- A comprehensive study on the dye adsorption behavior of polyoxometalate-complex nano-hybrids containing classic β-octamolybdate and biimidazole units
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Six new hybrids based on β-[Mo8O26]4? polyoxometalates, [Ni(H2biim)3]2[β-Mo8O26]?8DMF(1); (DMA)2[M(H2biim)2(H2O)2][β-Mo8O26]?4DMF (M = Ni (2), Co (3)), DMA = dimethyl-ammonium, H2biim=2,20-biimidazole); [M(H2biim)(DMF)3]2[β-Mo8O26]?2DMF (M = Zn (4), Cu (5)); [(DMA)2 [Cu(DMF)4][β-Mo8O26]?2DMF]n (6), have been successfully synthesized and characterized. Compounds 2–5 show favorable capacity to adsorb methylene blue (MB) at room temperature, and they can selectively capture MB molecules from binary-mixture solutions of MB/MO (MO = Methyl Orange), or MB/RhB (RhB = Rhodamine B). Compound 3 can uptake up to 521.7 mg g?1 MB cationic dyes rapidly, which perform the maximum adsorption in an hour among the reported materials as far as we know. The compounds are stable and still work very efficiently after three cycles. For compound 3, the preliminary adsorption mechanism studies indicated that the adsorption is an ion exchange process and the adsorption behavior of polyoxometalate-complex can be benefited from additional exchangeable protons in the complex cations.
- Liang, Shuang,Nie, Yan-Mei,Li, Sang-Hao,Zhou, Jian-Liang,Yan, Jun
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- Multiplex Proton-Transfer and Electron-Transfer Natures Based on the 2,2'-Bi-1H-imidazole System. I. Acid Dissociation Constants and Redox Properties in Solution
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The 2,2'-bi-1H-imidazole (H2BIM) derivatives were studied from the point of the interplay of proton-transfer (PT) and electron (charge)-transfer (CT) interactions.Seven new states among the speculated 25 independent species were identified based on the study of their redox and acid dissociation properties.Isoelectronic substitution of four sulfur atoms of the dication state of tetrathiafulvalene (TTF2+) by four imino groups was found to increase the stability of the dication state 2,2'-bi-1H-imidazolium (H4BIM2+) with aromatic 6?-6? character.The high PT character of H3BIM+ (2-(2-1H-imidazolyl)-1H-imidazolium) and H4BIM2+ compared with that of corresponding hydroquinone system was clearly observed.The onsite Coulomb repulsion energy for electron-transfer (U1CT) was evaluated for various ?-electron acceptor and donor systems.It was found that the U1CT values decrease linearly with increasing the length of a molecule, which can divide the molecular systems into two-classifications, i.e. electron and dications.The onsite Coulomb repulsion energy for two-step proton-transfer processess (U1PT) was newly defined and evaluated for the H2BIM, H4BIM2+, hydroquinone (H2Q), and bis(4-hydroxyphenyl) disulfide (HPDS) systems.The U1PT values become constant above a certain molecular length (rc).Below rc the U1PT values increase linearly with decreasing the distance r regardless of Wuerster and Weitz structures, approximately.The H2BIM (H4BIM2+) system has large U1PT values in comparison with H2Q and HPDS systems.
- Akutagawa, Tomoyuki,Saito, Gunzi
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- Bridged Derivatives of 2,2'-Biimidazole
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The reaction of 2,2'-biimidazole with 1,n-dihaloalkanes or o-xylylene dibromide leads to a series of N,N'-bridged derivatives.When these substances are treated with a second equivalent of 1,n-dihaloalkane, a series of bis-annelated biimidazolium salts is obtained.The conformations of these species are discussed with regard to their electronic absorption spectra and their 300-MHz 1H NMR spectra.The barriers for conformational inversion are found to be lower than for the corresponding bis-annelated 2,2'-bipyridinium salts.The redox properties of these salts are measured in CH3CN and DMSO, and their reductions are found to become increasingly more difficult and less reversible as the system becomes less planar.These results are explained primarily based on the greater N,N'-distance in 2,2'-biimidazole as compared with 2,2'-bipyridine.
