Indolizino[5,6-b]quinoxaline Derivatives: Intramolecular Charge Transfer Characters and NIR Fluorescence.

Indolizino[5,6-b]quinoxaline derivatives (1 a and 1 b) with a push-pull structure were prepared to show intramolecular charge-transfer properties. Compounds 1 a and 1 b are strongly fluorescent in aprotic solvents while symmetrical derivatives (2 a and 2 b) were non-fluorescent. The π-expanded α-α linked dimer (10) of indolizino[5,6-b]quinoxaline 1 b was serendipitously obtained to show NIR absorption over 800 nm and the fluorescence edge reached to 1400 nm.

An optically and thermally switchable electronic structure based on an anthracene-BODIPY conjugate.

An optically and thermally responsive boron dipyrromethene (BODIPY) dye, namely, meso-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dione) (DK)-linked, bicyclo[2.2.2]octadiene (BCOD)-fused BODIPY (BCOD-DK), was synthesized. The weakly luminous structure of BCOD-DK can be changed quantitatively to that of the strongly fluorescent BODIPY BCOD-Ant by optical excitation at the DK unit, which induces double decarbonylation of the DK unit to give an anthracene unit. The solvent effect on the fluorescence properties of BCOD-DK suggests that the dramatic change in fluorescence intensity is controlled by intramolecular electron transfer from the BODIPY moiety to the meso-DK substituent. BCOD-DK is converted to meso-DK benzene-fused BODIPY (Benzo-DK) by heating at 220 °C with 64-70 nm redshift of absorption and fluorescence peaks without changing the fluorescence quantum yield of ΦF =0.08 in dichloromethane. Benzo-DK can be converted to strongly fluorescent meso-anthracene benzene-fused BODIPY Benzo-Ant by optical excitation. Thus, BCOD-DK can show four different optical performances simply by irradiation and heating, and hence may be applicable for optical data storage and security data encryption.

9,9'-Anthryl-anthroxyl radicals: strategic stabilization of highly reactive phenoxyl radicals.

Stable 9,9'-anthryl-anthroxyl radicals were synthesized and isolated, and the structures were fully characterized by single crystal X-ray diffraction analysis and ESR measurement. The resonance structure and steric protection of the peripheral positions and the most reactive 9-position of anthracene prolong the half-life of the radical in solution to 11 days.

Solution-processed anthradithiophene-PCBM p-n junction photovoltaic cells fabricated by using the photoprecursor method.

P-n junction solar cells based on anthradithiophene (ADT) as a p-type semiconductor were fabricated by using the photoprecursor method in which an α-diketone-type precursor was spin-coated and then transformed to ADT in situ by photoirradiation. Combination with PC71BM as an n-layer material led to 1.54% photoconversion efficiency.

In situ preparation of highly fluorescent pyrene-dyes from non-luminous precursors upon photoirradiation.

The non-luminous precursor, 2-(1-pyrenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dione, was photochemically converted to highly-fluorescent 2-(1-pyrenyl)anthracene quantitatively in solution and in the PMMA film and the fluorescence quantum yield of the acene in benzonitrile was as high as 0.99.

FET performance and substitution effect on 2,6-dithienylanthracene devices prepared by photoirradiation of their diketone precursors.

Hole mobility was evaluated by top-contact bottom gate field effect transistor and time resolved microwave conductivity measurements in 2,6-dithienylanthracene and hexyl-substituted 2,6-dithienylanthracene films prepared by spin-coating of their α-diketone precursors followed by photoirradiation, revealing enough high potentials for semiconducting films with charge carrier mobilities of 0.8-0.9 cm(2) V(-1) s(-1) in the photo-irradiated films.