Synthesis characterization and crystal structure of 2-(3,4,5- trimethoxyphenyl)-1-(4-fluorophenyl)-4,5-diphenyl-1H-imidazole

Article abstract of DOI:10.1080/15421406.2013.875761

The title compound, C₃₀H₂₅FN₂O ₃, was prepared from the four-component one-pot condensation reaction and the product crystallized using dimethylformamide. The structure of the compound was established by elemental analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-Visible, and single-crystal X-ray diffraction. The compound crystallizes in the triclinic crystal system with the space group PP., with unit cell parameters a = 10.286(2) ?, b = 11.795(2) ?, c = 21.331(4) ?, α = 100.270(3)., β = 90.093(3)., γ = 90.062(3)., and Z = 4. The crystal and molecular structure of the title molecule is stabilized by intra-molecular interactions of types C-H?N and C-H?O.

Full text of DOI:10.1080/15421406.2013.875761

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Synthesis Characterization
and Crystal Structure of 2-
(3,4,5-trimethoxyphenyl)-1-(4-
fluorophenyl)-4,5-diphenyl-1H-imidazole
S. Vivekaa, M. Prabhuswamyb, Dineshaa, N. K. Lokanathb & G. K.
Nagarajaa
a Department of Chemistry, Mangalore University, Mangalore,
Karnataka, India
b Department of Studies in Physics, Mysore University, Mysore,
Karnataka, India
Published online: 27 May 2014.
To cite this article: S. Viveka, M. Prabhuswamy, Dinesha, N. K. Lokanath & G. K. Nagaraja
(2014) Synthesis Characterization and Crystal Structure of 2-(3,4,5-trimethoxyphenyl)-1-(4-
fluorophenyl)-4,5-diphenyl-1H-imidazole, Molecular Crystals and Liquid Crystals, 593:1, 261-270, DOI:
10.1080/15421406.2013.875761
To link to this article: http://dx.doi.org/10.1080/15421406.2013.875761
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Mol. Cryst. Liq. Cryst., Vol. 593: pp. 261–270, 2014
Copyright © Taylor & Francis Group, LLC
ISSN: 1542-1406 print/1563-5287 online
DOI: 10.1080/15421406.2013.875761
Synthesis Characterization and Crystal Structure
of 2-(3,4,5-trimethoxyphenyl)-1-(4-fluorophenyl)-
4,5-diphenyl-1H-imidazole
S. VIVEKA,1 M. PRABHUSWAMY,2 DINESHA,1
N. K. LOKANATH,2 AND G. K. NAGARAJA1,∗
1Department of Chemistry, Mangalore University, Mangalore, Karnataka, India
2Department of Studies in Physics, Mysore University, Mysore, Karnataka, India
The title compound, C30H25FN2O3, was prepared from the four-component one-pot con-
densation reaction and the product crystallized using dimethylformamide. The structure
of the compound was established by elemental analysis, Fourier transform infrared
spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-Visible, and single-crystal
X-ray diffraction. The compound crystallizes in the triclinic crystal system with the space
group P¯ı, with unit cell parameters a = 10.286(2) Å, b = 11.795(2) Å, c = 21.331(4)
Å, α = 100.270(3)◦, β = 90.093(3)◦, γ = 90.062(3)◦, and Z = 4. The crystal and
molecular structure of the title molecule is stabilized by intra-molecular interactions of
types C–H···N and C–H···O.
Keywords Crystallization; crystal structure; FTIR spectrum; imidazole; inter-
molecular interactions; multicomponent reaction; thermo gram
Introduction
Multicomponent reactions (MCRs) have attracted great interest in modern organic synthe-
sis and medicinal chemistry in recent years because they are one-pot processes bringing
together three or more components and show high atom economy and high selectivity.
Imidazole ring has been of great interest for the organic chemist due to their useful
biological and pharmacological aspects. The imidazole ring system is one of the most
important substructures and incorporated in a multitude of natural products and pharmaco-
logically active compounds such as the hypnotic agent etomidate [1], and the proton pump
inhibitor omeprazole [2]. From the literature, substituted imidazoles are known as inhibitors
of fungicides and herbicides, plant growth regulators, therapeutic agents, anticancer, and
anti-viral agents [3]. Some imidazole derivatives are found to be having a diverse activity
like anti-inflammatory, cardiovascular activity [4,5], antimicrobial activity [6], anti-fungal
activity [7], and anti-viral activity. Recently, tetrasubstituted imidazole scaffold has been a
core element in many biological systems like potent and specific ATP-mimetic inhibitors
of p38 MAP Kinase, as p38α mitogen-activated protein kinase inhibitors [8].
∗Address correspondence to Dr. G. K. Nagaraja, Department of Post Graduate Studies and
Research in Chemistry, Mangalore University, Mangalagangothri, Mangalore 574199, Karnataka,
India. E-mail: nagarajagk@gmail.com
261