- Thummel, Randolph P.,Goulle, Veronique,Chen, Baili
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- Studies of ruthenium(ii)-2,2′-bisimidazole complexes on binding to G-quadruplex DNA and inducing apoptosis in HeLa cells
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Three ruthenium(ii) complexes [Ru(bpy)2(biim)]2+ (1), [Ru(phen)2(biim)]2+ (2) and [Ru(p-mopip) 2-(biim)]2+ (3) (where bpy is 2,2′-bipyridine, phen is 1,10-phenanthroline, biim is 2,2′-bisimidazole and p-mopip is 2-(4-methoxyphenyl)-imidazo-[4,5f]phenanthroline), have been synthesized and characterized. The interactions of human telomeric DNA oligomers 5′-G 3(T2AG3)3-3′ (HTG21) with ruthenium(ii) complexes were investigated via UV-vis, fluorescence resonance energy transfer (FRET) melting assay, polymerase chain reaction (PCR) stop assay, and circular dichroism (CD) measurements. The results indicated that the three ruthenium(ii) complexes could stabilize the formation of human telomeric G-quadruplex DNA, and complex 2 was found to be the most efficient. In vitro cytotoxicity assay by MTT also showed that complex 2 was superior to complexes 1 and 3 in inhibiting the growth of cancer cells. Telomeric repeat amplification protocol (TRAP) showed that complexes 2 and 3 led to an inhibition of the telomerase activity, and complex 2 was the significantly better inhibitor. Flow cytometric analysis and evaluation of mitochondrial membrane potential demonstrated that complex 2 inhibited the growth of HeLa cells through induction of apoptotic cell death, as evidenced by the depletion of mitochondrial membrane potential in HeLa cells.
- Xia, Yu,Chen, Qingchang,Qin, Xiuying,Sun, Dongdong,Zhang, Jingnan,Liu, Jie
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- Tetracarboxyl-functionalized ionic liquid: Synthesis and catalytic properties
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Novel tetracarboxyl-functionalized 2,2′-biimidazolium-based ionic liquids (ILs) with different anions were synthesized in two steps from readily available and sustainable starting materials including ammonium acetate, glyoxal, and halogenated propionic acid. The functionalized IL exhibited higher catalytic activity towards the cycloaddition of CO2 to terminal epoxides. With propylene oxide as a substrate, the optimum yield of propylene carbonate reached 82.7% at an initial CO2 pressure of 2.0MPa for 4h at 140°C. Moreover, the functionalized IL catalyst displayed a high stability and can be reused for at least five cycles without obvious loss of catalytic activity. The results provide a simple and economical way to synthesize multi-functionalized imidazolium-based ILs with versatile potential applications.
- Feng, Miaona,Zhao, Guoying,Gao, Hongling,Zhang, Suojiang
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- Synthesis and Properties of 4,4',5,5'-Tetranitro-1H,1'H-2,2'-Biimidazole Salts: Semicarbazidium, 3-Amino-1,2,4-Triazolium, and 5-Aminotetrazolium Derivatives
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[Figure not available: see fulltext.] Ionic derivatives of 4,4',5,5'-tetranitro-1H,1'H-2,2'-biimidazole have recently been identified as interesting low-sensitivity explosive compounds that combine low vulnerability to mechanical stimuli with high performance. In this work, the synthesis of bis-semicarbazidium), bis(3-amino-1H-1,2,4-triazol-4-ium), and bis(5-amino-4H-tetrazol-1-ium) 4,4',5,5'-tetranitro-2,2'-biimidazol-1-ides is described, and some of their experimental and calculated explosive properties are presented. 4,4',5,5'-Tetranitro-1H,1'H-2,2'-biimidazole was synthesized by nitration of 2,2'-biimidazole with nitric acid in polyphosphoric acid and produced the salts in good yields and purity by reaction with semicarbazide hydrochloride in water, 3-amino-1,2,4-triazole in methanol, and 5-aminotetrazole in diethyl ether. The obtained salts were characterized by NMR and infrared spectroscopy, elemental analysis, thermal analysis, and small-scale safety testing impact and friction sensitivity). The measured densities and standard enthalpy of formation, as well as calculated performance characteristics are reported. The compounds are thermally stable up to 180–210°C and insensitive to mechanical stimuli and have slightly better performance than trinitrotoluene with regard to calculated detonation parameters.
- Lewczuk, Rafa?,Szala, Mateusz,Re?ko, Judyta,Klap?tke, Thomas M.,Cudzi?o, Stanis?aw
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- Fully C/N-Polynitro-Functionalized 2,2'-Biimidazole Derivatives as Nitrogen- and Oxygen-Rich Energetic Salts
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Through the use of a fully C/N-functionalized imidazole-based anion, it was possible to prepare nitrogen- and oxygen-rich energetic salts. When N,N-dinitramino imidazole was paired with nitrogen-rich bases, versatile ionic derivatives were prepared and fully characterized by IR, and 1H, and 13C NMR spectroscopy and elemental analysis. Both experimental and theoretical evaluations show promising properties for these energetic compounds, such as high density, positive heats of formation, good oxygen balance, and acceptable stabilities. The energetic salts exhibit promising energetic performance comparable to the benchmark explosive RDX (1,3,5-trinitrotriazacyclohexane). The combination of a fully C/N-functionalized biimidazole-based anion with nitrogen-rich cations gives rise to a series of nitrogen- and oxygen-rich energetic salts. Some of them show excellent detonation properties with acceptable thermal stabilities and sensitivities, which are comparable to the benchmark explosive RDX (1,3,5-trinitrotriazacyclohexane).
