Browsing by Author "Senthilvelan, Annamalai"

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A novel photoinduced ring opening and isomerization of adamantane-2-spiro isoxazolines using MO(CO)(6)
(2006-10-02)
Senthilvelan, Annamalai
;
Lee, Gene-Hsiang
;
Chung, Wen-Sheng
;
應用化學系
;
Department of Applied Chemistry
The MO(Co)(6)-mediated photoinduced ring-opening reactions of adamantane isoxazolines involve novel rearrangement that provide enaminoketones as major products and beta-hydroxy ketones as minor ones; in contrast, only beta-hydroxy ketones and alpha,beta-unsaturated ketones were obtained under thermal condition. (c) 2006 Elsevier Ltd. All rights reserved.
Capping the upper and lower rims of calix[4]arenes by aryl dinitrile oxide reactions
(2006-11-20)
Shiao, Ya-Jiun
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Chiang, Pei-Chen
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Senthilvelan, Annamalai
;
Tsai, Ming-Tsung
;
Lee, Gene-Hsiang
1, 3-Dipolar cycloadditions of upper- and lower-rim diallylcalix[4]arenes (1 and 3) with aryl dinitrile oxides provide a unique and efficient way of capping the calix[4]arenes. When dinitrile oxides reacted with 5-allylcalix[4]arene 7, they underwent a 1,3-dipolar cycloaddition on one side and an electrophilic substitution on the other side, which led to a novel type of asymmetric calix[4]arenes (9 and 12). (c) 2006 Elsevier Ltd. All rights reserved.
Cooperative Recognition of a Copper Cation and Anion by a Calix[4]arene Substituted at the Lower Rim by a beta-Amino-alpha,beta-Unsaturated Ketone
(2009)
Senthilvelan, Annamalai
;
ho, I. -Ting
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Chang, Kai-Chi
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Lee, Gene-Hsiang
;
Liu, Yi-Hung
We report herein a new ditopic calix[4]arene receptor 25,27-bis{[4-amino-4-(1-naphthyl)-2-oxo-3-butenyl]oxy}-26,28-dihydroxycalix[4]arene (2) for the simultaneous complexation of anionic and cationic species. The host molecule 25,27-bis{[3-(1-naphthyl)-5-isoxazolyl]methoxy}-26,28-dihydroxycalix[4]arene (1) was synthesised first and was followed by a [Mo(CO)(6)]mediated ring-opening reaction to give the target receptor 2. The binding properties of ligands 1 and 2 towards metal ions in CH(3)CN were investigated by UV/Vis and fluorescence spectroscopies. The results showed that both ligands I and 2 were highly selective for Cu(II) ions. Upon titration with Cu(II), the fluorescence of I was severely quenched, whereas 2 showed strong fluorescence enhancement because the metal ions help to lock the conformation of the fluorophores. During the complexation of 2 with Cu(II), the Cu(II) was reduced to Cu(I) by the free phenolic OH of 2, whereas the phenol was oxidised by Cu(II), after which it assisted in the trapping of Cu(I). Ditopic behaviour was observed for the complex 2 center dot Cu(I), which showed further enhancement of its fluorescence intensity upon complexation with anions such as acetate or fluoride.
MO(CO)(6)-mediated synthesis of calix[4]arenes carrying beta-hydroxy ketones or alpha,beta-unsaturated-beta-amino ketones
(2006-12-18)
Senthilvelan, Annamalai
;
Tsai, Ming-Tsung
;
Chang, Kai-Chi
;
Chung, Wen-Sheng
;
應用化學系
MO(CO)(6)-mediated ring opening reactions of calix[4]arene isoxazolines/isoxazoles provide a new synthetic methodology for calix[4]arenes carrying bifunctional beta-hydroxy ketones or alpha,beta-unsaturated-beta-amino ketones. MO(CO)(6) is a highly selective and convenient reagent for the ring opening process of these supramolecular isoxazolines/isoxazoles. (c) 2006 Elsevier Ltd. All rights reserved.
Triazole-modified calix[4]crown as a novel fluorescent on-off switchable chemosensor
(2007-08-16)
Chang, Kai-Chi
;
Su, In-Hao
;
Senthilvelan, Annamalai
;
Chung, Wen-Sheng
;
應用化學系
A novel fluorescent on-off switchable chemosensor 1 with two different types of cationic binding sites is synthesized, which is composed of a triazole-modified calix[4]crown in the 1,3-alternate conformation. Among 15 metal ions examined, the fluorescence of 1 was strongly quenched by Hg2+, Cu2+, Cr3+, and Pb2+; however, the revival of emission from the strongly quenched 1 center dot Pb2+ complex was achievable by the addition of K+, Ba2+, or Zn2+ ions. Thus, metal ion exchange can trigger an on-off switchable fluorescent chemosensor.