Versatile and green synthesis, spectroscopic characterizations, crystal structure and DFT calculations of 1,2,3?triazole?based sulfonamides

Article abstract of DOI:10.1016/j.molstruc.2016.11.027

A green, and practically reliable method for the synthesis of novel 1,2,3?triazole-based sulfonamides via copper (I)?catalyzed azide?alkyne [3 + 2] cycloaddition reaction was reported. The desired products were characterized by CHN analysis, FT-IR, ¹H and ¹³C NMR, ESI-MS spectroscopy, single crystal X-ray diffraction and density functional theory (DFT) geometry optimization and molecular orbital calculations. Mild and green reaction conditions, atom-economic and high yields (61–91%) make this protocol an attractive option for the synthesis of 1,2,3?triazoles bearing sulfonamide moiety. Geometrical structures, vibrational frequencies, ¹H and ¹³C chemical shift values, Mulliken charge distribution and electrophilicity index (HOMO-LUMO analysis) of the characterized structure of 3f in the ground state have been calculated with the aid of DFT studies. The calculated chemical shifts (NMR) and vibrational frequencies (FT-IR) are in compliance with the experimental findings. The aim of the DFT study was to make a reasonable assignment of vibrational bands and chemical shifts.

Full text of DOI:10.1016/j.molstruc.2016.11.027

Journal of Molecular Structure 1131 (2017) 73e78
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: http://www.elsevier.com/locate/molstruc
Versatile and green synthesis, spectroscopic characterizations, crystal
structure and DFT calculations of 1,2,3‒triazole‒based sulfonamides
Hamid Saeidian*, Hamed Sadighian, Morteza Abdoli, Morteza Sahandi
Department of Science, Payame Noor University (PNU), PO Box: 19395-4697, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A green, and practically reliable method for the synthesis of novel 1,2,3‒triazole-based sulfonamides via
copper (I)‒catalyzed azide‒alkyne [3 þ 2] cycloaddition reaction was reported. The desired products
were characterized by CHN analysis, FT-IR, 1H and 13C NMR, ESI-MS spectroscopy, single crystal X-ray
diffraction and density functional theory (DFT) geometry optimization and molecular orbital calculations.
Mild and green reaction conditions, atom-economic and high yields (61e91%) make this protocol an
attractive option for the synthesis of 1,2,3‒triazoles bearing sulfonamide moiety. Geometrical structures,
vibrational frequencies, 1H and 13C chemical shift values, Mulliken charge distribution and electrophi-
licity index (HOMO-LUMO analysis) of the characterized structure of 3f in the ground state have been
calculated with the aid of DFT studies. The calculated chemical shifts (NMR) and vibrational frequencies
(FT-IR) are in compliance with the experimental findings. The aim of the DFT study was to make a
reasonable assignment of vibrational bands and chemical shifts.
Received 31 August 2016
Received in revised form
5 November 2016
Accepted 7 November 2016
Available online 11 November 2016
Keywords:
1,2,3-Triazoles
Click chemistry
Sulfonamides
CuAAC reaction
DFT calculation
Electrophilicity index
© 2016 Elsevier B.V. All rights reserved.
1. Introduction
antibacterial and antifungal activities [10e12]. Prompted by these
facts, in this study 1,2,3‒triazole group has been coupled with
Sulfonamides are organic sulfur compounds which have
attracted great attention for their interesting pharmacological ac-
tivity [1e3]. On the other hand, 1,2,3‒triazoles have aroused high
favor in medicine for their diverse pharmacological and biological
sulfonamide moiety using CuAAC reaction to synthesis of a new
class of 1,2,3‒triazole-based sulfonamides (Scheme 1).