- Yin, Ping,He, Chunlin,Shreeve, Jean'ne M.
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- An ionic liquid-coordinated palladium complex: A highly efficient and recyclable catalyst for the Heck reaction
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The monoquaternary product of 2,2′-biimidazole with iodobutane is an ionic liquid that acts as both the solvent and ligand for catalytic reactions. A new palladium complex was prepared by adding PdCl2 to this ionic liquid to form a catalytic solution that is effective for Heck reactions with good recyclability.
- Xiao, Ji-Chang,Twamley, Brendan,Shreeve, Jean'ne M.
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- Energetic derivatives of 4, 4',5, 5'-Tetranitro-2, 2'-bisimidazole (TNBI)
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4, 4',5, 5'-Tetranitro-2, 2'-bisimidazole (TNBI) was synthesized by nitration of bisimidazole (BI) and recrystallized from acetone to form a crystalline acetone adduct. Its ammonium salt (1) was obtained by the reaction with gaseous ammonia. In order to explore new explosives or propellants several energetic nitrogen-rich 2:1 salts such as the hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6) and triaminoguanidinium 7 4, 4',5, 5'-tetranitro-2, 2'-bisimidazolate were prepared by facile metathesis reactions. In addition, methylated 1, 1'-dimethyl-4, 4',5, 5'-tetranitro-2, 2'-bisimidazole (Me2TNBI, 8) was synthesized by the reaction of 2 and dimethyl sulfate. Metal salts of TNBI can also be easily synthesized by using the corresponding metal bases. This was proven by the synthesis of pyrotechnically relevant dipotassium 4, 4',5, 5'-tetranitro-2, 2'-bisimidazolate (2), which is a brilliant burning component e.g. in near-infrared flares. All compounds were characterized by single crystal X-ray diffraction, NMR and vibrational spectroscopy, elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated using CBS-4M electronic enthalpies and the atomization method. With these values and mostly the X-ray densities different detonation parameters were computed by the EXPLO5 computer code. Due to the great thermal stability and calculated energetic properties, especially guanidinium salt 4 could be served as a HNS replacement. Copyright
- Klapoetke, Thomas M.,Preimesser, Andreas,Stierstorfer, Joerg
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- C6N10O4: Thermally Stable Nitrogen-Rich Inner Bis(diazonium) Zwitterions
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Two nitrogen-rich inner bis(diazonium) salts, the 4,4′-dinitro-5,5′-diazo-2,2′-bisimidazole (2) and the 4,4′-dinitro-5,5′-diazo-3,3′-bispyrazole (4) zwitterions, are described. Compound 2 was synthesized unexpectedly from the nitration of 4,4′-dinitro-5,5′-diamino-1H,1′H-2,2′-bisimidazole (1) in a mixture of trifluoroacetic anhydride and 100% nitric acid. Both 2 and 4 show good thermal stability, especially 2 has a decomposition temperature of 199 °C, which is the highest one in any of the reported hydrogen-free nitrogen-rich diazonium salts.
- Tang, Yongxing,Imler, Gregory H.,Parrish, Damon A.,Shreeve, Jean'ne M.
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- Syntheses of 2,2'-Diimidazole
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New methods of preparation of 2,2'-diimidazole have been developed, by the reaction of ammonia with 1,1-dibromoacetaldehyde (20percent yield) or with glyoxal sulfate (40percent), and by the cyclization of 1,2-dihydroxyethylenediamine dihydrochloride in the presence of sodium acetate (yield 60percent).
- Nurgatin, V. V.,Ginzburg, B. M.,Sharnin, G. P.,Polyanskii, V. F.