262
S. Viveka et al.
Table 1. Elemental analysis for C30H25FN2O3
Element
Experimental (%)
Calculated (%)
Carbon
Nitrogen
Hydrogen
74.99
5.80
5.21
74.98
5.83
5.24
Due to the importance of imidazole, many synthesis strategies have been developed.
2,4,5-triphenyl imidazoles was synthesized by 1, 2-dicarbonyl compound, various aldehy-
des, and ammonia in 1882 [9]. Crystal structure of the similar 2,4,5-triphenyl [10,11] and
1,2,4,5-tetraphenyl imidazole [12,13] was reported in the literature. The title compound
was synthesized via four-component single-pot condensation of a benzil with a substituted
benzaldehyde, ammonium acetate, and aniline.
As a result, encouraged by these pharmacological properties of imidazole and in
continuation of our interest in the synthesis of biologically active imidazole analogs, we
have synthesized the title compound and report the spectroscopic, crystal structure using
single-crystal X-ray diffraction.
Experimental
Materials and Methods
All chemicals were purchased commercially and used without prior purification. Infrared
spectra were recorded on a FT-IR spectrophotometer (SHIMADZU FT-IR spectrometer
Prestige-21) in the range 400–4000 cm−1 using the KBr pellets. A TA-SQT Q600 ther-
mogravimetric analyzer was used to obtain TGA curve under nitrogen atmosphere with a
Figure 1. UV-visible spectrum of the crystal.

Synthesis Characterization and Crystal Structure
263
Figure 2. TGA curve of crystal.
heating rate of 20◦C min−1. The UV-Vis spectrum was recorded in UV-Visible spectropho-
tometer (SHIMADZU, UV 2550, Japan). Elemental analysis was carried out by using
VARIO EL-III (Elementar Analysensysteme GmBH).
Synthesis of Compound 2-(3,4,5-trimethoxyphenyl)-1-(4-fluorophenyl)-4,5-diphenyl-
1H-imidazole
Benzil (10 mmol), 3,4,5-trimethoxy benzaldehyde (10 mmol), 4-fluoroaniline (10 mmol),
and ammonium acetate (12 mmol) were dissolved in boiling glacial acetic acid and refluxed
for 6-8 hr. The reaction progress was monitored by thin layer chromatography (TLC). After
the completion of the reaction, the reaction mixture was poured into ice water, the obtained
compound was recrystallized from dimethylformamide. The synthetic strategy of the title
compound is depicted in Scheme 1.
Product as white crystals (3.97 g, 83%) [m.p. 182◦C–185◦C].
Results and Discussion
Elemental Analysis
In order to confirm the chemical composition of the synthesized compound, carbon (C),
hydrogen (H), and nitrogen (N) analysis was carried out. The experimental and calculated
percentages of C, H, and N are given in Table 1. The differences between experimental
and calculated percentages of C, H, and N were very close to each other and within
the experimental errors. This confirms the formation of the product in the stoichiometric
proportion.
UV-Vis Spectral Analysis
The UV-Vis spectrum of the compound was shown in Fig. 1. The UV-Vis spectrum was
recorded by using dimethylformamide as a solvent. From the graph, it was observed that

264
S. Viveka et al.
Scheme 1. 2-(3,4,5-trimethoxyphenyl)-1-(4-fluorophenyl)-4,5-diphenyl-1H-imidazole.
the compound shows an absorption peak at 298 nm. The transmittance of the compound is
due to then-π∗ transition of the constituent –OCH3 group. scheme 1
Thermal Gravimetric Analysis (TGA)
The compound decomposes mainly in one stage on heating between 350◦C and 420◦C as
shown in Fig. 2. There was no much weight loss observed around 140◦C, which shows
the absence of moisture in the crystal. A weight loss of around 9% occurs within 350◦C
indicative of the loss of one molecule of –OCH3 from a compound and the maximum
about 75% weight loss between the 350◦C and 420◦C account for the removal of four
phenyl rings. Above 450◦C, 15% of the residue was left out, which was due to the charring
Figure 3. FTIR spectrum of the crystal.

