Supramolecular chirality-sensing DNA-mimicry of a norbornane derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring

Abstract

The molecular and crystal structure of a norbornane derivative decorated with isoxazoline and methyl-pyrolidine-2,5-dione ring, C19H20N2O5, were determined and characterized by single crystal X-ray diffraction and spectroscopic methods. Details of the molecular geometry having six stereogenic centers reveal that there are two enantiomeric forms in the crystal structure of the compound, S- and R-enantiomer named with respect to the majority of chiral centers. The same type enantiomers are used as building blocks in formation of noncovalent helices by weak C-H center dot center dot center dot O and C-H center dot center dot center dot N type H-bonds. While S-enantiomers form P-helix, R-enantiomers take part in the formation of M-helix. The intertwined P- and M-helices, yielding from supramolecular chirality of the compound, are interconnected by weak C-H center dot center dot center dot O type H-bonds. Thus, mixed-handed noncovalent DNA mimicry of the compound contrary to natural pure-handed DNA forms is established. The presence of weak H-bonds allowing DNA mimicry of the compound in a noncovalent manner is verified by QTAIM and Hirshfeld surface analyses. To the best of our knowledge, norbomane derivative examined here is the first example of noncovalent DNA-mimetic based on an unnatural organic small molecule. The stability level of the H-bonded helices of the compound is comparable to those of helical peptide chains, approximately half of their stabilities. (C) 2013 Elsevier B.V. All rights reserved.