2. Experimental
activities such as,
b‒lactamase inhibitors, anticancer, antifungal,
antiviral and anti‒HIV activities [4,5]. The synthesis of 1,2,3‒tri-
azoles strongly relies on copper (I)‒catalyzed azide‒alkyne [3 þ 2]
Huisgen cycloaddition reaction (CuAAC reaction). The potential of
this reaction type is very high, because alkyne and azide moieties
can be incorporated into a broad range of compounds. To date,
CuAAC reaction is the best and the most popular ‘click’ reaction, due
to high reliability and its wide range of applications in chemistry
and biochemistry [6]. However hundreds of scientific papers
describing the synthetic potencies of CuAAC have been published.
Nevertheless, relatively few examples in which this robust method
is applied to triazoles containing sulfonamide moiety exist [7e9]. It
is interesting to note that triazoles containing sulfonamide moiety
are known to have some biological and pharmaceutical properties,
such as aromatase inhibition, thrombin inhibition, antitumor,
2.1. General information
All the chemicals required for the synthesis of the 1,2,3‒tri-
azole‒based sulfonamides 3 were purchased from Sigma-Aldrich
(St. Louis, MO, USA), Fluka (Neu-Ulm, Germany) and Merck
(Darmstadt, Germany) companies and were used as received. The
all synthesized compounds 3 gave satisfactory spectroscopic data. A
Bruker (DRX-400 Avance) NMR was used to record the 1H NMR and
13C NMR spectra. All NMR spectra were determined in CDCl3 at
ambient temperature. LC-MS analysis was performed on an Agilent
1200 LC system (Agilent, Waldbronn, Germany). All the reactions
are monitored by thin layer chromatography (TLC) carried out on
silica gel with UV light and iodine, as detecting agents.
2.2. Computational details
All geometry optimizations and frequency calculations of all
species were carried out using the Gaussian 03 program [13].
* Corresponding author.
E-mail address: Saeidian1980@gmail.com (H. Saeidian).
http://dx.doi.org/10.1016/j.molstruc.2016.11.027
0022-2860/© 2016 Elsevier B.V. All rights reserved.

74
H. Saeidian et al. / Journal of Molecular Structure 1131 (2017) 73e78
NHR1
Cl
S
Y
R1
O
O
O
S
O
O
Br
N
S
NaN3, R2X, CuCl
Pyridine
r.t, 2 h
+ R1NH2
O
O
S
CH3CN, K2CO3
80 °C, 8 h
H2O/EtOH, 10 h
50 °C
O
Y
2
N
R1
N
N
N
1
Y
Y
CH3
R2
3
R1
=
R2
=
X = Br, I
Y = H, CH3
,
,
,
,
CH3 CH2CH3
Br
Scheme 1. The general method for synthesis of 1,2,3‒triazole‒based sulfonamides 3.
Density Functional Theory with the Becke three parameters hybrid
functional (DFT-B3LYP) calculations were performed with a 6-
31 þþG (d, p) basis set for all atoms. Vibrational frequencies were
calculated at the same level to ensure that each stationary point is a
real minimum. Harmonic-oscillator approximation was also used
for the thermodynamic partition functions. After geometry opti-
mization and frequency calculations, zero-point energies (ZPEs)
and thermal corrections are obtained at 298 K.