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- Hydrogen production from formic acid catalyzed by a phosphine free manganese complex: Investigation and mechanistic insights
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Formic acid dehydrogenation (FAD) is considered as a promising process in the context of hydrogen storage. Its low toxicity, availability and convenient handling make FA attractive as a potential hydrogen carrier. To date, most promising catalysts have been based on noble metals, such as ruthenium and iridium. Efficient non-noble metal systems like iron were designed but manganese remains relatively unexplored for this transformation. In this work, we present a panel of phosphine free manganese catalysts which showed activity and stability in formic acid dehydrogenation. The most promising results were obtained with Mn(pyridine-imidazoline)(CO)3Br yielding >14 l of the H2/CO2 mixture and proved to be stable for more than 3 days. Additionally, this study provides insights into the mechanism of formic acid dehydrogenation. Kinetic experiments, Kinetic Isotopic Effect (KIE), in situ observations, NMR labeling experiments and pH monitoring allow us to propose a catalytic cycle for this transformation.
- Léval, Alexander,Agapova, Anastasiya,Steinlechner, Christoph,Alberico, Elisabetta,Junge, Henrik,Beller, Matthias
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supporting information
p. 913 - 920
(2020/02/27)
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- A series of blue-green-yellow-red emitting Cu(I) complexes: Molecular structure and photophysical performance
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In this work, we designed a series of [Cu(N–N)(PPh3)2]BF4 complexes with different optical edge values and emission colors from blue to red, where N–N and PPh3 denoted a diamine ligand and triphenylphosphine, respectively. Six N–N ligands with various conjugation chains (short π chain, modest π chain and long π chain) were selected. A systematical comparison between these Cu(I) complexes was performed, so that the correlation between N–N structure and [Cu(N–N)(PPh3)2] photophysical performance was tentatively discussed. Their single crystal structure was found consistent with literature ones, forming a typical tetrahedral coordination geometry. Density functional theory calculation indicated that their onset electronic transition showed a mixed character of metal-to-ligand-charge-transfer and ligand-to-ligand-charge-transfer. Detailed analysis on photophysical parameters suggested that the absorption edge of [Cu(N–N)(PPh3)2]BF4 complex was controlled by conjugation length in diamine ligand. A wide absorption edge needed a short conjugation chain in diamine ligand. Similar tendency was found for their emission spectra. In addition, a long conjugation chain in diamine ligand widened emission spectra obviously. Emission dynamics showed slim correlation with diamine ligand conjugation length since the excited state was controlled mainly by dynamic procedure and steric factor of diamine ligands.
- Zhang, Liming,Zuo, Qinghui
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- Incrementing Stokes Shifts through the Formation of 2,2′-Biimidazoldiium Salts
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The formation of biimidazoldiium structures by the introduction of methyl substituents on the N atoms at the 3 and 3′ positions of 2,2′-biimidazoles led to increments in the Stokes shift of these structures. Based on time-dependent density functional theory (TDDFT) calculations, the imidazolium rings become distorted and the N atoms of the imidazolium rings underwent structural changes through sp2 to sp3 rehybridization in the excited states.
- Matsumoto, Shoji,Watanabe, Mei,Akazome, Motohiro
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supporting information
p. 3613 - 3617
(2018/06/26)
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- Effect of ancillary ligands on the properties of diphenylphosphoryl-substituted cationic Ir(iii) complexes
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A new class of diphenylphosphoryl-substituted cationic cyclometalated Ir(iii) complexes [Ir(POFdFppy)2(N^N)]+PF6- (dFppy = 2-(2,4-difluorophenyl)pyridine) (POF1-POF6) with different N^N ancillary ligands have been synthesized and characterized. The influences of N^N ancillary ligands on the photophysical and electrochemical properties of the Ir(iii) complexes have been investigated systematically. The results demonstrate that the photoluminescence quantum yields (ΦPL) of the complexes are dependent on the N^N ancillary ligands. POF1-POF3 equipped with phenanthroline or bipyridine ancillary ligands exhibit intense emission bands at 465-497 nm and high ΦPL in the range of 56-61% in CH2Cl2. The biimidazole-type complexes POF4-POF6 exhibit an obvious substituent effect on the photophysical and electrochemical properties. Although the emission spectra of POF4 and POF5 show similar fine structures, the ΦPL of POF5 bearing two methyl groups at the biimidazole moiety is remarkably lower (5%) than that of POF4 (45%, unmodified biimidazole). POF6 bearing two phenyl groups at the biimidazole moiety exhibits a red-shift and a weak emission band, and an extremely low ΦPL (3%). However, the photoluminescence quantum yields of POF5 and POF6 (35% and 41% in EC film, 40% and 65% in neat film, respectively) in the film increase effectively in comparison to those in solution. Cyclic voltammetry shows further that the structure of the ancillary ligand affects the redox properties. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to provide insights into the electronic structures of POF1-POF6. POF1 bearing a 1,10-phenanthroline moiety demonstrates the highest oxygen sensitivity.
