The structure of water nanowire

The artemisinins are important antimalarials due to their efficacy against drug resistant parasites.They reduce parasitemia, fever, and coma time in patients faster than other available medications.Most artemisinins are too water insoluble for intravenous use.Sodium alpha-artesunate is water soluble and is currently used in a number of nations to treat severe malaria, but is chemically unstable in solution.beta-Artelinic acid was designed and synthesized as a chemically stable alternative to artesunate that can be formulated for intravenous use.A substantial preclinical effort is underway to develop artelinic acid for clinical use in severe malaria.Artelinic acid itself is not very water soluble and must be converted to salt form to be sufficiently water soluble.Both the crystal structure (monoclinic, P21, a=9.260Å, b=12.572,c=19.200,β =92.27º,Z=2, R1=0.065, wR2=0.176)and elemental analysis show that crystalline artelinic acid is a hemihydrate.The water molecule links two artelinic acid molecules by forming hydrogen bonds to the carboxyl group and the ring ether oxygen atom of separate molecules.QM calculations show that the most negative electrostatic potential on the surface of artelinic acid is by these oxygen atoms.The ether group conformation of the two artelinic acid molecules differs with the phenyl group either perpendicular or close to parallel with the artemisinin ring system.The perpendicular conformation is more consistent with proton nmr.The axial position of the ether group and the peroxide bond length are consistent with crystal structures of other betaartemisinins.These experimentally determined geometries are important for developing accurate computational models for studying mechanism of action and structure-activity relationships.