15.23; 3e: 1H NMR (400 MHz, CDCl3):
d
¼ 1.39 (d, J ¼ 7.2 Hz, 3H),
2.45 (s, 3H), 4.40 (br s, 2H), 5.22 (q, J ¼ 7.2 Hz, 1H), 5.38 (s, 2H),
7.16e7.22 (m, 8H), 7.27 (d, J ¼ 8 Hz, 2H), 7.37e7.41 (m, 3H), 7.68 (d,
J ¼ 8.4 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d
¼ 16.99, 21.57, 39.13,
54.02, 55.94, 123.51, 127.1, 127.61, 127.74, 128.05, 128.26, 128.68,
129.05, 129.75, 134.63, 137.82, 139.55, 143.39, 146.1. Anal. Calcd for
C
25H26N4O2S: C 67.24, H 5.87, N 12.55, Found: C 67.17, H 5.96, N
12.48; 3f: 1H NMR (400 MHz, CDCl3):
d
¼ 1.38 (d, J ¼ 7.2 Hz, 3H),
2.45 (s, 3H), 4.40 (br s, 2H), 5.23 (q, J ¼ 7.2 Hz, 1H), 5.33 (s, 2H), 7.07
(d, J ¼ 8.4 Hz, 2H), 7.14e7.24 (m, 6H), 7.27 (d, J ¼ 7.6 Hz, 2H), 7.52 (d,
J ¼ 8.4 Hz, 2H), 7.69 (d, J ¼ 8.4 Hz, 2H). 13C NMR (100 MHz, CDCl3):
2.3. General procedure for the synthesis of 1,2,3‒triazole‒based
sulfonamides 3
d
¼ 16.91, 21.59, 39.05, 53.33, 55.92, 122.83, 127.09, 127.62, 127.74,
128.26, 129.68, 129.79, 132.20, 133.65, 137.69, 139.52, 143.49; FT-IR
(KBr): 2957, 2930, 1727, 1380, 1155, 813; Anal. Calcd for
To a suspension of CuCl (0.1 mmol) in H2O/EtOH (5 mL, 1:1),
were added sodium azide (1 mmol) and alkyl halide (1 mmol), and
the resulting mixture was stirred at room temperature for 1 h. N-
propargyl sulfonamides 2 (1 mmol) was added to the reaction
mixture and the mixture was stirred at 50 ꢀC for 9 h [14]. The
progress of the reaction was monitored by TLC. After completion of
the reaction, the catalyst was recovered by filtration. Water (5 mL)
was added to the reaction mixture and extracted with EtOAc
(3 ꢁ 10 mL) and dried over Na2SO4. The crude was concentrated
under vacuum and was purified by preparative TLC (eluent: pe-
troleum ether/ethyl acetate 3:1) to afford the desired products 3.
C
25H25BrN4O2S: C 57.14, H 4.80, N 10.66, Found: C 57.21, H 4.72, N
10.75; 3g: 1H NMR (400 MHz, CDCl3):
d
¼ 1.41 (d, J ¼ 6.8 Hz, 3H),
2.46 (s, 3H), 3.93 (s, 3H), 4.41 (br s, 2H), 5.23 (q, J ¼ 7.2 Hz, 1H),
7.16e7.23 (m, 5H), 7.31e7.33 (m, 3H), 7.72 (d, J ¼ 8.4 Hz, 2H). 13
C
NMR (100 MHz, CDCl3):
d
¼ 17.10, 21.58, 36.63, 39.14, 55.95, 124.76,
127.15, 127.57, 127.76, 128.27, 129.81, 137.69, 139.64, 143.51, 145.89.
MS (ESI): 371 [MþH]þ. Anal. Calcd for C19H22N4O2S: C, 61.60; H,
5.99; N, 15.12. Found: C, 61.74; H, 6.09. N, 15.27; 3h: 1H NMR
(400 MHz, CDCl3):
d
¼ 1.40e1.46 (m, 6H), 2.45 (s, 3H), 4.26 (q,
J ¼ 7.2 Hz, 2H), 4.42 (br s, 2H), 5.25 (q, J ¼ 6.8 Hz, 1H), 7.20 (m, 5H),
7.27 (s, 1H), 7.32 (d, J ¼ 8 Hz, 2H), 7.72 (d, J ¼ 8.4 Hz, 2H). 13C NMR