- Yu, Hongcui,Liu, Chun,Yu, Zhenni,Zhang, Liyan,Xiu, Jinghai
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supporting information
p. 3519 - 3527
(2017/04/13)
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- Cyclometalated IrIII Complexes as Mitochondria-Targeted Photodynamic Anticancer Agents
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Photodynamic therapy (PDT) is an attractive therapeutic modality with high therapeutic efficacy and less side effects compared with other therapies. Herein, we developed a series of cyclometalated IrIII complexes based on 2,2′-biimidazole with different alkyl substitutions (methyl, ethyl, propyl, and butyl). These complexes can efficiently produce singlet oxygen upon light irradiation. In vitro photocytotoxicity towards four cell lines (HeLa, A549, A549R, and LO2) was examined. Ir1–Ir5 show quick penetration of cells, remarkable mitochondrial accumulation, strong phototoxicity, and they exhibit high selectivity between tumor cells and normal cells. With the highest 1O2 quantum yields, Ir5 presents the best PDT efficiency with a high phototoxicity index (PI) value (PI = 150) towards HeLa cells. This work provides a valuable avenue to improve the PDT effect by tuning the lipophilicity and other properties with variation of the alkyl substitution on the photosensitizer. In addition, their satisfying PDT effect to a cisplatin-resistant cell line (A549R) may contribute to the future development of improved chemotherapeutics.
- Ouyang, Miao,Zeng, Leli,Qiu, Kangqiang,Chen, Yu,Ji, Liangnian,Chao, Hui
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p. 1764 - 1771
(2017/04/03)
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- Catalytic Application of an Octamolybdate Salt (H3biim)4[β-Mo8O26] in Olefin Epoxidation (H2biim = 2,2′-biimidazole)
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The octamolybdate salt (H3biim)4[β-Mo8O26] (1) has been prepared in good yield by hydrolysis of the complex [MoO2Cl2(H2biim)] (H2biim = 2,2′-biimidazole). Compound 1 showed a good performance as a (pre)catalyst for the epoxidation of olefins using either tert-butylhydroperoxide (TBHP) or hydrogen peroxide as oxidant. With the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide) as co-solvent and TBHP as oxidant, the catalyst system could be reused several times without loss of activity for the epoxidation of the bio-olefin methyl oleate (Ole). Compound 1 is the first polyoxomolybdate used for the Ole/TBHP reaction in IL medium.
- Neves, Patrícia,Amarante, Tatiana R.,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
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p. 841 - 850
(2016/03/19)
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- Solubilised bright blue-emitting iridium complexes for solution processed OLEDs
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Combining a sterically bulky, electron-deficient 2-(2,4-difluorophenyl)-4-(2,4,6-trimethylphenyl)pyridine (dFMesppy) cyclometalating C∧N ligand with an electron rich, highly rigidified 1,1′-(α,α′-o-xylylene)-2,2′-biimidazole (o-xylbiim) N∧N ligand gives an iridium complex, [Ir(dFMesppy)2(o-xylbiim)](PF6), that achieves extraordinarily bright blue emission (ΦPL = 90%; λmax = 459 nm in MeCN) for a cationic iridium complex. This complex is compared with two reference complexes bearing 4,4′-di-tert-butyl-2,2′-bipyridine, and solution-processed organic light emitting diodes (OLEDs) have been fabricated from these materials.
- Henwood, Adam F.,Bansal, Ashu K.,Cordes, David B.,Slawin, Alexandra M. Z.,Samuel, Ifor D. W.,Zysman-Colman, Eli
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supporting information
p. 3726 - 3737
(2016/05/19)
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- Nano magnetite supported metal ions as robust, efficient and recyclable catalysts for green synthesis of propargylamines and 1,4-disubstituted 1,2,3-triazoles in water
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Nano magnetite functionalized 2,2′-biimidazole complex of metal ions Cu(i), Cu(ii), Ni(ii) and Co(ii) were successfully synthesized and characterized by different techniques such as elemental analysis, FT-IR spectroscopy, X-ray diffraction (XRD), thermo gravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM with EDS), atomic absorption spectroscopy (AAS), inductively coupled plasma-optical emission spectrometry (ICP-OES) and vibrating sample magnetometer (VSM) instrument. The synthesized magnetic nanoparticles were used as heterogeneous catalysts for the synthesis of propargylamines via the three-component coupling reaction of aldehydes, alkynes and amines and one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles by the click reaction of primary halides or tosylates, sodium azide and terminal acetylenes in aqueous media. The prepared nanocatalyst can be facilely recovered and reused many times without a significant decrease in activity and selectivity. The high catalytic activity, thermal stability and reusability, simple recovery and eco-friendly nature of the catalyst make the present method particularly attractive in green chemistry.
