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974 results on '"Luh, Tien-Yau"'

203. Excimer Formation in a Confined Space: Photophysics of Ladderphanes with Tetraarylethylene Linkers.

Author

Chen , Chih‐Hsien, Satyanarayana, Kamani, Liu, Yi‐Hung, Huang, Shou‐Ling, Lim, Tsong‐Shin, and Luh, Tien‐Yau

Subjects
EXCIMERS, CHROMOPHORES, MONOMERS, WAVELENGTHS, POLYMERS
Abstract

Communication between chromophores is vital for both natural and non-natural photophysical processes. Spatial confinements offer unique conditions to scrutinize such interactions. Polynorbornene- and polycyclobutene-based ladderphanes are ideal model compounds in which all tetraarylethylene (TAE) linkers are aligned coherently. The spans for each of the monomeric units in these ladderphanes are 4.5-5.5 Å. Monomers do not exhibit emission, because bond rotation in TAE can quench the excited-state energy. However, polymers emit at 493 nm ( Φ=0.015) with large Stokes shift under ambient conditions and exhibit dual emission at 450 and 493 nm at 150 K. When the temperature is lowered, the emission intensity at 450 nm increases, whereas that at 493 nm decreases. At 100 K, both monomers and polymers emit only at 450 nm. This shorter-wavelength emission arises from the intrinsic emission of TAE chromophore, and the emission at 493 nm could be attributed to the excimer emission in the confined space of ladderphanes. The fast kinetics suggest diffusion-controlled formation of the excimer. [ABSTRACT FROM AUTHOR]

Published
2015
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212. Chelation-Assisted Regioselective C−O Bond Cleavage Reactions of Acetals by Grignard Reagents. A General Procedure for the Regioselective Synthesis of Protected Polyols Having One Free Hydroxy Group

Author

Cheng, Wen-Lung, primary, Shaw, Yeng-Jeng, additional, Yeh, Sue-Min, additional, Kanakamma, Puthuparampil P., additional, Chen, Yu-Huey, additional, Chen, Chuo, additional, Shieu, Jia-Cheng, additional, Yiin, Shaang-Jyh, additional, Lee, Gene-Hsiang, additional, Wang, Yu, additional, and Luh, Tien-Yau, additional

Published
1998
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233. Bisazafulleroids

Author

Shiu, Lung-Lin, primary, Chien, Kuo-Ming, additional, Liu, Tsang-Yu, additional, Lin, Tsung-I, additional, Her, Guor-Rong, additional, and Luh, Tien-Yau, additional

Published
1995
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239. Oxazolidinofullerene

Author

Shiu, Lung-Lin, primary, Chien, Kuo-Ming, additional, Liu, Tsang-Yu, additional, Lin, Tsung-I, additional, Her, Guor-Rong, additional, Huang, Shou-Ling, additional, and Luh, Tien-Yau, additional

Published
1994
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245. Oligonorbornenes with Hammock-Like Crown Ether Pendants as Artificial Transmembrane Ion Channel.

Author

Lin, Nai ‐ Ti, Xie, Chen ‐ Yu, Huang, Shou ‐ Ling, Chen, Chung ‐ Hsuan, and Luh, Tien ‐ Yau

Subjects
CROWN ethers, ION channels, CYCLOPOLYMERIZATION, LECITHIN, EGG yolk, MOIETIES (Chemistry), OLIGOMERS, CHEMICAL research
Abstract

Trimeric oligonorbornenes with hammock-like crown ether pendants 3b and 3c were selectively synthesized by cascade metathetical cyclopolymerization upon treatment with the first generation Grubbs catalyst. These crown-ether-containing oligonorbornenes are impregnated in egg yolk phosphatidylcholine (EYPC) liposome as an artificial ion channel. The efficiency of the sodium ion transport properties has been examined. Oligomer 3c having a polar hydroxy end group exhibits the highest transport efficiency, which is comparable with the best efficiencies reported in literature. The orientation of the crown ether moieties in these oligomers may be critical for the ion transport properties. [ABSTRACT FROM AUTHOR]

Published
2013
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247. Ladderphanes: A New Type of Duplex Polymers.

Author

Luh, Tien-Yau

Subjects
*POLYMERS, *CHEMICAL structure, *MACROCYCLIC compounds, *HYDROGEN bonding, *AROMATIC compounds, *DNA analysis
Abstract

A polymeric ladderphane is a step-like structure comprising multiple layers of linkers covalently connected to two or more polymeric backbones. The linkers can be planar aromatic, macrocyclic metal complexes, or three-dimensional organic or organometallic moieties. Structurally, a DNA molecule is a special kind of ladderphane, where the cofacially aligned base-pair pendants are linked through hydrogen bonding. A greater understanding of this class of molecules could help researchers develop new synthetic molecules capable of a similar transfer of chemical information. [ABSTRACT FROM AUTHOR]

Published
2013
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