Search results for "HIF"
showing 10 items of 1515 documents
Crystal structure of (E)-4-methoxy-2-{[(5-methylpyridin-2-yl)imino]methyl}phenol
2015
The molecule of the title Schiff base compound, C14H14N2O2, displays anEconformation with respect the imine C=N double bond. The molecule is approximately planar, with the dihedral angle formed by the planes of the pyridine and benzene rings being 5.72 (6)°. There is an intramolecular hydrogen bond involving the phenolic H and imine N atoms.
Synthesis, molecular structure, spectroscopic properties and stability of (Z)-N-methyl-C-2,4,6-trimethylphenylnitrone.
2015
Abstract New N-methyl-C-2,4,6-trimethylphenylnitrone 1 has been synthesized starting from N-methylhydroxylamine and mesitaldehyde. The product was fully characterized using different spectroscopic techniques; FTIR, NMR, UV–Vis, high resolution mass spectrometry and X-ray diffraction. The relative stability and percent of population of its two possible isomers (E and Z) were calculated using the B3LYP/6-311++G(d,p) method in gas phase and in solution. In agreement with the X-ray results, it was found that Z-isomer is the most stable one in both gas phase and solution. The molecular geometry, vibrational frequencies, gauge-including atomic orbital (GIAO), and chemical shift values were also c…
Binding and Fluorescent Sensing of Dicarboxylates by a Bis(calix[4]pyrrole)-Substituted BODIPY Dye
2013
A bis(calix[4]pyrrole)-substituted BODIPY ditopic receptor 1 has been synthesised and characterised. The binding and sensing properties of 1 towards several aliphatic and aromatic dicarboxylates have been evaluated by using UV/Vis fluorescence and 1H NMR spectroscopy. The receptor strongly binds linear α,ω-dicarboxylates of appropriate lengths (C9 and C10) by acting as a cleft. For all dicarboxylates, the binding event is detected by a bathochromic shift in the UV/Vis spectra of the receptor and by strong quenching of its fluorescence.
Erweiterte Konjugation in unsymmetrischen Stilbenylsquarainen
1998
Extended Conjugation in Stilbenylsquaraines Unsymmetrical 1-aryl-3-stilbenylsquaraines 2a–e and 1,3-bis(stilbenyl)squaraines 3a–c were prepared by CC coupling reactions of the corresponding substituted arenes with derivatives of squaric acid (Schemes 2 and 3). Dialkylamino and alkoxy groups enhance the solubility of these dyes and enlarge the intramolecular charge transfer of these donor–acceptor–donor systems. The extended conjugation of the stilbene units – in comparison with arene building blocks – leads to significant bathochromic shifts in the Vis/NIR absorption spectra.
Die kolorimetrische bestimmung höhermolekularer phenol-formaldehyd-kondensate in dimethylformamid-methanol-lösung mit FeCl3
1961
Phenol-Formaldehyd-Kondensate geben in einem Gemisch aus Dimethylformamid und Methanol (4:1, Vol.) mit FeCl3 · 6H2O eine Farbreaktion. Es konnten Bedingungen ausfindig gemacht werden, unter denen die Extinktion der Farbreaktion reproduzierbar und innerhalb der Meszeit konstant ist. Diese Farbreaktion wird von konstitutions- und molekulareinheitlichen Phenol-Formaldehyd-Kondensaten bis zum Molekulargewicht 900 gegeben, selbst wenn sie keine Hydroxymethylgruppen besitzen. Bei der Kondensation von 2,6-Dihydroxymethyl-4-methylphenol zu Polyhydroxydibenzylathern (Molekulargewicht bis 3400) zeigt sich eine charakteristische, hypsochrome Verschiebung des Absorptions maximums, wahrend die sauer erh…
13C NMR spectroscopic study of diphenyl ether and 28 of its polychlorinated derivatives
1993
The 13 C NMR chemical shifts and coupling constants for diphenyl ether and 28 environmentally interesting polychlorinated diphenyl ethers were measured and analysed
Novel Applications of Dynamic NMR in Organic Chemistry
2004
Abstract This review article is oriented on NMR applications in studying various dynamic processes of organic molecules. The topic as a whole is too large to be covered exhaustively in one article or by one author. Therefore, the literature searches are limited mainly for the years 1999–2001. Further, many interesting branches joined essentially with organic chemistry such as supramolecular and organometallic chemistry are left outside this article because there exist recent reviews on these topics. Similarly, the theoretical background of dynamic NMR is not included. The nature of dynamic NMR itself is changing with the recent progress in computational possibilities to estimate the differe…
Red- and Blue-Shifts in Oligo(1,4-phenyleneethynylene)s Having Terminal Donor−Acceptor Substitutions
2004
Four series of oligo(1,4-phenyleneethynylene)s (OPEs), 1−4 (a−d), each having a terminal dialkylamino group as their electron donor, were prepared by applying Sonogashira−Hagihara reactions and a protecting group strategy. To study the influence that the push−pull effect has on the long-wavelength absorption, three of the four series of OPEs contain terminal acceptor groups (CN, CHO, NO2). Extending the conjugation (increasing the number of repeat units, n) lowers the energy E(n) of the electron transition in the purely donor-substituted series 1a−4a (bathochromic shift). This effect is superimposed in the push−pull series 1−4 (b−d) by the effect of the intramolecular charge transfer (ICT),…
ChemInform Abstract: Synthesis and Spectroscopic Characterizations of Both 1-Ethyl-4,8- dihydro-10-methoxy-3-methyl-8-R1-6-R2-dipyrazolo(3,4-b:4′,3′-…
2010
The non-selective methylation of compounds 3a-d using ethereal diazomethane, allowed the synthesis of isomers 4 and 5 which were useful intermediates for the preparation, by a simple approach, of the title compounds 7 and 9. A complete assignment of the chemical shifts to the carbon atoms of the compounds 7 and 9 was performed by different nmr experiments, such as DEPT and XHDEPT for onebond CH correlations and COLOC experiments for long-range C-H correlations.
Konvergenz von Absorption und Fluoreszenz bei gekreuzt konjugierten Oligomeren aus Chalkon-Bausteinen
1999
The absorption and fluorescence spectra of two series of chalcone oligomers (1a–d) and (2a–d) are reported. Due to small or vanishing orbital coefficients (HMO calculation) within the cross-conjugated systems, the bathochromic shifts caused by the extension of the chains are modest. The effective conjugation lengths amount to 6 and 14 chalcone building blocks in the absorptions of the series 1 and 2. The convergence of the fluorescence bands is already reached in 1d and 2d with 4 and 8 enone units, respectively. Besides the uniform or alternate arrangement of the chalcone building blocks, the positions of the propoxy substituents show a considerable influence on the electronic transitions p…