Fermi Resonance of Infrared Vibrations in the —NH2 Groups of Polynucleotides

1971 ◽  
Vol 49 (23) ◽  
pp. 3795-3798 ◽  
Author(s):  
G. Zundel ◽  
W. D. Lubos ◽  
K. Kölkenbeck
Keyword(s):  
Hydrogen Bonds ◽  
Harmonic Vibration ◽  
Fermi Resonance ◽  
Bending Vibration ◽  
Doublet Structure ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
Band Pair ◽  
Hydrogen Bonded

The —NH2 group causes an intensive band pair in the i.r. spectra of DNA, r.RNA, poly (A + U), and poly (G + C). One band occurs at 3330, another at 3180 cm−1. This band pair is due to the NH stretching vibration of the hydrogen-bonded NH group as well as to the harmonic vibration of the —NH2 bending vibration, whereby these vibrations are coupled via Fermi resonance. This follows on comparison with papers on amines. The weak shoulder in the 3500–3400 cm−1 range is to be assigned to the stretching vibrations of the non hydrogen-bonded NH groups. The doublet structure disappears to a large extent in the denaturated DNA, since the strength of the Fermi resonance depends on the strength of the hydrogen bonds and the hydrogen bonds are of differing strength, due to the bending and stretching. The relative intensities of the two bands are interchanged in the corresponding band pair of the —ND2 groups, for which an explanation can also be given.

scholarly journals Theoretical Studies of Dynamic Interactions in Excited States of Hydrogen-Bonded Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Marek J. Wójcik ◽  
Marek Boczar ◽  
Łukasz Boda
Keyword(s):  
Hydrogen Bonds ◽  
Potential Energy ◽  
Benzoic Acid ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
Low Frequency ◽  
Fermi Resonance ◽  
Tunneling Splittings ◽  
Energy Surfaces ◽  
Hydrogen Bonded

Theoretical model for vibrational interactions in the hydrogen-bonded benzoic acid dimer is presented. The model takes into account anharmonic-type couplings between the high-frequency O–H and the low-frequency O⋯O stretching vibrations in two hydrogen bonds, resonance interactions between two hydrogen bonds in the dimer, and Fermi resonance between the O–H stretching fundamental and the first overtone of the O–H in-plane bending vibrations. The model is used for theoretical simulation of the O–H stretching IR absorption bands of benzoic acid dimers in the gas phase in the first excited singlet state. Ab initio CIS and CIS(D)/CIS/6-311++G(d,p) calculations have been carried out in the à state of tropolone. The grids of potential energy surfaces along the coordinates of the tunneling vibration and the low-frequency coupled vibration have been calculated. Two-dimensional model potentials have been fitted to the calculated potential energy surfaces. The tunneling splittings for vibrationally excited states have been calculated and compared with the available experimental data. The model potential energy surfaces give good estimation of the tunneling splittings in the vibrationally ground and excited states of tropolone, and explain monotonic decrease in tunneling splittings with the excitation of low-frequency out-of-plane modes and increase of the tunneling splittings with the excitation of low-frequency planar modes.

Theoretical Modeling of the N-H and N-D Stretching Bands of Hydrogen-Bonded 1-Methylthymine Crystal and Its Deuterated Form

2006 ◽  
Vol 2 (4) ◽  
pp. 205-219
Author(s):  
Marek Boczar ◽  
Łukasz Boda ◽  
Marek J. Wójcik
Keyword(s):  
Hydrogen Bonds ◽  
High Frequency ◽  
Molecular Crystals ◽  
Low Frequency ◽  
Unit Cell ◽  
Fermi Resonance ◽  
Bending Vibrations ◽  
Theoretical Simulation ◽  
Stretching Vibrations ◽  
Centrosymmetric Dimers

Theoretical model for vibrational interactions in the hydrogen bonds in molecular crystals with four molecules forming two centrosymmetric dimers in the unit cell is presented. The model takes into account anharmonic-type couplings between the high-frequency N-H(D) and the low-frequency N•••O stretching vibrations in each hydrogen bond, resonance interactions (Davydov coupling) between equivalent hydrogen bonds in each dimer, resonance interdimer interactions within an unit cell and Fermi resonance between the N-H(D) stretching fundamental and the first overtone of the N-H(D) in-plane bending vibrations. The vibrational Hamiltonian, selection rules, and expressions for the integral properties of an absorption spectrum are derived. The model is used for theoretical simulation of the νs stretching bands of 1-methylthymine and its ND derivative at 300 K. The effect of deuteration is successfully reproduced by our model.

scholarly journals Surface-enhanced infrared absorption studies towards a new optical biosensor

2016 ◽  
Vol 7 ◽  
pp. 1736-1742 ◽  
Author(s):  
Lothar Leidner ◽  
Julia Stäb ◽  
Jennifer T Adam ◽  
Günter Gauglitz
Keyword(s):  
Infrared Absorption ◽  
Resonance Effect ◽  
Optical Biosensor ◽  
Fermi Resonance ◽  
Infrared Range ◽  
Bending Vibration ◽  
Thickness Change ◽  
Additional Information ◽  
Surface Enhanced ◽  
Stretching Vibration

Reflectometric interference spectroscopy (RIfS), which is well-established in the visual regime, measures the optical thickness change of a sensitive layer caused, e.g., by binding an analyte. When operated in the mid-infrared range the sensor provides additional information via weak absorption spectra (fingerprints). The originally poor spectra are magnified by surface-enhanced infrared absorption (SEIRA). This is demonstrated using the broad complex fluid water band at 3300 cm−1, which is caused by superposition of symmetric, antisymmetric stretching vibration, and the first overtone of the bending vibration under the influence of H-bonds and Fermi resonance effect. The results are compared with a similar experiment performed with an ATR (attenuated total reflectance) set-up.

