Theoritical study on an anomalous isotopic effect on the position and integrated intensity of the ir stretching vibration band for medium-strong and strong hydrogen bonds

1981 ◽  
Vol 62 (3) ◽  
pp. 319-331 ◽  
Author(s):  
Yves Guissani ◽  
Henryk Ratajczak
Keyword(s):  
Hydrogen Bonds ◽  
Isotopic Effect ◽  
Vibration Band ◽  
Integrated Intensity ◽  
Stretching Vibration

Infrared spectra of hydrogen bonded adducts of 2,6-dichlorophenols and oxygen bases

1985 ◽  
Vol 63 (12) ◽  
pp. 3568-3572 ◽  
Author(s):  
R. Wolny ◽  
A. Koll ◽  
L. Sobczyk
Keyword(s):  
Infrared Spectra ◽  
Infrared Region ◽  
Hydroxyl Group ◽  
Vibration Band ◽  
Inversion Point ◽  
Integrated Intensity ◽  
Stretching Vibration ◽  
Background Absorption ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Infrared spectra of hydrogen bonded complexes of 2,6-dichlorophenol derivatives and oxygen bases have been studied over a broad ΔpKa range (from −10.55 to +1.69). For the complexes of 1:1 stoichiometry typical evolution of spectra, similar to those for other hydrogen bonded systems, have been found. With an increase of ΔpKa the hydroxyl group stretching vibration band shifts to lower frequencies until the inversion region is reached, where hydrogen bonded (HB) and proton transfer (PT) forms occur in equilibrium, then abroad background absorption is observed. The centre of gravity of the broad protonic bands, veg, calculated from the integrated intensity over the whole infrared region have been correlated with ΔpKa and the contribution of the PT form. It has been shown that the minimum on the plot veg vs. ΔpKa is reached close to the inversion point, where KPT = 1. The observed correlations and the change in the shape of the broad protonic absorption are consistent with expectations of theories based on the concept of the double minimum potential function and the stochastic mechanisms of band broadening.

POSSIBILITY OF MOLECULAR-SWITCH WITH CONTROLLED HYDROGEN BOND: UTILITY OF COMBINATION OF 2,2′-BIIMIDAZOLE AND REDOX-ACTIVE LIGAND

2005 ◽  
Vol 04 (01) ◽  
pp. 333-344 ◽  
Author(s):  
HIROTOSHI MORI ◽  
EISAKU MIYOSHI
Keyword(s):  
Density Functional ◽  
Molecular Level ◽  
Molecular Switch ◽  
Vibration Band ◽  
Functional Theory ◽  
Inorganic Molecule ◽  
Redox Active Ligand ◽  
Active Ligand ◽  
Redox Active ◽  
Stretching Vibration

A new inorganic molecule [ Co(Hbim) ( C 6 H 4 O 2)( NH 3)2]2 that can be used as a new optically durable molecular switch was theoretically designed in the framework of density functional theory. Three stable minima, belonging to 1 A g , 5 A 1, and 9 A g states, were found in the complex. Theoretically predicted infrared spectra of the complexes showed that a strong peak of NH stretching vibration is observed at 2690, 2120, and 2770 cm -1 in the 1 A g , 5 A 1, and 9 A g states, respectively. The apparent red shift of the NH stretching vibration band in the 5 A 1 state make it possible to distinguish the electronic state from others (1 A g and 9 A g ). This means that the complex can be used as a molecular level switch whose memory can be stably read by IR light without any photoreaction process; namely, without memory degradation.

Synthesis, spectroscopic (FT–IR and UV–Vis), crystallographic and theoretical studies, and a molecular docking simulation of an imatinib-like template

2019 ◽  
Vol 75 (12) ◽  
pp. 1681-1689
Author(s):  
Rodolfo Moreno-Fuquen ◽  
Kevin Arango-Daraviña ◽  
Esteban Garcia ◽  
Juan-C. Tenorio ◽  
Javier Ellena
Keyword(s):  
Crystal Growth ◽  
Hydrogen Bonds ◽  
Docking Simulation ◽  
Myelogenous Leukemia ◽  
Amino Group ◽  
Protein Residues ◽  
Function Analyzer ◽  
Stretching Vibration ◽  
Donor Acceptor ◽  
Ft Ir