Synthesis Characterization and Crystal Structure
265
Table 2. Crystal data and structure refinement
CCDC deposition number
931149
Empirical formula
Formula weight
C30H25FN2O3
480.52
Temperature
296(2) K
Wavelength
0.71073 Å
¯
Crystal system, space group
Unit cell dimensions
Triclinic, Pı
a = 10.286(2) Å α = 100.270(3)◦
b = 11.795(2) Å β = 90.093(3)◦
c = 21.331(4) Å γ = 90.062(3)◦
2546.5(9) Å3
Volume
Z, Calculated density
Absorption coefficient
F(000)
4, 1.253 Mg m−3
0.086 mm−1
1008
Crystal size
Theta range for data collection
Limiting indices
Reflections collected/unique
Completeness to theta = 25.35
Refinement method
Data/restraints/parameters
Goodness of fit on F2
Final R indices [I > 2σ(I)]
R indices (all data)
0.20 × 0.20 × 0.18 mm
1.75◦–25.35◦
−12 ≤ h ≤ 12, −14 ≤ k ≤ 14, −25 ≤ l ≤ 25
24531/9279 [R(int) = 0.0280]
99.9%
Full-matrix least square on F2
9279/0/655
1.029
R1 = 0.0479, wR2 = 0.1116
R1 = 0.0672, wR2 = 0.1221
0.150 and −0.189 e.Å−3
Largest diff. peak and hole
Figure 4. ORTEP diagram of the title molecule with 50% probability displacement thermal ellip-
soids.

266
S. Viveka et al.
Figure 5. Packing of molecules when viewed down the a-axis. Dashed lines indicate hydrogen-bond
interactions.
of carbon or due the imidazole ring. Thus, the TG study confirms the formation of the
compound in the stoichiometric ratio.
FT-IR Spectral Analysis
The Fourier transform infrared spectroscopy (FT-IR) spectrum of the crystal structure was
shown in Fig. 3. The peak at 1681 cm−1 was corresponded to the C N asymmetric stretch-
ing vibration. The peaks observed at 1340 cm−1 were assigned for the C N stretching,
Figure 6. Packing of molecules when viewed down the b-axis. Dashed lines indicate hydrogen-bond
interactions.

Synthesis Characterization and Crystal Structure
267
Figure 7. Packing of molecules when viewed down the c-axis. Dashed lines indicate hydrogen-bond
interactions.
1130 cm−1 for the C O stretching vibration, and 1047 cm−1 were assigned for the C F
stretching.
Single-Crystal X-Ray Diffraction Method
Single crystal of the suitable size of the title compound was selected for data collection.
X-ray intensity data were collected on Oxford Xcalibur Eos (Nova) CCD diffractometer
with X-ray generator operating at 50 kV and 1 mA, using MoKα radiation (λ 0.7107
Å) [14]. Data were collected for 606 frames per set with different settings of φ (0◦, 90◦,
180◦), keeping the sample to detector distance of 60.62 mm and the 2θ value fixed at
25◦. A complete dataset is reduced using the software CrysAlis PRO [15]. The structure
was solved by direct methods and refined by full-matrix least-square method on F2 using
SHELXS and SHELXL programs [16]. All hydrogen atoms were positioned geometrically
and refined using a riding model. The geometrical calculations were carried out using the
program PLATON [17]. The molecular and packing diagrams were generated using the
software MERCURY [18].
The crystal data and structure refinement details are reported in Table 2.
The Oak Ridge Thermal Ellipsoid Plot (ORTEP) diagram of the molecule with 50%
probability displacement thermal ellipsoids is shown in Fig. 4.
The packing of molecules when viewed down a-axis, b-axis, and c-axis is given in
Figs. 5, 6, and 7, respectively.
Two symmetry-independent molecules (A and B) are present in the asymmetric unit,
consisting of an imidazole ring, two phenyl rings, a methoxy-substituted phenyl ring, and
a fluorine-substituted phenyl ring.
The methoxy-substituted phenyl ring forms a dihedral angle of 22.09(9)◦ in molecule A
and 22.20(9)◦ in molecule B with respect to imidazole ring, corresponding to axial position.
However, phenyl ring C6A/C7A/C8A/C9A/C10A/C11A of molecule A and phenyl ring
C6B/C7B/C8B/C9B/C10B/C11B of molecule B are in equatorial positions with respect to
imidazole ring N1A/C2A/N3A/C4A/C5A of molecule A and N1B/C2B/N3B/C4B/C5B of
molecule B, as confirmed by the similar dihedral angles 79.40(10)◦, which deviates from
the dihedral angle value of 68.2(3)◦ reported earlier for the similar molecular structure of
1-(4-chlorophenyl)-4,5-diphenyl-2-(3,4,5-trimethoxyphenyl)-1H-imidazole [12].
A dihedral angle of 2.60(10)◦ is observed between phenyl ring C12A/C13A/
C14A/C15A/C16A/C17A and the imidazole ring N1A/C2A/N3A/C4A/C5A of molecule
A and between phenyl ring C12B/C13B/C14B/C15B/C16B/C17B and imidazole ring

