Microheterogeneity in binary mixtures of aliphatic alcohols and alkanes: ATR-IR/NIR spectroscopic and chemometric studies

Wrzeszcz, W.; Tomza, Paweł; Kwaśniewicz, Michał; Mazurek, Sylwester; Czarnecki, Mirosław A.

doi:10.1039/c6ra18692k

Cited by 13 publications

(8 citation statements)

References 25 publications

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“…This will further highlight the role of conformational flexibility of aliphatic alcohols on their spectral features. The conformational selectivity of the hydrogen bonding formations involving alcohol molecules has been recognized in the literature, ,, and the present work may provide further insights into this phenomenon, including recent investigated hydrogen-bonded heteroclusters involving alcohol molecules and the resulting microheterogeneity. , Therefore, we believe that our study very well fits to the current trends in the exploration of the structural and spectroscopic properties of aliphatic alcohols.…”

Section: Introductionsupporting

confidence: 78%

“…The conformational equilibrium of aliphatic alcohols, and in particular the internal rotation about C–O(H) bond, has attracted constant attention ,− with very recent report involving pulsed jet FT microwave spectroscopy and quantum mechanical study as a good example . Moreover, subtle effects of hydrogen bonding leadings to the formation of various heteroclusters in a binary alcohol/water and alcohol/hydrocarbon mixtures have recently been reported; these microscale effects are believed to be expressed directly as heterogeneity of such binary systems observed experimentally by NIR spectroscopy. , The coexistence of conformational isomers and the impact of temperature and concentration on conformational equilibria of contributing alcohol may play a role in the formation of such heteroclusters. NIR spectroscopy also has been well established in the field of applied studies in which alcohols were focused on, i.e., with very recent reports in this field …”

Section: Introductionmentioning

confidence: 99%

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Temperature Drift of Conformational Equilibria of Butyl Alcohols Studied by Near-Infrared Spectroscopy and Fully Anharmonic DFT

et al. 2017

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Conformational isomerism of aliphatic alcohols with respect to the internal rotation of C-O(H) group and its impact on near-infrared (NIR) spectra has been known in the literature. However, no attempt has ever been made to investigate systematically whether and how the conformational flexibility of the aliphatic chain determines the observed NIR data of aliphatic alcohols. In the present study NIR spectra of four kinds of butyl alcohols, 1-butanol, 2-butanol, isobutanol, and tert-butyl alcohol, were investigated in diluted (0.1 M) CCl solutions. The experimental NIR spectra of butyl alcohols were accurately reproduced and explained in a fully anharmonic DFT study by means of generalized second-order vibrational perturbation theory (GVPT2). Entire conformational populations were taken into account in each case. On the basis of the theoretical study, influences of conformational flexibility with respect to internal rotations not only about the C-O bond, but also about the C-C bonds have been well evidenced in the experimental spectra. The conformational isomerism affects significantly the shape of NIR spectra. The temperature-dependent NIR spectra of butyl alcohols show changes in the band shape and a blue-shift of the overtone band due to the stretching mode of free OH group, and its intensity decreases with increasing temperature. These effects can be closely monitored by two-dimensional correlation spectroscopy (2D-COS). In this work, the experimental 2D-COS patterns have been successfully reproduced, based on DFT calculated NIR spectra of conformational isomers of the studied molecules and their Boltzmann coefficients over the corresponding temperature range. Thus, the experimentally observed effects are fully reflected in the DFT study, which leads to the conclusion that the main factor in the temperature-dependent spectral changes of 2ν band of aliphatic alcohols in the diluted phase, where no self-association occurs, is played by the changes in the relative population of their conformational isomers.

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Section: Introductionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Temperature Drift of Conformational Equilibria of Butyl Alcohols Studied by Near-Infrared Spectroscopy and Fully Anharmonic DFT

et al. 2017

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“…Therefore, the percolation composition is consistent with contact occurring between initially free octanol molecules in a close-packed structure containing dodecane molecules. This interpretation is supported by a near-IR study reported by Wrzeszcz et al [7] showing that the highest population of free hydroxyl groups in the hexane/hexanol system occurs at 0.23 mole fraction, indicating that alcohol hydrogen bonding (i.e., octanol-octanol contact in our case) is not fully established below this composition. Exceeding this concentration results in increased alcohol-alcohol contacts, as also observed in other studies [6,42,45,51], leading to more extensive hydrogen bonding and aggregation (see Figure 1b), which enables more effective conduction.…”

Section: Electrical Conductivity Considerationssupporting

confidence: 87%

“…Previous studies on associating liquids [4] have employed a variety of techniques to investigate, for example, hydrogen bonding [5], nanostructuring and self-assembly [6], and microheterogeneity [7,8]; of particular focus has been to understand the solvent properties of alcohols [9]. 1…”

