Metal halide perovskite nanostructures hold great promises as nanoscale light sources for integrated photonics due to their excellent optoelectronic properties. However, it remains a great challenge to fabricate halide perovskite nanodevices using traditional lithographic methods because the halide perovskites can be dissolved in polar solvents that are required in the traditional device fabrication process. Herein, we report single CsPbBr nanoplate electroluminescence (EL) devices fabricated by directly growing CsPbBr nanoplates on prepatterned indium tin oxide (ITO) electrodes via a vapor-phase deposition. Bright EL occurs in the region near the negatively biased contact, with a turn-on voltage of ∼3 V, a narrow full width at half-maximum of 22 nm, and an external quantum efficiency of ∼0.2%. Moreover, through scanning photocurrent microscopy and surface electrostatic potential measurements, we found that the formation of ITO/p-type CsPbBr Schottky barriers with highly efficient carrier injection is essential in realizing the EL. The formation of the ITO/p-type CsPbBr Schottky diode is also confirmed by the corresponding transistor characteristics. The achievement of EL nanodevices enabled by directly grown perovskite nanostructures could find applications in on-chip integrated photonics circuits and systems.

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Seven new taxoids, taxezopidines B-H (1-7), have been isolated from seeds and stems of Japanese yew Taxus cuspidata Sieb. et Zucc. and the structures elucidated on the basis of spectroscopic data. Taxezopidine B (1) is the first taxoid with a double bond at C-3 and C-4.Chemical studies on constituents of different yew trees have resulted in the isolation of a large number of taxoids. 1 In our continuing search for bioactive taxoids, we previously isolated a series of new taxoids, taxuspines A-H and J-Z 2-9 and taxezopidine A, 10 from stems, leaves, and seeds of the Japanese yew Taxus cuspidata Sieb. et Zucc. (Taxaceae). Further invenstigation on extracts of seeds and stems of T. cuspidata have led to isolation of seven new taxoids, taxezopidines B-H (1-7) (Chart 1). In this paper, the isolation and structure elucidation of 1-7 are described. Results and DiscussionThe methanolic extract of seeds of T. cuspidata collected at Sapporo was partitioned between toluene and water, and then the aqueous layer was extracted with chloroform. The chloroform-soluble portion was purified by successive chromatographies on a silica gel column followed by a reversed-phase column to afford taxezopidines B (1, 0.000 25%), C (2, 0.000 52%), and D (3, 0.000 63%). Alternatively, the methanolic extract of yew stems was partitioned between toluene and water, and the toluene-soluble portions were again subjected to successive chromatographies on a silica gel column followed by reversed-phase column to afford taxezopidines E (4, 0.000 36%), F (5, 0.000 28%), G (6, 0.000 15%), and H (7, 0.000 14%) together with known taxoids, baccatin III, 11 N-methylpaclitaxel C, 12 and 10-(β-hydroxybutyryl)-10-deacetylpaclitaxel. 13 Taxezopidine B (1) was obtained as a colorless amorphous solid, and the molecular formula was established to be C 26 H 38 O 10 by HRFABMS [m/z 511.2529 (M + H) + , ∆ -1.4 mmu]. IR absorptions implied that 1 possessed hydroxy (3446 cm -1 ) and ester (1718 cm -1 ) groups. Analyses of the 1 H and 13 C NMR data and HMQC spectrum provided evidence that 1 possesses three acetyl groups, one tetrasubstituted olefin, one ketone carbon, four oxymethines, two methines, one oxymethylene, three methylenes, two quaternary carbons, one oxygenated quaternary carbon, and four methyl groups. The 1 H-1 H COSY spectrum revealed the connectivities of C-1 to C-2, C-5 to C-7, C-9 to C-10, C-12 to C-18, and C-14 to C-1. In the HMBC spectrum, long-range 1 H-13 C correlations of H 2 -14 and H 3 -18 to C-13 (δ 209.5), H-1 to C-11, H 2 -14 to C-15, H 3 -18 to C-11, and H 2 -14 to C-12 indicated that 1 possessed a cyclohexanone moiety (ring A), while the correlations of H 3 -16 and H 3 -17 to C-1, C-11, and C-15 revealed that Me-16 and Me-17 were attached at C-15. HMBC cross-peaks of H-2 to C-3, C-8, and C-15 and H-10 to C-11 and C-15 revealed the presence of an eight-membered ring (ring B), while the presence of a cyclohexene moiety with an olefin at C-3 (ring C) was deduced from HMBC correlations of H-5 to C-20, H-2 and H-20b to C-3 and C-4, and H 3 -19...