Category Archives: Molecular Structure

Thiophenol stacking motions

An investigation on the thiophenol dimer and trimer was published in the Journal of Physical Chemistry Letters. The weakly-bound dimer adopts a stacked structure, while simultaneously maintaining a weak S-H···S hydrogen bond. Two isomers were detected for the dimer in the gas-phase. Notoriously, a large-amplitude motion was observed in one of the dimers, exchanging the proton donor and aceptor thiol groups.

 


Cracking DNA for students

Alberto Lesarri gave a talk at the “Diego de Praves” Secondary School in Valladolid last February 2, replicating the 1950’s DNA X-ray diffraction experiment with a laser pointer and a light bulb. This demonstration experiment basically shows the diffraction of an helix, giving opportunity to talk of the experimental work of Rosalind Franklin, as explained in 2018 in the American Journal of Physics.

You can compare the pointer diffraction, with the real pattern below:


Matrine isomerism

An investigation on matrine , a tetracyclic bis-quinolizidine alkaloid from the Sephora plants, was published in January 2021 in Journal  of Organic Chemistry. The molecule showed two (trans and cis) isomers in the gas-phase, confirming conformational rearrangements in matrine alkaloids. Matrine alkaloids have four stereogenic carbon centers, producing a large family of 16 stereoisomers in 8 enantiomeric pairs.


CPC cover

An investigation on diphenyl disulfide has been highlighted in the cover of CPC. This collaboration with Jean Demaison and Natalja Vogt uses a combination of supersonic jet experimental data and high-level ab initio calculations for the precise determination of the equilibrium molecular structure. The cover features the biologically and industrially important disulfide bridge.


Pseudopelletierine in CEJ

An article on the methyl inversion and structure of the tropane alkaloid pseudopelletierine has been published in Chemistry: A European Journal. The article  includes extensive (multi-isotopologue) rotational data, together with theoretical calculations on the equilibrium structure of the molecule, in collaboration with Jean Demaison and Natalja Vogt.

In the figure below the inversion potential of the methyl group in pseudopelletierine and the pomegranate tree, where this alkaloid can be found.

 


Cotinine in Chemistry News

A work on the nicotinoid cotinine in collaboration with Emilio Cocinero in Bilbao has been highlighted in ChemistryViews (the electronic Chemistry magazine by Wiley and ChemPubSoc) and the Cover of Chemistry: A European Journal. The manuscript presents a rotational investigation of cotinine, where two conformations were found and compared to nicotine.

Below the note in ChemistryViews

… and the cover of CEJ:


Enflurane published

The conformational landscape of enflurane was published in Chemistry – A European Journal. This report closes a series or rotational investigations on volatile and injection anesthetics, including among others sevoflurane, isoflurane and propofol. Enflurane has three distinct rotamers in the gas phase, originated by the internal rotation of the terminal chlorine atom. The presence of hyperfine interations and different isotopologues resulted in a crowded spectrum, as can be observed in the figure below.figure-ethrane-web


B. Sc. Exams

Congratulations to Elena Caballero-Mancebo who passed her¬†B. Sc. dissertation last July 15th at the UVa Faculty of Sciences. Elena’s work was titled “Molecular Modelling and Rotational Spectroscopy¬†of Multiconformational Systems” and got a qualification of 9/10.

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PCCP cover

A work on the intermolecular cluster pyridine-methane in collaboration with the group of  Walther Caminati has been chosen as cover of PCCP. Methane behaves in the complex as a noble gas, binding on top of the aromatic ring. This T-shape structure contrasts with the in-plane structure of other pyridine clusters involving halomethanes.

portada_PCCP_pyr-CH4


ISMS meeting

The International Symposium on Molecular Spectroscopy (ISMS), a landmark for the high-resolution Spectroscopy community, will move to Champaign-Urbana this year (June, 16-20). The meeting follows 68 succesful editions at the Ohio State University (Columbus, OH). Our group collaborates in five communications.

TOC caprolactone version 2

We show in the figure above two conformations observed for the floppy seven-membered ring of caprolactone.