Mixed-Valent Trinuclear CoIII-CoII-CoIII Complex with 1,3-Bis(5-chlorosalicylideneamino)-2-propanol

A mixed-valent trinuclear complex with 1,3-bis(5-chlorosalicylideneamino)-2-propanol (H₃clsalpr) was synthesized, and the crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. The molecule is a trinuclear Co^III-Co^II-Co^III complex with octahedral geometries, having a tetradentate chelate of the Schiff-base ligand, bridging acetate, monodentate acetate coordination to each terminal Co³⁺ ion and four bridging phenoxido-oxygen of two Schiff-base ligands, and two bridging acetate-oxygen atoms for the central Co²⁺ ion. The electronic spectral feature is consistent with the mixed valent Co^III-Co^II-Co^III. Variable-temperature magnetic susceptibility data could be analyzed by consideration of the axial distortion of the central Co²⁺ ion with the parameters Δ = –254 cm⁻¹, λ = –58 cm⁻¹, κ = 0.93, tip = 0.00436 cm³ mol⁻¹, θ = –0.469 K, g_z = 6.90, and g_x = 2.64, in accordance with a large anisotropy. The cyclic voltammogram showed an irreversible reduction wave at approximately −1.2 V·vs. Fc/Fc⁺, assignable to the reduction of the terminal Co³⁺ ions.     

An electrically conductive metallocycle: densely packed molecular hexagons with π-stacked radicals

Electrical conduction among metallocycles has been unexplored because of the difficulty in creating electronic transport pathways. In this work, we present an electrocrystallization strategy for synthesizing an intrinsically electron-conductive metallocycle, [Ni₆(NDI-Hpz)₆(dma)₁₂(NO₃)₆]·5DMA·nH₂O (PMC-hexagon) (NDI-Hpz = N,N′-di(1H-pyrazol-4-yl)-1,4,5,8-naphthalenetetracarboxdiimide). The hexagonal metallocycle units are assembled into a densely packed ABCABC… sequence (like the fcc geometry) to construct one-dimensional (1D) helical π-stacked columns and 1D pore channels, which were maintained under the liberation of H₂O molecules. The NDI cores were partially reduced to form radicals as charge carriers, resulting in a room-temperature conductivity of (1.2–2.1) × 10⁻⁴ S cm⁻¹ (pressed pellet), which is superior to that of most NDI-based conductors including metal–organic frameworks and organic crystals. These findings open up the use of metallocycles as building blocks for fabricating conductive porous molecular materials.

Intrinsically electron-conductive metallocycle was synthesized. π-Radicals play a key role in constructing π-stacked columns among molecular hexagons and achieving high electrical conductivity over 10⁻⁴ S cm⁻¹ in polycrystalline pellet.     

On the dynamics of ferro- and antiferro-electric liquid crystals

Abstract

In this work, a set of Landau–Ginzburg equations to investigate the dynamic properties of ferro- and antiferro-electric smectic phases is formulated on the basis of the elastic continuum theory of compressible smectics. In the present framework, the polarization electric field is consistently taken into account through the Poisson equation as seen in our previous work. As a practical application, a few numerical results are presented for the surface-stabilized geometry with inclined and chevron layer structures. An asymmetric bistable switching is found to be achieved in the chevron layer structure under an alternating external field. In an inclined layer structure, however, a symmetric switching is found to be possible. In addition, it is first presented from a theoretical standpoint that the compressible smectic layer structure may be drastically deformed in the chevron and inclined layer structures with a sufficiently large external field.     

The effect of interfacial miscibility on the cell morphology of polyethylene terephthalate/bisphenol a polycarbonate blend foams

Annealing polyethylene terephthalate (PET)/polycarbonate (PC) blends enhance the transesterification reaction and increase the amount of copolymer at the interface of both polymers. The copolymer enhances the compatibility of PET with PC, because it contains both PET and PC blocks, which causes the interface between PET and PC to become fuzzy. When the PET/PC undergoes batch physical foaming with CO₂, the copolymer significantly changes the resulting cell morphology, that is, the annealing time. Before annealing or in the absence of the copolymer, bubble nucleation occurs and dominates growth at the interface. When the PET/PC blends are annealed, the interface impedes bubble nucleation and growth. The polymer is stretched at the interface by bubble growth, forming fibril‐like structures connecting two polymer domains at the interface. Increased annealing time causes the interface to become more homogeneous and makes heterogeneous bubble nucleation difficult. At higher copolymer concentrations, the interface of PET and PC becomes fuzzy and the cell morphology becomes like those of foamed homogeneous polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012