Metal-Dependent Cytotoxic and Kinesin Spindle Protein Inhibitory Activity of Ru, Os, Rh, and Ir Half-Sandwich Complexes of Ispinesib-Derived Ligands

Ispinesib is a potent inhibitor of kinesin spindle protein (KSP), which has been identified as a promising target for antimitotic anticancer drugs. Herein, we report the synthesis of half-sandwich complexes of Ru, Os, Rh, and Ir bearing the ispinesib-derived N,N-bidentate ligands (R)- and (S)-2-(1-amino-2-methylpropyl)-3-benzyl-7-chloroquinazolin-4(3H)-one and studies on their chemical and biological properties. Using the enantiomerically pure (R)- and (S)-forms of the ligand, depending on the organometallic moiety, either the SM,R or RM,S diastereomers, respectively, were observed in the molecular structures of the Ru- and Os(cym) (cym = η6-p-cymene) compounds, whereas the RM,R or SM,S diastereomers were found for the Rh- and Ir(Cp*) (Cp* = η5-pentamethylcyclopentadienyl) derivatives. However, density functional theory (DFT) calculations suggest that the energy difference between the diastereomers is very small, and therefore a mixture of both will be present in solution. The organometallics exhibited varying antiproliferative activity in a series of human cancer cell lines, with the complexes featuring the (R)-enantiomer of the ligand being more potent than the (S)-configured counterparts. Notably, the Rh and Ir complexes demonstrated high KSP inhibitory activity, even at 1 nM concentration, which was independent of the chirality of the ligand, whereas the Ru and especially the Os derivatives were much less active

LaSeTe₂-Temperature Dependent Structure Investigation and Electron Holography on a Charge-Denstiy-Wave-Hosting Compound

Single crystals of LaSeTe2 have been prepared by reaction of the elements in a LiCl/RbCl flux at 970 K for seven days. Satellite reflections observed in diffraction experiments indicate the presence of an incommensurate lattice distortion, which is of the charge-density-wave (CDW) type. The modulated structure has been solved from X-ray data at 173, 293, and 373 K. LaSeTe2 crystallizes in the 3+1-dimensional orthorhombic superspace group Cmcm(00γ)s00 (No. 63.2) with lattice parameters of a = 4.295(1), b = 25.371(4), c = 4.306(1) Å (173K), a = 4.297(1), b = 25.408(4), c = 4.309(1) Å (293 K), and a = 4.309(1), b = 25.481(6), c = 4,321(1) Å (373 K). The modulation vector q = (0, 0, 0.288) does not change over the temperature interval. Electron holographic investigations confirm the existence of the modulation and help to visualize the charge-density wave

Structure of BiRe2O6 re-investigated using single-crystal neutron Laue diffraction

Single crystals of BiRe 2 O 6 of typical volume 0.03 mm 3 were grown by chemical vapor transport and characterized using room-temperature single-crystal neutron diffraction in monoclinic C 2/ c symmetry with cell parameters a = 16.1178(11), b = 4.9235(3), c = 5.5278(3) Ã… and β = 92.475(5) ° ( R all = 11.39 wR all = 7.97). The structure contains ordered layers of corner sharing units of Re 2 O 10 with Re-Re distances of 2.519(1) Ã…. The unit cell is doubled along c in comparison to previous studies based on X-ray diffraction data where the layer stacking was described as disorderd. © 2010, Insitute of Physics