How to solvate diol for VCD studies?
Luisa and visiting student Juliana from J. Batista’s group answer this question in our latest publication in PCCP. Read here: dx.doi.org/10.1039/C9CP06030H
Solvent effects on the VCD spectra of chiral alcohol
Luisa’s first paper is out! In her Masters thesis, she investigated solvent effects on the VCD spectra of a series of chiral alcohols and developed guidelines on how to account for explicit solvation in the computational analysis of the spectra. The results have now been published in PCCP. Congrats!
Perspective article on AC determinations by VCD
Christian, Tino and Nora have made some efforts to prepare a review article on AC determinations by VCD spectroscopy. The paper outlines the general work flow and the experimental requirements without going into too much technical detail – the ideal overview for those interested in getting an AC from VCD. In the second part, the article summarizes about 100 examples for AC determination published in the last decade. Give it a read.
New job for the community
This month, Christian became member of the editorial board of the Wiley-VCD journal Chirality – the journal for the community of chiroptical spectroscopists, chiral recognition and chiral separations.
The groups grows
This month, we group got three new members and a status update. Kevin finished his Masters (congrats! :D) and stays with us for a project in the framework of the research training group “Confinement controlled chemistry”.
Dr. Daniel Demarque joint the group as Postdoc. He has been visiting PhD student in 2017 and now returns with a prestigious Alexander-von-Humboldt Postdoc Fellowship! Congrats as well!
Michael Kemper joins us as new PhD student. He received his BSc and MSc from the University Duisburg-Essen for work in Carsten Schmucks lab. Welcome to the world of VCD, Michael! 😀
VCD in liquid rare gases: First paper on CryoVCD
The matrix-isolation technique allows us to study chiral molecules in frozen rare-gas matrices. This is advantages especially if reactive/instable species are to be examined. A thermodynamic equilibrium cannot be reached, tho. Therefore, we developed CryoVCD, a new technique that allows us to record VCD spectra of chiral molecules in liquid rare-gases as solvents. This requires low temperatures (-100°C for xenon) and elevated pressures (3-5 bar for Xe). We have faced the challenges of developing such system and show in our recent PCCP paper that it actually works!
The experiment got the nickname “R2D2”. If you are curious why, feel free to visit us and see R2D2 yourself.
Christian becomes Heisenberg fellow of the DFG
Today Christian has received the great news that he is officially accepted in the Heisenberg programme of the DFG! This is not only a great honor, it also shows a great appreciation of all the group has achieved in the last years! Thank you!
Along with it came a new DFG project on MI-VCD. Yes, we are looking for more PhD students!
On the cover of ChemEurJ!
In our recent paper in ChemEurJ, we investigate how carboxylic acids bind to Takemoto’s bifunctional thiourea catalyst Our work got highlighted as hot paper and we got the chance to be featured on the cover of ChemEurJ again!
Funding in the Boehringer Ingelheim Plus-3 Programme
We have received the great news that Christian’s grant application in the Boehringer Ingelheim Foundation’s perspective Programme “Plus 3” has been granted! Find out more in the university’s press release and expect exciting results from our studies on chiral recognition through halogen bonding in the near future!
Read more in the university’s press release.
Bye bye Masters, hello PhD project!
Luisa finished her Masters thesis – Congrats!! – and stays with us for a challenging PhD project in the framework of the Research Training Group “Confinement controlled chemistry”.
New paper: Explicit Solvation of Carboxylic Acids
On the basis of a comprehensive analysis of experimental and theoretical IR and vibrational circular dichroism (VCD) spectra, we make suggestions for solvation schemes for carboxylic acids. More specifically, we have studied two chiral carboxylic acids in solvents of different polarity and hydrogen bonding capabilities and verify previously proposed solute–solvent structures for their general applicability.
The first PhD on VCD from Bochum has defended – Congrats Dr. Corina
Corina successfully defended her PhD Thesis on Sep 28th. Congrats for this nice Piece of work! 🙂 She’ll stay as postdoc for another year or two and continue the work on matrix-Isolation VCD spectroscopy.
Poster Prize for Corina
Corina won a poster prize (1st place) at the Chirality meeting 2018 at Princeton Univeristy for her poster on matrix-Isolation VCD spectroscopy! Congrats!! 🙂
How to treat CF-vibrations?
Our recent contribution to PCCP highlights the surprising performance of the M06-2X functional in the prediction of C-F stretching vibrations and traces it back to a fortunate compensation of Errors.
Nora and Tino start their PhD projects
… after completing their Masters projects in our lab. Congratulations on your wonderful thesis! Tino will work on active conformations of asymmetric catalyst. Nora will take care of the new instrumentation for measurements in liquid rare gases, which she set up during her Masters thesis project, and measure binding enthalphies of halogen bonded complexes.
