Search

The effective magneto-optical properties of novel nonanuclear Tb(III) complexes with Tb-O lattice (specifically, [Tb9(sal-R)16(μ-OH)10]+NO3-, where sal-R = alkyl salicylate (R = -CH3 (Me), -C2H5 (Et), -C3H7 (Pr), or -C4H9 (Bu)) are reported. The geometrical structures of these nonanuclear Tb(III) complexes were characterized using X-ray single-crystal analysis and shape-measure calculation. Optical Faraday rotation was observed in nonanuclear Tb(III) complexes in the visible region. The Verdet constant per Tb(III) ion of the Tb9(sal-Me) complex is 150 times larger than that of general Tb(III) oxide glass. To understand their large Faraday rotation, electron paramagnetic resonance measurements of Gd(III) complexes were carried out. In this Report, the magneto-optical relation to the coordination geometry of Tb ions is discussed. [ABSTRACT FROM AUTHOR]

Here, we report the direct visualization of the assembly/disassembly processes of photoresponsive DNA origami nanostructures which can be placed on a lipid bilayer surface. The observation relies on controlled interactions between the bilayer components and cholesterol moieties introduced to the hexagonal origami structures, one of whose outer edges carries Azo-ODNs. The bilayer-placed hexagonal dimer was disassembled into monomer units by UV irradiation, and reversibly assembled again during visible light irradiation. These dynamic processes were directly monitored with high-speed atomic force microscopy. The successful application of our approach should facilitate studies of interactive and functional behaviors of various DNA nanostructures. [ABSTRACT FROM AUTHOR]

Site-specific recombination involves reciprocal exchange between defined DNA sites. The reaction initiates from the formation of a recombinase-DNA synaptic complex, in which two recombination sites arrange in an appropriate configuration. However, there is incomplete information about how the topological state of the substrate influences the synapsis and outcome of the reaction. Here, we show that Cremediated recombination can be regulated by controlling the orientation and topology of the loxP substrate in a DNA frame nanoscaffold. High-speed atomic force microscopy analyses revealed that the loxP-containing substrate strands in the antiparallel orientation can be recombined only through formation of synaptic complexes. By tethering Holliday junction (HJ) intermediates to DNA frames in different connection patterns and using them as a starting substrate, we found that the topological state of the HJ intermediates dictates the outcome of the resolution. Our approach should provide a new platform for structural-functional studies of various DNA targeting enzymes, especially which require formation of synaptic complexes. [ABSTRACT FROM AUTHOR]

A new class of oligothienoquinoidal derivatives with newly employed (acyl)cyanomethylene termini are reported. For the synthesis of (acyl)cyanomethylene-substituted thienoquinoidals, similar methods successfully employed for the synthesis of related dicyanomethylene- or ((alkyloxy)carbonyl)cyanomethylene-substituted thienoquinoidals were not applicable, and thus a new synthetic route was developed. The introduced (acyl)cyanomethylene terminal groups act both as a solublizing group to facilitate solution processability and an electron-withdrawing group to keep the LUMO energy levels sufficiently low for n-channel organic semiconductors. The LUMO energy levels estimated from their reduction potential are ∼4.2 eV below the vacuum level, which just falls in between those for the corresponding dicyanomethylene- and ((alkyloxy)carbonyl)cyanomethylene-substituted thienoquinoidals. This qualitatively agrees with the electron-withdrawing nature of the terminal groups; the order of the electron withdrawing nature is cyano- > acyl- > (alkyloxy)carbonyl- groups. Spin-coating chloroform solutions of (acyl)cyanomethylene-substituted thienoquinoidals gave homogeneous thin films on the Si/SiO2substrates, and the thin films based on the terthienoquinoidal derivatives became highly crystalline upon thermal annealing. The annealed film acted as the active semiconducting channel in the FET devices under ambient conditions, and the electron mobilities extracted from the saturation regime were ∼0.06 cm2V−1s−1. These n-channel FET characteristics are nearly the same or slightly better than those of the FETs based on the related ((alkyloxy)carbonyl)cyanomethylene-terminated terthienoquinoidal, indicating that the (acyl)cyanomethylene moiety is a useful terminal group on the thienoquinoidals for the development of soluble n-channel organic semiconductors. [ABSTRACT FROM AUTHOR]