Adenine as a Halogen Bond Acceptor: A Combined Experimental and DFT Study

Yannick Roselló,Miquel Barceló-Oliver,Elies Molins,Mónica Benito,Antonio Frontera

doi:10.3390/cryst9040224

Yannick Roselló, Miquel Barceló-Oliver + Show 3 more

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https://doi.org/10.3390/cryst9040224

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Abstract

In this work, we report the cocrystallization of N9-ethyladenine with 1,2,4,5-tetrafluoro-3,6-diiodobenzene (TFDIB), a classical XB donor. As far as our knowledge extends, this is the first cocrystal reported to date where an adenine derivative acts as a halogen bond acceptor. In the solid state, each adenine ring forms two centrosymmetric H-bonded dimers: one using N1···HA6–N6 and the other N7···HB6–N6. Therefore, only N3 is available as a halogen bond acceptor that, indeed, establishes an N···I halogen bonding interaction with TFDIB. The H-bonded dimers and halogen bonds have been investigated via DFT (Density Functional Theory) calculations and the Bader’s Quantum Theory of Atoms In Molecules (QTAIM) method at the B3LYP/6-311+G* level of theory. The influence of H-bonding interactions on the lone pair donor ability of N3 has also been analyzed using the molecular electrostatic potential (MEP) surface calculations.

Highlights

IntroductionHydrogen bonding (HB) is often the predominant interaction and a common tool in supramolecular chemistry and crystal engineering [2]
Non-covalent interactions are crucial in regulating how molecules interact with one another [1].Hydrogen bonding (HB) is often the predominant interaction and a common tool in supramolecular chemistry and crystal engineering [2]
Interactions involving halogens are known as halogen bonding (XB) [9]

Summary

Introduction

Hydrogen bonding (HB) is often the predominant interaction and a common tool in supramolecular chemistry and crystal engineering [2]. A σ-hole is usually defined as an electropositive potential along the vector of a covalent bond. It is located at the σ* orbital of that bond [5,6]. Such σ-holes are commonly found on non-metals such as tetrel, pnicogen, and chalcogen and halogen atoms [5,7,8]. The halogen-bonding interaction has been used in supramolecular chemistry, catalysis, and crystal engineering [9]. The biological significance of halogen bonding was demonstrated in

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Discussion

Conclusion