Boron dipyrromethenes (BODIPYs) with bulky triphenylsilylphenyl(ethynyl) and triphenylsilylphenyl substituents on pyrrole sites were prepared via Hagihara-Sonogashira and Suzuki-Miyaura cross-coupling with ethynyl-terminated tetraphenylsilane and boronic acid-terminated tetraphenylsilane. The chromophores are designed to prevent intermolecular π-π stacking interaction and enhance fluorescence in the solid state. Single crystals of 1 a and 2 b for X-ray structural analysis were obtained, and weak π-π stacking interactions of the neighboring BODIPY molecules were observed. Spectroscopic properties of all of the dyes in various solvents and in films were investigated. Triphenylsilylphenyl-substituted BODIPYs generally show more pronounced increases in solid-state emission than triphenylsilylphenyl(ethynyl)-substituted BODIPYs. Although the simple BODIPYs do not exhibit any fluorescence in the solid state (Φ=0), arylsilyl-substituted BODIPYs exhibit weak to moderate solid-state fluorescence with quantum yields of 0.03, 0.07, 0.10, and 0.25. The structure-property relationships were analyzed on the basis of X-ray crystallography, optical spectroscopy, cyclic voltammetry, and theoretical calculations.

In this study, we report a feasible strategy for fabricating high-dielectric-constant polymer composites for applications in energy storage devices and embedded capacitors. Hierarchical flower-like TiO2 particles were prepared via a facile solvothermal process and incorporated into the P(VDF-HFP) matrix. The temperature and frequency dependent dielectric properties of flower-like TiO2/P(VDF-HFP) composites as well as commercial TiO2/P(VDF-HFP) composites were investigated. The results reveal that the flower-like TiO2 particles are more effective in increasing the dielectric constant of P(VDF-HFP) when compared with commercial TiO2. Typically, the dielectric constant of the P(VDF-HFP) composite filled with 20 vol % flower-like TiO2 reaches 83.1 at 100 Hz, in contrast to 43.4 for the composite filled with 20 vol % commercial TiO2 and 11.3 for pristine P(VDF-HFP). Also, the flower-like TiO2-filled composites exhibit similar characteristic breakdown strengths to their commercial TiO2-filled counterparts. The significant improvement in the dielectric constant could be attributed to the enhancement of Maxwell-Wagner-Sillars polarization, which originates from the sophisticated morphology of flower-like TiO2 particles.

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The synthesis of a series of 1,2‐diamino‐o‐carboranes (1–4) is reported. The molecular structures of these diamino‐o‐carboranes are remarkable as the inner‐cluster C−C bonds are all ultra‐long (162.7–193.1 pm) and vary substantially with small variations in the substituents. The results of quantum mechanical investigations suggest that the origin of the bond elongation is significant in‐plane negative hyperconjugation of lone pairs of the nitrogen substituents with the σ* orbitals of the C−C bonds in o‐carboranes.