Gas phase observation of the first overtone of the H—F stretching fundamental in hydrogen bonded complexes

1979 ◽  
Vol 57 (11) ◽  
pp. 1341-1349 ◽  
Author(s):  
J. W. Bevan ◽  
B. Martineau ◽  
C. Sandorfy
Keyword(s):  
Gas Phase ◽  
Coupling Constant ◽  
Phase Observation ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
Anharmonicity Constants ◽  
Bonded Complexes ◽  
Hydrogen Bonded

First overtones of H—F and D—F stretching vibrations in hydrogen bonded complexes with dimethylether, diethylether, and acetone have been measured in the gas phase. The assignment of the observed bands is discussed together with previously made observations on the fundamentals. Anharmonicity constants of the order of −200 and −100 cm−1 are determined for the most probable assignments from the available data for the H—F and D—F stretching vibrations (ν1) while their values in the "free" H—F and D—F molecules are −90 and −46 cm−1 respectively. The spectra are compatible with a coupling constant between the ν1 and the bridge stretching vibration (ν3) of the order of +70 cm−1.

scholarly journals IR-UV Double Resonance Spectrum of Acetylene Below and Above the Predissociation Threshold

1994 ◽  
Vol 14 (1-3) ◽  
pp. 161-182 ◽  
Author(s):  
Masaaki Fujii ◽  
Shigeki Tanabe ◽  
Yasuo Okuzawa ◽  
Mitsuo Ito
Keyword(s):  
Double Resonance ◽  
Supersonic Jet ◽  
Fermi Resonance ◽  
Resonance Spectroscopy ◽  
Fundamental Vibration ◽  
Vibrationally Excited ◽  
Bending Vibration ◽  
Acetylene Molecule ◽  
Stretching Vibration ◽  
The Difference

The Ã1Au ← X˜1∑g+ electronic transition of the vibrationally excited acetylene molecule was studied by IR–UV double resonance spectroscopy in gas and in a supersonic jet. The C–H antisymmetric stretching vibration νCHant in the à state was clearly observed when the molecule was excited to the νCHsym + νCHant combination vibration in the X˜ state by the IR laser. When the νCHant fundamental vibration was excited, the C–H in-plane cis-bending vibration νcis(in) in the à state was observed strongly, while νCHant almost disappeared. The difference was interpreted in terms of Fermi resonance of the νCHant fundamental vibration in X˜. The predissociation threshold was newly determined to be 46,439˼46,673 cm-1 (133.11 ± 0.33 kcal/mol). In the region above the predissociation threshold, strong vibrational mixing was found. The higher members of the progression of the trans-bending vibration starting from νCHant were assigned. It was suggested that the nonradiative relaxation accelerated in the region above 51,744 cm-1.

scholarly journals Femtosecond Mid-Infrared Spectroscopy of Hydrogen-Bonded Liquids

1999 ◽  
Vol 19 (1-4) ◽  
pp. 83-90 ◽  
Author(s):  
S. Woutersen ◽  
U. Emmerichs ◽  
H. J. Bakker
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectroscopy ◽  
Hydrogen Bonds ◽  
Pump Probe ◽  
Mid Infrared ◽  
Hydrogen Bond Strength ◽  
Stretching Vibration ◽  
Probe Spectroscopy ◽  
Femtosecond Time Scale ◽  
Hydrogen Bonded

We perform femtosecond mid-infrared pump-probe spectroscopy on hydrogen-bonded ethanol dissolved in CCl4. We find that upon excitation of the OH-stretching vibration the hydrogen bonds are predissociated on a femtosecond time scale, and that the predissociation time constant depends strongly on the hydrogen-bond strength.

Infrared spectra and substituent effects in 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones

1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Wave Number ◽  
Vibrational Coupling ◽  
Wave Numbers ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
The Relationship ◽  
Derivatives Of ◽  
Effect Of Structure

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

scholarly journals Taming nitroformate through encapsulation with nitrogen-rich hydrogen-bonded organic frameworks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jichuan Zhang ◽  
Yongan Feng ◽  
Richard J. Staples ◽  
Jiaheng Zhang ◽  
Jean’ne M. Shreeve
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Energetic Materials ◽  
Decomposition Temperature ◽  
High Oxygen Content ◽  
The Poor ◽  
Simple Preparation ◽  
First Time ◽  
Hydrogen Bonded

AbstractOwing to its simple preparation and high oxygen content, nitroformate [−C(NO2)3, NF] is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.

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