- N-(3-Imidazolyl)propyl dansylamide as a selective Hg2+ sensor in aqueous media through electron transfer
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Abstract N-Imidazolylpropyl dansylamide 1 was synthesized for the sensing of metal ions and found to be selective and sensitive toward Hg2+ ions in a PBS-EtOH (1:4, pH = 7.4) solution. The sensing ability of probe 1 was examined by UV-Vis, fluorescence, and 1H NMR spectroscopy. The sensing of Hg2+ exhibited a quenching of emission band at λmax = 515 nm of probe 1, which was associated with quenching of green fluorescence emission under 365 nm illumination. Probe 1 showed a good association constant with Hg2+ (Ka = 6.48 × 104 M-1) with a stoichiometry of 1:1 in PBS-EtOH (1:4, pH = 7.4) having the lowest detection limit of 1 μM for Hg2+; on the other hand, probe 2, which has no imidazole moiety, was not able to detect any metal ion. In the case of probe 1, electrons on the imidazole nitrogen are available for electron transfer (ET), which was responsible for its green emission band that was quenched on addition of Hg2+; this clearly indicates that these electrons were used for the formation of a coordinate bond with Hg2+ and that ET was switched off.
- Kumar, Ashwani,Kim, Hong-Seok
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- Synthesis of amphiphilic polyhedral oligomeric silsesquioxane having a hydrophobic fluorescent dye group and its formation of fluorescent nanoparticles in water
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In this study, we synthesized an amphiphilic polyhedral oligomeric silsesquioxane (POSS) having controlled numbers of hydrophilic and fluorescent hydrophobic groups (seven and one, respectively) by the successive reactions of a starting compound, octa(3-aminopropyl)-POSS, with gluconolactone and with dansyl chloride under appropriate conditions. The product formed fluorescent nanoparticles with relatively welldefined morphology in water by self-aggregation, which was confirmed by SEM, DLS, and fluorescence measurements.
- Kuwahara, Shin-Ya,Yamamoto, Kazuya,Kadokawa, Jun-Ichi
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- Fluorescence ratiometric selective recognition of Cu2+ ions by dansyl-naphthalimide dyads
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(Chemical Equation Presented) Chimeric dyads 1a and 1b based on dansyl and naphthalimide units linked through the polymethylene group were synthesized, and their photophysical and interactions with various metal ions were investigated under different conditions. These dyads showed dual emission centered at around 375 and 525 nm, respectively, due to the locally excited state of the naphthalimide chromophore and energy-transfer-mediated emission (FRET) from the dansylmoiety. When titrated with various metal ions, these systems exhibited unusual selectivity for Cu2+ ions as compared to Na+, Li+, K+, Zn2+, Pb2+, Hg 2+, Co2+, Fe2+, Cd2+, Mg 2+, and Ba2+ ions and signaled the binding event through inhibition of FRET mediated emission at 525 nm with concurrent enhancement in the emission intensity of the naphthalimide chromophore at 375 nm. The uniqueness of these dyads is that they form stable 2:1 stoichiometric complexes involving sulfonamide functionality and act as visual fluorescence ratiometric probes for the selective recognition of Cu2+ ions.
- Jisha, Vadakkancheril S.,Thomas, Anu J.,Ramaiah, Danaboyina
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- Synthesis of readily accessible BODIPY-based fluorescence derivatization reagents for amines
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Two BODIPY-based fluorescence derivatization reagents (FDRs) for amines were synthesized in a simple manner with practically acceptable yields via five steps. Both FDRs showed prompt reactivity, even against sterically hindered amines, to afford the corresponding FDR-labeled products in good yields. The solvent effect upon the fluorescence intensity of the derivatized amine was also investigated in a methanol-water binary solvent system to demonstrate that the strong fluorescence intensity was maintained in the solvent with a 0-60% water ratio. The detection limits of the new FDRs were estimated to be 20 fmol, which makes it much more sensitive than commercially available FDRs. The Japan Institute of Heterocyclic Chemistry.
- Saito, Ryota,Ito, Eri
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experimental part
p. 2599 - 2608
(2011/04/24)
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- Methods and Compounds for Detection of Medical Disorders
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The invention provides methods for detection of medical disorders, associated with cellular oxidative stress, cell degeneration and/or cell death. The invention further relates to compounds comprising a thiol (—SH) group, for detecting cells undergoing ox
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Page/Page column 9-10
(2008/06/13)
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- STUDY ON THE REACTION OF MONOFUNCTIONAL FLUORESCENT REAGENTS IN ORGANIC SOLUTIONS BY FLUOROMETRY.
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Reactions of some fluorescent reagents with substrates, used widely in biochemistry for quantitative analysis of some functional groups in aqueous media, have been studied in organic solutions with a view that they may be used also in the area of synthetic polymer science. Reactions studied by fluorometry were (i) 5-dimenthylamino-1-naphtalensulfonyl chloride with butylamine, (ii) 2-naphthalensulfonyl chloride with butylamine, and (iii) N-(1-naphthyl)maleimide with 1-pentanethiol. In polar solvents all the fluorescent probes studied are too labile and converted spontaneously into fluorescent compounds. In less polar solvents, however, such side reactions do not take place and the reaction of fluorescent reagents with substrates proceeds quantitatively with a simple second-order kinetics. The second-order rate constants for the three reactions are of the order of 10** minus **3 to 10** minus **1 M** minus **1 s** minus **1 in the range of about 30 to 50 degree C, and they increase with the solvent polarity. This work is pertinent to polymers.
- Okamoto,Uchiyama,Mita
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p. 3068 - 3072
(2007/10/02)
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