نتایج جستجو برای: intramolecular hydrogen bond

تعداد نتایج: 210500  

Journal: :Organic & biomolecular chemistry 2015
Masoud Samet Alireza Fattahi Steven R Kass

Different strategies are employed in designing strong and selective anion receptors but stereoelectronic effects have been largely ignored. In this work, the stereo configuration of a non-interacting ether is found to have a large impact of more than two orders of magnitude on the binding of a rigid diol with tetrabutylammonium chloride in acetonitrile-d3. A favorable carbon-oxygen dipole and a...

2005
Chuanzhong Wang Zhangyi Liang Jianbin Huang

A novel Gemini amphiphile, N,N′-bis-(4-decyloxy-2-hydroxybenzylidene)-ethane-1,2-diamine, was synthesized and characterized. This amphiphile is capable of forming stable monolayer at air–water interface. The limiting area has a minimum when the pH value of subphase is 12. The unique behavior is attributed to the formation of intramolecular hydrogen bond between hydroxyl groups. The existence of...

2010
Naser Eltaher Eltayeb Siang Guan Teoh Suchada Chantrapromma Hoong-Kun Fun

The title compound, C(13)H(10)ClNO(2), exists in a trans configuration about the central C=N bond. The two benzene rings are almost coplanar, making a dihedral angle of 2.48 (10)°. An intra-molecular O-H⋯N hydrogen bond generates an S(6) ring motif. In the crystal structure, O-H⋯O hydrogen bonds link the mol-ecules into chains along [101]. Short C⋯Cl contacts [3.584 (2)-3.646 (2) Å] are observe...

2011
Mingjian Cai

The title compound, C(11)H(8)Br(2)N(4), is a Schiff base obtained from 6-bromo-picolinaldehyde and 5-bromo-pyridine-3,4-diamine. The mol-ecule has an E configuration about the C=N bond and the dihedral angle between the two pyridine rings is 14.02 (1)°. The observed conformation is stabilised by an intramolecular N-H⋯N hydrogen bond. In the crystal, mol-ecules are stacked along the b axis and a...

1998
Doukeni Missopolinou Costas Panayiotou

Cooperativity in hydrogen bonding has been repeatedly invoked in the literature. Very often a distinction is made between the association constant for the “dimer” formation and the corresponding constant for the formation of association complexes beyond dimer. This work examines this cooperativity hypothesis and proposes a straightforward manner of integrating it in the framework of the lattice...

Journal: :Proteins 2005
Sheldon Park Jeffery G Saven

Buried solvent molecules are common in the core of globular proteins and contribute to structural stability. Folding necessitates the burial of polar backbone atoms in the protein core, whose hydrogen-bonding capacities should be satisfied on average. Whereas the residues in alpha-helices and beta-sheets form systematic main-chain hydrogen bonds, the residues in turns, coils and loops often con...

Journal: :Molecules 2014
Maximiliano Martínez-Cifuentes Boris E Weiss-López Leonardo S Santos Ramiro Araya-Maturana

Intramolecular hydrogen bonds (IHBs) play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculation...

2008
Xue-Qun Fu Wei Wang

In the title compound, [Fe(C(5)H(5))(C(13)H(9)N(2))], the dihedral angle between the substituted cyclo-penta-dienyl plane and the plane of the pyridine ring is 8.43 (14)°. The double bond adopts a Z configuration. In the crystal structure, weak C-H⋯N inter-actions link the molecules into a zigzag chain. A weak intramolecular C-H⋯N hydrogen bond is also present.

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2003
Iztok Turel Amalija Golobic

Ciprofloxacin belongs to a family of quinolone antibacterial agents. The crystal structure of ciprofloxacin hydrochloride 1,34-hydrate was determined. Most of the bond lengths and angles of the ciprofloxacin cation are very similar to those of ciprofloxacin hexahydrate, which appears in the zwitterionic form. The exceptions are the carbon-oxygen bond distances in the carboxylic group, since in ...

2009
Hoong-Kun Fun Reza Kia Hadi Kargar Arezoo Jamshidvand

The title Schiff base compound, C(22)H(28)N(2)O(4), lies across a crystallographic inversion centre and adopts an E configuration with respect to the C=N bond. Pairs of weak inter-molecular C-H⋯O inter-actions link neighbouring mol-ecules into dimers with an R(2) (2)(28) ring motif. The crystal structure is stabilized by inter-molecular C-H⋯π inter-actions. An intramolecular O-H⋯N hydrogen bond...

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