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Orbital interactions and charge redistribution in weak hydrogen bonds: Watson–Crick GC mimic involving CH proton donor and F proton acceptor groups
Author(s) -
Guerra Célia Fonseca,
Baerends Evert Jan,
Bickelhaupt F. Matthias
Publication year - 2006
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.21039
Subject(s) - chemistry , steric effects , hydrogen bond , thymine , computational chemistry , ab initio , molecular orbital , crystallography , density functional theory , hydrogen , proton , stereochemistry , molecule , dna , organic chemistry , biochemistry , physics , quantum mechanics
The discovery by Kool and coworkers that 2,4‐difluorotoluene (F) mimics thymine (T) in DNA replication has led to controversy regarding the question of whether this mimic has the capability of forming hydrogen bonds with adenine (A). Recently, we have provided evidence for an important role of both hydrogen bonding and steric effects in the replication of DNA. In the present work, we extend our study to mimics (G FC′N′ and C N′NF ) of the bases guanine (G) and cytosine (C). We address not only the question of the strengths of the hydrogen bonds in G FC′N′ C N′NF as compared with those in GC but we focus in particular on the nature of these interactions. Thus, we have analyzed G FC′N′ C N′NF and GC at the BP86/TZ2P level of density functional theory (DFT). In line with previous experience, this approach is shown to achieve close agreement with the available data from ab initio computations and experiment: the complexation energy of G FC′N′ C N′NF (‐4.1 kcal/mol) is confirmed to be much weaker indeed than that of GC (‐26.1 kcal/mol). Interestingly, the weak hydrogen bonds in G FC′N′ C N′NF still poses a significant orbital interaction component that resembles the situation for the more strongly bound GC, as follows from (1) an analysis of the orbital electronic structure of G FC′N′ C N′NF and GC, (2) a quantitative decomposition of the G FC′N′ C N′NF and GC bond energies, as well as (3) a quantitative decomposition of the charge redistribution associated with the G FC′N′ C N′NF and GC interactions based on the Voronoi deformation density (VDD) method. The VDD method allows us to decompose the charge redistribution Δ Q per atom into a component associated with the Pauli repulsive orbital interactions and a component associated with the bonding orbital interactions: Δ Q = Δ Q Pauli + Δ Q oi . Implications of our findings for the mechanism of DNA replication are discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006