VCD on a supramolecular H-bonding motif
This work shows that the intuitive assumption of the sterically less hindered amide group being solvated preferentially does not hold for the cases of two 2,6-pyridinediyl-dialkylamides. Using vibrational circular dichroism (VCD) spectroscopy, solvation is found to induce significant conformational changes, which are not immediately apparent from 1H NMR data.
The work got rated as “hot paper” by the reviewers and was featured on the front cover of Chem. Eur. J. Read more about it in the Cover Profile or of course in the paper.
Chirality induction in supramolecular assemblies
Can a supramolecular self-assembled capsule feel the chirality of its guest? In this collaboration with K. Tiefenbacher (U Basel), we show: Yes it can.
Perspective article in PCCP
A lot of our studies use stereochemistry as probe for intermolecular interactions. Christian summarizes these ideas in a recent Perspective Article for PCCP, which is also featured on the cover page.
How to solvate R-COOH?
In this PCCP article, we report how different solvents affect the VCD spectral signatures of a chiral carboxylic acid, and show that sometimes even ACN needs to be considered explicitly to reproduce the experimentally observed spectra.
As part of the special issue on solvation of the german chemistry journal “Chemie in unserer Zeit”, Christian writes about the solvation shell around chiral molecules and how it can be affected by the solute.
Angewandte Paper on Photochemical Switching
The chiroptical properties of both the E- and Z-isomer of a champhorquinone imine derivative are studied by means of MI-VCD spectroscopy, which is showcased as a powerful tool for the characterization of the switching states of chiral molecular motors.
Analyzing VCD spectra with MD simulations
By combining results from DFT and semi-empirical REMD simulations, we analyzed the VCD of an N,C-protected valine.
Hot paper on substrate binding to thioureas
Using VCD, the conformational preferences of a chiral thiourea in different solvents and its interaction with an acetate anion were investigated. Characteristic spectral signatures were found for different groups of conformers and showcase the potential of using VCD spectroscopy to study reactant–catalyst interactions.
Solvation and dihydrogen bonding
…of a chiral secondary amine borane has been studied in chloroform and acetonitrile.
Our first paper on Matrix-VCD!
In our new paper on MI-VCD, we show that the conformation of a chiral molecule can be significantly distorted due to matrix packing effects.
The absolute configurations of large flexible diterpenes
… have been thought to very difficult to assign using VCD spectroscopy due to the high conformational flexiblity. We show in our Chem Comm paper that it’s actually feasible.
New Paper in Angewandte Chemie on Asymmetric Induction
In collaboration with Benjamin List from the Max-Planck-Institut for Coal Research, VCD spectroscopy was used to study the transmission of stereochemical information in a chiral ion pair based catalyst. Spectral features indicative of chirality transfer from the chiral anion to the achiral cation can be correlated with the enantioselectivity of the catalyst.
Work featured in Bunsenmagazin
Chirality as probe for intermolecular interactions is the fundamental idea of many of our research projects. In advance of the Bunsentagung, the annual meeting of the German Society for Physical Chemistry, Christian presents a review in the Bunsenmagazin.
Corina’s first day
Today, Corina joins the lab as the first PhD student. She got her MSc degree in physical organic chemistry in Wolfram Sander’s group and decided to move to the lab next door to work on interactions of chiral molecules. Welcome and good luck. 🙂
Angewandte Paper on Dihydrogen bonding
A chiral amine–borane is investigated by VCD spectroscopy. By comparison of experimental and calculated spectra, a unique VCD pattern associated with the formation of dihydrogen-bonded dimers in solution is identified. Different dihydrogen binding arrangements in solution and in solid state are characterized.
Paper on chiral polymers in PCCP
Solvent-driven chiroptical switching of a helical chiral poly(carbodiimide): In collaboration with the group of Bruce Novak (University of Texas, Dallas), we investigate the structural changes of a chiral polymer upon change of solvent polarity and temperature and observe the flipping of polymer side groups and a shrinking of the backbone.
New Paper in Inorganic Chemistry
Solvent-effects in chiral transition metal complex: A comparison between the experimental and calculated VCD spectra proves the existence of both Δ and Λ isomers in an acetonitrile solution. However, a significant shift of the equilibrium toward the Λ diastereomer is found for the complex in dimethyl sulfoxide.
First paper on cyclic peptides in collaboration with the Sander group
VCD instrumentation arrived
Last monday, the VCD instrument arrived savely in the basement lab in NC 05/655. A great technician from Bruker Optics installed it during this week and now it’s finally running. Research can start!