268
S. Viveka et al.
Table 3. Selected bond lengths and bond angles [Å, ◦]
F1A—C14A
F1B—C14B
1.360(2)
1.360(2)
O3B—C4B
O3B—C10B
1.365(2)
1.415(3)
O1A—C6A
1.373(2)
N1A—C11A
1.442(2)
O1A—C8A
1.425(3)
N1A—C1A
1.375(2)
O2A—C9A
1.432(3)
N1A—C24A
1.393(2)
O2A—C5A
1.373(2)
N2A—C17A
1.380(2)
O3A—C10A
1.417(3)
N2A—C1A
1.318(2)
O3A—C4A
1.361(2)
N1B—C24B
1.394(2)
O1B—C8B
1.424(3)
N1B—C11B
1.438(2)
O1B—C6B
1.367(2)
N1B—C1B
1.378(2)
O2B—C5B
1.373(2)
N2B—C1B
1.320(2)
O2B—C9B
1.428(3)
N2B—C17B
1.380(2)
C6A—O1A—C8A
C5A—O2A—C9A
C4A—O3A—C10A
C6B—O1B—C8B
C5B—O2B—C9B
C4B—O3B—C10B
C1A—N1A—C11A
C1A—N1A—C24A
C11A—N1A—C24A
C1A—N2A—C17A
C1B—N1B—C11B
C1B—N1B—C24B
C11B—N1B—C24B
C1B—N2B—C17B
N1A—C1A—N2A
N1A—C1A—C2A
N2A—C1A—C2A
O3A—C4A—C3A
O3A—C4A—C5A
O2A—C5A—C6A
O2A—C5A—C4A
O1A—C6A—C5A
O1A—C6A—C7A
N1A—C11A—C12A
117.09(16)
114.80(15)
118.57(16)
116.79(16)
114.87(15)
118.45(16)
128.11(14)
107.18(13)
124.63(14)
106.59(14)
128.19(14)
106.86(13)
124.86(13)
106.68(14)
110.75(15)
126.76(15)
122.49(15)
123.87(17)
115.82(16)
119.21(16)
121.27(16)
115.88(16)
123.87(16)
120.19(15)
N1A—C11A—C16A
F1A—C14A—C15A
F1A—C14A—C13A
N2A—C17A—C24A
N2A—C17A—C18A
N1A—C24A—C17A
N1A—C24A—C25A
N1B—C1B—N2B
N1B—C1B—C2B
N2B—C1B—C2B
O3B—C4B—C3B
O3B—C4B—C5B
O2B—C5B—C4B
O2B—C5B—C6B
O1B—C6B—C5B
O1B—C6B—C7B
N1B—C11B—C12B
N1B—C11B—C16B
F1B—C14B—C13B
F1B—C14B—C15B
N2B—C17B—C18B
N2B—C17B—C24B
N1B—C24B—C17B
N1B—C24B—C25B
119.53(15)
118.45(18)
118.44(18)
110.10(15)
119.05(15)
105.38(14)
121.51(15)
110.87(15)
126.56(15)
122.57(15)
123.92(17)
115.52(16)
121.39(16)
119.20(16)
115.69(16)
124.14(17)
119.82(15)
119.98(15)
118.45(18)
118.60(18)
119.11(15)
109.89(15)
105.70(14)
121.33(15)
N1B/C2B/N3B/C4B/C5B of molecule B, which shows that they have occupied the ax-
ial positions. These values of dihedral angles deviate much from 41.7(1)◦, reported earlier
for the molecular structure 2-(2-methylphenyl)-4,5-diphenyl-1H-imidazole [19]. A dihe-
dral angle of 45.01(10)◦ between imidazole rings in molecule A and in molecule B shows
that they are in bisectional positions. The fluorine-substituted phenyl ring forms a dihedral
angle of 72.59(10)◦ in molecule A and molecule B with respect to imidazole ring, corre-
sponding to equatorial position. Overall, two molecules A and B in the asymmetric unit are
geometrically identical with one another.

