Posts Tagged ‘Potential theory’

A record polarity for a neutral compound?

Friday, April 13th, 2018

In several posts a year or so ago I considered various suggestions for the most polar neutral molecules, as measured by the dipole moment. A record had been claimed[cite]10.1002/anie.201508249[/cite] for a synthesized molecule of ~14.1±0.7D. I pushed this to a calculated 21.7D for an admittedly hypothetical and unsynthesized molecule. Here I propose a new family of compounds which have the potential to extend the dipole moment for a formally neutral molecule up still further.

(more…)

The dipole moments of highly polar molecules: glycine zwitterion.

Saturday, December 24th, 2016

The previous posts produced discussion about the dipole moments of highly polar molecules. Here to produce some reference points for further discussion I look at the dipole moment of glycine, the classic zwitterion (an internal ion-pair).

(more…)

A molecular balance for dispersion energy?

Sunday, February 7th, 2016

The geometry of cyclo-octatetraenes differs fundamentally from the lower homologue benzene in exhibiting slow (nuclear) valence bond isomerism rather than rapid (electronic) bond-equalising resonance. In 1992 Anderson and Kirsch[cite]10.1039/P29920001951[/cite] exploited this property to describe a simple molecular balance for estimating how two alkyl substituents on the ring might interact via the (currently very topical) mechanism of dispersion (induced-dipole-induced-dipole) attractions. These electron correlation effects are exceptionally difficult to model using formal quantum mechanics and are nowadays normally replaced by more empirical functions such as Grimme's D3BJ correction.[cite]10.1002/jcc.21759[/cite] Here I explore aspects of how the small molecule below might be used to investigate the accuracy of such estimates of dispersion energies.

(more…)