Frequency Shifts Of Bands Research Articles

Spectral manifestations of intermolecular and interionic hydrogen bonding in adducts of various acids with pyridine

The band pattern evolutions, intensity enchancements and frequency shifts of the ν AH bands as well as PMR chemical shifts of the active proton in systems pyridine (Py)-acid (AH) have been studied, the latter changing within a wide acidity range; i.r. and PMR spectra of pyridinium (Py +H) salts existing as ionic pairs Py +H… −A in solutions have been also measured. The observed ν AH intensity attains a value as high as 40 darks, the ν AH low-frequency shift ~ ̊ 2200 cm − and the chemical shift δ-14 ppm, the respective H-bonding enthalpy −ΔH being about 15 kcal/mole. A gradual “proton transfer” has been considered from the acid AH to Py via strengthening intermolecular H-bonds AH…Py and further via weakening interionic H-bonds A −…H +Py to a final state of “purely ionic” pair A −+Py +H. A common spectral behaviour of the H-bonds AH…Py and “ionic pairs” A −…H +Py as well as a similarity of the both types in the vicinity of the quasisymmetric complex A…H…Py have been demonstrated. Complicated i.r. band patterns in strong H-bonds and Fermi resonance perturbations of the ν OH and ν NH bands in H-complexes ROH…Py and “ionic pairs” A −…H +Py have been discussed. H-bonding energies in the “ionic pairs” have been estimated.

Infrared Study of Aniline Adsorbed on Aluminum Halides and on Gallium Chloride

Abstract Infrared study was made on aniline adsorbed on aluminum chloride, bromide and iodide. Aniline-d0 (C6H5NH2), aniline-N,N-d2, aniline-d5 (C6D5NH2) and aniline-d7 were used. Aniline-d0–gallium chloride system was studied for comparison. Only the bands associated with amino group showed large frequency shifts on complex formation. The structures of adsorbed molecules were discussed in terms of the frequency shift of bands, especially of those assigned to C–N stretching and ND2 bending modes. The interaction of adsorbed aniline with aluminum chloride is rather weak and predominantly ionic. A strong chemisorption with the formation of an essentially covalent N···Al bond can be deduced for aniline adsorbed on aluminum bromide, iodide and gallium chloride. Such an ionic adsorption on aluminum chloride can be understood by considering the ionic structure of solid aluminum chloride. Some of the observed bands for aniline-d5 are (cm−1); 3424, 3350, 3312 (NH str.), 1620 (NH2 bend.) and 1300 (CN str.).

ChemInform Abstract: AN INFRARED INVESTIGATION OF HYDROGEN BONDING OF METHANOL, ETHANOL, 1‐PROPANOL, AND 1‐BUTANOL IN SOLUTION

Chemischer InformationsdienstVolume 6, Issue 19 Article ChemInform Abstract: AN INFRARED INVESTIGATION OF HYDROGEN BONDING OF METHANOL, ETHANOL, 1-PROPANOL, AND 1-BUTANOL IN SOLUTION DAHWEI LIU, DAHWEI LIUSearch for more papers by this authorCHIH-LUEH WANG, CHIH-LUEH WANGSearch for more papers by this authorTUNLI CHEN, TUNLI CHENSearch for more papers by this author DAHWEI LIU, DAHWEI LIUSearch for more papers by this authorCHIH-LUEH WANG, CHIH-LUEH WANGSearch for more papers by this authorTUNLI CHEN, TUNLI CHENSearch for more papers by this author First published: May 13, 1975 https://doi.org/10.1002/chin.197519097AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue19May 13, 1975 RelatedInformation

The raman spectra of chlorine and bromine complexes with amines: Frequency shifts, force coefficients and intensity changes

The Raman spectra of molecular complexes of Cl2 and Br2 with NH3, pyridine, methyl- and ethylamines have been obtained at low temperatures. Frequency shift and intensity increase of the halogen bands have been observed at complexation. The normal coordinates have been calculated for the pyridine-halogen complexes using a linear triatomic model.

An Infrared Investigation of Hydrogen Bonding of Methanol, Ethanol, 1‐Propanol, and 1‐Butanol in Solution

AbstractThe aggregation phenomena of simple alcohols caused by hydrogen bonding in several organic solvents are studied by I. R. spectroscopy. The association constants of cyclic dimer of alcohols in CCI4 are evaluated, and the importance of solvent bascity effecting on the OH band frequency shift has been discussed.

Mode-Grüneisen parameters in disordered molecular crystals: Raman spectra of NH 4Br and NH 4I under hydrostatic pressure

The Raman spectrum of NH 4I has been measured under hydrostatic pressure. The high pressure phase of NH 4I was identified with the disordered CsCl-type phase by comparing the spectrum with that of NH 4 Br. The mode-Grünesen parameters of NH 4Br and NH 4I were determined from the frequency shift of phonon bands under hydrostatic pressure. These values were compared with the thermodynamic value and that obtained from the Slater relation. Contributions to the thermodynamic Grüneisen constant are discussed from free energy terms of NH + 4-orientation and -interactions with lattice modes.

