Two-State or Non-Two-State? An Excess Spectroscopy-based Approach to Differentiate the Existing Forms of Molecules in Liquids Mixtures

Zhou, Yu; Zheng, Yujun; Sun, Hai-Yuan; Deng, Geng; Yu, Zhi‐Wu

doi:10.1038/srep16379

Cited by 36 publications

(23 citation statements)

References 27 publications

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“…On contrast, the excess peaks of NMF in Fig. 3B are similar to a simple two-state transformation situation45.…”

Section: Resultsmentioning

confidence: 78%

“…These results imply the apparent different interaction modes of the two analog molecules in interacting with DMSO. Furthermore, both positive and negative peak positions in the excess spectra are relatively fixed, suggesting that the self-associating complex of NMF and NMA, as well as the newly formed complexes between NMF/NMA and DMSO, are stable45.…”

Section: Resultsmentioning

confidence: 99%

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Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs

Zhou

Deng

Zheng

et al. 2016

Sci Rep

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Cooperative behaviors of the hydrogen bonding networks in proteins have been discovered for a long time. The structural origin of this cooperativity, however, is still under debate. Here we report a new investigation combining excess infrared spectroscopy and density functional theory calculation on peptide analogs, represented by N-methylformamide (NMF) and N-methylacetamide (NMA). Interestingly, addition of the strong hydrogen bond acceptor, dimethyl sulfoxide, to the pure analogs caused opposite effects, namely red- and blue-shift of the N−H stretching infrared absorption in NMF and NMA, respectively. The contradiction can be reconciled by the marked lowering of the energy levels of the self-associates between NMA molecules due to a cooperative effect of the hydrogen bonds. On the contrary, NMF molecules cannot form long-chain cooperative hydrogen bonds because they tend to form dimers. Even more interestingly, we found excellent linear relationships between changes on bond orders of N−H/N−C/C = O and the hydrogen bond energy gains upon the formation of hydrogen bonding multimers in NMA, suggesting strongly that the cooperativity originates from resonance-assisted hydrogen bonds. Our findings provide insights on the structures of proteins and may also shed lights on the rational design of novel molecular recognition systems.

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“…On contrast, the excess peaks of NMF in Fig. 3B are similar to a simple two-state transformation situation45.…”

Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs

Zhou

Deng

Zheng

et al. 2016

Sci Rep

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“…[48] To determine the origin of the excessp eaks, quantum chemical calculations are required. In other words, there are four distinct forms of acetonitrile molecules existing in the mixtures.…”

Section: Resultsmentioning

confidence: 99%

Evidence that Acetonitrile is Sensitive to Different Interaction Sites of Ionic Liquids as Revealed by Excess Spectroscopy

et al. 2017

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By studying the interactions between an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and a co-solvent acetonitrile, the C≡N stretching vibration is found to be sensitive to different interaction sites as shown by excess infrared spectroscopy. Four existing forms of acetonitrile molecules are identified and a detailed transformation process of the ionic liquid upon dilution is obtained. Such characteristics of the nitrile group are discussed from the viewpoint of its ability to form hydrogen bonds with proton donors. It is believed that this is due to the intermediate charge donating ability of the C≡N group as compared with other groups such as S=O, CH , and aromatic C-H.

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“…In the case of DMSO, S=O interacts strongly with the cation, but interaction of back methyl groups is approximately the same with the anion as compared to AN. An observation worth mentioning is that the introduction of the second DMSO molecule raises the stabilization energy by 48 It is necessary to mention here that S=O can make two hydrogen bonds at the same time, while C-H can make only one. Moreover, the back methyl groups of DMSO can also play the role of hydrogen bond donors.…”

Section: Quantum Chemical Calculations For the Interactionsmentioning

confidence: 99%

“…Spectral analysis regarding IL-AN and IL-DMSO interactions in this work are limited to these regions. If either a positive or a negative peak in a series of excess spectra is immobile, then most likely it represents a distinct species in the mixtures [32,47,48]. Positive peaks are at- tributed here to the formation of new complexes, while negative peaks are from complexes in pure IL.…”

Section: Ir Spectra Of Pure [Bmpyrr] + [Tfsi] − Dmso-d 6 and CD 3 Cnmentioning

confidence: 99%

Microscopic study of binary mixtures between pyrrolidinium bis(triflorosulfonyl)imide and dimethyl sulfoxide/acetonitrile

Ashraf

Zhou

et al. 2016

Sci. China Chem.

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Molecular interactions of a representative pyrrolidinium-based ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(triflorosulfonyl)-imide ([BMPyrr][TFSI]) with dimethyl sulfoxide (DMSO) and acetonitrile (AN) have been analyzed in this work. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and density functional theory (DFT) calculations are used in the investigation, while excess infrared spectra and two-dimensional correlation spectroscopy are used to explore the data in detail. It has been found that the molecular solvents can interact with TFSI  (mainly with S=O and weakly with S-N-S group). AN interacts feebly with BMPyrr + as compared with the strong interaction of DMSO. The strength of the interactions depends on the electron donating ability of the solvent. Upon mixing, hydrogen bonds regarding C−Hs in cation and S-N-S in anion are weakened, while that regarding S=O in anion is strengthened. Among the C−Hs which are connected directly with the N of the cation, C1−H is the main interaction site for both DMSO and AN. This means that C1−H is the most acidic hydrogen in pyrrolidinium cation. ATR-FTIR, DFT calculations, excess infrared spectrum, two-dimensional correlation spectroscopy, ionic liquid, hydrogen bondCitation:

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Two-State or Non-Two-State? An Excess Spectroscopy-based Approach to Differentiate the Existing Forms of Molecules in Liquids Mixtures

Cited by 36 publications

References 27 publications

Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs

Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs

Evidence that Acetonitrile is Sensitive to Different Interaction Sites of Ionic Liquids as Revealed by Excess Spectroscopy

Microscopic study of binary mixtures between pyrrolidinium bis(triflorosulfonyl)imide and dimethyl sulfoxide/acetonitrile

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