Category Archives: New Results!

Sulfur hydrogen bonds

Category : Hydrogen Bonding , MW Spectroscopy , New Results! , Non-covalent Interactions

Hydrogen bonds (HBs) involving sulfur are considered much weaker than those of more electronegative atoms. We recently published a comparison between the HBs in the furfuryl mercaptan – water dimer and compared the HBs with those in furfuryl alcohol. The investigation was published in Chemistry – A European Journal. and highlighted in the Journal cover.

The cover below shows a 3D map of electronegativity along the periodic table and the observed dimers.

 

Pseudopelletierine in CEJ

Category : Alkaloids , Molecular Structure , MW Spectroscopy , New Results!

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.

 

Sparteine in PCCP

Category : Alkaloids , Hydrogen Bonding , Microsolvation , New Results! , Non-covalent Interactions , Publications

The dimer sparteine-water has been highlighted as cover of PCCP and part of “2017 PCCP HOT Articles“. Sparteine is a tetracyclic quinolizidine 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 used in metal complexation. Kinetic reasons explain that the cluster retains the monomer trans conformation.

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

Cotinine in Chemistry News

Category : Molecular Structure , New Results! , Nicotinoids , Publications

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

Category : Group News , Molecular Structure , MW Spectroscopy , New Results!

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

Ribofuranose published

Category : New Results! , Ring puckering

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).

 

New PCCP cover

Category : Dispersive interactions , MW Spectroscopy , New Results! , Publications , Weak Hydrogen Bonds

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

PCCP cover

Category : Dispersive interactions , Intermolecular Clusters , Molecular Structure , New Results! , Weak Hydrogen Bonds

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

Category : Group News , Molecular Structure , MW Spectroscopy , New Results! , Ring puckering

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.

Sevoflurane···benzene

Category : Intermolecular Clusters , Molecular Structure , MW Spectroscopy , New Results! , Weak Hydrogen Bonds

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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Online: 2010|Updated: 2017