Effect of high pressures on molecular electronic spectra and electronic relaxation

The purpose of this paper has been to develop a theoretical model which can be used to deal with the effect of high pressure on the spectral band shapes and frequency shifts of molecular electronic spectra, rates of electronic relaxation, transformation of electronic structures, etc. We have shown that this model predicts that the pressure-induced frequency shifts of vibronic bands are the same for different vibronic bands, the pressure dependence of the frequency shifts is parabolic, the relation between the rate of nonradiative decays and external pressure is exponential, and the pressure effect on the rate of nonradiative decays and the pressure-induced frequency shift of the corresponding electronic transition are closely related.

Frequency shifts in the electronic spectra of some methylated naphthalenes and anthracenes and their radical ions

The electronic spectra of 11 methylated naphthalenes, 3 methylated anthracenes and their radical ions have been studied, with particular reference to the frequency shifts of certain characteristic absorption bands. Simple molecular orbital theory gives a reasonable correlation with the magnitude and direction of these frequency shifts, with the exception of the 2a– bands in the substituted naphthalenes.

Far-Infrared Spectra and Lattice Vibrations of Barium Chloride Dihydrate

Abstract The far-infrared spectra of barium chloride dihydrate and its deutero analog were measured in the region of 60–4000 cm−1. The assignment of the infrared bands due to crystal water and crystal heavy water was made on the basis of the band frequency shift associated with deuteration. The optically-active lattice vibrations were calculated in order to assign the far-infrared bands and elucidate the nature of the vibrations.

Spectroscopic method of measuring the stresses at stress raisers in polymers

A method of measuring the mechanical stresses near stress raisers from the frequency shift of the IR absorption bands is proposed. The stresses at the edge of an ellipse as determined by IR spectroscopy, from the birefringence, and by theoretical calculation are compared. It is shown that the results coincide. The stress near the tip of a crack has been measured by the IR spectroscopy technique. It is shown that these stresses may be ten or more times greater than the external tensile stress.

Excitation Spectrum of Interacting Polaritons in Dielectric Crystals

The excitation spectrum of interacting polariton waves in the infrared region of frequencies of dielectric crystals has been studied using the double-time Green's-function method. The Dyson equation describing the spectrum of interacting polariton fields is derived in a general form, and then the polarization operator and the polariton Green's function are evaluated in two successive approximations. Use has been made of two "equivalent" renormalized Hamiltonian representations, which are correct in the lowest and first approximations, respectively. The polariton Green's function is expressed, in the second approximation, in terms of the renormalized polariton frequencies, where the frequency of each polariton mode contains anharmonic corrections to all orders. Expressions are developed for the frequency shift and spectral width of the fundamental absorption bands. It is shown that the renormalization of the polariton frequencies directly affects the temperature dependence of the frequency shift and width of the infrared absorption bands. The retardation effects reduce the magnitudes of the anharmonic coupling functions. In the region of wave vectors where retardation may be neglected, the phonon excitation spectrum has been considered and compared with the results derived from previous studies.

Infrared spectra of coordinated acrylonitrile

The infrared spectra of a variety of acrylonitrile—metal complexes have been investigated in the NACl region. The frequency shifts of certain bands indicate that both resonance and inductive effects increase in the acrylonitrile molecule upon coordination. The strongest evidence is obtained from examination of the vinyl out-of-plane hydrogen deformations, in which a crossover of the vinyl twist and wag frequencies is observed.

The hydrogen bondVII. The intermolecular hydrogen bond between phenol and olefins

The frequency shift of the phenolic OH band, Δν, accompanying the formation of a hydrogen bonded complex between phenol and various unsaturated hydrocarbons in carbon tetrachloride has been determined. The following values of Δν were found for alkyl substituted ethylenes: RCHCH 2 65, RCHCHR 90, R 2CCH 2 100, R 2CCHR 110, R 2CCR 2 125, indicating that alkyl groups increase the basicity of ethylenes. 1:3-Butadienes and allenes are less basic than mono-olefins as measured by Δν, and acetylenes are more basic than olefins. If the equilibrium constant for the formation of the hydrogen bonded complex is used as a criterion of basicity, the introduction of alkyl groups again increases basicity but now the dienes are more basic than the mono-olefins.

Raman Spectra of Polycrystalline Methylene Halides

The Raman spectra of CH2Cl2, CH2Br2, and CH2I2 have been observed at 77° and 195°K. Band splitting due to the crystal field has been found for the Raman bands ν3, ν4, and ν9 of CH2Cl2 and for the band ν1 of CH2Br2. No apparent splitting has been observed for the Raman bands of CH2I2. The band splittings and frequency shifts of the intramolecular vibrations are discussed. The Raman bands due to the lattice vibrations have been obtained and tentative assignments are presented for some of the bands. Much temperature effect has been found on the Raman frequencies of the lattice vibrations.

Infrared Spectra of Acyclic Imides. I. Two Modifications of Diacetamide in the Crystalline State

Abstract Two crystal forms have been found for diacetamide (the form A and the form B). Infrared spectra of these two forms of diacetamide and diacetamide-d have been measured in the region 3600 to 400 cm−1 and many differences of absorption bands have been observed. It has been shown that these differences of absorption bands can be explained to result from rotational isomerism. The trans-trans planar structure of the –CONHCO–group has been proposed to correspond approximately to the molecular structure of the unstable form (the form B) of diacetamide. The frequency shifts of absorption bands on deuteration in the potassium bromide region has been discussed to give support to this interpretation. An assignment has been given to each absorption band in the potassium bromide region for the form A and the form B of diacetamide and diacetamide-d.

Frequency Shift of the CO Stretching Band in Polypeptides and Proteins

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