The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Masaki Matsui - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Fluorescence properties of novel squarylium–boron complexes
Organic Chemistry Frontiers, 2017Co-Authors: Yasuhiro Kubota, Masahiro Tsukamoto, Katsuhiro Ohnishi, Jiye Jin, Kazumasa Funabiki, Masaki MatsuiAbstract:A novel boron complex based on a squarylium dye was synthesized by a simple two-step procedure starting from the pyrrole derivative. The absorption and Fluorescence Maxima of the squarylium–boron complex were slightly blue-shifted relative to those of the corresponding squarylium dye, and the Fluorescence quantum yield of the former increased significantly. Deprotonation of the squarylium–boron complex led to the formation of the corresponding anion, with a further blue-shift of the absorption and Fluorescence Maxima.
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Solid-state Fluorescence of pyridinium styryl dyes
Dyes and Pigments, 2013Co-Authors: Masaki Matsui, Yasuhiro Kubota, Kazumasa Funabiki, Kohtaro Ooiwa, Ayumi Okada, Hiroyasu SatoAbstract:Abstract 1-Alkyl-2-[4-(diethylamino)styryl]pyridinium salts showed Fluorescence Maxima at around 650 nm in the solid state depending on the alkyl group and counter anion. 1-Butyl-2-[4-(diethylamino)styryl]pyridinium bis(perfluorobutylsulfonyl)imide exhibited the Fluorescence maximum at 652 nm with the highest quantum yield 0.16 in the crystalline form. The single X-ray crystallography suggests that this compound exhibits isolated dimer-type packing leading to Fluorescence in the solid state.
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Fluorescence properties of indolenine semi-squarylium dyes
Tetrahedron, 2012Co-Authors: Masaki Matsui, Yasuhiro Kubota, Toshihiro Shibata, Masato Fukushima, Kazumasa FunabikiAbstract:Abstract 3-Butoxy-4-(1-butyl-3,3-dimethyl-3H-indol-2-ylidenemethyl)-3-cyclobut-1,2-dione exhibited the most intense florescence at Fluorescence Maxima 536 and 563 nm with Fluorescence quantum yield 0.21 among any indolenine semi-squarylium dyes in the crystalline form due to the isolated dimer-type molecular packing and its suitable melting point. This compound showed aggregation-induced emission enhancement.
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Red solid-state fluorescent aminoperfluorophenazines
Tetrahedron Letters, 2009Co-Authors: Masaki Matsui, Yasuhiro Kubota, Rie Ikeda, Kazumasa FunabikiAbstract:Abstract The solid-state Fluorescence of 2-amino-, 2-ethylamino, 2-diethylamino-, and 2,7-bis(diethylamino)perfluorophenazines was examined. They showed their Fluorescence Maxima in the range of 584–637 nm. The solid-state Fluorescence quantum yield of 2-diethylamino derivative was highest among these derivatives, there being 0.22. X-ray crystallographic analysis suggests that the 2-diethylamino derivative has no strong intermolecular interactions among adjacent molecules to show intense Fluorescence, whereas the other derivatives have network NH/F hydrogen, π–π, and CH/F interactions to reduce solid-state Fluorescence intensity.
Kazumasa Funabiki - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Fluorescence properties of novel squarylium–boron complexes
Organic Chemistry Frontiers, 2017Co-Authors: Yasuhiro Kubota, Masahiro Tsukamoto, Katsuhiro Ohnishi, Jiye Jin, Kazumasa Funabiki, Masaki MatsuiAbstract:A novel boron complex based on a squarylium dye was synthesized by a simple two-step procedure starting from the pyrrole derivative. The absorption and Fluorescence Maxima of the squarylium–boron complex were slightly blue-shifted relative to those of the corresponding squarylium dye, and the Fluorescence quantum yield of the former increased significantly. Deprotonation of the squarylium–boron complex led to the formation of the corresponding anion, with a further blue-shift of the absorption and Fluorescence Maxima.
