G. Dikmen and D. Hür
ChemicalPhysics530(2020)110601
Table 4
Calculation UV–VIS of title molecule in water and DMSO solvents by TD-DFT
method at B3LYP/6-311++G(d,p) basis set.
Excited state
Solvents
E(eV)
Wavelength (nm)
F
65 → 67
Water
DMSO
Water
DMSO
0.2145
0.1943
0.2185
0.1976
266
241
271
245
0.0144
0.0156
0.0153
0.0170
65 → 68
C3/C5 → H8/H9, C4 → H9/H8, C18 → H25/H26 and C24 → H25/H26
connections can clearly be seen.
There is a only one nitrogen atom in the title molecule and this atom
was observed at 110.85 ppm in the 15N-1H HMQC NMR spectrum.
Moreover, as seen in Fig. 8, it was also determined that H19 atom
As seen in Fig. 9 as well, hydrogen atoms bonded to oxygen atom
and chemical shift values of oxygen atoms were determined using
17O-1H HMQC NMR experiment. According to obtained spectrum,
chemical shift values of O21, O22 and O14, O15 atoms bonded to H27,
H28 and H29, H30 atoms, respectively.
3.4. Optical properties
In order to determine optical properties of title molecule, UV–VIS
absorption spectrophotometer was used. UV–VIS absorption spectrum
of title compound measured in water and DMSO solvents at room
temperature. UV–VIS spectrum of title molecule was computed using
method of TD-DFT/B3LYP with 6-311++G(d,p) basis set. All of the
UV–VIS spectra are presented in Fig. S8. In water solvent, strong ab-
sorption bands were observed at 236 nm and 281 nm, these bands were
observed at 238 nm and 284 nm in DMSO solvent. On the other hand,
these bands were calculated as 241 nm and 266 nm in water, 245 nm
and 271 nm in DMSO (Table 4). Energy values of these absorption
bands are 0.1943 and 0.2145 nm in water, 0.1976 and 0.2185 nm in
DMSO, respectively. The considered absorption peaks are accredited to
the π → π* transition in the organic cation. The results indicated that
the most absorption peak was calculated for transfer from electron level
of 65 → 67 with 241 nm, E = 0.1943 eV and F = 0.0156.
3.5. Electronic property
3.5.1. Frontier molecular orbital analysis
HOMO is highest occupied molecular orbital and LUMO is lowest
unoccupied molecular orbital. HOMO is ability of electron giving of a
molecule, whereas LUMO is ability of electron accepting. The nodes of
HOMO orbital located on the ring and oxygen atoms. But, the nodes of
LUMO located symmetrically all over the title molecule (Fig. 10). Red
respectively. Moreover, HOMO and LUMO show the π bonding char-
acter and π anti bonding character, respectively [28]. Energy gap de-
termines charge transfer from HOMO to LUMO and charge transfer
interactions in the molecule. HOMO and LUMO energies were calcu-
lated by B3LYP/6*311++G(d,p) method for gas phase. The energy gap
indicates the eventual charge transfer interactions occurring in the
molecule. The energy gap is that
Fig. 10. Atomic orbital compositions of the frontier molecular orbital for title
molecule.
chemical computations.
To summarize, the following conclusions can be drawn:
(i) The B3LYP functional is reliable for characterizing title molecule.
(ii) tc tautomer form was found having the lowest optimized energy in
the gas phase among the calculated conformers.
(iii) It was observed that there was a good agreement between ex-
perimental and theoretical vibration wavenumbers.
(iv) Synthesied molecule fully was characterized with NMR spectro-
scopy and it was observed that the molecule was synthesized
successfully. However, it was esterified using D2O solvent and title
molecule transform monomer and trimer structures.
EnergyHOMO = −7.0725 eV
EnergyLUMO = −1.7764 eV
Energy GapHOMO-LUMO = 5.2961 eV
(v) It was found that B3LYP/6-31++G(d,p) level of theory indicates
big frequency deviations for particularly OH stretchings of the title
molecule. For the low wavenumber region experimental and cal-
culated values were found more close to each other.
4. Conclusions
The structural and vibrational analyses of title molecule were per-
formed using FT-IR, Raman, NMR spectroscopies and quantum
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Dikmen, G?khan
