Publication details

Short but Weak: The Z-DNA lone-pair...Pi Conundrum Challenges Standard Carbon Van der Waals Radii



Year of publication 2020
Type Article in Periodical
Magazine / Source Angewandte Chemie International Edition
MU Faculty or unit

Faculty of Science

Keywords Naphthalenediimide; Anions; Cations
Description Current interest in lone-pair center dot center dot center dot pi (lp center dot center dot center dot pi) interactions is gaining momentum in biochemistry and (supramolecular) chemistry. However, the physicochemical origin of the exceptionally short (ca. 2.8 angstrom) oxygen-to-nucleobase plane distances observed in prototypical Z-DNA CpG steps remains unclear. High-level quantum mechanical calculations, including SAPT2 + 3 interaction energy decompositions, demonstrate that lp center dot center dot center dot pi contacts do not result from n ->pi* orbital overlaps but from weak dispersion and electrostatic interactions combined with stereochemical effects imposed by the locally strained structural context. They also suggest that the carbon van der Waals (vdW) radii, originally derived for sp(3) carbons, should not be used for smaller sp(2) carbons attached to electronwithdrawing groups. Using a more adapted carbon vdW radius results in these lp center dot center dot center dot pi contacts being no longer of the sub-vdW type. These findings challenge the whole lp center dot center dot center dot pi concept that refers to elusive orbital interactions that fail to explain short interatomic contact distances.

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