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Solid-state Fluorescence of pyridinium styryl dyes
Dyes and Pigments, 2013Co-Authors: Masaki Matsui, Yasuhiro Kubota, Kazumasa Funabiki, Kohtaro Ooiwa, Ayumi Okada, Hiroyasu SatoAbstract:Abstract 1-Alkyl-2-[4-(diethylamino)styryl]pyridinium salts showed Fluorescence Maxima at around 650 nm in the solid state depending on the alkyl group and counter anion. 1-Butyl-2-[4-(diethylamino)styryl]pyridinium bis(perfluorobutylsulfonyl)imide exhibited the Fluorescence maximum at 652 nm with the highest quantum yield 0.16 in the crystalline form. The single X-ray crystallography suggests that this compound exhibits isolated dimer-type packing leading to Fluorescence in the solid state.
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Fluorescence properties of indolenine semi-squarylium dyes
Tetrahedron, 2012Co-Authors: Masaki Matsui, Yasuhiro Kubota, Toshihiro Shibata, Masato Fukushima, Kazumasa FunabikiAbstract:Abstract 3-Butoxy-4-(1-butyl-3,3-dimethyl-3H-indol-2-ylidenemethyl)-3-cyclobut-1,2-dione exhibited the most intense florescence at Fluorescence Maxima 536 and 563 nm with Fluorescence quantum yield 0.21 among any indolenine semi-squarylium dyes in the crystalline form due to the isolated dimer-type molecular packing and its suitable melting point. This compound showed aggregation-induced emission enhancement.
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Red solid-state fluorescent aminoperfluorophenazines
Tetrahedron Letters, 2009Co-Authors: Masaki Matsui, Yasuhiro Kubota, Rie Ikeda, Kazumasa FunabikiAbstract:Abstract The solid-state Fluorescence of 2-amino-, 2-ethylamino, 2-diethylamino-, and 2,7-bis(diethylamino)perfluorophenazines was examined. They showed their Fluorescence Maxima in the range of 584–637 nm. The solid-state Fluorescence quantum yield of 2-diethylamino derivative was highest among these derivatives, there being 0.22. X-ray crystallographic analysis suggests that the 2-diethylamino derivative has no strong intermolecular interactions among adjacent molecules to show intense Fluorescence, whereas the other derivatives have network NH/F hydrogen, π–π, and CH/F interactions to reduce solid-state Fluorescence intensity.
Yasuhiro Kubota - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Fluorescence properties of novel squarylium–boron complexes
Organic Chemistry Frontiers, 2017Co-Authors: Yasuhiro Kubota, Masahiro Tsukamoto, Katsuhiro Ohnishi, Jiye Jin, Kazumasa Funabiki, Masaki MatsuiAbstract:A novel boron complex based on a squarylium dye was synthesized by a simple two-step procedure starting from the pyrrole derivative. The absorption and Fluorescence Maxima of the squarylium–boron complex were slightly blue-shifted relative to those of the corresponding squarylium dye, and the Fluorescence quantum yield of the former increased significantly. Deprotonation of the squarylium–boron complex led to the formation of the corresponding anion, with a further blue-shift of the absorption and Fluorescence Maxima.
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Solid-state Fluorescence of pyridinium styryl dyes
Dyes and Pigments, 2013Co-Authors: Masaki Matsui, Yasuhiro Kubota, Kazumasa Funabiki, Kohtaro Ooiwa, Ayumi Okada, Hiroyasu SatoAbstract:Abstract 1-Alkyl-2-[4-(diethylamino)styryl]pyridinium salts showed Fluorescence Maxima at around 650 nm in the solid state depending on the alkyl group and counter anion. 1-Butyl-2-[4-(diethylamino)styryl]pyridinium bis(perfluorobutylsulfonyl)imide exhibited the Fluorescence maximum at 652 nm with the highest quantum yield 0.16 in the crystalline form. The single X-ray crystallography suggests that this compound exhibits isolated dimer-type packing leading to Fluorescence in the solid state.
