XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
329
T9: P–3
Comparison of the conformational behavior of
3-(methylaminomethylene)-pentane-2,4-dione (MAMP)
and 3-(dimethylaminomethylene)-pentane-2,4-dione (DMAMP)
using vibrational and NMR spectra and ab initio calculations
Anton Gatial
1
, Martin Gróf
1
, Viktor Milata
2
, Nadežda Prónayová
3
, and Peter Herich
1
1
Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of
Technology, Radlinského 9, SK-81237 Bratislava, Slovakia, e-mail: anton.gatial@stuba.sk
2
Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of
Technology, Radlinského 9, SK-81237 Bratislava, Slovakia
3
Central Laboratories, Faculty of Chemical and Food Technology, Slovak University of Technology,
Radlinského 9, SK-81237 Bratislava, Slovakia
The aim of this work is the conformational study and interpretation of vibrational and NMR spectra of
the title compounds H3C-NH-CH=C(COCH3)2 (MAMP) and (H3C)2N-CH=C(COCH3)2 (DMAMP).
Both belong to the so-called push-pull olefines which are often used as starting reactants or intermediates in
many organic syntheses. The high polar character of push-pull ethylenes and the electronic interactions
between substituents are responsible for their non-linear optical properties. The electron donor methylamino
group in the investigated compound has a special influence on its conformational equilibria due to the
possibility to create an intramolecular hydrogen bond. DMAMP has no such possibility.
MAMP can theoretically exist in eight EZa, EEa, ZEa, ZZa, EZs, EEs, ZEs and ZZs conformations
where the first and second letters express the orientation of the carbonyl oxygen to the C=C bond for trans
and cis acetyl group, respectively, and the conformational possibility due to the anti and syn orientation of
the methylamino group to the C=C bond is denoted by the third letter. DMAMP can theoretically exist in
four EZ, EE, ZE and ZZ conformations with the same meaning of both letters as for MAMP and no
conformational possibilty for dimethylamino group. This work contains theoretical calculations and X-ray,
vibrational and NMR study as well. X-ray study revealed EZa conformer and EZ conformer in solid state
for MAMP and DMAMP, respectively. In the IR and Raman spectra in very polar solvents only one
conformer is present but in less polar solvents the second one is observed. MP2 and DFT calculations in
different basis sets predict for MAMP and as well as for DMAMP the conformer with EZ orientation of
both acetyl groups as the most stable one followed by the ZZ one (Table 1) and with anti orientation of
methylamino group. It has been shown that the conformers with E orientations of both acetyl groups are not
the stable ones. These observations are explained by the influence of environment polarity on the
conformational equilibrium and are discussed with respect to the SCRF solvent effect calculations using the
PCM model.
Table 1. MP2/cc-pVTZ calculated ab initio relative energies ∆E and dipole moments µ
of MAMP and DMAMP conformers in vacuum (a – not found).
MAMP
EZa
EZs
EEa EEs
ZEa
ZEs
ZZa
ZZs
∆E (kJ/mol)
0.00 42.72
a
a
38.30 49.64 8.44 46.81
µ (D)
5.32
5.62
6.18
5.24
2.08
2.80
DMAMP
EZ
EE
ZE
ZZ
∆E (kJ/mol)
0.00
a
5.27
3.46
µ (D)
5.92
5.83
3.07
Keywords: conformational analysis; vibrational and NMR spectra; push-pull compounds; ab initio calculations
Acknowledgment
This work has been supported by Ministry of Education, Science, Research and Sport of the Slovak Republic
within the Research and Development Operational Programme for the project "University Science Park of STU
Bratislava", ITMS 26240220084 and by High Performance Computing center at Slovak University of Technology
in Bratislava (SIVVP project No. 26230120002), both co-funded by the European Regional Development Funds.
Also the support from the Slovak Research and Development Agency (projects APVV-15-0079 and APVV-0038-
11) and the Scientific Grant Agency of the Ministry of Education of Slovak Republic (projects VEGA No.
1/0598/16 and 1/0829/14) is appreciated.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
330
T9: P–4
Density functional computations of IR and NMR spectra, molecular
geometry and some molecular properties of 3-(N-morpholinyl
carbodithioate)-2-(4-methoxyphenyl)chroman-4-one
Gosav Steluta
1
, Maftei Dan
2
, and Paduraru Nicoleta
1
1
Chemistry, Physics and Environment Department, "Dunarea de Jos" University, Domneasca St. 47,
800008 Galati, Romania, e-mail: Steluta.Gosav@ugal.ro
2
Chemistry Department, "Al.I. Cuza" University, 11 Carol I Bldv. RO-700506, Iasi, Romania
The aim of the present study was to characterize a flavanone, i.e. 3-(N-morpholinyl
carbodithioate)-2-(4-methoxyphenyl)chroman-4-one [1] by IR and NMR spectroscopy in
conjunction with Density Functional Theory (DFT) calculations. Quantum mechanical
calculations were carried out in the ground state using four functionals, i.e. B3LYP, PBE1PBE,
CAM-B3LYP and ωB97X-D, with the same basis set namely, 6-311G(d,p). The comparison
among the experimental and calculated geometrical parameters of the studied molecule showed
that the DFT/B3LYP/6-311G(d,p) method gives the best results.
The calculation of NMR spectrum of the studied flavanone was performed by using the
GIAO (Gauge-Including Atomic Orbitals) method with the hybrid B3LYP, WP04, WC04, and
PBE1PBE functionals in conjunction with 6-311++G(d,p) and cc-pVDZ basis sets. Theoretical
13C and 1H chemical shift values (with respect to TMS) were reported and compared with
experimental data, showing a very good agreement for both 13C and 1H.
In order to assess the chemical potential of 3-(N-morpholinyl carbodithioate)-2-(4-
methoxyphenyl)chroman-4-one, the main quantum molecular descriptors, such as the Ghose-
Crippen octanol-water partition coefficient, the dipole moment, the energy of the highest/lowest
occupied/unoccupied molecular orbital, the electronegativity, the chemical hardness/softness
and the Ghose-Viswanadhan-Wendoloski drug-like indices have been computed. Also, the
molecular electrostatic potential (MEP) map (Fig.1), computed in order to identify the sites of
the studied flavonoid that are most likely to interact with electrophilic and nucleophilic species,
is discussed.
Fig.1. Molecular electrostatic map of anti diastereisomer of studied compound.
Keywords: DFT; FTIR; NMR; B3LYP; WP04; WPC04
References
[1] L.G. Bahrin, P.G. Jones, H. Hopf, Beilstein J. Org. Chem. 8 (2012) 1999.
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