The temperature-induced changes in hydrogen bonding of decan-1-ol in the pure liquid phase studied by two-dimensional Fourier transform near-infrared correlation spectroscopy

Abstract

Fourier transform near-infrared (FT-NIR) spectra of decan-1-ol in the pure liquid phase were investigated in the regions of the Ðrst and second overtones of the OH stretching vibration over the temperature range 15È76 ¡C. The dynamics of temperature-induced changes in the hydrogen bonding were explored by the 2D correlation approach. It was found that the Ðrst overtone of the monomer band is split into two peaks (7087 and 7114 cm~1). The peaks originate from the rotational isomerism of the OH group. Although the trans-isomer (at 7114 cm~1) is more stable than the gauche-isomer (at 7087 cm~1), the intensity of the band due to the former is weaker in the pure liquid phase. In dilute solutions the situation is reversed. This e †ect can be explained by higher accessibility of the OH proton in the trans-position. Therefore, the population of the free protons in the trans-position is reduced faster with increase in concentration. The band attributed to the free terminal OH groups in open chain polymers was not observed in the 2D correlation spectra of neat decan-1-ol. As for butanols, studied previously, the populations of the polymers and cyclic dimers vary faster than that of the monomers. When the temperature is raised, the population of the monomers increases faster where that of the polymers decreases more slowly. Hence it is concluded that the growth in the population of the monomeric species comes from dissociation of the intermediate species. These 2D correlation studies on alcohols in the pure liquid state suggest that the degree of association in the saturated straight-chain alcohols decreases with increase in chain length.

Molecular Self-Assembling of Butan-1-ol, Butan-2-ol, and 2-Methylpropan-2-ol in Carbon Tetrachloride Solutions as Observed by Near-Infrared Spectroscopic Measurements

“…2-methylpropan-2-ol. Czarnecki et al 6 have also postulated the same order of the self-association for the three kinds of butanols. In addition, it should be noted that the peak positions of the bands due to the free OH groups for the three kinds of butanols are slightly different from each other: 1407 nm (7107 cm 2 1 ) for butan-1-ol, 1411 nm (7087 cm 2 1 ) for butan-2-ol, and 1415 nm (7067 cm 2 1 ) for 2-methylpropan-2-ol, respectively.…”

Advances in two-dimensional correlation spectroscopy

“…For example, temperature-dependent NIR spectra of decanol for hydrogen bonding study and rotational isomerism detection were reported by Czarnecki et al [122]. Temperature-dependent NIR of hydrogen-bonded octanol for second overtones, indicating the presence of dimers, and splitting of monomer bands due to conformers were also studied [123].…”

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

“…A number of QM studies on NIR spectra of basic molecules have been reported over the last few years (Beć et al, 2016a, 2018a; Grabska et al, 2017a,b). Vibrational studies of these systems are relatively important for our understanding of the general spectra-structure correlations (Czarnecki et al, 2000; Wojtków and Czarnecki, 2006; Michniewicz et al, 2007, 2008; Haufa and Czarnecki, 2010) and the role of conformational isomerism (Czarnecki et al, 2006; Wojtków and Czarnecki, 2006), structure and dynamics of hydrogen-bonding, self-association mechanisms and intermolecular interactions (Czarnecki and Ozaki, 1999; Czarnecki et al, 2000, 2010; Czarnecki, 2003; Czarnecki and Wojtków, 2004; Michniewicz et al, 2007; Haufa and Czarnecki, 2010), in particular the interactions with solvent molecules (e.g., water, nonpolar solvents) (Gonjo et al, 2011; Tomza and Czarnecki, 2015), or chiral discrimination (Czarnecki, 2003); the temperature influence on the above effects was often also examined (Czarnecki and Ozaki, 1999; Iwahashi et al, 2000; Šašić et al, 2002; Wojtków and Czarnecki, 2005, 2006, 2007; Grabska et al, 2017a). In the above contexts, alcohol molecules have remained among those investigated most frequently in physicochemical NIRS; often, the lack of QM spectra simulations hindered full comprehension therein.…”

“…NIRS manifests unique suitability for investigating intermolecular interactions, e.g., hydrogen-bonding. Not without reason, this aspect is strongly focused in physicochemical NIRS (Czarnecki and Ozaki, 1999; Czarnecki et al, 2000, 2010; Czarnecki, 2003; Czarnecki and Wojtków, 2004; Michniewicz et al, 2007; Gonjo et al, 2011; Tomza and Czarnecki, 2015). The potential of QM simulations has long been utilized in MIR and Raman studies.…”