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Fluorescence properties of indolenine semi-squarylium dyes
Tetrahedron, 2012Co-Authors: Masaki Matsui, Yasuhiro Kubota, Toshihiro Shibata, Masato Fukushima, Kazumasa FunabikiAbstract:Abstract 3-Butoxy-4-(1-butyl-3,3-dimethyl-3H-indol-2-ylidenemethyl)-3-cyclobut-1,2-dione exhibited the most intense florescence at Fluorescence Maxima 536 and 563 nm with Fluorescence quantum yield 0.21 among any indolenine semi-squarylium dyes in the crystalline form due to the isolated dimer-type molecular packing and its suitable melting point. This compound showed aggregation-induced emission enhancement.
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Red solid-state fluorescent aminoperfluorophenazines
Tetrahedron Letters, 2009Co-Authors: Masaki Matsui, Yasuhiro Kubota, Rie Ikeda, Kazumasa FunabikiAbstract:Abstract The solid-state Fluorescence of 2-amino-, 2-ethylamino, 2-diethylamino-, and 2,7-bis(diethylamino)perfluorophenazines was examined. They showed their Fluorescence Maxima in the range of 584–637 nm. The solid-state Fluorescence quantum yield of 2-diethylamino derivative was highest among these derivatives, there being 0.22. X-ray crystallographic analysis suggests that the 2-diethylamino derivative has no strong intermolecular interactions among adjacent molecules to show intense Fluorescence, whereas the other derivatives have network NH/F hydrogen, π–π, and CH/F interactions to reduce solid-state Fluorescence intensity.
Robert West - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and High Solid-State Fluorescence of Cyclic Silole Derivatives
Organometallics, 2014Co-Authors: Yuanjing Cai, Kerim Samedov, Brian S. Dolinar, Zhegang Song, Ben Zhong Tang, Chaocan Zhang, Robert WestAbstract:Cyclotetrasiloxanes 1–3 containing different silole-based fluorogenic units (silafluorene, 1,3-diphenyl-9-silafluorene, tetraphenylsilole) were synthesized by cohydrolysis and condensation reactions. Their optical properties in solution and as crystals were studied. These compounds have low quantum yields in solution (Φfl = 0.01–0.18) with Fluorescence Maxima at 359–375 nm for silafluorene-containing compounds 1 and 3 and at 491 nm for AEE-active tetraphenylsilole compound 2. However, 1–3 have high solid-state quantum yields (Φfl = 0.65–0.78) with Fluorescence Maxima at 377–390 nm for compounds 1 and 3 and at 517 nm for tetraphenylsilole- and silafluorene-containing compound 2. Packing analysis of 1–3 in the crystal structure and MO and excited-state calculations were performed to explore possible Fluorescence mechanisms in these compounds.
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Ring‐Shaped Silafluorene Derivatives as Efficient Solid‐State UV‐Fluorophores: Synthesis, Characterization, and Photoluminescent Properties
Chemistry (Weinheim an der Bergstrasse Germany), 2014Co-Authors: Yuanjing Cai, Kerim Samedov, Brian S. Dolinar, Chaocan Zhang, Haley Albright, Ilia A. Guzei, Robert WestAbstract:Four ring-shaped silafluorene-containing com- pounds (1-4) were synthesized and characterized as poten- tially promising monomers for fluorescent polymers. Their optical properties in solution and solid state (thin film and powder) were studied. These compounds have low quantum yields in solution (Ffl = 0.13-0.15) with Fluorescence Maxima at about 355 nm, but high quantum yields in the solid state (powder, Ffl = 0.35-0.54) with Fluorescence Maxima at about 377 and 488 nm. Influence of the substituents and the number of silafluorene units in 1-4 on their optical proper- ties was investigated. Extensive study of the X-ray crystal structures of 1-4 was undertaken to analyze and qualitative- ly estimate the role, extent, and influence of silafluorene moieties' interactions on solid-state fluorescent properties. Excited state UV/Vis and theoretical molecular orbital (MO) calculations were performed to explore possible fluores- cence mechanisms and differences in quantum yields among these compounds.
