نتایج جستجو برای: conventional and unconventional intramolecular hydrogen bond
تعداد نتایج: 16884356 فیلتر نتایج به سال:
In the crystal structure, the mol-ecule of the title compound, C(14)H(16)N(2)O(6), is located on an inversion centre. The amide -NHCO- plane makes a dihedral angle of 34.08 (9)° with the benzene ring. The mol-ecules are connected via inter-molecular O-H⋯N hydrogen bonds into a two-dimensional network parallel to the bc plane. An intramolecular N-H⋯O hydrogen bond is also observed.
The ir-spectra in the N-H stretching region of Piv-Pro-NHMe and Boc-Pro-NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the N-H stretching bands, i t has been shown that the characteristic N-H stretching band due to the C7 intramolecular hydrogen bond is around 3335 cm-'. Intermolecular hydroge...
Herein, the conventional and unconventional hydrogen bonding potential of adenine in APA for double zipper helical assembly of deoxyoligonucleotides is demonstrated under ambient conditions. The quantum mechanical calculations supported the formation of hybrid DNA ensembles.
The least-squares planes defined by the aromatic moieties in the title aniline derivative, C(13)H(13)NS, are nearly perpendicular to each other, forming a dihedral angle of 87.80 (7)°. Apart from a weak intramolecular N-H⋯S hydrogen bond, a co-operative set of N-H⋯N hydrogen bonds present in the crystal structure leads to the formation of tetra-meric units.
The conformational populations of cis-1,3-cyclopentanedicarboxylic acid (1) and its mono- and dianion were established in DMSO solution by comparing the vicinal proton–proton coupling constants (3J(HH)) obtained in solution to their theoretical counterparts. Geometries used for 3J(HH) theoretical estimation (using Karplus-type equations) were obtained from optimized structures at the B3LYP/6-31...
Stereo-selectively synthesized 1,3-poly-alcohols are introduced as low-dimensional spectroscopic model systems for molecular dynamics in hydrogen-bonded networks. The molecular and vibrational structures of the artificial networks are studied by means of density functional theory. The flexibility of the networks and the time scales associated with hydrogen-bond breakage and formation are invest...
The equilibrium for formation of the intramolecular hydrogen bond (KHB) in a series of substituted salicylate monoanions was investigated as a function of delta pKa, the difference between the pKa values of the hydrogen bond donor and acceptor, in both water and dimethyl sulfoxide. The dependence of log KHB upon delta pKa is linear in both solvents, but is steeper in dimethyl sulfoxide (slope =...
We report detailed studies on the characterization of an intramolecular NH-F hydrogen bond formed within a fluorinated "proton sponge" derivative. An ammonium ion, generated from 8-fluoro-N,N-dimethylnaphthalen-1-amine, serves as a charged hydrogen bond donor to a covalently bound fluorine appropriately positioned on the naphthalene skeleton. Potentiometric titrations of various N,N-dimethylnap...
Using Hartree–Fock (HF) and ِِDensity Functional Theory (DFT) calculations the thermodynamic properties such as thermal energy , , thermal enthalpy , , thermal entropy , , thermal Gibbs free energy , , heat capacity ,Cv, and molecular structures of several species involving in keto↔enol tautomerism related to acetaldehyde (A), 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and acetylacetone (AA) h...
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