Honami Yamane

Efficient light absorbers based on thiophene-fused boron dipyrromethene (BODIPY) dyes.

We present the development of the thiophene-fused boron dipyrromethene derivatives as efficient light absorbers. The two strategies for the evolution of the optical properties such as the peak positions of absorption wavelengths and molar extinct coefficients were established by the substituent effects: by introducing iodine groups, the bathochromic shifts of the peak positions (+15 nm) and the enhancement of molar extinct coefficients were simultaneously received owing to the heavy atom effect. Next, it was found that the modification with the trifluoromethyl group contributed to the large bathochromic shift (+60 nm) because of the lowering effect on the lowest unoccupied molecular orbital of the dye by the substituent. Finally, we obtained the dyes with large molar extinct coefficients (184,140 M(-1) cm(-1) at 592 nm, 72,180 M(-1) cm(-1) at 623 nm), sharp absorption bands, and low emissions.

Preservation of main-chain conjugation through BODIPY-containing alternating polymers from electronic interactions with side-chain substituents by cardo boron structures

This manuscript describes the synthesis and electronic structures of the modified boron dipyrromethene derivatives containing cardo boron. By using organometallic reagents, the replacement of fluorine groups to aryl substituents with electron-donating groups and/or electron-withdrawing groups was accomplished, resulting in the formation of cardo boron. From the theoretical calculations and optical measurements, electronic structures in the main-chain conjugation were evaluated. In summary, it was clearly shown that cardo boron can efficiently isolate the main-chain conjugation from the electronic interaction with the side chains since the optical properties were highly preserved from the introduction of the side-chain substituents. Our findings should be fundamentally significant for the application of cardo boron-containing conjugated polymers as a scaffold to construct a multi-functional unit by the assembly of functional units.

Liquid scintillators with near infrared emission based on organoboron conjugated polymers

The organic liquid scintillators based on the emissive polymers are reported. A series of conjugated polymers containing organoboron complexes which show the luminescence in the near infrared (NIR) region were synthesized. The polymers showed good solubility in common organic solvents. From the comparison of the luminescent properties of the synthesized polymers between optical and radiation excitation, similar emission bands were detected. In addition, less significant degradation was observed. These data propose that the organoboron conjugated polymers are attractive platforms to work as an organic liquid scintillator with the emission in the NIR region.

Synthesis and color tuning of boron diiminate conjugated polymers with aggregation-induced scintillation properties

We report film-type scintillators based on conjugated polymers with aggregation-induced emission (AIE) properties and the modulation of their scintillation abilities by chemical modification. Alternating copolymers containing a series of boron diiminates with various substituents and comonomers were synthesized via the palladium-catalyzed cross-coupling reaction. The synthesized polymers showed AIE properties. In addition, the corresponding emission colors to photoluminescence were also obtained with X-ray excitation. These data suggest that the AIE-active polymers should be a promising platform for developing a function-tunable plastic scintillator.

Synthesis of a near-infrared light-absorbing polymer based on thiophene-substituted Aza-BODIPY

AbstractAn alternating conjugated polymer with thiophene-substituted aza-boron dipyrromethene (BODIPY) was synthesized in which the carbon atom at the meso-position in the ligand moiety was replaced by nitrogen. Initially, it was found that the synthesized polymer had a significant near-infrared (NIR) light-absorbing ability. In the absorption spectrum, a large absorption band (molar extinct coefficient εmax = 48,000 M−1 cm−1) with a peak at 864 nm was detected in the deep NIR region, even above 1300 nm. From cyclic voltammetry (CV) data, the energy levels of the frontier orbitals were determined. Accordingly, the polymer had a deep lowest unoccupied molecular orbital (LUMO) level (−4.01 eV), and this value was similar to that of the monomer. This result indicates that extension of π-conjugation throughout the polymer main-chain influenced only the highest occupied molecular orbital (HOMO) level while preserving the LUMO.The alternating conjugated polymer was synthesized with thiophene-substituted aza-boron dipyrromethene. The synthesized polymer had the near-infrared light-absorbing ability (molar extinct coefficient: 48,000 M−1cm−1) in the region over 1300 nm with the peak at 864 nm. From the electrochemical data, it was found that the polymer had the deep lowest unoccupied molecular orbital (LUMO) level. This result means that only the highest occupied molecular orbital level was influenced and the LUMO can be preserved by extension of π-conjugation through the polymer main-chain.

Pure-color and dual-color emission from BODIPY homopolymers containing the cardo boron structure

Versatile luminescent properties such as pure-color and dual-color emission are reported with homopolymers composed of modified boron dipyrromethene (BODIPY) involving cardo boron. By linking phenyl groups to the boron atom, the cardo structure was constructed on BODIPY, and the homopolymer was prepared via oxidation coupling. From the emission measurements, it was found that the emission band was obtained from the phenyl-bearing homopolymer in the longer wavelength region than that of the small molecule. In particular, pure-color emission, which can be represented by the narrow peak width at half height, was obtained from the polymer. Next, we modified the cardo structure with anthracene units. Optical measurements revealed that the polymer provided dual emission bands from the anthracene unit and the polymer main-chain simultaneously in the emission spectrum. It was implied that molecular motions in the excited state could be suppressed at the cardo boron in the polymer. Thus, such unique and useful luminescent behaviors were obtained from conjugated polymers.

High Surface Area, Thermally Stable, Hydrophobic, Microporous, Rigid Gels Generated at Ambient from MeSi(OEt)3/(EtO)3SiCH2CH2Si(OEt)3 Mixtures by F−-Catalyzed Hydrolysis

High surface area materials are of considerable interest for gas storage/capture, molecular sieving, catalyst supports, as well as for slow-release drug-delivery systems. We report here a very simple and fast route to very high surface area, mechanically robust, hydrophobic polymer gels prepared by fluoride-catalyzed hydrolysis of mixtures of MeSi(OEt)3 and bis-triethoxysilylethane (BTSE) at room temperature. These materials offer specific surface areas up to 1300 m2  g-1 , peak pore sizes of 0.8 nm and thermal stabilities above 200 °C. The gelation times and surface areas can be controlled by adjusting the solvent volume (dichloromethane), percent fluoride (as nBu4 NF or TBAF) and the BTSE contents. Polymers with other corners and linkers were also explored. These materials will further expand the materials databank for use in vacuum insulation panels and as thermally stable release and capture media.