T. Tang et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 144–151
145
Table 1
play a key role in the performance of biological systems, such as
Crystal data and structure refinement for the title compound.
antimalarial, antifungal, antitumoral, anti-allergic, anti-inflamma-
tory and antiviral drugs [12–15]. It has also been used [16–20] in
DNA-binding, DNA-photocleavage, third-order non-linear optical
(NLO) materials, and asymmetric catalysis. The compound 2-(1H-
Imidazo [4,5-f][1,10] phenanthrolin-2-yl) phenol (IPP) is one of
the derivatives of 1,10-phenanthroline. The title compound has
multiple binding sites (N, O) and has interesting optical properties.
In order to present an in-depth study of IPP, we report a synthesis
route, and in addition, the purpose for this work is (i) to determine
the structure with X-ray diffraction and compare it to DFT calcula-
tions, (ii) to thoroughly study the vibration spectra of this molecule
and to identify the various normal modes with the aid of HF and
DFT studies, (iii) to compare the different DFT methods for the cal-
culated vibration spectra, and (iv) to calculate the absorption
bands in CH3OH solution with an optimized geometry by using
the time-dependent density functional theory (TDDFT) at B3LYP/
6-311GÃÃ, B3LYP/LANL2DZ, HF/6-311GÃÃ and HF/LANL2DZ level
associated with the polarized continuum model (PCM).
Empirical formula
Formula weight
Temperature
Radiation
Space group
a (Å)
C19H12N4O
312.33
296(2)
Mo Ka (k = 0.71073 Å)
PÀ1
9.920(3)
12.306(3)
12.444(4)
89.173(4)
78.586(4)
77.837(4)
1455.0(7)
4
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dc/(g cmÀ3
l
)
1.426
0.093
/mmÀ1
Crystal size (mm)
h range for data collection
Index ranges
0.2 Â 0.2 Â 0.15
1.67–25.00°
À11 6 h 6 11
À14 6 k 6 13
À14 6 l 6 14
10277
Total reflections
Goodness-of-fit on F2
1.007
R indices [I > 2
r
(I)]
0.0563
R indices (all data)
Largest difference peak and hole
0.1393
0.18/À0.23
Experimental and computational section
Experimental
1,10-Phenanthroline-5, 6-dione 0.5302 g (2.5 mmol), 2-
hydroxybenzaldehyde 0.4580 g (3.75 mmol) and ammonium ace-
tate 3.8542 g (0.05 mol) were dissolved in glacial acetic acid. The
mixture was refluxed for 2 h, and cooled to room temperature; it
was then diluted with water and neutralized with concentrated
aqueous ammonia; immediately a yellow precipitate was formed,
which was washed with water. The compound was purified by
recrystallization with glacial acetic acid and acetonitrile. The
absorption UV–Vis spectrum in CH3OH solution shows three max-
imum bands at 237.0, 274.0 and 335.0 nm.
A mixture of 0.0312 g (0.1 mmol) IPP, l mL (99%) triethylamine
and 15 mL deionized water was sealed in a Teflon-lined stainless
steel autoclave, and then heated at 160 °C for 72 h, and then cooled
to room temperature. Colorless, transparent block-shaped crystals
were obtained.
Methods of calculation
The geometry optimization proceeded in two steps; firstly, the
initial geometry was constructed by MM+ molecular modeling
with the HyperChem 6.0 package [24]. Secondly, the equilibrium
geometry was optimized ab initio by restricted Hartree–Fock (HF)
and density functional theory (DFT) B3LYP (Becke’s three parame-
ters hybrid method with the Lee, Yang and Parr non-local functions
[25,26]) levels of theory with 6-311GÃÃ and LANL2DZ (Los Alamos
ECP plus double-zeta) [27,28] basis sets. The structure was found
to be a minimum since there is no imaginary frequency in the fre-
quency calculation. Time-dependent density functional theory
(TDDFT) [29] excited-state calculations were determined at the
HF/6-311GÃÃ, HF/LANL2DZ, B3LYP/6-311GÃÃ and B3LYP/LANL2DZ
level of theory both in gas phase and in CH3OH solution. A polariz-
able continuum model (PCM) [30] including the solvent effect was
chosen for excitation energy calculations. All calculations were
performed using the Gaussian 09W program package [31]. All
geometries converged perfectly. The vibrational frequencies and
intensities were computed in a similar fashion.
X-ray diffraction measurements of the crystal were performed
on a Bruker Smart Apex CCD diffractometer at 296 K. The intensity
data were collected using graphite monochromated Mo K
a radia-
tion (k = 0.71073 Å). The data collection 2h range was 5.44–
39.60°. No significant decay was observed during the data collec-
tion. The raw data were processed to give structure factors using
the SAINT-plus program [21].
Empirical absorption corrections were applied to the data sets
using the SADABS program [22]. The structure was solved by direc-
tion method and refined by full matrix least-squares against F2 for
all data using SHELXTL software [23]. All non-hydrogen atoms in
the compound were anisotropically refined. All hydrogen atoms
were included in the calculated positions and refined using a riding
model with isotropic thermal parameters 1.2 times larger than
those of the parent atoms. The crystal data, further details of the
experimental conditions and the structure refinement parameters
for the compound are given in Table 1 and the atomic numbering
scheme is shown in Fig. 1.
The FT-IR spectrum of the title compound was recorded as KBr
discs using an AVATAR 360 spectrophotometer in the range of
400–4000 cmÀ1 at room temperature. The Raman spectrum was
recorded on a Bruker RFS 100/S FT-Raman spectrometer in the
50–3000 cmÀ1 regions with a diode-pumped air-cooled Nd-YAG la-
ser source giving 1283 nm as an exciting line at 75 mW powers.
The electronic spectra were recorded on a UV–Vis 916 spectropho-
tometer in the region of 200–800 nm using CH3OH as the solvent.
Results and discussion
Molecular geometry
The optimized geometry with atomic numbering scheme for the
title compound is shown in Fig. 1. Crystal data are summarized in
Table 1. The selected experimental bond lengths and angles are gi-
ven in Table 2. In the compound, the experimental bond length of
C21–O27 (1.352(3) Å) is typical for a C–O single bond. The theoret-
ical bond length of C–O was obtained by B3LYP/6-311GÃÃ
,
(1.342 Å), and HF/LANL2DZ, (1.361 Å), which agree well with the
experimental value. The DFT (B3LYP/6-311GÃÃ, B3LYP/LANL2DZ)
and HF (HF/6-311GÃÃ, HF/LANL2DZ) methods were used for geo-
metrical optimization of the IPP molecule. The theoretical results
show all atoms nearly co-planar, and all optimized bond lengths
and angles agree well with the experimental values.
The optimized parameters of the title compound with DFT
(B3LYP/6-311GÃÃ
,
B3LYP/LANL2DZ) and HF (HF/6-311GÃÃ
,
HF/
LANL2DZ) methods are listed in Table 2. The overall magnitude
Tang, Tingting
