Browsing by Author "Chu, Jean-Ho"

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Biscalix[4]arene Derivative As a Very Efficient Phase Selective Gelator for Oil Spill Recovery
(2013-11-15)
Tsai, Chia-Chen
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Cheng, Ying-Tsai
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Shen, Li-Ching
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Chang, Kai-Chi
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Ho, I-Ting
A biscalixarene framework, without long alkyl chains, has been readily synthesized in three steps starting from the parent calix[4]arene. The biscalix[4]arene 1 was able to form organogels in various alcoholic solvents; furthermore, it exhibited an excellent phase selective gelation property that is potentially useful in oil spill recovery.
Calix[4]arene with Lower-Rim beta-Amino alpha,beta-Unsaturated Ketones Containing Bis-Chelating Sites as a Highly Selective Fluorescence Turn-On Chemosensor for Two Copper(II) Ions
(2011-03-01)
Ho, I-Ting
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Chu, Jean-Ho
;
Chung, Wen-Sheng
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應用化學系
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Department of Applied Chemistry
We report herein the synthesis of a fluorescence turn-on chemosensor, 25,27-bis{N-[1-(4-{[4-amino-4-(1-naphthyl)-2oxo- 3-butenyl]oxy}phenyl)aminocarbonyl]methoxy}-26,28-dihydroxycalix[4]arene (3b), which is highly selective toward Cu(2+). The fluorescence intensity of 3b was enhanced upon adding [Cu(ClO(4))(2)], which reached a maximum with approximately 4 equiv. of Cu(2+) but then started to decrease in intensity at higher Cu(2+) concentrations. Job plot experiments revealed a 1:2 binding stoichiometry of 3b with Cu(2+). Based on (1)H NMR titration results, we infer that there are two possible binding sites for Cu(2+) in 3b: one at the lower-rim phenolic-OH and amide groups, and the second at the beta-amino alpha,beta-unsaturated ketone groups. It is important to note that during the complexation of 3b with [Cu(ClO(4))(2)], the Cu(2+) ions were reduced to Cu(+) by both the phenolic OH and the amines of the beta-amino alpha,beta-unsaturated ketones. Furthermore, control compounds 6 and 9b were synthesized to clarify the possible binding sites of Cu(2+) in 3b. By comparing the binding constants of 3b, 6, and 9b with Cu(2+), we found that 3b exhibited a positive allosteric behavior toward the coordination of two Cu(2+) ions.
Evolution of nano- to microsized spherical assemblies of fluorogenic biscalix[4]arenes into supramolecular organogels
(2013)
Tsai, Chia-Chen
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Chang, Kai-Chi
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Ho, I-Ting
;
Chu, Jean-Ho
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Cheng, Ying-Tsai
A biscalix[4]arene (1) capable of spontaneous self-assembly into nanoparticles and microspheres in CH3CN was serendipitously observed, and it eventually formed stable blue-light emitting supramolecular organogels.
Regioselectivity in the 1,3-dipolar cycloaddition of adamantylidenefulvene and its modification by inclusion in cyclodextrins' solutions
(2006-07-31)
Chu, Jean-Ho
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Li, Wan-Sheung
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Chao, Ito
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Lee, Gene-Hsiang
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Chung, Wen-Sheng
The 1,3-dipolar cycloaddition of adamantylidenefulvene (1) with 2 equiv of nitrile oxides 2a-d gave 1/1 cycloadducts, 3a-d and 4a-d, as the major products, and four other 1/2 minor cycloadducts 5-8a,b. The ratios of 1/1 cycloadducts 3a-d to 4a-d in THF solution were about 1/1 in the four different nitrile oxides 2a-d studied and microwave was found to accelerate the reactions and enhance their yields. It is noteworthy that the regioselectivity of 3a/4a was enhanced to 71/29 in beta-cyclodextrin (beta-CD) aqueous solution compared to that of 40/60 in the absence of P-CD. The regioselectivity of 3b/4b was further enhanced to 99/1 when 4-tert-butylphenyl hydroximinoyl chloride (9b) was complexed with beta-CD and then proceeded to react with 1; this is in sharp contrast with that of 33/67 in the absence of beta-CD. The binding constant of 1 center dot beta-CD in acetone-d(6)/D2O (1/1) was determined to be 188 +/- 9 M-1 by H-1 NMR titration experiments. The binding mode of 1 center dot beta-CD was further determined by ROESY experiment. Furthermore, molecular dynamic simulations were carried out to provide information of the complexation modes of 1 center dot beta-CD, 3a center dot beta-CD, 4a center dot beta-CD, 9a center dot beta-CD, and 9b center dot beta-CD. It was found that both steric and electrostatic effects play important roles in determining the regio- and stereochemistry of 1,3-dipolar cycloaddition of 1. Finally, beta-CD is shown to serve as a chiral shift reagent to differentiate the enantiomers of 4a in H-1 NMR. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis of 9,10-Bis-ketoenaminoanthryl and 9,10-Bisi-isoxazolylanthryl Linked Biscalix[4]arenes: Atropisomers and Molecular Recognitions
(2012-03-02)
Tsai, Chia-Chen
;
Ho, I-Ting
;
Chu, Jean-Ho
;
Shen, Li-Ching
;
Huang, Shou-Ling
An efficient synthetic pathway for the synthesis of biscalix[4]arenes 5-10 using 1,3-dipolar cycloaddition reactions is reported. Biscalix[4]arene 10 is capable of forming a complex with methyl viologen because of favorable cation-pi interactions and a proper cavity size to accommodate the guest. Moreover, biscalix[4]arenes 8a and 8b were found to be atropisomers at room temperature. These two conformers were unable to exchange at room temperature because of the restricted rotation of the C-9-C-11 or C-10-C-12 bonds of the beta-amino-alpha,beta-unsaturated ketones of anthracene.