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Short but Weak: The Z‐DNA Lone‐Pair⋅⋅⋅π Conundrum Challenges Standard Carbon Van der Waals Radii
Author(s) -
Kruse Holger,
Mrazikova Klaudia,
D'Ascenzo Luigi,
Sponer Jiri,
Auffinger Pascal
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202004201
Subject(s) - lone pair , van der waals force , chemistry , context (archaeology) , van der waals radius , crystallography , supramolecular chemistry , chemical physics , carbon fibers , atomic physics , molecular physics , physics , quantum mechanics , materials science , molecule , crystal structure , paleontology , composite number , composite material , biology
Current interest in lone‐pair⋅⋅⋅π (lp⋅⋅⋅π) interactions is gaining momentum in biochemistry and (supramolecular) chemistry. However, the physicochemical origin of the exceptionally short (ca. 2.8 Å) 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⋅⋅⋅π contacts do not result from n→π* 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 electron‐withdrawing groups. Using a more adapted carbon vdW radius results in these lp⋅⋅⋅π contacts being no longer of the sub‐vdW type. These findings challenge the whole lp⋅⋅⋅π concept that refers to elusive orbital interactions that fail to explain short interatomic contact distances.