PD Research Report for the 2015 year
Name

Krzysztof BEC,
(Professor Yukihiro Ozaki Research Group, Graduate School of Scienceand Technology)

Research Theme

Spectroscopic studies of the chiral discrimination effect in optically active
aliphatic alcohols

Research Period

06, 01, 2015 ~ 02, 28, 2016

Research Results
The proposed research focused on investigation of chiral aliphatic alcohols by
Two-Dimensional Correlation (2D-COS) FT-NIR spectroscopy and anharmonic quantum chemical
calculations. However, due to previously unexpected imperfect condition of the Perkin Elmer FT-NIR
spectrometer, the research plan was modified. The experimental condition were deemed not good for
application of 2D-COS. The observed background instability of the spectrometer was investigated and it
was found, that a complex spectrometer service is needed. Therefore my research work focused on other,previously unplanned, research topics. The research topics that I worked on are listed below.
1. Spectroscopic and Theoretical Study in the Near-Infrared Region of Low Concentration
Aliphatic Alcohols
This research topic focused on application of the novel and powerful quantum chemical
methods for the NIR spectroscopy. The theoretical prediction of vibrational spectra has widely been used
as a strong support for interpreting IR spectra for many years. However, NIR spectroscopy has been
unable to benefit fully from advances in quantum chemistry because of not enough reliability to predict
entire NIR spectra of molecules of reasonable size and high computational cost of theoretical approaches.
Recent (2014 year) introduction of second-order vibrational perturbation theory (VPT2), allows forprediction of overtones and combination modes and for modeling of NIR spectra. In this project we usednovel DFT methods (including double hybrid B2PLYP functional, with empirical dispersion correction)and innovative “spectroscopic” basis sets (SNSD and SNST) with VPT2-based calculation of NIR
spectra of aliphatic alcohols in diluted phase (methanol, ethanol, 1-propanol). Additionally, othermethods were used for comparison and evaluation (DFT-B3LYP, MP2), polarized continuum (PCM)
solvent models were tested as well. The results allowed for a very accurate prediction of entire NIR
spectra of the studied systems, in the region of 7500 – 3700 cm-1. For the first time prediction of entire
NIR spectra was reported, also this is the first time of application of VPT2 method to the spectra ofaliphatic alcohols. Thermodynamics data and rotational isomerism of aliphatic alcohols were taken into
account as well. The obtained results enabled us for a very deep and insightful analysis of the NIR
spectra of studied molecules, to the point where bands originating from individual conformational
isomers could be identified. Decomposition of the major band in this region, the first overtone of the OH
stretching band, could be also supported by the results of quantum calculation. This research allowed fora significant improvement of the current knowledge about NIR spectra of aliphatic alcohols. The resultswere submitted to Physical Chemistry Chemical Physics journal (K. B. Beć, Y. Futami, M. J. Wójcik andY. Ozaki, Spectroscopic and Theoretical Study in the Near-Infrared Region of Low Concentration
Aliphatic Alcohols; currently under review).
2. Hydrogen bonding in the acetic acid dimer by FT-NIR spectroscopy and anharmonic quantum
chemical calculation study
In this project we focused on quantum chemical study of NIR vibrational modes (overtones,combinations) of hydrogen bonded acetic acid. In particular, the properties of double hydrogen bondbridge formed in acetic acid dimer, was studied in detail. The acetic acid is an important system forstudies of hydrogen bonding, due to high hydrogen bond stabilization energy and formation of dimer,
which exhibits interesting properties. In this work, acetic acid (acac), deuterated acetic acid (acac-d) andtrifluoroacetic acid (acac-3F) were chosen as objects of the study. The experimental work was focusedon measuring NIR spectra of these systems in a wide range of concentrations (solution in CCl 4 ), both asingle compound and mixed systems (acac:acac-d; acac:acac-3F; acac-d:acac-3F; in each case withvarying concentrations of both ingredients; wide range of concentration was studied to elucidate theformation of dimeric forms). The experimental was supported by extensive quantum chemical
calculation. Again, novel DFT methods (double hybrid B2PLYP functional) and basis set (SNSD,“spectroscopic” basis set) were employed; novel VPT2 method was used for the prediction of NIR
spectra of monomeric and dimeric species. It was found that the observed broad spectral feature, mainly
determining the NIR spectra of acetic acids, should be contributed to the combination mode of the twostretching modes of the double-hydrogen-bonded bridge in dimeric species; this is in contrast withpreviously accepted explanation, indicating that the broad structure originates from OH first overtone
band. The results of this project are now being prepared as a manuscript (K. B. Beć, Y. Futami, M. J.
Wójcik and Y. Ozaki, Hydrogen bonding in the acetic acid dimer by FT-NIR spectroscopy andanharmonic quantum chemical calculation study; in preparation).
3. Quantitative FT-NIR spectroscopy of polyphenolic compounds in the rosemary extract
In this project NIR spectroscopy, chemometrics and quantum chemical methods were applied
for the analysis of polyphenolic compounds in the extract of rosemary medicinal plant. The plyphenolic
compounds that can be found in medicinal plants (gallic acid, ellagic acid, rosmarinic acid, carnosol andcarnosic acid). A large number of rosemary extract samples (over 40 samples) was measured by diffuse
reflectance Fourier transform NIR spectrometer (DRIFT) and the results were analyzed by PLS
regression chemometrics method. Additionally, the theoretical spectra of the polyphenols werecalculated by quantum chemical methods. DFT-B3LYP/SNSD method was applied and anharmonic
infrared spectroscopy was obtained by VPT2 method. Due to large size of studied molecules, and theirpolycrystalline phase, approximations were necessary. Yet, our calculated spectra were accurate enoughto allow for identification of major bands in the rosemary samples. This project was carried out incollaboration with Professor Christian W. Huck from University of Innsbruck. A manuscript, to which
this research contributed, is currently being prepared.