Browsing by Author "Tasi, Cheng-Hsun"

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Light Fluorous-Tagged Traceless One-Pot Synthesis of Benzimidazoles Facilitated by Microwave Irradiation
(2012-06-01)
Tseng, Chih-Chung
;
Tasi, Cheng-Hsun
;
Sun, Chung-Ming
;
應用化學系
;
Department of Applied Chemistry
A novel protocol for rapid assemble of benzimidazole framework has been demonstrated. This method incorporated with light fluorous-tag provides a convenient method for diversification of benzimidazoles and for easy purification via fluorous solid-phase extraction (F-SPE) in a parallel manner. The key transformation of this study involves in situ reduction of aromatic nitro compound, amide formation, cyclization and aromatization promoted by microwave irradiation in a one-pot fashion. The strategy is envisaged to be applied for the establishment of drug-like small molecule libraries for high throughput screening.
Nanoindentation pop-in effects of Bi2Te3 thermoelectric thin films
(2015-02-15)
Jian, Sheng-Rui
;
Tasi, Cheng-Hsun
;
Huang, Shiau-Yuan
;
Luo, Chih-Wei
;
電子物理學系
The structural, surface morphological and nanomechanical characteristics of Bi2Te3 thin films are investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques. The Bi2Te3 thin films are deposited on c-plane sapphire substrates using pulsed laser deposition (PLD). The XRD result showed that Bi2Te3 thin film had a c-axis preferred orientation and a smoother surface feature from AFM observation. Nanoindentation results exhibit the discontinuities (so-called multiple "pop-ins" event) in the loading segments of the load-displacement curves, indicative of the deformation behavior in the hexagonal-structured Bi2Te3 thin film is the nucleation and propagation of dislocations. Based on this scenario, an energetic estimation of nanoindentation-induced dislocation resulted from pop-in effects is made. Furthermore, the hardness and Young\'s modulus of Bi2Te3 thin films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode. The obtained values of the hardness and Young\'s modulus are 5.7 +/- 0.8 GPa and 158.6 +/- 6.2 GPa, respectively. (C) 2014 Elsevier B.V. All rights reserved.
Nanomechanical properties of Bi2Te3 thin films by nanoindentation
(2015-01-15)
Tasi, Cheng-Hsun
;
Tseng, Yu-Chin
;
Jian, Sheng-Rui
;
Liao, Ying-Yen
;
Lin, Chih-Ming
In this study, the microstructural, morphological and nanomechanical properties of Bi2Te3 thin films are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nanoindentation techniques. The Bi2Te3 thin films were deposited on c-plane sapphire substrates using pulsed laser deposition (PLD) under the various helium gas pressures. The XRD results indicated that the Bi2Te3 thin films are textured with the c-axis preferentially oriented normal to the films surface. Both the grain size and surface roughness of the Bi2Te3 thin films exhibit an increasing trend with increasing the helium gas pressure. Furthermore, the hardness and Young\'s modulus of the Bi2Te3 thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode were found to range from 2.92 +/- 0.12 to 4.02 +/- 0.14 GPa and from 106.31 +/- 0.63 to 127.46 +/- 9.21 GPa, respectively, when the helium gas pressure was increased from 2 x 10(-5) to 2 x 10(-3) Torr. (C) 2014 Elsevier B.V. All rights reserved.
Traceless polymer-supported divergent synthesis of quinoxalinones by microwave irradiation
(2012-05-06)
Shen, Chien-Hung
;
Tseng, Chih-Chung
;
Tasi, Cheng-Hsun
;
Shintre, Suhas A.
;
Chen, Li-Hsun
A novel protocol for rapid assemble of quinoxalinones framework has been demonstrated. This method incorporated with soluble polymer support provides a convenient approach for diversification of heterocyclic compounds and for easy purification via facile precipitation from reaction matrix. The key transformation of this study involves in situ reduction of aromatic nitro compound, tandem lactamization concomitant with traceless cleavage of the polymer support under microwave irradiation in a one-pot fashion. Moreover, forward synthetic routes were introduced to maximize complexity of the master intermediate on which further chemical elaboration was applied. The strategy is envisaged to apply for establishment of drug-like small-molecule libraries for high-throughput screening. (C) 2012 Elsevier Ltd. All rights reserved.
Traceless polymer-supported divergent synthesis of quinoxalinones by microwave irradiation
(2012-05-06)
Shen, Chien-Hung
;
Tseng, Chih-Chung
;
Tasi, Cheng-Hsun
;
Shintre, Suhas A.
;
Chen, Li-Hsun
A novel protocol for rapid assemble of quinoxalinones framework has been demonstrated. This method incorporated with soluble polymer support provides a convenient approach for diversification of heterocyclic compounds and for easy purification via facile precipitation from reaction matrix. The key transformation of this study involves in situ reduction of aromatic nitro compound, tandem lactamization concomitant with traceless cleavage of the polymer support under microwave irradiation in a one-pot fashion. Moreover, forward synthetic routes were introduced to maximize complexity of the master intermediate on which further chemical elaboration was applied. The strategy is envisaged to apply for establishment of drug-like small-molecule libraries for high-throughput screening. (C) 2012 Elsevier Ltd. All rights reserved.