Browsing by Author "Wu, Yen-Hsing"

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Naked eye and fluorescent detections of Hg2+ ions and Cysteine via J-aggregation and deaggregation of a perylene bisimide derivative
(2014-04-01)
Fang, Hsiao-Ping
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Shellaiah, Muthaiah
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Singh, Ashutosh
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Raju, Mandapati V. Ramakrishnam
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Wu, Yen-Hsing
Selective naked eye and fluorescent sensor responses of a 1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) derivative are reported for the first time toward Hg2+ ions and Cysteine (Cys) via J-aggregation and deaggregation mechanisms. The J-aggregation and deaggregation of PBI induced by Hg2+ and Cys were well established by UV-vis/PL and H-1 NMR titrations. The 1:1 stoichiometry of PBI-Hg2+ and Cys-Hg2+/PBI ensembles were elucidated from the jobs plots based on their UV-vis spectral changes. The linear complex formation by PBI-Hg2+ ensemble was confirmed through FT-IR and H-1 NMR spectral studies and well supported by its reversible nature upon the addition of pentamethyl diethylene triamine (PMDTA). The positive cooperativities of Hg2+ and Cys (with PBI) in PBI-Hg2+ and Cys-Hg2+/PBI ensembles were evidenced from the Hill plots based on their fluorescence binding isotherms. The detection limits of Hg2+ ions and Cys were calculated as 36.6 and 91.3 nM, respectively, by standard deviations and linear fittings of their Stern-Volmer (KSV) constants and relative fluorescence intensity changes, respectively. Furthermore, the sensor properties of PBI were well investigated by KSV constants, pH values, time effects, and time resolved photoluminescence (TRPL) spectra. (C) 2013 Elsevier B.V. All rights reserved.
Novel dithieno-benzo-imidazole-based Pb2+ sensors: substituent effects on sensitivity and reversibility
(2012)
Satapathy, Rudrakanta
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
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Department of Materials Science and Engineering
Two novel dithieno-benzo-imidazole-based compounds (M2 and A2) showed remarkable sensitivities towards Pb2+ by 12-fold enhancement and 10-fold decay of fluorescence, respectively, in aqueous solutions. Substituent effects of different dithieno-benzo-imidazole-based moieties (M1, M2, A1 and A2) on the quantum yields, fluorescence lifetimes and sensitivities to Pb2+ along with the reversibilities by S2- were investigated.
Novel pyrene- and anthracene-based Schiff base derivatives as Cu2+ and Fe3+ fluorescence turn-on sensors and for aggregation induced emissions
(2013)
Shellaiah, Muthaiah
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Wu, Yen-Hsing
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Singh, Ashutosh
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Raju, Mandapati V. Ramakrishnam
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Lin, Hong-Cheu
Novel pyrene- and anthracene-based Schiff base derivatives P1 and A1 were synthesized via a one-pot reaction and utilized as fluorescence turn-on sensors towards Cu2+ and Fe3+ ions, respectively, and for aggregation induced emissions (AIEs). P1 in CH3CN and A1 in THF illustrated the fluorescence turn-on sensing towards Cu2+ and Fe3+ ions, respectively, via chelation enhanced fluorescence (CHEF) through excimer (P1-P1* and A1-A1*) formation. The 2 : 1 stoichiometry of the sensor complexes (P1 + Cu2+ and A1 + Fe3+) were calculated from Job plots based on UV-Vis absorption titrations. In addition, the binding sites of sensor complexes (P1 + Cu2+ and A1 + Fe3+) were well established from the H-1 NMR titrations and supported by the fluorescence reversibility by adding metal ions and PMDTA sequentially. The detection limits (LODs) and the association constant (K-a) values of P1 + Cu2+ and A1 + Fe3+ sensor responses were calculated by standard deviations, linear fittings and from their fluorescence binding isotherms. More importantly, P1 + Cu2+ and A1 + Fe3+ sensors were found to be active in wide ranges of pHs (1-14 and 2-14, respectively). Moreover, the time effect along with the enhancements of quantum yield (Phi) and time resolved photoluminescence (TRPL) decay constant (tau) towards sensor responses were investigated. Similarly, P1 in CH3CN and A1 in THF showed AIEs by increasing the aqueous media concentration from 0% to 90%, with altered fluorescence peak shifts (red and blue shifts, respectively). As well as tau value enhancements, the Phi values of 0.506 and 0.567 (with 630- and 101-fold enhancements) were acquired for P1 in CH3CN : H2O (20 : 80) and A1 in THF : H2O (40 : 60), respectively.
Novel Thieno-imidazole Based Probe for Colorimetric Detection of Hg2+ and Fluorescence Turn-on Response of Zn2+
(2012-05-18)
Satapathy, Rudrakanta
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
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Department of Materials Science and Engineering
Novel thieno-imidazole based polymer P showed both colorimetric and ratiometric detections of Hg2+ as well as fluorometric detection of Zn2+ via fluorescence turn-on response with augmented lifetime. Its model polymer M did not show any such sensing capability under similar conditions, which further confirmed the unique sensitivity of P toward Hg2+ and Zn2+ via the chelation of metal ions to both "S" and "N" heteroatoms.