- Tajbakhsh, Mahmood,Farhang, Maryam,Baghbanian, Seyed Meysam,Hosseinzadeh, Rahman,Tajbakhsh, Mahghol
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p. 1827 - 1839
(2015/03/18)
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- Nano Fe3O4 supported biimidazole Cu(i) complex as a retrievable catalyst for the synthesis of imidazo[1,2-a]pyridines in aqueous medium
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A novel magnetically recoverable nano-catalyst based on a biimidazole Cu(i) complex has been synthesized by covalent grafting of biimidazole on chloride-functionalized silica@magnetite nanoparticles, followed by metalation with CuI. The synthesized catalyst was characterized by various techniques such as CHN, NMR, FT-IR, TG/DTG, SEM, TEM, EDS, XRD, AAS, ICP-OES and VSM which revealed the superparamagnetic nature of the particles. The amount of Cu in the catalyst was measured to be 1.2 mmol g-1 by ICP-OES and AAS. From electron microscopy (SEM and TEM) studies it can be inferred that the particles are mostly spherical in shape and have an average size of 20 nm. Elemental and thermo gravimetric analysis (CHN and TG) results indicate the loading amount of functionalized organic groups on the magnetic material was 1.4 mmol g -1. The prepared nanocatalyst was shown to have excellent and green catalytic activity in the synthesis of imidazo[1,2-a]pyridines in aqueous media. The catalyst can be easily recovered by applying an external magnetic field and reused for atleast 10 times without deterioration in catalytic activity.
- Tajbakhsh, Mahmood,Farhang, Maryam,Hosseinzadeh, Rahman,Sarrafi, Yaghoub
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p. 23116 - 23124
(2014/06/24)
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- Blue emitting cationic iridium complexes containing two substituted 2-Phenylpyridine and One 2,2'-biimidazole for solution-processed organic light-emitting diodes (OLEDs)
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Two new blue emitting cationic iridium(III) complexes with two substituted 2-phenlypyridine ligands as main ligands and one 2,2'-biimidazole as an ancillary ligand, [(L1)2Ir(biim)]Cl (1) and [(L2)2Ir(biim)]Cl (2), where L1 = 2-(2',4'-difluorophenyl)-4-methylpyridine, L2 = 2-(2',4'-difluoro-3'- trifluoromethylphenyl)-4-methylpyridine and biim = 2,2'-biimidazole, were synthesized for applications in phosphorescent organic lightemitting diodes (PhOLEDs). Their photophysical, electrochemical and electroluminescent (EL) device performances were examined. The photoluminescent (PL) spectra revealed blue phosphorescence in the 450 to 485 nm range with a quantum yield of more than 10%. The iridium(III) compounds studied showed good solubility in organic solvents with no solvatochromism dependent on the solvent polarity. The solutionprocessed OLEDs were prepared with the configuration, ITO/PEDOT:PSS (40 nm)/mCP:Ir(III) (70 nm)/ OXD-7 (20 nm)/LiF (1 nm)/Al (100 nm), by spin coating the emitting layer containing the mCP host doped with the iridium phosphors. The best performance of the fabricated OLEDs based on compound 1 showed an external quantum efficiency of 4.5%, luminance efficiency of 8.52 cd A-1 and blue emission with the CIE coordinates (x,y) of (0.16, 0.33).
- Yun, Seong-Jae,Seo, Hoe-Joo,Song, Myungkwan,Jin, Sung-Ho,Kim, Young Inn
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p. 3645 - 3650
(2013/01/16)
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- Synthesis, characterization, and surface studies of conjugated polymers possessing 2,2'-biimidazole moieties
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Two novel 2,2'-biimidazole-thiophene structures, 5,5'-bis(2,2'-bithiophene- 5-yl)-1,1'-dimethyl-2,2'-biimidazole and 5,5'-bis(3,4-ethylenedioxythiophene-2- yl)-1,1'-dimethyl-2,2'-biimidazole, have been synthesized and electrochemically polymerized. These materials underwent facile oxidation on Pt and ITO surfaces in CH2Cl2/Bu4NPF6 to yield conjugated, electroactive polymer films. The films were characterized with cyclic voltammetry, electronic absorption spectroscopy, and atomic force microscopy.
- Walker,Douglas,Mac Lean
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experimental part
p. 729 - 737
(2009/12/04)
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- Br?nsted acidic imidazolium salts containing perfluoroalkyl tails catalyzed one-pot synthesis of 1,8-dioxo-decahydroacridines in water
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One-pot three-component synthesis of 1,8-dioxo-9,10-diaryl-decahydroacridines in water was efficiently realized in the presence of the Br?nsted acidic imidazolium salts containing perfluoroalkyl tails in good yields. The method provided several advantages such as low catalyst loading; recycle of the catalyst and simple work procedure.
