Category Archives: Non-covalent Interactions

Serendipitous experiment

Chemistry World has informed that the group of Prof. Jens-Uwe Grabow in Hannover (Germany) recently reported a serendipitous experiment in which they observed a rare non-covalent interaction between a molecule of OCS and a Xe atom. The group was checking a microwave spectrometer when they noticed the rotational transitions from the OCS···Xe heterodimer. The original work is published in PCCP.

The PCCP TOC graphic (PCCP, 2020, 22, 5615)

Non-covalent interactions

We published in Chemistry: A European Journal a Minireview on rotational studies of non-covalent interactions, which appeared in the Reviews Showcase section of the Journal. In the article, entitled “The Hydrogen Bond and Beyond: Perspectives for Rotational Investigations of Non‐Covalent Interactions“, we emphasize how the new broadband microwave techniques have boosted the possibilities for analyzing larger clusters and weaker interactions with rotational resolution.

The forest of non-covalent interactions has more trees than expected. Read the minireview to check out why.

Aniline trimer

A rotational investigation of the aniline trimer was published in Angewandte Chemie. The work, done in collaboration with Cristobal Pérez (Hamburg) and Brooks Pate (Virginia), found three isomers of the aniline trimer and two isomers of the monohydrated dimer. The trimer is more complex than the analogue phenol trimer, where the stronger O-H···O interaction produce a single (symmetric) isomer. In the aniline trimer, stabilized by N-H···N and N-H···Pi, interactions one of the observed species is also a symmetric rotor.

The figure shows the symmetric isomer of the aniline trimer, observed in a jet expansion.

Sulfur hydrogen bonds

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.

 


Sparteine in PCCP

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).