نتایج جستجو برای: intramolecular hydrogen bond
تعداد نتایج: 210500 فیلتر نتایج به سال:
The structures of the mono- and the dihalogenated N-unsubstituted 2-aminobenzamides were characterized by means of the spectroscopic (¹H-NMR, UV-Vis, FT-IR, and FT-Raman) and X-ray crystallographic techniques complemented with a density functional theory (DFT) method. The hindered rotation of the C(O)-NH₂ single bond resulted in non-equivalence of the amide protons and therefore two distinct re...
In the title mol-ecule, C(16)H(16)O(3), the ring system is planar and an intramolecular hydrogen bond is present. The mol-ecular packing is dominated by an inter-molecular hydrogen bond and by π-stacking inter-actions [inter-planar separation 3.8012 Å].
the crystal structure of the compound c20 h24 n2 o24 was determined by direct methods. thecrystals are monoclinic, space group p21/n, and unit cell parameters are: a= 10.2342 (9), b=4.8763 (5),c=19.3578 (11) a, β =98.9632 (10) o ,v=956.6 (5) a3, z=2, dc=1.239grm-3, dm=1.22grm-3. the final rfactorsare converged to r=0.059 and rw=0.056 for 553 independent observed reflections. themolecules are li...
Chiral diamine-derived hydrogen-bond donors were evaluated for their ability to effect stereocontrol in an intramolecular hetero-Diels-Alder (HDA) reaction hypothesized in the biosynthesis of brevianamides A and B. Collectively, these results provide proof of principle that small-molecule hydrogen-bond catalysis, if even based on a hypothetical biosynthesis construct, holds significant potentia...
The title compound, C23H24N4OS, contains a highly asymmetric bifurcated intramolecular hydrogen bond between the hydroxy group and two pyrazole N atoms. The compound associates into centrosymmetric dimers in the crystal through two unique C-H...pi interactions, which are in turn linked into a (6,3)-network through an additional intermolecular C-H...N hydrogen bond.
A "V"-shaped Hammett plot shows that resonance-assisted hydrogen bonding does not dictate the strength of the intramolecular hydrogen bond in the E isomers of hydrazone-based switches because it involves an aromatic pyridyl ring.
The synthesis and physicochemical properties of a range of 2- and 6-amido-3-hydroxypyridin-4-ones are described. All the amido-substituted 3-hydroxypyridin-4-ones have lower pK(a) values than 1,2-dimethyl-3-hydroxypyridin-4-one (deferiprone). This is due to the inductive effect of the amido group. Furthermore, the pK(a) values of the 3-hydroxy group in 1-nonsubstituted pyridinones are dramatica...
Intramolecular hydrogen bond (HB) formation was analyzed in the model compounds N-(2-benzoylphenyl)acetamide, N-(2-benzoylphenyl)oxalamate and N1,N2-bis(2-benzoylphenyl)oxalamide. The formation of three-center hydrogen bonds in oxalyl derivatives was demonstrated in the solid state by the X-ray diffraction analysis of the geometric parameters associated with the molecular structures. The solven...
A previously unexplained effect in the relative rate of excited-state intramolecular proton transfer (ESIPT) in related indole derivatives is investigated using both theory and experiment. Ultrafast spectroscopy [ J. Phys. Chem. A, 2015, 119, 5618-5625 ] found that although the diol 1,3-bis(2-pyridylimino)-4,7-dihydroxyisoindole exhibits two equivalent intramolecular hydrogen bonds, the ESIPT r...
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