- Shen, Wei,Wang, Li-Min,Tian, He,Tang, Jun,Yu, Jian-jun
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body text
p. 522 - 527
(2009/11/30)
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- BINUCLEAR METAL COMPLEX, METAL COMPLEX DYE, PHOTOELECTRIC TRANSDUCER AND PHOTOCHEMICAL BATTERY
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A novel binuclear metal complex according to the present invention is an asymmetric binuclear metal complex represented by the general formula: (L1)2M1(BL)M2(L2)2(X)n, wherein M1 and M2, which may be identical or different, represent a transition metal; L1 and L2, which are different, represent a chelate ligand capable of polydentate coordination and two L1s may be different and two L2s may be different; BL represents a bridge ligand having at least two heteroatom-containing cyclic structures, the heteroatoms contained in the cyclic structures being ligand atoms coordinating to M1 and M2; X represents a counter ion; and n is the number of counter ions needed to neutralize the charge of the complex. And the binuclear metal complex is useful as a metal complex dye.
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Page/Page column 23-24
(2008/06/13)
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- ELECTROCHEMICAL AFFINITY BIOSENSOR SYSTEM AND METHODS
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The present invention provides novel osmium-based electrochemical species for the detection of wide variety of analytes using immunological techniques. The present invention also provides diagnostic kits and test sensors supporting electrode structures that can be used with the osmium-based electrochemical species. The test sensor can be fabricated to support interdigitated arrays of electrodes that have been designed to provide amplification of the electrical signal amplification desired to analyze analytes that may be present at low concentrations.
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Page/Page column 77; Sheet 31
(2010/02/11)
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- Preparation method of 2,2'-bi-1H-imidazole using glyoxal and an ammonium salt
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Disclosed is a preparation method of 2,2′-bi-1H-imidazole using glyoxal and an ammonium salt as starting materials through a safe, simple and easily controlled synthetic process with a high yield.
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Page/Page column 2
(2008/06/13)
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- Long tethers binding redox centers to polymer backbones enhance electron transport in enzyme "wiring" hydrogels
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A redox hydrogel with an apparent electron diffusion coefficient (Dapp) of (5.8 ± 0.5) × 10-6 cm2 s-1 is described. The order of magnitude increase in Dapp relative to previously studied redox hydrogels results from the tethering of redox centers to the backbone of the cross-linked redox polymer backbone through 13 atom spacer arms. The long and flexible tethers allow the redox centers to sweep electrons from large-volume elements and to collect electrons of glucose oxidase efficiently. The spacer arms make the collection of electrons from glucose oxidase so efficient that glucose is electrooxidized already at -0.36 V versus Ag/AgCl, the reversible potential of the redox potential of the FAD/FADH2 centers of the enzyme at pH 7.2. The limiting current density of 1.15 mA cm-2 is reached at a potential as low as -0.1 V versus Ag/AgCl. The novel redox center of the polymer is a tris-dialkylated N,N′-biimidazole Os2+/3+ complex. Its redox potential, -0.195 V versus Ag/AgCl, is 0.8 V reducing relative to that of Os(bpy)2+/3+, its 2,2′-bipyridine analogue.
- Mao, Fei,Mano, Nicolas,Heller, Adam
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p. 4951 - 4957
(2007/10/03)
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- Regioselective symmetrical bromination of protected 2,2′-biimidazole
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Treatment of the benzyl and (trimethylsilylethoxymethyl) SEM protected 2,2′-biimidazoles, 2a and 2b, with 2 equivalents of N-bromosuccinimide (NBS) allows obtaining the 5,5′-dibromo and 4,4′-dibromo substituted biimidazoles, 3a and 5b respectively. The use of 4 equivalents of NBS, followed by treatment of the corresponding tetrabromoderivatives 4a and 5b with butyl lithium (BuLi), yields the 4,4′-dibromoderivatives 5a (G=Bn) and 5b (G=SEM).
