Browsing by Author "Ho, I-Ting"

Now showing 1 - 11 of 11

1,3-Alternate Calix[4]arene as a Homobinuclear Ditopic Fluorescent Chemosensor for Ag(+) Ions
(2011-10-04)
Ho, I-Ting
;
Haung, Kuan-Chang
;
Chung, Wen-Sheng
;
應用化學系
;
Department of Applied Chemistry
A novel 1,3-alternate calix[4]arene L, containing two different cationic binding sites of bis-triazoles and bis-enaminone groups, was synthesized and shown to be a homobinuclear ditopic fluorescent chemosensor for Ag(+) ions. The fluorescence intensity of L was selectively enhanced by binding with Ag(+) ions in methanol/chloroform (49:1, v/v) cosolvent. In the presence of most competing metal ions, L retains its selectivity toward Ag(+) ion. The binding constants K(1) and K(2) of the successive complexation of L with the first and second Ag(+) ions were calculated to be 4.46 x 10(3) and 9.20 x 10(4)M(-1), respectively. The higher K(2) value revealed that a positive allosteric effect participated in the complexation of L with the second equivalent of Ag(+). Based on (1)H NMR titration results, we inferred that the two distal bis-enaminone and bis-triazole groups on L cooperatively coordinated to Ag(+) ions with the help of cation-pi interactions from the phenoxy rings. Furthermore, the ESI-MS spectrometry clearly proved the formation of the homobinuclear complex L center dot(Ag(+))(2), because a base peak at m/z of 750.1701 was detected and its isotope pattern was in excellent agreement with the calculated one.
1,3-Alternate Calix[4]arene as a Homobinuclear Ditopic Fluorescent Chemosensor for Ag+ Ions
(2011-10-04)
Ho, I-Ting
;
Haung, Kuan-Chang
;
Chung, Wen-Sheng
;
應用化學系
;
Department of Applied Chemistry
A novel 1,3-alternate calix[4]arene L, containing two different cationic binding sites of bis-triazoles and bis-enaminone groups, was synthesized and shown to be a homobinuclear ditopic fluorescent chemosensor for Ag+ ions. The fluorescence intensity of L was selectively enhanced by binding with Ag+ ions in methanol/chloroform (49:1, v/v) cosolvent. In the presence of most competing metal ions, L retains its selectivity toward Ag+ ion. The binding constants K-1 and K-2 of the successive complexation of L with the first and second Ag+ ions were calculated to be 4.46 x 10(3) and 9.20 x 10(4)M(-1), respectively. The higher K-2 value revealed that a positive allosteric effect participated in the complexation of L with the second equivalent of Ag+. Based on H-1 NMR titration results, we inferred that the two distal bis-enaminone and bis-triazole groups on L cooperatively coordinated to Ag+ ions with the help of cation-pi interactions from the phenoxy rings. Furthermore, the ESI-MS spectrometry clearly proved the formation of the homobinuclear complex L center dot(Ag+)(2), because a base peak at m/z of 750.1701 was detected and its isotope pattern was in excellent agreement with the calculated one.
Biscalix[4]arene Derivative As a Very Efficient Phase Selective Gelator for Oil Spill Recovery
(2013-11-15)
Tsai, Chia-Chen
;
Cheng, Ying-Tsai
;
Shen, Li-Ching
;
Chang, Kai-Chi
;
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
;
Chu, Jean-Ho
;
Chung, Wen-Sheng
;
應用化學系
;
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.
Design and synthesis of triazolyl coumarins as Hg2+ selective fluorescent chemosensors
(2012)
Ho, I-Ting
;
Lai, Ting-Ling
;
Wu, Ren-Tsung
;
Tsai, Ming-Tsung
;
Wu, Chun-Ming
A series of triazolyl coumarin derivatives L1-L4, with and without spacer groups between the coumarin and the triazole groups, were synthesized as fluorescent sensors to study their binding ability and selectivity toward metal ions. Ligand L3, which contains an acetyl linker between the triazole and the coumarin, exhibited a high selectivity toward Hg2+ in polar protic solvents MeOH-CHCl3 (9 : 1, v/v) with fluorescent enhancement, furthermore, it was found to bind two Hg2+ at a high concentration (>12.5 mM) of Hg(ClO4)(2). In contrast, L4, in which position 4 of the triazole unit was replaced by a benzyl group instead of the 4-tert-butylphenoxymethyl group used in L1-L3, showed a binding stoichiometry toward only one Hg2+. On the basis of the fluorescent sensing, IR, and H-1 NMR titration results of ligands L1-L4, we proposed that not only the acetyl C=O but also the ether group of the 4-tert-butylphenoxymethyl of L3 assisted the triazole nitrogen atoms in the complexation of Hg2+ to form a 1 : 2 complex (L3 center dot(Hg2+)(2)).
