- Chromophore Orientation-Dependent Photophysical Properties of Pyrene-Naphthalimide Compact Electron Donor-Acceptor Dyads: Electron Transfer and Intersystem Crossing
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In order to study the effect of mutual orientation of the chromophores in compact electron donor-acceptor dyads on the spin-orbit charge transfer intersystem crossing (SOCT-ISC), we prepared naphthalimide (NI)-pyrene (Py) compact electron donor-acceptor dyads, in which pyrene acts as an electron donor and NI is an electron acceptor. The connection of the two units is at the 4-C and 3-C positions of the NI unit and the 1-position of the pyrene moiety for dyads NI-Py-1 and NI-Py-2, respectively. A charge transfer absorption band was observed for both dyads in the UV-vis absorption spectra. Upon nanosecond pulsed laser excitation, long-lived triplet states (lifetime is 220 μs) were observed and the triplet state was confined to the pyrene moiety. The ISC efficiency is moderate to high in nonpolar to polar solvents (singlet oxygen quantum yield: φ? = 14-52%). Ultrafast charge separation (ca. 0.81 ps) and charge recombination-induced ISC (?3.0 ns) were observed by femtosecond transient absorption spectroscopy. Time-resolved electron paramagnetic resonance spectroscopy confirms the SOCT-ISC mechanism; interestingly, the observed electron spin polarization pattern of the triplet state is chromophore orientation-dependent; and the population rates of the triplet sublevels of NI-Py-1 (Px:Py:Pz = 0.2:0.8:0) are drastically different from those of NI-Py-2 (Px:Py:Pz = 0:0:1).
- Imran, Muhammad,Sukhanov, Andrey A.,Maity, Partha,Elmali, Ayhan,Zhao, Jianzhang,Karatay, Ahmet,Mohammed, Omar F.,Voronkova, Violeta K.
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- Boranephosphonate DNA-Mediated Metallization of Single-Walled Carbon Nanotubes
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Single-walled carbon nanotubes (SWNTs), when dispersed in DMSO with boranephosphonate DNA (bpDNA), were efficiently metalized with silver, gold, and palladium nanoparticles (NPs). This was possible by first adsorbing boranephosphonate DNA onto the surface of SWNTs and then bathing with silver, gold, and palladium metal salts, which form the corresponding nanoparticles by reduction of their respective ions without addition of any external reducing agent. Reduction of a redox dye, 2,6-dichlorophenolindophenol (DCPIP), by Pd nanoparticle conjugates (PdNP/bpDNA/SWNT) disclosed the efficient electron transfer properties of these metallized SWNTs. These PdNP/bpDNA/SWNT conjugates were also successfully used to catalyze Heck and Suzuki coupling reactions. Boranephosphonate DNA-mediated metallization of SWNTs therefore provides a new method for fabricating well-defined SWNT-based nanostructures. This discovery should reveal unexpected applications in various research areas ranging from nanoelectronic devices to nanoscale SWNT supported multimetallic catalysts having different compositions.
- Ganguly, Saheli,Paul, Sibasish,Yehezkeli, Omer,Cha, Jennifer,Caruthers, Marvin H.
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- Ring Contraction of Tropylium Ions into Benzenoid Derivatives
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We report a method to convert substituted tropylium ions into benzenoid derivatives.
- Crocker, Reece D.,Dinh, An H.,Lyons, Demelza J. M.,Mai, Binh Khanh,Nguyen, Thanh Vinh,Ton, Nhan N. H.
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supporting information
p. 2520 - 2525
(2022/04/12)
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- Sterically enhanced 2-iminopyridylpalladium chlorides as recyclable ppm-palladium catalyst for Suzuki–Miyaura coupling in aqueous solution
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Sterically hindered 2-iminopyridine derivatives and their palladium chlorides complexes are designed and prepared, which efficiently promote the Suzuki–Miyaura coupling (SMC) reaction in aqueous solution. Besides the good to excellent yields and broad substrate scope, these catalysts can be reused for at least four new batches of the substrates. Spontaneous separation of coupling products in the aqueous reaction medium is the additional striking feature of this catalytic process. Furthermore, catalytic performance of palladium complexes bearing the azo-bridged phenyl groups was greatly influenced by the UV irradiation due to the cis/trans photoisomerization of azo unit of the catalysts. In conclusion, titled palladium complexes provide a green, sustainable, cost-effective, and convenient process to synthesize SMC products at multi-gram-scale reaction.
