Papers by Keyword: Fluorescence

Abstract: A new fluorescent probe 1, bearing a pyridine group as receptor for H⁺ and a coumarin dye as fluorophore, was synthesized and characterized by ¹H NMR, ¹³C NMR, ESI-Ms and single crystal X-ray diffraction analysis. The probe exhibited fluorescence ratiometric response to acidic pH. With decreasing of the pH from 8.32 to 2.49, the fluorescence emission spectra exhibited large red shift from 541 to 631 nm, with the emission ratios (I₅₄₁ /I₆₃₁) changed dramatically from 25.9 to 0.08, and the pK_a value was calculated to be 5.45. Probe 1 exhibited high selectivity to pH, other interference species including metal ions and amino acid exerted no visible effect on probe 1 detecting pH. The intracellular pH imaging applications proved that the probe is suitable for monitoring acidic pH fluctuations in living cells.

Abstract: A rhodamine-based fluorescent compound, spiro[1H-isoindole-1,9′-[9H]xanthen] -3(2H)-one, ′,6′-bis(diethylamino)-2-[(1-methylethylidene)-amino] (RB1), is developed to detect and inhibit the refractory steel corrosion in 3% NaCl solution. The inhibition effect was evaluated by electrochemical measurements. RB1 suppresses the cathodic corrosion reaction and shifts the corrosion potential toward more negative values. RB1 exhibits a turn-on fluorescence emission in the presence of Fe ³⁺ ions. The selectivity of RB1 over other commonly coexistent Cu²⁺, Fe ²⁺ and Mn²⁺ was investigated. The variation of the fluorescence intensity is correlated to that of weight-loss. RB1 has a potential application as corrosion inhibitor and corrosion indicator in some industry process.

Abstract: In the present work, Cerium Fluoride (CeF₃) was selected as the host material because of its High density, fast response and high radiation resistance, efficient absorption and energy transfer by host (to activator). Rare earths have been used to show the process of Quantum Cutting (QC) via energy transfer process between Tb³⁺ and Yb³⁺ incorporated in CeF₃. For the synthesis of CeF₃ nanoparticles codoped with Tb³⁺ and Yb³⁺ ion, co-precipitation route was employed. Different doping concentrations were prepared to study the changes that take place in the luminescence spectra of the composition. Thus, concentration dependent study of the fluorescence of CeF₃: Tb³⁺, Yb³⁺ was carried out. These materials have great applications in solar cell devices as quantum efficiencies up to 200 % can be achieved.

Abstract: Luminescence is "cold light", light from other sources of energy, which can take place at normal and lower temperatures. There are several varieties of luminescence, each named according to what the source of energy is, or what the trigger for the luminescence is. Luminescence is a collective term for different phenomena where a substance emits light without being strongly heated, i.e., the emission is not simply thermal radiation. This definition is also reflected by the term "cold light".

Abstract: biphenyl Derivative was synthesized by Wittig-Homer reaction. Its crystal structure was determined by X-ray diffraction method. The fluorescence properties of the title compound in solvents were investigated.

Abstract: 4,4'-(o-benzonitrile) divinylbenzene compound was synthesized by Wittig-Homer reaction. Its crystal structure was determined by X-ray diffraction method. The fluorescence properties of the title compound in acetone solvents were investigated.

Abstract: A novel photochromic diarylethene based on pyrimidine moiety was synthesized. Its properties, including photochromism and fluorescence were investigated in detail. The compound exhibited remarkable photochromism, changing from colorless to red after irradiation with UV light. The fluorescence had a remarkable initial increase with subsequent dramatic decrease with increasing concentration. The results indicated that the pyrimidine moiety played a very important role during the process of photochromic reaction for the diarylethene derivative.

Abstract: An unsymmetrical photochromic diarylethene was synthesized and its photochromism and fluorescent properties were investigated in detail. The compound exhibited remarkable photochromism, changing from colorless to violet after irradiation with 297 nm UV light, in which absorption maxima were observed at 535 nm in hexane and at 541 nm in PMMA amorphous films, respectively. The fluorescence intensity of diarylethene 1o decreased upon irradiation with 297 nm UV light, in which fluorescence peaks were observed at 448 nm in hexane and at 426 nm in PMMA amorphous films, respectively. And the modulation efficiency were 12% and 75% in both hexane and PMMA films.

Abstract: A novel photochromic diarylethene with a six-membered pyrimidine was synthesized to investigate its photochromic behaviors. This compound exhibited reversible photochromism, changing from colorless to red after irradiation with UV light both in solution and in poly-methyl methacrylate (PMMA) amorphous film. Moreover, it exhibited remarkable fluorescence switching in solution. The results indicated that the pyrimidine moiety played a very important role during the process of photochromic reaction for the diarylethene derivative.

Abstract: An asymmetrical photochromic diarylethene 1-[2-trifluoromethylpheny-2-[2-methyl-5-(3,5-difluorophenyl)-3-thienyperfluorocyclopentene (1o) was synthesized and its phtochromic, fluorescent properties in both solution and PMMA films were investigated in detail. This compound exhibited remarkable photochromism, upon irradiation with 297 nm UV light, the colorless solution of 1o turned to plum with a new visible absorption band centered at 544 nm (ε =3.75 × 10³ L mol^-1 cm^-1) attributable to the closed-ring isomer 1c.The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer in PMMA films and in hexane. The emission intensity of diarylethene 1o in a photostationary state was quenched to ca. 64% in hexane and 27% in PMMA films.