Jon Rourke and collaborators report in ACS nano on the structural analysis of graphene oxide (GO) by transmission electron microscopy (TEM). Electron diffraction shows that on average the underlying carbon lattice maintains the order and lattice-spacings of graphene; a structure that is clearly resolved in 80 kV aberration-corrected atomic resolution TEM images. These results also reveal that single GO sheets are highly electron transparent and stable in the electron beam, and hence ideal support films for the study of nanoparticles and macromolecules by TEM. We demonstrate this through the structural analysis of physiological ferritin, an iron-storage protein. http://dx.doi.org/ 10.1021/nn900694t

The team studied the binding mode adopted by picolinamide derivatives in organometallic Os^II and Ru^II half-sandwich complexes and showed that it can lead to contrasting cancer cell cytotoxicity. N-Phenyl picolinamide derivatives (XY) in Os^II (1, 3−5, 7, 9) and Ru^II (2, 6, 8, 10) complexes [(η⁶-arene)(Os/Ru)(XY)Cl]ⁿ⁺, where arene = p-cymene (1−8, 10) or biphenyl (9), can act as N,N- or N,O-donors. Electron-withdrawing substituents on the phenyl ring resulted in N,N-coordination and electron-donating substituents in N,O-coordination. Dynamic interconversion between N,O and N,N configurations can occur in solution and is time- and temperature- (irreversible) as well as pH-dependent (reversible). The neutral N,N-coordinated compounds (1−5 and 9) hydrolyzed rapidly (t_1/2 ≤ min), exhibited significant (32−70%) and rapid binding to guanine, but no binding to adenine. The N,N-coordinated compounds 1, 3, 4, and 9 exhibited significant activity against colon, ovarian, and cisplatin-resistant ovarian human cancer cell lines (3 4 > 1 > 9). In contrast, N,O-coordinated complexes 7 and 8 hydrolyzed slowly, did not bind to guanine or adenine, and were nontoxic. http://dx.doi.org/10.1021/jm900731j

2-tert-Butyl-6-(4-fluorophenyl)pyridine reacts with K₂PtCl₄ via the activation of an sp² C−H bond to give a cyclometalated complex that contains a bifurcated agostic interaction. Rearrangement of this complex results in the activation of an sp³ C−H bond, and reaction eventually leads to a doubly cyclometalated complex where both sp² and sp³ C−H bonds have been activated. Deuterium exchange studies show that a delicate balance exists between the two cyclometalations.

http://dx.doi.org/10.1021/ja905046n