2.4. Spectroscopic data of the products 3a-k
(100 MHz, CDCl3):
d
¼ 15.38, 16.95, 21.56, 39.13, 45.22, 55.90,
3a: 1H NMR (250 MHz, CDCl3):
(s, 2H), 5.37 (s, 2H), 7.15e7.66 (m, 15H) ppm. 13C NMR (62.5 MHz,
CDCl3):
d
¼ 2.40 (s, 3H), 4.34 (s, 2H), 4.39
122.96, 127.09, 127.60, 127.76, 128.27, 129.79, 137.80, 139.69, 143.45,
145.50. MS (ESI): 385 [MþH]þ. Anal. Calcd for C20H24N4O2S: C,
62.48; H, 6.29; N, 14.57. Found: C, 62.35; H, 6.38. N, 14.64; 3i: 1H
d
¼ 21.51, 42.21, 51.17, 54.03, 123.12, 127.22, 127.68, 128.04,
NMR (400 MHz, CDCl3):
d
¼ 1.41 (d, J ¼ 6.8 Hz, 3H), 4.42 (br s, 2H),
128.41, 128.70, 129.08, 129.65, 134.41, 135.82, 136.89, 143.41,
143.71 ppm. Anal. Calcd for C24H24N4O2S: C, 66.64; H, 5.59; N,
12.95. Found: C, 66.57; H, 5.64. N, 13.04; 3b: 1H NMR (400 MHz,
5.26 (q, J ¼ 6.8 Hz, 1H), 5.36e5.44 (m, 2H), 7.16e7.21 (m, 8H),
7.39e7.50 (m, 5H), 7.58 (t, J ¼ 7.9 Hz, 1H), 7.81 (d, J ¼ 7.6 Hz, 2H). 13
C
NMR (100 MHz, CDCl3):
d
¼ 17.15, 39.01, 54.30, 56.08, 127.07, 127.68,
CDCl3):
d
¼ 2.45 (s, 3H), 4.36 (s, 2H), 4.43 (s, 2H), 5.36 (s, 2H), 7.08
127.75, 128.11, 128.31, 128.74, 129.06, 129.17, 132.64, 134.55, 139.39,
140.75. Anal. Calcd for C24H24N4O2S: C 66.64, H 5.59, N 12.95,
Found: C 66.73, H 5.50, N 12.87; 3k: 1H NMR (400 MHz, CDCl3):
(d, J ¼ 8 Hz, 2H), 7.23 (m, 5H), 7.26e7.28 (m, 3H), 7.52 (d, J ¼ 8.4 Hz,
2H), 7.69 (d, J ¼ 8 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d
¼ 21.59,
42.39, 51.44, 53.43, 123.29, 127.28, 127.76, 128.47, 128.74, 129.71,
129.75, 132.30, 133.43, 135.82, 136.74, 143.59, 144.09. MS (ESI): 511
and 513 [MþH]þ. Anal. Calcd for C24H23BrN4O2S: C, 56.36; H, 4.53;
N, 10.95. Found: C, 56.27; H, 4.66. N, 11.09; 3c: 1H NMR (400 MHz,
d
¼ 1.42 (d, J ¼ 6.8 Hz, 3H), 4.42 (br s, 2H), 5.25 (q, J ¼ 6.8 Hz, 1H),
5.35 (br s, 2H), 7.07 (d, J ¼ 8 Hz, 2H), 7.16e7.20 (m, 5H), 7.49e7.63
(m, 5H), 7.83 (d, J ¼ 7.6 Hz, 2H). 13C NMR (100 MHz, CDCl3):
d
¼ 17.15, 39.18, 53.33, 56.09, 122.88, 127.04, 127.69, 127.73, 128.30
CDCl3):
d
¼ 2.46 (s, 3H), 3.97 (s, 3H), 4.38 (s, 2H), 4.43 (s, 2H),
7.21e7.29 (m, 6H), 7.32 (d, J ¼ 8 Hz, 2H), 7.73 (d, J ¼ 8 Hz, 2H) . 13
C
(2C), 129.19, 129.69, 132.20, 132.68, 133.67, 139.40, 140.71. Anal.
Calcd for C24H23BrN4O2S: C 56.36, H 4.53, N 10.95, Found: C 56.45, H
4.61, N 11.07.
NMR (100 MHz, CDCl3):
d
¼ 21.56, 36.57, 42.15, 51.07, 124.37, 127.34,
127.72, 128.48, 128.76, 129.73, 135.91, 136.94, 143.57. MS (ESI): 357
[MþH]þ. Anal. Calcd for C18H20N4O2S: C, 60.65; H, 5.66; N, 15.72.
