describes the lack of mirror symmetry in the unit cell. Its relation to molecular chirality is not obvious, but still an open question, which can be addressed with chiroptical tools. Vibrational circular dichroism (VCD) denotes chiral infrared (IR) spectroscopy that is susceptible to both, the molecular as well as the intermolecular space by means of vibrational transitions. When carried out in the solid state, VCD delivers a very rich set of non‐local contributions that are determined by crystal packing and collective motion. Since its discovery in the 1970s, VCD has become the method of choice for the determination of absolute configurations, but its applicability reaches beyond towards the study of different crystal forms and polymorphism. This brief review summarises the theoretical concepts of crystal chirality and how computations of solid‐state VCD can shed light into the intimate connection of chiral structure and vibrational optical activity.

28 October 2020 in Physical Chemistry Chemical Physics
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KBKatia Le Barbu-Debus
Katia Le Barbu-Debus
JBJessica Bowles
Jessica Bowles
SJSascha Jähnigen
Sascha Jähnigen
CCCarine Clavaguéra
Carine Clavaguéra
FCFlorent Calvo
Florent Calvo
AZAnne Zehnacker-Rentien
Anne Zehnacker-Rentien
Solvation effects are essential for defining the shape of vibrational circular dichroism (VCD) spectra. Several approaches have been proposed to include them into computational models for calculating VCD signals, in particular those resting on the “cluster-in-a-liquid” model. Here we examine the capabilities of this ansatz on the example of flexible (1S,2S)-trans-1-amino-2-indanol solvated in dimethyl sulfoxide (DMSO). We compare cluster sets obtained from static calculations with results from explicit molecular dynamics (MD) trajectories based on either force field (FF) or first-principles (FP) methods. While the FFMD approach provides a broader sampling of configurational space, FPMD and time-correlation functions of dipole moments account for anharmonicity and entropy effects in the VCD calculation. They provide a means to evaluate the immediate effect of the solvent on the spectrum. This survey singles out several challenges associated with the use of clusters to describe solvation effects in systems showing shallow potential energy surfaces and non-covalent interactions. Static structures of clusters involving a limited number of solvent molecules satisfactorily capture the main effects of solvation in the bulk limit on the VCD spectra, if these structures are correctly weighted. The importance of taking into consideration their fluxionality, i.e. different solvent conformations sharing a same hydrogen bond pattern, and the limitations of small clusters for describing the solvent dynamics are discussed.

26 July 2021 in The Journal of Physical Chemistry Letters
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SJSascha Jähnigen
Sascha Jähnigen
AZAnne Zehnacker-Rentien
Anne Zehnacker-Rentien
RVRodolphe Vuilleumier
Rodolphe Vuilleumier

27 December 2022 in Angewandte Chemie International Edition
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SJSascha Jähnigen
Sascha Jähnigen
KBKatia Le Barbu‐Debus
Katia Le Barbu‐Debus
RGRégis Guillot
Régis Guillot
RVRodolphe Vuilleumier
Rodolphe Vuilleumier
AZAnne Zehnacker-Rentien
Anne Zehnacker-Rentien
Solid‐State Vibrational Circular Dichroism (VCD) can be used to determine the absolute structure of chiral crystals, but its interpretation remains a challenge in modern spectroscopy. In this work, we investigate the effect of a twofold screw axis on the solid‐state VCD spectrum in a combined experimental and theoretical analysis of P21 crystals of (S)‐(+)‐1‐indanol. Even though the space group is achiral, a single proper symmetry operation has an important impact on the VCD spectrum, which reflects the supramolecular chirality of the crystal. Distinguishing between contributions originating from molecular chirality and from chiral crystal packing, we find that while IR absorption hardly depends on the symmetry of the space group, the situation is different for VCD, where completely new non‐local patterns emerge. Understanding the two underlying mechanisms, namely gauge transport and direct coupling, will help to use VCD to distinguish polymorphic forms.

2 August 2021 in Physical Chemistry Chemical Physics
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SJSascha Jähnigen
Sascha Jähnigen
DSDaniel Sebastiani
Daniel Sebastiani
RVRodolphe Vuilleumier
Rodolphe Vuilleumier
We present a computational study of vibrational circular dichroism (VCD) in solutions of (S)-lactic acid, relying on ab initio molecular dynamics (AIMD) and full solvation with bulk water.