Browsing by Author "Hung, Hao-Chih"

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Different sensing modes of fluoride and acetate based on a calix[4]arene with 25,27-bistriazolylmethylpyrenylacetamides
(2014)
Hung, Hao-Chih
;
Chang, Yung-Yu
;
Luo, Liyang
;
Hung, Chen-Hsiung
;
Diau, Eric Wei-Guang
25,27-Bis{1'-N-(1-pyrenyl)-aminocarbonylmethyl-1H-[1',2',3']tri-azolyl-4'-methoxy}-26,28-dihydroxycalix-[4]arene, 4, is synthesized as a fluorescent chemosensor for the selective detection of both anions and ion pairs in MeCN. Sensor 4 uses bis-triazoles as ligands to bind a metal ion, bis-amides and bis-triazoles as the sites to recognize anions, and pyrenes as fluorophores. Among eight anions screened, chemosensor 4 showed a marked fluorescence change toward F-, H2PO4- and AcO-, but 4 responded to each anion in a distinct way. In the presence of F- at low concentrations, the dynamic excimer emission of compound 4 at lambda(max) 482 nm was quenched, but an emission at lambda(max) 472 nm appeared at large doses of F-. A control compound 6 showed very similar red shifts in the UV-vis and excitation spectra as 4 did, and its 472 nm emission band grew as the fluoride doses increased. Thus, the growth of the 472 nm emission of 4 and 6 in the presence of excess F- may be because strong H-bonding interactions of amido protons with F- favoured the formation of pyrene dimers in the ground state with charge transfer characteristics. The addition of H2PO4-, unlike F-, to a solution of 4 showed an enhanced monomer emission but a decreased excimer emission (lambda(max) 482 nm). Adding AcO- to 4 produced a systematic change from a dynamic excimer (lambda(max) 482 nm) to lambda(max) 472 nm but with very little change in the UV-vis spectrum. Time-resolved fluorescence measurements on compound 6 with F- and AcO- confirmed that the 472 nm emission band mainly came from static excimers for the former, but was partly from a dynamic excimer for the latter because it contained a growth component in the fluorescence decay traces. Without pre-treatment with an anion, chemosensor 4 showed recognition of only metal ions Cu2+, Hg2+ and Cr3+, but it became sensitive to Ag+ when it was pretreated with fluoride.
Dual-mode recognition of transition metal ions by bis-triazoles chained pyrenes
(2009-01-21)
Hung, Hao-Chih
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Cheng, Chi-Wen
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Ho, I-Ting
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Chung, Wen-Sheng
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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.
Highly Selective Fluorescent Sensors for Hg(2+) and Ag(+) Based on Bis-triazole-Coupled Polyoxyethylenes in MeOH Solution
(2009-12-01)
Hung, Hao-Chih
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Cheng, Chi-Wen
;
Wang, Yu-Yun
;
Chen, Yu-Jen
;
Chung, Wen-Sheng
Fluorescent chemosensors 6-9, with variable length polyoxyethylenes between two triazolylmethyl ether units, have been synthesized under "click" conditions in which the bis-triazoles and polyoxyethylenes were used as metal-ion binding sites and the pyrenes as fluorophores. Of the 15 metal ions screened, the fluorescence of chemosensors 6-9 in methanol solution was found to be selectively quenched by only Hg(2+) and Ag(+). In contrast, the fluorescence of control compound 10, a [(triazol-4-yl)methoxymethyl]pyrene, was quenched by only Hg(2+). These results imply that the recognition of Hg(2+) does not need the cooperation of two triazole groups. Binding constants for the interactions of 6-9 with Ag(+) increased as the chain length of the polyoxyethylene increased. Finally, a very high selectivity of compound 9 towards Hg(2+) in aqueous methanol solution was observed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Highly Selective Fluorescent Sensors for Hg2+ and Ag+ Based on Bis-triazole-Coupled Polyoxyethylenes in MeOH Solution
(2009-12-01)
Hung, Hao-Chih
;
Cheng, Chi-Wen
;
Wang, Yu-Yun
;
Chen, Yu-Jen
;
Chung, Wen-Sheng
Fluorescent chemosensors 6-9, with variable length polyoxyethylenes between two triazolylmethyl ether units, have been synthesized under "click" conditions in which the bis-triazoles and polyoxyethylenes were used as metal-ion binding sites and the pyrenes as fluorophores. Of the 15 metal ions screened, the fluorescence of chemosensors 6-9 in methanol solution was found to be selectively quenched by only Hg2+ and Ag+. In contrast, the fluorescence of control compound 10, a [(triazol-4-yl)methoxymethyl]pyrene, was quenched by only Hg2+. These results imply that the recognition of Hg2+ does not need the cooperation of two triazole groups. Binding constants for the interactions of 6-9 with Ag+ increased as the chain length of the polyoxyethylene increased. Finally, a very high selectivity of compound 9 towards Hg2+ in aqueous methanol solution was observed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Photochemistry of benzene and quinoxaline fused Delta(2)-1,2,3-triazolines and their trapping products
(2010-01-02)
Chen, Yu-Jen
;
Hung, Hao-Chih
;
Sha, Chin-Kang
;
Chung, Wen-Sheng
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應用化學系
The benzene and quinoxaline fused Delta(2)-1,2,3-triazolines 1a and 1b were synthesized in good yields using Knoevenagel condensation and intramolecular 1,3-dipolar cycloaddition as two of the key reactions. Photolysis (254 nm) of Delta(2)-1,2,3-triazoline 1a or 1b in acetonitrile led to the homolytic cleavage of nitrogen that generated diethyl diazomalonate 7, highly reactive intermediates aziridines 8a,b, and isoindoles B. The latter two species subsequently underwent rearrangement to give the nitrogen extrusion products 9a,b, and polymers. Furthermore, the reactive intermediates were trapped by dienophiles to give the corresponding cycloadducts. Subsequent rearrangement of the N-bridged cycloadducts gave N-substituted pyrrolo[3,4-b]quinoxalines 12b and 15b in 6% and 9% yields, respectively. Irradiation of 1a in the presence of fumaronitrile led to the isolation of cycloadduct 16a with retention of stereochemistry. Thermal reaction of 1b gave more nitrogen extruded product 9b (58-63% yield) than that by photolysis (5-23% yield), which implied that zwitterionic intermediate might be involved in the former. (C) 2009 Elsevier Ltd. All rights reserved.