Simple pyridyl-salicylimine-based fluorescence "turn-on" sensors for distinct detections of Zn2+, Al3+ and OH- ions in mixed aqueous media
(2013)
Shellaiah, Muthaiah
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
;
Department of Materials Science and Engineering
Simple pyridyl-salicylimine derivatives (F1, F2 and F3) are reported for the first time as fluorescence "turn-on" sensors for distinct detections of Zn2+, Al3+ and OH- ions in mixed-aqueous media CH3CN/H2O with volume ratios of 6/4 and 3/7 (at pH = 7 and 25 degrees C) via internal charge transfer (ICT), chelation enhanced fluorescence (CHEF), and deprotonation mechanisms. F1 and F2 show diverse turn-on sensing applications to Zn2+, Al3+ and OH- ions, but F3 exhibited the fluorescence turn-on sensing to Al3+ and OH- ions in CH3CN/H2O (6/4; vol/vol). F1+Zn2+ and F2+Zn2+ complexes revealed the reversibilities and ratiometric displacements of Zn2+ with ethylene diamine tetra acetic acid (EDTA) and Al3+ ions, respectively, in CH3CN/H2O (6/4; vol/vol). On the other hand, F1, F2 and F3 in CH3CN/H2O (3/7; vol/vol) showed sensitivities only to Al3+ ions but negligible selectivities to OH- ions. Stoichiometry of all sensor complexes were calculated as 1 : 1 by job's plots based on UV/Vis and PL titrations. The complex formation and binding sites of all sensor materials were well characterized by H-1, C-13 NMR, and mass (FAB) spectral analysis. Detection limits were calculated from standard deviations and linear fitting calculations. The association constant (log K-a) values of sensor complexes were evaluated from the fluorescence binding isotherms. The fluorescence decay constant (tau) values were estimated from time resolved fluorescence studies. Time, temperature, pH and solvent concentration effects towards sensor responses were fully investigated in this report.
Synthesis and Characterization of Reversible Chemosensory Polymers: Modulation of Sensitivity through the Attachment of Novel Imidazole Pendants
(2012-12-01)
Satapathy, Rudrakanta
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Padhy, Harihara
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
Three novel electron donoracceptor conjugated polymers (P1P3) bearing various imidazole pendants have been synthesized. Their excellent photophysical and electrochemical properties make them suitable transduction materials for chemosensing applications. Indeed, polymers P1P3 have been found to show remarkable sensing capabilities towards H+ and Fe2+ in semi-aqueous solutions. Upon titration with H+, polymers P1 and P2 showed hypsochromic shifts of their absorptions and photoluminescence (PL) maxima with enhanced fluorescence intensities. However, P3 showed diminished absorption and fluorescence intensities under similar conditions due to static quenching. The anomalous behavior of P3 compared with P1 and P2 has been clarified in terms of electronic distributions through computational analysis. Furthermore, P3 (KSV=1.03x107) showed a superior sensing ability towards Fe2+ compared with P1 (KSV=2.01x106) and P2 (KSV=4.12x106) due to its improved molecular wire effect. Correspondingly, the fluorescence lifetime of P3 was greatly decreased (almost 11-fold) compared to those of polymers P1 (4.6-fold) and P2 (6.2-fold) in the presence of Fe2+. By means of a fluorescence on-off-on approach, chemosensing reversibilities in protonationdeprotonation and metallationdemetallation have been achieved by employing triethylamine (TEA) and the disodium salt of ethylenediaminetetraacetic acid (Na2-EDTA)/phenanthroline, respectively, as suitable counter ligands. 1H NMR titrations have revealed the unique behavior of P3 compared with P1 and P2. To the best of our knowledge, there have been no previous reports of Fe2+ sensors based on single imidazole receptors conjugated to a main-chain polymer showing such a diverse sensitivity pattern depending on their attached substituents.
Synthesis and study of novel supramolecular nanocomposites containing aryl-imidazo-phenanthroline-based metallo-polymers (H-donors) and surface-modified ZnO nanoparticles (H-acceptors)
(2013-01-07)
Fang, Hsiao-Ping
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Wu, Yen-Hsing
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Lin, Hong-Cheu
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材料科學與工程學系
;
Department of Materials Science and Engineering
Four novel metallo-polymers (P1-P4) containing aryl-imidazo-phenanthrolines (AIP) ligands (incorporated with phenyl and fused-thiophene cores) were synthesized and characterized. Interestingly, P1-P4 exhibited electrochromism during the oxidation processes of cyclic voltammogram studies. In addition, P1-P4 were blended with surface-modified pyridyl-ZnO nanoparticles (ZnOpy as proton acceptors) to form nanocomposites, where P3-P4 were functionalized with carboxylic acid pendants (as proton donors) on the polymer backbones to study for the H-bonded effects on surface-modified ZnOpy nanoparticles. In order to investigate the nanocomposites containing metallo-polymers P1-P4 and surface-modified ZnOpy nanoparticles, nanocomposites P1-P4/ZnOpy were characterized by UV-visible (UV) absorption spectra, Fourier transform infrared (FT-IR), photoluminescence (PL) spectra, time-resolved photoluminescence decays, X-ray diffraction (XRD) measurements, and transmission electron microscopy (TEM) analyses. In contrast to nanocomposites P1/ZnOpy and P2/ZnOpy, higher crystallinities with a distinct layered-structure of H-bonded nanocomposites P3/ZnOpy and P4/ZnOpy in XRD measurements were induced by the introduction of surface-modified ZnOpy nanoparticles to metallopolymers P3 and P4, correspondingly. Furthermore, due to the supramolecular interactions of surface-modified ZnOpy nanoparticles with metallo-polymers P3-P4, TEM images verified that ZnOpy nanoparticles were more homogeneously distributed in nanocomposites P3-P4/ZnOpy (with H-bonds) than those in P1-P2/ZnOpy (without H-bonds), respectively. (C) 2012 Elsevier Ltd. All rights reserved.