What can tell the quantum chemical topology on carbon–astatine bonds?

ABSTRACT

The nature of carbon–astatine bonds involved in some model species that mimic ²¹¹At-labelled biomolecules, was investigated by means of ELF and QTAIM analyses in a context of two-component relativistic computations. The nature of the bonded carbon atom proved to be decisive. When At is bonded to an ethynyl group, some charge delocalisation with the vicinal triple C–C bond strengthens the At–C bond and gives it a multiple bond character. However, At displays also a large positive charge which may alter the in vivo stability of such At–C bonds. In the case of an isopropyl group, the At–C bond is less polarised but also much weaker. In contrast, the bond remains strong whilst retaining a small At positive charge when At is bonded to an sp² carbon atom. Hence, these latter results rationalise why aromatic or aryl groups appear reasonably suited for a priori stable radiolabelling of biomolecules with ²¹¹At in the context of alpha therapy.

GRAPHICAL ABSTRACT

Keywords:

• QTAIM
• ELF
• topological analysis
• quantum chemical topology
• relativistic effects
• astatine
• radiolabelling

Acknowledgments

The authors would like to dedicate this article to Prof Andreas Savin on the occasion of his 65th birthday.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by grants funded by the French National Agency for Research [grant number ANR-2010-BLAN-0807], with ‘Investissements d'Avenir’ [grant number ANR-11-EQPX-0004, ANR-11-LABX-0018]. It was carried out using HPC resources from GENCI-CINES/IDRIS [grant number 2015-c2015085117]; CCIPL (‘Centre de Calcul Intensif des Pays de la Loire’)