The aim of the present study was to report the crystal structure and spectroscopic, electronic, supramolecular and electrostatic properties of a new polymorph of 4-(pyridin-2-yl)pyrimidin-2-amine (C9H8N4). The compound was synthesized under microwave irradiation. The single-crystal X-ray structure analysis revealed an angle of 13.36 (8)° between the planes of the rings, as well as molecules linked by Nsp 2—H...N hydrogen bonds forming dimers along the crystal. The material was analyzed by FT–IR vibrational spectroscopy, while a computational approach was used to elucidate the vibrational frequency couplings. The existence of Nsp 2—H...N hydrogen bonds in the crystal was confirmed spectroscopically by the IR peaks from the N—H stretching vibration shifting to lower wavenumbers in the solid state relative to those in the gas phase. The supramolecular studies confirmed the formation of centrosymmetric R 2 2(8) rings, which correspond to the formation of dimers that stack parallel to the b direction. Other weak C—H...π interactions, essential for crystal growth, were found. The UV–Vis spectroscopic analysis showed a donor–acceptor process, where the amino group acts as a donor and the pyridine and pyrimidine rings act as acceptors. The reactive sites of the molecule were identified and their quantitative values were defined using the electrostatic potential model proposed in the multifunctional wave function analyzer multiwfn. The calculated interaction energies between pairs of molecules were used to visualize the electrostatic terms as the leading factors against the dispersion factors in the crystal-growth process. The docking results showed that the amino group of the pyrimidine moiety was simultaneously anchored by hydrogen-bonding interactions with the Asp427 and His407 protein residues. This compound could be key for the realization of a series of syntheses of molecules that could be used as possible inhibitors of chronic myelogenous leukemia.

13C Isotopic Effect on the Raman Spectrum and Structure of C60 Fullerene

1994 ◽  
Vol 359 ◽  
Author(s):  
Pham V. Huong ◽  
Denis JÉrÔme ◽  
Pascale Auban-Senzier ◽  
Patrick Bernier
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Frequency Shift ◽  
Organic Compounds ◽  
Isotopic Effect ◽  
Experimental Result ◽  
C60 Fullerene ◽  
Strongly Coupled ◽  
Stretching Vibration ◽  
Bond Character

ABSTRACTThe Raman spectrum of 13C enriched C60 samples is recorded and analyzed in comparison with that of undoped 12C60. Comparison with the isotopic effect in diamond and in other infinite solid networks is also made.A frequency shift depending on the amount of 13C is observed for the C=C stretching vibration, without any splitting. This effect is unusual and is a proof that the C=C is not localized and its double bond character is not isolated but strongly coupled with other bonds in the cage. If the CC bond was independent as in small or non-spherical molecules such as organic compounds, an isotopic effect of Δv ≃ 30 cm-1 for 12C=13C and Δv ≃ 60 cm−1 for 13C=13C could be expected and a splitting could appear in the case of uncompleted 13C substitution and variable relative intensities could be observed. It is not the case of 13C60.In isotopic C60, all C=C vibrations in the spherical network are stronglycoupled ; an average isotopic mass must be considered for the randomly distributed isotopic atoms in the material to interpret the experimental result. C60 has thus more solid than molecule behavior.

An isotopic effect in self-assembly of amphiphilic block copolymers: the role of hydrogen bonds

Soft Matter ◽  
2009 ◽  
Vol 5 (24) ◽  
pp. 5003 ◽  
Author(s):  
Rina Shvartzman-Cohen ◽  
Chun-lai Ren ◽  
Igal Szleifer ◽  
Rachel Yerushalmi-Rozen
Keyword(s):  
Block Copolymers ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Isotopic Effect ◽  
Amphiphilic Block Copolymers

Vibrational band intensities in substituted anilines

1957 ◽  
Vol 243 (1233) ◽  
pp. 143-153 ◽  
Keyword(s):  
Linear Relation ◽  
Vibrational Band ◽  
Vibration Band ◽  
Substituted Anilines ◽  
Absorption Bands ◽  
Bond Stretching ◽  
Infra Red ◽  
Analogous Data ◽  
Stretching Vibration ◽  
Stretching Vibrations

The infra-red absorption bands associated with the stretching vibrations of the NH 2 group in a series of meta - and para -substituted anilines have been examined. The effect of the sub­stituet groups upon the frequencies and intensities of the bands has been correlated with their Hammett σ factors. The widths of the bands have also been found to depend upon the position and nature of substituent. The linear relation between log (intensity) and σ suggested previously on the basis of other data has been found to hold in this case too. Measurements in several solvents have been compared, and surprising variations of band intensity have been found. Analogous data have been obtained for the N—H bond stretching vibration band in substituted N -methyl anilines. The effect of ortho substituents has also been examined in a few cases.

Alignment Change of Discotic Liquid Crystal Domains with Wavelength Tunable CO2 Laser Irradiation

2010 ◽  
Vol 428-429 ◽  
pp. 284-287
Author(s):  
Hirosato Monobe ◽  
Yo Shimizu
Keyword(s):  
Liquid Crystal ◽  
Laser Irradiation ◽  
Liquid Crystalline ◽  
Device Fabrication ◽  
Vibration Band ◽  
Discotic Liquid Crystal ◽  
Wavelength Tunable ◽  
Crystalline Semiconductor ◽  
Linearly Polarized ◽  
Stretching Vibration

Infrared-induced alignment change with wavelength tunable CO2 laser irradiation for columnar liquid crystal domains was investigated for a triphenylene-based discotic liquid crystal. A uniformly aligned alignment change of domains was observed when a plused linearly polarized infrared laser light corresponding to the wavelength of the aromatic C-O-C stretching vibration band (9.65µm) was irradiated while it was not re-aligned uniformly with continious wave irradiation. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophase as a liquid crystalline semiconductor.

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