Section: Introductionmentioning

confidence: 99%

Electrical Conductivity and Viscosity in Binary Organic Liquid Mixtures: Participation of Molecular Interactions and Nanodomains

Taylor

Zeng

2020

Colloids and Interfaces

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The present work aims to shed light on recent literature reports suggesting that ionic species are implicated in the electrical conductivity of 1-octanol and its mixtures with hydrocarbons. Other workers have questioned this interpretation, and herein, based on new experimentation and with reference to various literature studies, we consider that molecular interactions are more likely to be responsible. To investigate this, we have studied mixtures of 1-octanol and either silicone oil (SO) or n-dodecane as nonpolar components, using dielectric (in particular electrical conductivity) and viscometric measurements. With reference to the literature, the self-association of alcohols is known to create microheterogeneity in the neat liquids and in mixtures with nonpolar, low dielectric constant liquids, and it has previously been considered to be responsible for the particular solvent properties of alcohols. The present results suggest that the electrical conductivity of alkane/alcohol systems may have similar origins, with percolating pathways formed from octanol-rich nanodomains comprising polar regions containing hydrogen-bonded hydroxyl groups and nonpolar regions dominated by alkyl chains. The percolation threshold found for dodecane/octanol mixtures, in which interactions between the component molecules are found from viscosity measurements to be repulsive, agrees well with results from experimental and theoretical studies of disordered arrangements of packed spheres, and moreover, it is consistent with other published alkane/alcohol results. On the other hand, the situation is more complex for SO/octanol mixtures, in which interactions between the two components are attractive, based on viscosity data, and in which the phase separation of SO occurs at high octanol concentrations. Overall, we have concluded that electrical conductivity in octanol (and potentially all liquid alcohols) and its mixtures with nonpolar molecules, such as alkanes, is consistent with the presence of conducting networks comprising octanol-rich nanodomains formed by self-association, and not as a result of ionic conduction.

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“…Low band intensities enable systematic studies of the molecules in solution with a widely spread concentration range. This provides the possibility of a comprehensive investigation of intermolecular interactions, association mechanisms, solvent effects, molecular self-organization, and the structure of liquid phase (Czarnecki et al, 2015; Wrzeszcz et al, 2016a,b). In the NIR region, the bands originating from X-H (e.g., C-H, O-H, N-H) vibrations are strongly articulated.…”

Section: Near-infrared Spectroscopy the Tale Of An Ugly Ducklingmentioning

confidence: 99%

Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments

2019

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Near-infrared (12,500–4,000 cm −1 ; 800–2,500 nm) spectroscopy is the hallmark for one of the most rapidly advancing analytical techniques over the last few decades. Although it is mainly recognized as an analytical tool, near-infrared spectroscopy has also contributed significantly to physical chemistry, e.g., by delivering invaluable data on the anharmonic nature of molecular vibrations or peculiarities of intermolecular interactions. In all these contexts, a major barrier in the form of an intrinsic complexity of near-infrared spectra has been encountered. A large number of overlapping vibrational contributions influenced by anharmonic effects create complex patterns of spectral dependencies, in many cases hindering our comprehension of near-infrared spectra. Quantum mechanical calculations commonly serve as a major support to infrared and Raman studies; conversely, near-infrared spectroscopy has long been hindered in this regard due to practical limitations. Advances in anharmonic theories in hyphenation with ever-growing computer technology have enabled feasible theoretical near-infrared spectroscopy in recent times. Accordingly, a growing number of quantum mechanical investigations aimed at near-infrared region has been witnessed. The present review article summarizes these most recent accomplishments in the emerging field. Applications of generalized approaches, such as vibrational self-consistent field and vibrational second order perturbation theories as well as their derivatives, and dense grid-based studies of vibrational potential, are overviewed. Basic and applied studies are discussed, with special attention paid to the ones which aim at improving analytical spectroscopy. A remarkable potential arises from the growing applicability of anharmonic computations to solving the problems which arise in both basic and analytical near-infrared spectroscopy. This review highlights an increased value of quantum mechanical calculations to near-infrared spectroscopy in relation to other kinds of vibrational spectroscopy.

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Microheterogeneity in binary mixtures of aliphatic alcohols and alkanes: ATR-IR/NIR spectroscopic and chemometric studies

Abstract: This work evidences microheterogeneity and deviation from the ideality in binary mixtures of aliphatic alcohols and alkanes.

Cited by 13 publications

References 25 publications

Temperature Drift of Conformational Equilibria of Butyl Alcohols Studied by Near-Infrared Spectroscopy and Fully Anharmonic DFT

Temperature Drift of Conformational Equilibria of Butyl Alcohols Studied by Near-Infrared Spectroscopy and Fully Anharmonic DFT

Electrical Conductivity and Viscosity in Binary Organic Liquid Mixtures: Participation of Molecular Interactions and Nanodomains

Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments

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