Density functional theory computations and block-localized wavefunction analyses for 57 hydrogen-bonded base pairs document excellent linear correlation between the gas-phase association energies and the degree of aromaticity gain of paired bases ( r = 0.949), challenging prevailing views of factors that underlie the proposed electronic complementarity of A·T(U) and G·C base pairs. Base pairing interactions can polarize the π-electrons of interacting bases to increase (or decrease) cyclic 4 n + 2π electron delocalization, resulting in aromaticity gain (or loss) in the paired bases, and become strengthened (or weakened). The potential implications of this reciprocal relationship for improving nucleic acid force-fields and for designing robust unnatural base pairs are discussed.
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On the reciprocal relationship between σ-hole bonding and (anti)aromaticity gain in ketocyclopolyenes
σ-Hole bonding interactions ( e.g. , tetrel, pnictogen, chalcogen, and halogen bonding) can polarize π-electrons to enhance cyclic [4 n ] π-electron delocalization ( i.e. , antiaromaticity gain) or cyclic [4 n + 2] π-electron delocalization ( i.e. , aromaticity gain). Examples based on the ketocyclopolyenes: cyclopentadienone, tropone, and planar cyclononatetraenone are presented. Recognizing this relationship has implications, for example, for tuning the electronic properties of fulvene-based π-conjugated systems such as 9-fluorenone.
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- Award ID(s):
- 1751370
- NSF-PAR ID:
- 10213904
- Date Published:
- Journal Name:
- Organic & Biomolecular Chemistry
- Volume:
- 18
- Issue:
- 27
- ISSN:
- 1477-0520
- Page Range / eLocation ID:
- 5125 to 5129
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Textbook explanations for the associations of multipoint hydrogen-bonded arrays have long hinged on the secondary electrostatic interaction (SEI) model, which suggests that array association strengths depend on the proton donor (D) and acceptor (A) patterns of the interacting units. Here, computational results based on the block-localized wavefunction (BLW) method reveal limitations of the SEI model, demonstrating instead that, in the gas-phase (and in implicit chloroform solvation), the inherent free-energies of associations of multipoint hydrogen-bonded arrays correlate with the degree of “aromaticity gain” ( i.e. , the amount of increased cyclic π-electron delocalization) in arrays upon complexation. Excellent correlations for 46 triply ( r = 0.940) and quadruply ( r = 0.959) hydrogen-bonded arrays are presented.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0OB01076F