Synthesis Characterization and Crystal Structure
269
Table 4. Selected torsion angles [◦]
N(3A)–C(2A)–C(18A)–C(23A)
−21.4(2)
158.72(16)
156.56(17)
−23.4(3)
108.9(2)
−74.7(2)
−70.5(2)
105.9(2)
21.5(2)
N(1A)–C(2A)–C(18A)–C(23A)
N(3A)–C(2A)–C(18A)–C(19A)
N(1A)–C(2A)–C(18A)–C(19A)
C(2A)–N(1A)–C(27A)–C(28A)
C(5A)–N(1A)–C(27A)–C(28A)
C(2A)–N(1A)–C(27A)–C(32A)
C(5A)–N(1A)–C(27A)–C(32A)
C(23B)–C(18B)–C(2B)–N(3B)
C(19B)–C(18B)–C(2B)–N(3B)
C(23B)–C(18B)–C(2B)–N(1B)
C(19B)–C(18B)–C(2B)–N(1B)
C(4B)–C(5B)–C(6B)–C(11B)
N(1B)–C(5B)–C(6B)–C(11B)
C(4B)–C(5B)–C(6B)–C(7B)
N(1B)–C(5B)–C(6B)–C(7B)
C(25A)–O(2A)–C(21A)–C(22A)
C(25A)–O(2A)–C(21A)–C(20A)
C(2B)–N(1B)–C(27B)–C(32B)
C(5B)–N(1B)–C(27B)–C(32B)
C(2B)–N(1B)–C(27B)–C(28B)
C(5B)–N(1B)–C(27B)–C(28B)
C(4A)–C(5A)–C(6A)–C(11A)
N(1A)–C(5A)–C(6A)–C(11A)
C(4A)–C(5A)–C(6A)–C(7A)
N(1A)–C(5A)–C(6A)–C(7A)
C(25B)–O(2B)–C(21B)–C(20B)
C(25B)–O(2B)–C(21B)–C(22B)
−156.31(17)
−158.78(16)
23.4(3)
−99.1(2)
79.7(2)
79.0(3)
−102.3(2)
113.0(2)
−71.4(2)
70.5(2)
−105.6(2)
−108.9(2)
75.0(2)
98.8(2)
−79.7(2)
−79.5(3)
102.0(2)
71.6(2)
−113.0(2)
Bond lengths, bond angles, and torsion angles are given in Tables 3 and 4. Hydrogen-
bond geometry is listed in Table 5.
The molecular structure involves Cg–Cg interactions between the ring N1A/C2A/N3A/
C4A/C5A and its adjacent ring N1A/C2A/N3A/C4A/C5A in the asymmetric unit with a
centroid–centroid distance of 5.943(15) Å, slippage of 3.521 Å, and symmetry code, 1−x,
1−y, −z. The crystal structure is stabilized by the interactions: C25A–H25C···Cg3 (where
Table 5. Hydrogen-bond geometry [Å, ◦]
D–H···A
d(D–H)
d(H···A)
d(D···A)
<(DHA)
C(13A)–H(13A)···N(3A)a
C(13B)–H(13B)···N(3B)a
C(23A)–H(23A)···N(3A)a
C(23B)–H(23B)···N(3B)a
C(25A)–H(25C)···O(1A)a
C(25B)–H(25D)···O(1B)a
0.93
0.93
0.93
0.93
0.96
0.96
2.46
2.46
2.53
2.53
2.40
2.39
2.819(2)
2.818(2)
2.842(2)
2.847(2)
2.977(3)
2.973(3)
103
103
100
100
118
118
aIntra-molecular hydrogen-bond interaction.

270
S. Viveka et al.
Cg3 is C12A/C13A/C14A/C15A/C16A/C17A with a symmetry code x, 1+y, z) with a
C–Cg distance of 3.551(2) Å, C–H···Cg angle of 127◦, and C25B–H25D···Cg8 (where Cg8
is C12B/C13B/C14B/C15B/C16B/C17B with a symmetry code x, 1+y, z) with a C–Cg
distance of 3.548(2) Å, C–H···Cg angle of 127◦.
The molecular structure of the title molecule is stabilized by the intra-molecular inter-
actions of types C H···N and C H···O.
Conclusion
Single crystal was grown by the slow evaporation method. The elemental analysis confirms
the formation of the compound in a stoichiometric ratio. The UV-Vis spectrum reveals the
properties of the crystals. TGA was carried out to study the thermal behavior of the crystal.
The FTIR spectrum characterizes the presence of various functional groups. The single-
crystal X-ray diffraction study indicates that the compound crystallizes in the triclinic
crystal system.
Acknowledgment
The authors gratefully acknowledge the UGC and DST-PURSE for the financial assistance
and Mangalore University, USIC for their instrumental facilities.
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