- Sanchez-Garcia, David,Borros, Salvador,Nonell, Santi,Borrell, Jose I.,Colominas, Carles,Teixido, Jordi
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p. 733 - 735
(2007/10/03)
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- The Synthesis of Some Lipophilic Tetradentate Ligands for Use in the Formation of Metal-Linked Polymers
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Two lipophilic tetradentate ligands, 5,5'-di-t-butyl- and 5,5'-dihexyl-2,2'-bipyrimidine, were prepared via either Ullmann or nickel(0)-promoted reactions in low but useful yields.Approaches towards the synthesis of lipophilic ligands based on 2,2'-biimidazole, namely 4,4',5,5'-tetrabutyl-2,2'-biimidazole (from decane-4,5-dione) and various 4,4',5,5'-tetra(arylamino)-2,2'-biimidazoles (from 4,4',5,5'-tetrabromo-2,2'-biimidazole and arylamines), and a 2,2'-bibenzimidazole, 5,5',6,6'-tetra(octyloxy)-2,2'-bibenzimidazole (from N,N'-bisoxamide), were uniformly unsuccessful for preparing the 2,2'-biheteroaryl compounds.
- Crossley, Maxwell J.,Gorjian, Sargon,Sternhell, Sever,Tansey, Kerrie M.
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p. 723 - 738
(2007/10/02)
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- A Convenient Synthetic Route to 2,2'-Biimidazole
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Convenient two step procedures for the synthesis of 2,2'-biimidazole (3) and its dihydrochloride salt (4) starting with bis-methylimidate (1) in an overall yield of 72 and 83percent, respectively, are reported.Bis-methylimidate (1) was treated with two equivalents of aminoacetaldehyde dimethyl acetal under acid-catalyzed conditions to provide bis-N-(2,2-dimethoxyethylacetamidine) dihydrochloride (2) in 84percent yield.Fusion of 2 with an equivalent of p-toluenesulfonic acid at 200 deg C gave 3 in 86percent yield.Alternatively, 2 was refluxed with 5 molar hydrochloric acid to provide4 as well as 3 in combined yield of 99percent.Evidence is presented for the intermediacy of 2-imidazole (5) in the formation of the title compound.Water-soluble 4 is converted to 3 by treatment with potassium carbonate.
- Matthews, Donald P.,Whitten, Jeffrey P.,Carthy, James R. Mc
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p. 336 - 337
(2007/10/02)
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- Synthesis, electron paramagnetic resonance, and magnetic studies of binuclear bis(η5-cyclopentadienyl)titanium(III) compounds with bridging pyrazolate, biimidazolate, and bibenzimidazolate anions
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The preparation and characterization of three binuclear Ti(III) complexes, [(η5-C5H5)2Ti] 2(BiIm), [(η5-C5H5)2Ti] 2(BiBzIm), and [(η5-C5H5)2Ti(pz)]2, where BiIm2- is the dianion of 2,2′-biimidazole, BiBzIm2- is the dianion of 2,2′-bibenzimidazole, and pz- is the anion of pyrazole, are reported. The first two air-sensitive compounds are thermally quite stable due to the bis-bidentate nature of the bridging anions, BiIm2- and BiBzIm2-. Antiferromagnetic exchange interactions are present in the first two complexes where J = -25.2 cm-1 for the BiIm2--bridged Ti(III) complex and J = -19.2 cm-1 for the BiBzIm2--bridged complex, as indicated by magnetic susceptibility data taken from 270 to 4.2 K. In contrast, the bis(pyrazolate)-bridged dimer acts as a normal paramagnet down to 4.2 K with no signs of an antiferromagnetic interaction. An explanation for this difference is presented in terms of the structure of the two types of complexes. Frozen-glass EPR spectra of all three binuclear Ti(III) complexes are characteristic of triplet-state (S = 1) spectra with appreciable zero-field splittings. The triplet-state spectra of the three complexes are fit to theoretical equations to give the zero-field splitting parameters D (axial) and E (nonaxial), e.g., for [(η5-C5H5)2Ti]2(BiIm) it is found that |D| = 0.0214 cm-1 and |E| = 0.0018 cm-1. Excellent agreement between actual Ti-Ti distances from crystal structures and the calculated distances based on the observed D values is obtained. The 77 K X-band EPR glass (toluene-benzene, 4:1) spectrum of the analogous monomeric complex (N-methylbibenzimidazolato)bis(η5-cyclopentadienyl)titanium(III) shows both titanium hyperfine (A = 11.0 G) and nitrogen superhyperfine (A = 2.2 G) structure. The nitrogen superhyperfine structure indicates that the two coordinated nitrogen atoms of the N-methylbibenzimidazolate are essentially equivalent and demonstrates that appreciable unpaired electron density is found on these two nitrogen atoms in agreement with the observed superexchange interaction in the BiIm2- and BiBzIm2- complexes.
- Fieselmann, Benjamin F.,Hendrickson, David N.,Stucky, Galen D.
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p. 2078 - 2084
(2007/10/04)
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