Browsing by Author "Chen, Sheng-Yuan"

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[3+2] Cycloaddition of Dialkyl (E)-Hex-2-en-4-ynedioates to [60]Fullerene by Phosphane-Promoted Tandem alpha(delta ')-Michael Additions
(2012-05-01)
Chuang, Shih-Ching
;
Deng, Jie-Cheng
;
Chan, Fu-Wei
;
Chen, Sheng-Yuan
;
Huang, Wei-Je
Organophosphanes promote the [3+2] cycloaddition reactions of dialkyl (E)-hex-2-en-4-ynedioates and [60]fullerene, giving a series of cyclopenteno-fullerenes 3ak bearing phosphorus ylides. This cycloaddition reaction is initiated by the attack of nucleophilic phosphanes at the a(d')-C atom of the dialkyl (E)-hex-2-en-4-ynedioate, which generates a 1,3-dipolar species. These 1,3-dipoles then react with C60 followed by intramolecular cyclization to give cyclopenteno-fullerenes in moderate-to-good yields. In a cyclic voltmmetry study, these novel fullerenes show a larger cathodic shift in their first reduction potential relative to [6,6]phenyl-C61 methyl butyrate, which indicates that these new derivatives possess higher LUMO energy levels.
Atomic Imaging of Molybdenum Oxide Nanowires with Unique and Complex Periodicity by Advanced Electron Microscopy
(2020-03-11)
Ting, Yi-Hsin
;
Huang, Chun-Wei
;
Yasuhara, Akira
;
Chen, Sheng-Yuan
;
Chen, Jui-Yuan
Crystalline Mo5O14 exhibits distinctive structural features such as tunnel structure and pseudolamellar arrangement according to the ideal model. However, the spatial resolution of the conventional technique of transmission electron microscopy (TEM) is insufficient to distinguish the actual positions of atoms. In this work, we aimed to systematically analyze and identify the Mo5O14 nanowires fabricated by the chemical vapor deposition (CVD) process. Utilizing high-angle annular dark-field (HAADF), annular bright-field (ABF), and enhanced annular bright-field (E-ABF) within the scanning transmission electron microscope (STEM) mode reveals the structural features at the atomic scale. In addition, the ultrahigh resolution images have confirmed the crystallographic insights in [001] growth direction for the Mo5O14 nanowires with a tunnel structure throughout the nanowire. The cross-sectional images show the unique close-packed plane and atomic arrangement with a network of MoO6 octahedra and MoO7 pentagonal bipyramids. These results are consistent with the theoretical atomic arrangement, supporting the realization of Mo5O14-type catalysts used in the selective oxidation process and battery applications.
Face-on reorientation of pi-conjugated polymers in thin films by surface-segregated monolayers
(2020-04-07)
Wang, Wei-Chih
;
Chen, Sheng-Yuan
;
Yang, Yaw-Wen
;
Hsu, Chain-Shu
;
Tajima, Keisuke
A new pi-conjugated polymer based on naphthalenediimide with a branched semifluoroalkyl side chain (FNDIT2) was synthesized and used to change the polymer orientations in thin films. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy revealed that FNDIT2 spontaneously forms surface-segregated monolayers in blend films with other pi-conjugated polymers to adopt a preferred face-on orientation, with the pi-plane of the polymer aligned more parallel to the surface. Thermal annealing of the films induced further reorientation of the polymers inside the films closer to the face-on orientation, as shown by two-dimensional grazing-incidence wide-angle X-ray scattering. The induced face-on orientations in the films led to higher charge mobility in the vertical direction. This study provides a general and versatile strategy to control the molecular orientation in thin films and enhance the performance of thin-film organic electronics.
Fullerene Derivatives Incorporating Phosphoramidous Ylide and Phosphoramidate: Synthesis and Property
(2009-07-03)
Chen, Sheng-Yuan
;
Cheng, Rai-Long
;
Tseng, Cheng-Kuo
;
Lin, Ya-Shiuan
;
Lai, Li-Hsiang
The reaction of dimethyl acetylenedicarboxylate (DMAD) with C(60) in the presence of hexamethylphosphorous triamide (HMPT) or hexaethylphosphorus triamide (HEPT) results in fullerene derivatives incorporating HMPT or HEPT ylides. The ylide derivatives exhibit unusual electronic absorptions in the visible region (435-660 nm), likely due to the presence of the ylide moiety. Electrochemical studies revealed that the first reductive potential of these compounds was more negative relative to those of both C(60) (Delta E = 130 mV) and a simple Bingel adduct (Delta E = 90 mV). A phosphoramidate side product, which resulted from the addition of HMPT or HEPT to C(60) followed by hydrolysis, exhibited a featureless absorption spectrum in the visible region and a more negative first reductive potential (Delta E = 70 mV) relative to that of C(60).