- Synthesis and characterization of a new red-emitting Ca2+ indicator, calcium ruby
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Equation Presented Calcium Ruby m-Cl (X = H, Y = Cl) is a visible-light excited red-emitting calcium concentration ([Ca2+]) indicator dye (579/598 nm peak excitation/emission) with a side arm for conjugation via EDC or click chemistry. Its larg
- Gaillard, Stephane,Yakovlev, Aleksey,Luccardini, Camilla,Oheim, Martin,Feltz, Anne,Mallet, Jean-Maurice
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p. 2629 - 2632
(2008/02/10)
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- Mechanism of replacement of the nitro group and fluorine atom in meta-substituted nitrobenzenes by phenols in the presence of potassium carbonate
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The relative mobilities of the nitro group and fluorine atom in 1,3-dinitrobenzene and 1-fluoro-3-nitrobenzene by the action of phenols in the presence of potassium carbonate in dimethylformamide at 95-125°C were studied by the competing reaction method. The rate constant ratios k(NO 2)/k(F) were correlated with the differences between the corresponding activation parameters (ΔΔH≠ and ΔΔS≠). The greater mobility of the nitro group was found to be determined by the entropy control of the reactivity of arenes. The activation parameters (ΔH≠ and ΔS≠) were calculated, and the enthalpy-entropy compensation effect was revealed. The reaction mechanism is discussed.
- Khalfina,Vlasov
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p. 978 - 983
(2007/10/03)
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- Relative Mobilities of the Fluorine Atom and the Nitro Group in m-Fluoronitro- and m-Dinitrobenzenes in Reactions with Phenoxide, Benzenethiolate, and Nitrite Ions in Dipolar Aprotic Solvents
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The nitro group in m-dinitrobenzene is readily replaced by the action of phenol and benzenethiol in DMF or DMSO in the presence of potassium carbonate at 90-170°C. The nitrite ion thus formed almost does not influence the process. The mobility of the nitro group in m-dinitrobenzene in reactions with phenoxide and benzenethiolate ions in DMF is 1.3-1.9 times higher than the mobility of the fluorine in m-fluoronitrobenzene.
- Khalfina,Vlasov
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p. 665 - 670
(2007/10/03)
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- INTRAMOLECULAR EXCHANGE COUPLING OF ARYLNITRENES BY OXYGEN
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A series of m,n'-diazidodiphenyl ethers (m -1, and also showed a weak dinitrene quintet spectrum with /D/hc/=0.162 cm-1 having ESR spectral intensity vs temperature dependence (Curie law) consistent with either a high-spin ground state or a very small singlet-quintet gap.Di(3-azidophenyl) ether gave a strong mononitrene peak with /D/hc/=0.996 cm-1 and a quintet dinitrene ESR spectrum (/D/hc/=0.162 cm-1) which exhibited non-linear Curie law intensity behavior consistent with the quintet being a thermally populated excited state 40 cal mol-1 above a singlet ground state.Di(4-azidophenyl) ether gave a strong mononitrene peak with /D/hc/=0.961 cm-1, but no observable spectrum related to a high-spin open-shell dinitrene.The results are consistent with oxygen being a weak exchange coupling linker in pi-conjugated open-shell molecules.The observed ground-state spin multiplicities are in accord with qualitative superexchange and connectivity models, despite any perturbations due to resonance effects between the oxygen linker and p-nitrene sites.
- Minato, Masaki,Lahti, Paul M.
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p. 495 - 502
(2007/10/02)
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- Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by Fluoride
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The synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described.Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1-Fluoro-3-nitrobenzene (2) was obtained from 1,3-dinitrobenzene (1), and 1-fluoro-3,5-dinitrobenzene (9) as well as 1,3-difluoro-5-nitrobenzene (10) from 1,3,5-trinitrobenzene (8) in yields up to 92percent by reaction of nitro compounds with potassium fluoride in sulfolane at 180-200 deg C in the presence of phthaloyl dichloride (6); 1,2-difluoro-4-nitrobenzene (12) was formed in 58percent yield from 2,4-dinitro-1-fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
- Effenberger, Franz,Streicher, Willi
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p. 157 - 162
(2007/10/02)
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