Raman and DFT study of hydrogen‐bonded 2‐ and 3‐chloropyridine with methanol

Singh, Devender; Vikram, K.; Singh, Dheeraj K.; Kiefer, W.; Singh, Ranjan K.

doi:10.1002/jrs.2015

Cited by 23 publications

(11 citation statements)

References 38 publications

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“…Our DFT calculations assign the following Raman bands to modes with ν(C–Cl) contributions: 628, 679, 796, 817, 832, and 1110/1098 cm −1 . In this range, only three bands at 724, 1080, and 1144 cm −1 have been assigned as ν(C–Cl) in pure 2‐chloropyridine …”

Section: Discussionmentioning

confidence: 99%

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Cañamares

Feis

2013

J Raman Spectroscopy

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Thiacloprid is a widely used pesticide belonging to the neonicotinoid class, which is characterized by a selective activity against insects and a reduced acute toxicity for humans. The importance of the environmental impact of neonicotinoids is being intensively researched, in order to evaluate the danger they pose for useful insects. Physical methods which allow the characterization of neonicotinoids in diluted aqueous solutions are therefore desirable. We present a study of Raman and surface‐enhanced Raman scattering (SERS) spectroscopy on thiacloprid in solid state, in acetone solution, and adsorbed onto silver and gold hydrosols at μM concentration. Density functional theory calculations allow the individualization of the most stable molecular structure, both in gas phase and in solution, and of the corresponding Raman spectra. The vibrational assignments lead to an interpretation of the differences between SERS and ordinary Raman spectra based on the possible interactions between the molecule and the metal surface, the main one involving the iminocyano group. Formation of a charge‐transfer complex is suggested by the dependence of the SERS spectra on the laser excitation wavelength. We evaluate the applicability of SERS spectroscopy to the chemical analysis of thiacloprid comparing SERS with current analytical methods. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Cañamares

Feis

2013

J Raman Spectroscopy

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“…Concentration‐dependent Raman study gives clear idea of hydrogen bonding patterns in organic as well as aqueous solutions and helps to understand their solute–solvent interaction behavior. In some recent studies by our group, strong hydrogen bonding has been observed in aqueous solutions such as pyridine–water, pyrimidine–water and many other systems. In pyridines/pyrimidine + H 2 O mixtures, at higher water concentration the original reference peak of solute completely vanishes.…”

Section: Introductionmentioning

confidence: 99%

Raman signatures of strong and weak hydrogen bonds in binary mixtures of phenol with acetonitrile, benzene and orthodichlorobenzene

Singh

Gangopadhyay

Nandi

et al. 2016

J. Raman Spectrosc.

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The present study aims at investigating the effect of hydrogen bonds of phenol in binary mixtures of phenol with three solvents viz. acetonitrile, orthodichlorobenzene and benzene respectively in order of decreasing hydrogen bond strength. Raman spectroscopy in correlation with density functional theory (DFT) calculations has led to a profound understanding of changes in structure, energy, dipole moment and other physical and chemical properties of phenol pertaining to hydrogen bond formation in solution. The spectral variation in wavenumber and linewidth of ring deformation, ring stretching, C≡N stretching and C―H stretching modes have been analyzed in detail. The breaking of self association of phenol in solution and formation of strong or weak hydrogen bonds depending on the nature of the solvent has been discussed by comparing the Raman and DFT results for three different solvents. Copyright © 2016 John Wiley & Sons, Ltd.

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“…For the DFT calculations, the hybrid exchange functional wB97X‐D and the Gaussian type split basis set 6‐311++G(d,p) were used. DFT calculations have been demonstrated to contribute substantially for the understanding of experimental findings of ILs . The studied ion pairs and their water‐associated clusters were simulated without having any restrictions in the input geometries.…”

Section: Methodsmentioning

confidence: 99%

Impact of water on the hydrogen bonding between halide‐based ion‐pairs investigated by Raman scattering and density functional theory calculations

Pandey

Sanchora

Rana

et al. 2019

J Raman Spectroscopy

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We present a study of the impact of water on the size-and electronegativitydependent hydrogen bonds between cation and anion of imidazolium-based ionic liquids (ILs) with halide anions. We have combined Raman spectroscopy with density functional theory (DFT) computations to characterize the intermolecular associations of cation-anion-water moieties. The Raman band at~1,422 cm −1 , which is assigned to the ν(N─CH 2 ─CH 3 ) vibration of the ethyl chain in the neat ion pairs (pure ion pairs), is blue shifted by +7, +4, and +3 cm −1 for 1-ethyl-3-methylimidazolim (C 2 mim) cation-based C 2 mim X ion pairs with X = Cl, Br, and I, respectively, in a water-rich environment. Simultaneously, upon dilution, a new peak at~1,438 cm −1 starts to appear at the high-wavenumber side with continuously increasing intensity. These significant perturbations of the ν(N─CH 2 ─CH 3 ) vibrational mode in water environment are a clear indication of the change in the alkyl chain conformation. Further, the relative intensities of the Raman bands at~2,946 and~2,950 cm −1 corresponding to ν s (CH 2 ) and ν as (CH 3 ) of the ethyl chain, respectively, were significantly changed upon dilution, which also confirms the conformational change of the alkyl chain. The Raman band belonging to the C 4/5 ─H stretch mode was significantly blue shifted by +33, +41, and +42 cm −1 going from the studied neat ion pairs having Cl, Br, and I anions to the corresponding water mixtures, respectively. Significant changes were also observed for the ν(C 2 ─H) vibrational mode of the ion pairs in water environment;here, we observed blue shifts of +60, +51, and +50 cm −1 for ion pairs having Cl, Br, and I anions, respectively. These results confirm the weakening of the ion-pair interaction due to the interaction with water molecules. In contrast to the ILs with halide anions, C 2 mim BF 4 does not show any variation in the Raman peak positions upon dilution. Experimental results are nicely supported by the results of DFT calculations, and a sensible connection was established. K E Y W O R D Sionic liquids, hydrogen bonds, Raman spectroscopy, density functional theory calculations Deepak K. Pandey and Paridhi Sanchora Authors have contributed equally

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Raman and DFT study of hydrogen‐bonded 2‐ and 3‐chloropyridine with methanol

Cited by 23 publications

References 38 publications

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Raman signatures of strong and weak hydrogen bonds in binary mixtures of phenol with acetonitrile, benzene and orthodichlorobenzene

Impact of water on the hydrogen bonding between halide‐based ion‐pairs investigated by Raman scattering and density functional theory calculations

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