نتایج جستجو برای: resonance assisted hydrogen bond

تعداد نتایج: 535876  

Journal: :Molecules 2017
Malose Jack Mphahlele Marole Maria Maluleka Lydia Rhyman Ponnadurai Ramasami Richard Mokome Mampa

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...

2011
Carlos Bustos Luis Alvarez-Thon Daniela Barría Juan-Guillermo Cárcamo Maria Teresa Garland

The title compound, C(22)H(18)N(2)O(3) is the second monoclinic polymorph (P2(1)/c) of the compound, the first being reported in space group P2(1) [Bertolasi et al. (1993 ▶). J. Chem. Soc. Perkin Trans. 2, pp. 2223-2228]. In the mol-ecular structure of the title compound, the inter-planar angle between the benzoyl units is 80.04 (5)°, while the corresponding angles between the phenyl-hydrazinyl...

Journal: :Dalton transactions 2013
Yuka Kobayashi Satoshi Sumi Takeshi Terauchi Daisuke Hashizume

A single crystal of anilinium tetrathiafulvalene-2-carboxylate exhibits a characteristic electrical conduction; it is a semiconductor with activation-type transport above 200 K; σ(rt) = 0.16 S cm(-1) with an activation energy of 0.11 eV. On the other hand, below 200 K, it does not obey the Arrhenius relation but is conductive even at 4 K with 2.1 × 10(-4) S cm(-1) at a frequency of 2 MHz. Its b...

Journal: :Dalton transactions 2015
Fengfeng Xue Yunsheng Ma Zhiguo Zhou Lijie Qin Yang Lu Hong Yang Shiping Yang

Nanowires of a pyridyl-functionalized iridium complex are transformed into microcubes as a result of hydrogen-bond-assisted second-sphere coordination between pyridyl groups and monovalent anions of 1,3,5-benzenetricarboxylic acid (H2BTC(-)). This is accompanied by a blue-shift of the phosphorescence from 662 to 638 nm.

Journal: :Molecules 2004
Pablo Ballester Magdalena Capó Antoni Costa Pere M Deyà Antoni Frontera Rosa Gomila

A dinuclear self-assembled cationic macrocycle based on Pt(II)-N(pyridine) coordinative bonds and having competitive triflate anions, as metal counterions, is used in the construction of [2]rotaxane and [2]pseudorotaxane architectures assisted by hydrogen bonding. The kinetic lability of the Pt(II)-N(pyridine) coordinative bond controls the dynamics of the [2]rotaxane.

Journal: :journal of dental research, dental clinics, dental prospects 0
mehdi abed kahnemooyi amir ahmad ajami soodabeh kimyai fatemeh pournaghiazar siavash savadi oskoee mohammad ali mhammadi torkani

background and aims. studies have shown decreased bond strength of composite resin to human and bovine bleached enamel. this study evaluated the effect of sodium ascorbate and delayed bonding on the bond strength of two adhesive systems to bleached enamel. materials and methods. the labial surfaces of 150 sound bovine incisor teeth were abraded with abrasive paper. the teeth were randomly divid...

Journal: :Physical chemistry chemical physics : PCCP 2017
Jeffrey M Rodgers Rachel M Abaskharon Bei Ding Jianxin Chen Wenkai Zhang Feng Gai

The C[double bond, length as m-dash]O/C[triple bond, length as m-dash]N stretching vibration arising from a carbonyl/nitrile functional group in various molecular systems has been frequently used to assess, for example, local hydrogen-bonding interactions, among other applications. However, in practice it is not always easy to ascertain whether the carbonyl or nitrile group in question is engag...

Journal: :organic chemistry research 2016
raheleh afzali mohammad vakili sayyed faramarz tayyari hossein eshghi

molecular structure, isomerism, conformational stability and intramolecular hydrogen bonding (ihb) of cis-enol forms of 1-(n-pyridyl)butane-1,3-diones (npbd) (n = 2, 3, or 4) have been investigated by means of density functional theory (dft) calculations. energy differences for all possible npbd cis-enol forms of isomers with respect to the most stable form of the corresponding isomer have been...

2015
Chien Ing Yeo Yee Seng Tan Edward R. T. Tiekink

The crystal and mol-ecular structures of the title salt, C8H8N3S2 (+)·Cl(-), (I), and salt hydrate, C8H7ClN3S2 (+)·Cl(-)·H2O, (II), are described. The heterocyclic ring in (I) is statistically planar and forms a dihedral angle of 9.05 (12)° with the pendant phenyl ring. The comparable angle in (II) is 15.60 (12)°, indicating a greater twist in this cation. An evaluation of the bond lengths in t...

2013
S. Heydarian

Proton transfer and hydrogen bonding are two aspects of the chemistry of hydrogen that respectively govern the behaviour and structure of many molecules, both simple and complex. All the theoretical enol and keto conformations of 1,3-diphenyl-1,3propandion known as dibenzoylmethane (DBM), have been investigated by means of atoms in molecules (AIM) theory. It was found that the most stable confo...

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