I. Timtcheva - One of the best experts on this subject based on the ideXlab platform.
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Fluorescence Characteristics of Variously Charged Asymmetric Monomethine Cyanine Dyes in the Presence of Nucleic Acids
Journal of Fluorescence, 2002Co-Authors: Todor Deligeorgiev, I. Timtcheva, Vera Maximova, Nikolai Gadjev, Karl-heinz DrexhageAbstract:Three asymmetric monomethine cyanine dyes bearing one, two, and three positive charges have been synthesized, and their absorption and Fluorescence characteristics in the presence of nucleic acids were studied. The Maxima of their longest wavelength absorption band lie between 500 and 520 nm. The dyes do not show Fluorescence of their own in TE buffer (pH 5 7.5), but become strongly fluorescent (QF 5 0.2‐0.6) on binding to double-stranded DNA. The Fluorescence Maxima of the investigated dye-dsDNA complexes are in the region of 530‐550 nm. The influence of the dye/DNA ratio on both the position and intensity of the Fluorescence Maxima of the complexes is investigated.
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New asymmetric monomethine cyanine dyes for nucleic-acid labelling: absorption and Fluorescence spectral characteristics
Journal of Photochemistry and Photobiology A: Chemistry, 2000Co-Authors: I. Timtcheva, Todor Deligeorgiev, Vera Maximova, D. Zaneva, Ivan IvanovAbstract:Abstract Absorption spectra and Fluorescence properties of a series of newly synthesized asymmetric monomethine cyanine dyes are studied. The dyes carry one or two positive charges. They are devoid of their own Fluorescence in solution and become fluorescent upon binding to nucleic acids only. The Fluorescence Maxima of the new dyes are localized between 530 and 650 nm. The wavelength and intensity of Fluorescence are dependent on molecular structure of the dye, type of nucleic acid and the concentration of both nucleic acid and salts. Some of the dyes are capable of distinguishing between single-stranded and double-stranded (ds) polynucleotides giving Fluorescence Maxima localized at different wavelengths. Detection threshold for dsDNA for most of the dyes is comparable to that of ethidium bromide. The sensitivity of the dye-dsDNA complexes to NaCl concentrations show that the new dyes interact with dsDNA by both intercalation and electrostatically.
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Synthesis of homodimeric monomethine cyanine dyes as noncovalent nucleic acid labels and their absorption and Fluorescence spectral characteristics
Dyes and Pigments, 2000Co-Authors: Todor Deligeorgiev, I. Timtcheva, Vera Maximova, Nikolai Gadjev, Haralambos E. Katerinopoulos, Evangelia FoukarakiAbstract:Abstract Several novel homodimeric asymmetric monomethine cyanine dyes based on the thiazole orange (TO) chromophore were synthesised via an improved synthetic procedure. The two TO chromophores [1-(ω-bromoalkyl)-4-[(3-methyl-2-(3H)-benzothiazolilyden)methyl] quinolinium iodide], with different chain lengths of the methylene linker between the quinolinium ring and the quaternary ammonium nitrogen, were connected by bisquaternization with N,N,N′,N′-tetramethyl-1,3-propanediamine, N,N,N′,N′-tetramethyl-1,6-hexanediamine, 1,4-diazabicyclo- [2,2,2]octane and 1,4′-bipyridine. The homodimeric dyes have large molar absorptivity (e 130 000–180 000 l mol−1 cm−1) at 505–506 nm. In the presence of ds DNA, their Fluorescence Maxima were located at 530–534 nm and the Fluorescence quantum yields were in the range 0.48–0.96. Fluorescence Maxima between 560–650 nm and Fluorescence quantum yields of 0.3–0.8 were observed in the presence of ss DNA.
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Effect of the medium acidity on the photophysical characteristics of some 2-aryl- and 2-hetaryl-benzothiazoles
Dyes and Pigments, 1997Co-Authors: Ivan Petkov, Todor Deligeorgiev, I. TimtchevaAbstract:Abstract The absorption and Fluorescence spectral characteristics of 2-aryl- and 2-hetaryl-benzothiazoles and their protonated forms in solution were studied. The influence of structural modifications on the position of their absorption and Fluorescence Maxima, as well as interesting features with respect to competition in protonation between the benzothiazole and aniline or hetaryl nitrogen atom in the ground ( S 0 ) state has been studied. The influence of pH on the absorption and the emission spectra of all the compounds has been investigated in order to identify the ground state species present as a function of acidity.