- Lin, Wenhua,Zhang, Liping,Ma, Yanping,Liang, Tongling,Sun, Wen-Hua
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- From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
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The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
- De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
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p. 133 - 147
(2021/05/10)
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- Suzuki-Miyaura Cross-Coupling of Sulfoxides
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The utilization of diphenyl sulfoxides as versatile electrophilic coupling partners for the Suzuki-Miyaura reaction via C-S bond cleavage was successfully developed under palladium-N-heterocyclic carbene catalysis. The reactions showed good functional group compatibility, proceeded well under mild conditions, and provided biaryls in yields of up to 96%. A wide range of useful functional groups, such as fluoro, chloro, ether, hydroxyl, amide, cyano, keto, trimethylsilyl (TMS), and ester were tolerated under the reaction conditions; however, the use of phenylboronic anhydride and arylboronic acid pinacol esters generally would lead low yields. Good regioselectivity for the electron-poor phenyl group was achieved when unsymmetrical diphenyl sulfoxides were used. The protocol is applicable at the gram scale even with half the amount of catalyst. Density functional theory calculations were performed to investigate the reaction mechanism, indicating that the reaction occurred through oxidative addition, transmetalation, and reductive elimination to provide the final coupling product.
- Abduhulam, Hayrul,Cao, Changsheng,Chen, Qianwei,Dang, Yanfeng,Li, Chengxi,Shi, Yanhui,Wu, Shufeng,Yan, Shuqin
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p. 8168 - 8176
(2020/09/18)
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- A [...] derivative and its preparation method and application
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The invention relates to the field of organic electroluminescent materials, and in particular relates to a pyrene derivative as well as a preparation method and application thereof; the pyrene derivative provided by the invention is that large substituent group units having different electronic properties and rigid structures are introduced at the positions of 1-, 3-, 6- and 8- of pyrene; intermolecular phi-phi stacking can be inhibited through molecular coplanar damage; therefore, an exciplex is difficult to form; the crystallization process is inhibited; the film-forming property is improved; therefore, the purpose of improving device properties is achieved; because an electron donor and an electron acceptor are introduced at special positions, a pyrene ring is asymmetrically functionalized; push-pull type molecular is constructed; intramolecular charge transfer is induced to generate; the charge transmission capability of the material is increased; and an organic light-emitting material having blue light property and high fluorescence quantum yield can be prepared. Compared with the existing light-emitting material, the light-emitting efficiency, the colour purity and the stability of the material are greatly improved.
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- Highly Emissive Organic Single-Molecule White Emitters by Engineering o-Carborane-Based Luminophores
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The development of organic single-molecule solid-state white emitters holds a great promise for advanced lighting and display applications. Highly emissive single-molecule white emitters were achieved by the design and synthesis of a series of o-carborane-based luminophores. These luminophores are able to induce multiple emissions to directly emit high-purity white light in solid state. By tuning both molecular and aggregate structures, a significantly improved white-light efficiency has been realized (absolute quantum yield 67 %), which is the highest value among the known organic single-molecule white emitters in the solid state. The fine-tuning of the packing modes from H- to J- and cross-stacking aggregates as well as intermolecular hydrogen bonds are successful in one molecular skeleton. These are crucial for highly emissive white-light emission in the solid state.
- Tu, Deshuang,Leong, Pakkin,Guo, Song,Yan, Hong,Lu, Changsheng,Zhao, Qiang
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supporting information
p. 11370 - 11374
(2017/09/11)
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- Gold-Catalyzed Suzuki Coupling of ortho-Substituted Hindered Aryl Substrates
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A method that allows hindered ortho-substituted aryl iodides to be efficiently coupled to phenylboronic acid using a gold-catalyzed C?C bond formation is presented. The use of a molecularly-defined dinuclear gold chloride catalytic precursor that is stabilized by a new tetradentate (N,N′)-diamino-(P,P′)-diphosphino ferrocene hybrid ligand in a Suzuki-type reaction is described for the first time. Electron-rich isopropyl groups on phosphorus were found essential for a superior activity, while the performances of a set of analogous gold dinuclear complexes that were fully characterized by multinuclear NMR spectroscopy and XRD analysis, were investigated. Therefore, arylation of para and ortho-substituted iodoarenes bearing electron-rich, electron-poor functional groups, and even hindered polycyclic aromatic compounds is described.
- Dwadnia, Nejib,Roger, Julien,Pirio, Nadine,Cattey, Hélène,Ben Salem, Ridha,Hierso, Jean-Cyrille
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supporting information
p. 459 - 464
(2017/02/23)
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- Ferrocene catalysed C–H arylation of arenes and reaction mechanism study using cyclic voltammetry
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Ferrocene catalysed C–H arylation of benzene using aryldiazonium salt is studied. Yield of biphenyl in this reaction was found to be better than some of the known methods. Aryldiazonium salts with electron withdrawing groups produced excellent yields (upto 85%) in C–H arylation. Applicability of this reaction was studied on several arenes and heteroarene such as benzene, naphthalene, anthracene, pyrene and pyridine. Catalytic role of ferrocene in aryl radical formation was studied by cyclic voltammetry of phenyldiazonium tetrafluoroborate. In presence of ferrocene more radical formation was observed. This reaction model works at ambient temperature and features the use of inexpensive catalyst for the synthesis of biaryl derivatives.
