Category Archives: New Results!

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Sparteine in PCCP

The dimer sparteine-water has been published in PCCP. Sparteine is a tetracyclic quinilizidine alkaloid used in assymetric synthesis, with two trans and cis conformations. We investigated whether addition of a water molecule flips the molecule by formation of a double hydrogen bond to the cis diamine. However, kinetic reasons explain that the cluster retains the monomer trans conformation.

In the picture below the conversion between the observed trans isomer (above) and the alternative cis isomer (below).


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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:


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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


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Ribofuranose published

An article on ribofuranose appeared in Chemical Communications last April 1. In this work we explored the conformational properties of the biologically-active five-membered ring form of ribose using its rotational signature in a jet expansion. Previous studies in the gas phase and crystal structures had shown that the isolated molecule adopts a six-membered pyranose form, strikingly different to the biological use of ribose, as in RNA. Our spectroscopic information made possible a direct comparison of the observed gas phase preferences with the crystal structures.

Figure ribofuranosa

In the figure above the two observed structures of methyl-beta-ribofuranoside and a diagram showing the puckering properties of the molecule (intramolecular hydrogen bond parameters in angstrom).

 


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New PCCP cover

New cover on PCCP! A work in collaboration with the Brooks H. Pate group in Virginia was featured as cover of PCCP in the July 28th issue. We show how transient chirality in the anesthetic sevoflurane is stabilized on formation of the dimer, as two different diastereoisomers (homochiral: left/left or right/right; heterochiral: left/right or right/left) are formed and distinguished by their spectral rotational signature. The structure of the dimers were fully resolved usign isotopic information, rendering information on the weak hydrogen bonds stabilizing the cluster.

PCCP cover sevo2sevo2


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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


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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.


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Sevoflurane···benzene

A work in collaboration with the Pate group in Virginia examined the weakly-bound cluster of sevoflurane···benzene ans was published in Angewandte Chemie. The primary interaction is a relatively strong C-H···pi hydrogen bond. The presence of additional C-H···F weak interactions hinders the six-fold symmetric internal rotation of benzene around sevoflurane. This is probably the first time that such a V6 barrier has been determined in a intermolecular complex.

sevo-benzene

 


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propofol hexamer

Category : New Results!

A large cluster or a reverse micelle: A work on the propofol hexamer led by José Andrés Fernández gets a cover in Angewandte Chemie.

               ppf6


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Phenol dimer and trimer

Category : New Results!

Rotational spectroscopy expands to larger molecules and clusters. A work in collaboration with the Pate group in Virginia reveals the structure of the phenol dimer and trimer, pinpointing the position of each atom of the cluster. The phenol trimer is a barrel-like symmetric top.

phenol2