Dual-mode recognition of transition metal ions by bis-triazoles chained pyrenes
(2009-01-21)
Hung, Hao-Chih
;
Cheng, Chi-Wen
;
Ho, I-Ting
;
Chung, Wen-Sheng
;
應用化學系
Fluorescent chemosensors 7-10, with variable methylene chain length as spacers between the two triazole methyl ether units, have been synthesized under 'Click' condition, where the bistriazoles are used as the metal ion binding sites and the pyrenes as the fluorophores. Compound 10, having the longest methylene chain among 7-10, shows monomer and excimer fluorescence quenching in acetonitrile toward Ni(2+), Pb(2+), Cu(2+), Hg(2+), and Cr(3+) ions, however, it shows an enhanced monomer but a decreased excimer emission when complexed with Cd(2+) and Zn(2+) ions. (C) 2008 Elsevier Ltd. All rights reserved.
Evolution of nano- to microsized spherical assemblies of fluorogenic biscalix[4]arenes into supramolecular organogels
(2013)
Tsai, Chia-Chen
;
Chang, Kai-Chi
;
Ho, I-Ting
;
Chu, Jean-Ho
;
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.
Synthesis and Characterization of Adducts Formed in the Reactions of Safrole 2',3'-Oxide with 2'-Deoxyadenosine, Adenine, and Calf Thymus DNA
(2012-02-01)
Shen, Li-Ching
;
Chiang, Su-Yin
;
Ho, I-Ting
;
Wu, Kuen-Yuh
;
Chung, Wen-Sheng
Safrole (1) is a natural product found in herbs and spices. Upon uptake, it can be metabolized to safrole 2',3'-oxide [(+/-)-SFO, 2], which can react with DNA bases to form DNA adducts. The reactions of 2 with 2'-deoxyadenosine (3) and adenine (8) under physiological conditions (pH 7.4, 37 degrees C) were carried out to characterize its possible adducts with adenine. Four adducts were isolated by reverse-phase liquid chromatography and their structures were characterized by UV/Vis, 1H and 13C NMR spectroscopy and MS. The reaction of 2 with 3 produced two regioisomers, N1?-SFO-dAdo (4) and N6?-SFO-dAdo (5), in 4.24.5?% yield, and the reaction of 2 with 8 generated N3?-SFO-Ade (9) and N9?-SFO-Ade (10) in 1.02.4?% yield. Using HPLCESI-MS/MS, we traced the amounts of the four adducts formed when calf thymus DNA (10 mg) was treated with 2 (60 mu mol) and the levels of 4, 5, and 9 were determined to be 2000, 170, and 660 adducts per 106 nucleotides, respectively. Adduct 10 was not detected under these conditions. These results suggested that stable DNA adducts of 2 were formed in vitro, and further studies on the formation of these DNA adducts in vivo may help to elucidate their role in safrole carcinogenicity.
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.
Synthesis of upper-rim allyl- and p-methoxyphenylazocalix[4]arenes and their efficiencies in chromogenic sensing of Hg2+ ion
(2007-03-30)
Ho, I-Ting
;
Lee, Gene-Hsiang
;
Chung, Wen-Sheng
;
應用化學系
;
Department of Applied Chemistry
A series of upper-rim p-allyl and p-methoxyphenylazocalix[4]arenes (6, 8, 9a, b, and 10a,b) were synthesized and shown to exhibit substantial color changes upon complexation with Hg2+ ion. Both the upper-rim p-allyl- and p-methoxyphenylazo groups on calix[4]arenes are proven to be key components in the recognition of Hg2+ ion. Job's plots revealed 1:1 binding stoichiometry for all these p-allyl- and p-arylazo-coupled calix[4]arenes with Hg2+ ions and Benesi-Hilderbrand plots were used for determination of their association constants. Our results also demonstrated that two p-methoxyphenylazo groups prefer to bind Hg2+ in a distal orientation rather than a proximal one, and if there are three p-methoxyphenylazo groups, the third flanking p-methoxyphenylazo group plays a role in disturbing the binding of the two distal diazo groups. Furthermore, it should be noted that triazocalix[4]arenes (6, 9a, and 9a) responded to all 14 metal ions without showing much preference among the eight transition-metal ions screened in this work (Cr3+, Ni2+, Cu2+, Ag+, Cd2+, Hg+, Hg2+, and Pb2+).
The Synthesis of Rigid Polycyclic Structures for the Study of Diatropic or Steric Effects of a Phenyl Ring on CF Bond
(2013-12-20)
Chang, Yung-Yu
;
Ho, I-Ting
;
Ho, Tse-Lok
;
Chung, Wen-Sheng
;
應用化學系
Polycyclic compounds 1a-c were synthesized to study the diatropic effects of a flanking phenyl ring on nearby CH and CF bonds. F-19 NMR spectra of 1b and 1c were strongly deshielded compared with those of the ring-opened compounds 3b, 7b, and 7c. DMol3 calculations on 1a-c provided quantitative bond lengths and torsional angles to support the conclusion that the downfield shifts in the F-19 NMR spectra are mainly due to steric interactions between the CF bonds and the pi clouds of the phenyl ring(s).