- Dixit, Swati,Siddiqui, Qamar Tabrez,Muneer, Mohammad,Agarwal, Neeraj
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p. 4228 - 4231
(2016/08/25)
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- An easily prepared palladium-hydrogel nanocomposite catalyst for C-C coupling reactions
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Supported metallic nanoparticles are important composite materials owing to their enormous potential for applications in various fields. In this work, palladium nanoparticles were prepared in situ in a calcium-cholate (Ca-Ch) hydrogel by reduction with sodium cyanoborohydride. The hydrogel matrix appeared to assist the controlled growth as well as stabilization of palladium nanoparticles. The palladium nanoparticle/Ca-Ch hydrogel hybrid was characterized by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Furthermore, the PdNP/Ca-Ch hybrid xerogel was shown to act as an active catalyst for the Suzuki reaction under aqueous aerobic conditions. The PdNP/Ca-Ch xerogel retains its catalytic activities on storage for several months.
- Maity, Mitasree,Maitra, Uday
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supporting information
p. 18952 - 18958
(2014/12/10)
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- Fast thermal evaporation in purification of 1,4-Di(pyren-1-ly)benzene
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This work presents a fast purification system that involves a vertical quartz tube and vacuum sublimation for separation without dilution. This system produced re-crystallized 1,4-di(pyren-1-yl)benzene (DPB) in a few hours following the synthesis of pyrene derivatives with a mole yield ratio of 1,4-di(pyrene-1-yl)benzene to 1-phenylpyrene (1PP) of 5:1. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) were utilized to identify the products. Finally, the lifetimes of pyrene derivatives DPB and 1PP were determined by exponential regression to be 10.0 ± 0.14 and 3.3 ± 0.15 ns, respectively. From the lifetime measurements, the purity of the photo-responsive materials could be easily determined. To prevent red-shift of electro-luminescence (EL) spectra by the energy transfer mechanism, it has acquired to elect transfer layers for pure electroluminescence. Aco-catalytic reaction reduced the amount of impurities and eliminated the need for the use of a solvent in the purification step.
- Hsu, Chung-Yi,Lin, Hung-Yin,Yan, Xuan-You,Huang, Tsung-Syun,Su, Yan-Kuin,Whang, Thou-Jen
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p. 289 - 296
(2012/08/08)
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- LIGHT-EMITTING ELEMENT MATERIAL PRECURSOR BODY AND PRODUCTION METHOD THEREFOR
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Disclosed are a method which can produce a chemical compound precursor body for a light-emitting element material which is difficult to produce using conventional methods, and a method for therefrom producing a suitable material and an organic electroluminescent element utilizing same. The disclosed precursor body for a light-emitting element material is represented by general formula 1. [Formula 1] (wherein, R1 - R6 may be the same or different from each other, and are chosen from the set consisting of hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thieoether group, an aryl group, a heteroaryl group, and a halogen. However, of R1 - R6, at least one must have a condensed aromatic hydrocarbon with at least two rings.)
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Page/Page column 15
(2012/02/15)
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- Organic light emitting material and organic light emitting device using the same
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Disclosed is an organic light emitting material having the following chemical formula, for improving luminous efficiency, where R1, R2, R3 and R4 denote materials selected from an aromatic group with 6-24 carbon atoms (C6-C24), the group being independently substituted or unsubstituted, preferably, an aromatic group with 6-24 carbon atoms (C6-C24), the group consisting of trimethylsilane (TMS), CN, halogen (F, Cl, Br) alkyl groups with 1-4 carbon atoms (C1-C4).
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- Synthesis and spectroscopic properties of arene-substituted pyrene derivatives as model compounds for fluorescent polarity probes
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In this paper, the syntheses of a variety of substituted phenyl pyrenes 5a-n by Suzuki cross-coupling and of two decoupled analogues 10 and 17 are reported. These compounds have been investigated by fluorescence spectroscopy. The solvatochromism of their emission bands (Stokes shift) and the quantum yields in methylcyclohexane and acetonitrile have been determined. Furthermore, the crystal structure of a pyrenyl-tris(2,2′-bipyridine)ruthenium(II) complex 19 is presented.
- Beinhoff, Matthias,Weigel, Wilfried,Jurczok, Martin,Rettig, Wolfgang,Modrakowski, Claudia,Bruedgam, Irene,Hartl, Hans,Schlueter, A. Dieter
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p. 3819 - 3829
(2007/10/03)
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