Papers by Keyword: Fluorescence

Abstract: This paper introduces a sensitivity improvement of biochemical sensor by a combination of self-assembly of particles and optical lens. Typical biochemical sensor utilizes fluorescence emitted as a result of specific reaction. The sensitivity can be enhanced with the increase in surface area of self-assembled fine particles. In addition, optical lens was used to convergent the fluorescent light to simplify the system configuration. Silica particles of 1m diameter were assembled on a convex lens and modified with protein labeled with fluorescent material. Then, the spatial distribution of fluorescence was measured by changing the angle from the optical axis and distance from the lens. The results show sensitivity improvement up to 600 %. However, it was found that the effect of scattering should be taken into account for further sensitivity improvement.

Abstract: A novel photochromic diarylethene, 1-[(2-methyl-5-(4-fluorophenyl)-3-thienyl)]-2-(2-methyl-1-naphthyl) perfluorocyclopentene (1o), was synthesized. Its optoelectronic properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous films, fluorescences switch were investigated in detail. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 511 nm in hexane and at 522 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light.

Abstract: A novel photochromic diarylethene，1-(3,5-dimethyl-4-isoxazolyl)-2-[2-methyl-5-(10-phenanthrenyl)-3-thienyl]Perfluorocyclopentene was synthesized and its photochromic and fluorescent properties were also investigated. The compound exhibited remarkable photochromism, changing from colorless to pink after irradiation with UV light both in solution and in PMMA film. The fluorescence intensity declined remarkably，when irradiation with UV light. Using this diarylethene 1 as optical storage was performed successfully.

Abstract: A new unsymmetrical photochromic diarylethene, 1-(3,5-dimethyl-4-isoxazolyl)-2-[2-methyl-5-(4-formylphenyl)-3- thienyl]perfluorocyclopentene(1a) were synthesized, and its properties, such as photochromism and fluorescence properties, were investigated in detail. The results showed that this compound had good thermal stability and exhibited reversible photochromism, changing from colorless to darkred after irradiation with UV light both in solution and in PMMA amorphous film, the maxima absorption of its closed-ring isomer 1b are 529 nm and 541 nm respectively. The open-ring isomer of the diarylethene 1a exhibited relatively strong fluorescence at 492 nm in hexane solution (2 × 10^-5 mol/L) when excited at 418 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light. This new photochromic system also exhibited remarkable optical storage character.

Abstract: A novel unsymmetrical photochromic diarylethene bearing bisthiophene moiety 1-[2,5-dimethyl-3-thienyl]-2-[2-methyl-5-(2-methylphenyl)-3-thienyl]perfluoroyclopentene (1o) was synthesized and its photochromic, fluorescent and optical storage properties were also investigated. The compounds exhibited remarkable photochromism both in solution and in PMMA film. The result indicated that the diarylethene 1o changed the color from colorless to purple upon irradiation with 297 nm UV light, in which absorption maxima were observed at 527 and 541 nm in hexane and PMMA film, respectively. The open-ring isomer of the diarylethene 1 also exhibited relatively strong fluorescence both in hexane and PMMA film. The fluorescence intensity declined along with the photochromism upon irradiation with 297 nm light. In addition, optical recording using diarylethene 1c as recording medium was carried out successfully.

Abstract: A new photochromic diarylethene, 1-[2-methyl-(5-(4- dioxolane)phenyl)-3-thienyl]-2-(2-methyl-3-benzofuran) perfluorocyclopentene (1o), was synthesized and its photochromic and fluorescent properties were investigated.The product has been characterized by elemental analyses, NMR spectrometry, UV/vis spectrophotometry and Fluorescence spectrophotometry. This diarylethene exhibited reversible photochromism and notable fluorescence photoswitches both in solution and in PMMA films, changing from colorless to pink after irradiation with 297 nm UV light.

Abstract: A new unsymmetrical photochromic diarylethene bearing a benfuran and a thiophene aryl unit 1-(2-methyl-3-benfuran)-2-{2-methyl-5-[2-(1,3-dioxolane)]-3-thienyl}perfluorocyclopentene (1o) has been synthesized. It’s optoelectronic properties, such as photochromism in solution as well as in polymethylmethacrylate(PMMA) amorphous films, fluorescence and photon-mode polarization multiplexing holographic recording were investigated. Diarylethene 1o changed the color from colorless to red upon irradiation with 313 nm UV light, in which absorption maxima were observed at 509 nm in hexane and at 520 nm in PMMA amorphous film, respectively. This new photochromic system also exhibited remarkable fluorescence intensity and clear fluorescent switches by photo irradiation in solution. Finally, rewritable holographic optical storage using 1a was performed.

Abstract: A new photochromic diarylethene bearing naphthyl unit was synthesized efficiently. Its photochromic properties and the fluorescence property were examined in hexane solution and in PMMA film. The concentration effect in hexane solution was investigated also. The results indicated that the photochromic diarylethene have good photochromic property and exhibit remarkable fluorescence switching property and when the concentration at 2 × 10-5 mol/L the fluorescence peak have the maximum.

Abstract: Photochromism; Diarylethene materials; Fluorecence; Reaction kinetics. Abstract. A new unsymmetrical photochromic diarylethene, 1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-formyl-phenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized, and its photochromic properties and reaction kinetics were investigated, respectively. The compound exhibited good photochromism both in solution and in PMMA film with alternating irradiation by UV/Vis light. The cyclization processes of compound 1a belong to the zeroth order reaction, while the cycloreversion processes belong to the first order reaction. The optical recording results indicated that the new photochromic diarylethene can be applied in high capacity optical storage.

Abstract: In this work, we demonstrate the functionalization of zinc oxide nanowires with carboxylic acid moieties and investigate their potential application as p-nitrophenol sensors. First, synthesis of high quality zinc oxide nanowires along with appropriate characterization results is discussed. Subsequently, oleic acid, as a model system, is used to examine functionalization behavior of nanowire surface. Vibrational spectroscopic techniques are employed to determine nature of bonding and orientation of oleic acid molecule at nanowire surface. Photoluminescence properties of modified- and unmodified ZnO nanowires with oleic acid were investigated. Based on these results, an appropriate receptor capable of sensitive optical detection of p-nitrophenol is proposed. In addition, results on sensing mechanism of the receptor based on fluorescence quenching are reported, which highlight the capability of selective and sensitive detection of p-nitrophenol analyte using the receptor.