Abstract
The asymmetric unit of the centrosymmetric title salt solvate, 2C17H17F6N2O+· C4H4O4 2-·CH3CH2OH, (systematic name: 2-{[2,8-bis-(tri-fluoro-meth-yl)quinolin-4-yl](hy-droxy)meth-yl}piperidin-1-ium butane-dioate ethanol monosolvate) comprises two independent cations, with almost superimposable conformations and each approximating the shape of the letter L, a butane-dioate dianion with an all-trans conformation and an ethanol solvent mol-ecule. In the crystal, supra-molecular chains along the a-axis direction are sustained by charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) and ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds. These are connected into a layer via C-F⋯π(pyrid-yl) contacts and π-π stacking inter-actions between quinolinyl-C6 and -NC5 rings of the independent cations of the asymmetric unit [inter-centroid separations = 3.6784 (17) and 3.6866 (17) Å]. Layers stack along the c-axis direction with no directional inter-actions between them. The analysis of the calculated Hirshfeld surface reveals the significance of the fluorine atoms in surface contacts. Thus, by far the greatest contribution to the surface contacts, i.e. 41.2%, are of the type F⋯H/H⋯F and many of these occur in the inter-layer region. However, these contacts occur at separations beyond the sum of the van der Waals radii for these atoms. It is noted that H⋯H contacts contribute 29.8% to the overall surface, with smaller contributions from O⋯H/H⋯O (14.0%) and F⋯F (5.7%) contacts.
Highlights
Malaria continues to be a major worldwide health issue and vast populations in tropical countries, including visitors to those regions, are susceptible to the disease, which is spread by parasites such as Plasmodium falciparum (Maguire et al, 2006)
Mefloquine, [2,8-bis(trifluoromethyl)quinolin-4-yl]-piperidin-2-ylmethanol, is a drug used against malaria (Tickell-Painter et al, 2017)
Further support for proton transfer leading to the formation of piperidin-1-ium cations is supported by the pattern of hydrogen bonding involving the ammonium-N—H hydrogen atoms, as discussed below in Supramolecular features
Summary
Malaria continues to be a major worldwide health issue and vast populations in tropical countries, including visitors to those regions, are susceptible to the disease, which is spread by parasites such as Plasmodium falciparum (Maguire et al, 2006). Mefloquine, [2,8-bis(trifluoromethyl)quinolin-4-yl]-piperidin-2-ylmethanol, is a drug used against malaria (Tickell-Painter et al, 2017). The molecule contains two adjacent chiral centres, i.e. one at the carbon atom carrying the hydroxy group and one at the link connecting the piperidinyl ring to the rest of the molecule. The drug is commonly marketed as Lariam, which is the hydrochloride salt, comprising (R*,S*)-(2-{[2,8-bis(trifluoromethyl)quinolin-4-yl](hydroxymethyl)piperidin-1-ium chloride and its (S*,R*) enantiomer. While the former is effective against malaria, the latter has an affinity for the adenosine acceptors in the brain, inducing serious psychiatric and neurologic sideeffects (Nevin, 2017). Cg1 is the centroid of the (N1,C1–C4,C9) ring. Symmetry codes: (i) x À 1; y; z; (ii) Àx; Ày þ 2; Àz; (iii) Àx; Ày þ 1; Àz
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