Found: C, 60.80; H, 5.53. N, 15.86; 3d: 1H NMR (400 MHz, CDCl3):
3. Results and discussion
d
¼ 1.45 (t, J ¼ 7.2 Hz, 3H), 2.42 (s, 3H), 4.28 (q, J ¼ 7.6 Hz, 2H), 4.40
(s, 2H), 4.44 (s, 2H), 7.24e7.28 (m, 6H), 7.32 (d, J ¼ 8.4 Hz, 2H), 7.72
3.1. Synthesis 1,2,3‒triazole‒based sulfonamides 3
(d, J ¼ 8 Hz, 2H). 13C NMR (100 MHz, CDCl3):
¼ 15.34, 21.55, 42.31,
d
45.22, 51.21, 122.62, 127.30, 127.72, 128.47, 128.76, 129.73, 136.01,
The starting alkyne bearing sulfonamide 2 are readily prepared
in house [14]. Treatment of para-toluene sulfonyl chloride with
amine in pyridine at room temperature for 2 h gave the
137.03, 143.25, 143.51. MS (ESI): 371 [MþH]þ. Anal. Calcd for
C
19H22N4O2S: C, 61.60; H, 5.99; N, 15.12. Found: C, 61.71; H, 5.83. N,

H. Saeidian et al. / Journal of Molecular Structure 1131 (2017) 73e78
75
corresponding sulfonamide in excellent yields (>85%). The N-
propargylsulfonamides 2 were then prepared in high yield (>78%)
by the treatment of the synthesized sulfonamide with propargyl-
bromide in the presence of K2CO3 in refluxing acetonitrile for 8 h.
The [3 þ 2] cycloaddition reaction of 2 with alkyl azide (R2N3) in the
presence of CuCl (10 mol %) led to the desired 1,2,3‒triazole‒based
sulfonamides 3 in high yield after 10 h at 50 ꢀC H2O/EtOH.
Preliminary investigation of the model reaction (benzyl bro-
mide, sodium azide and N-propargyl sulfonamide 2-(N-benzyl-N-
tosylprop-2-yn-1-amine)) showed that the cycloaddition reaction
did not proceed in the absence of catalyst after 8 h, while good
results were obtained in the presence of CuCl after 10 h. In the
mixed solvent EtOH/H2O the corresponding triazole 3a was ob-
tained in excellent yield. Furthermore, the effect of temperature
was also examined by carrying out the model reaction in the
presence of CuCl (10 mol%) at room temperature (25 ꢀC) and 50 ꢀC.
It was observed that the yield was increased as the reaction tem-
perature was raised to 50 ꢀC. In order to prove the applicability of
the optimized reaction condition for the synthesis of various 1,2,3-
triazoles bearing sulfonamide group, we examined various com-
bination of substrates. All the reactions efficiently proceed to give
the corresponding 1,2,3-triazole derivatives in good yields (Scheme
2).
€
Fig. 1. Rontgen crystal structure of 3f.
monochromated MoK⍺ radiation (k ¼ 0.71073 Å). Crystallographic
data for the structural analysis have been deposited to Cambridge
Crystallographic Data Centre, with CCDC reference number
1456414. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
dataerequest/cif. A summary of crystal data and data collection
parameters are presented in Table 1.
3.2. Structural characterization of 1,2,3‒triazole‒based
sulfonamides 3
The structure of the products were confirmed by CHN, 1H NMR,
13C NMR and FT-IR analysis. The 1H NMR and 13C NMR spectra of the
products clearly indicated the formation of the desired products 3.
The 1H NMR spectrum of 3f consisted of a doublet line at
d
¼ 1.38 ppm to the methyl group, five benzylic protons at
d
¼ 4.40e5.33 ppm and 13 protons for aromatic rings and one
Table 1
heterocycle proton at
NMR spectrum of 3f showed 18 resonances.
d
¼ 7.07e7.69 ppm. The 1H‒decoupled 13C
Crystallographic data of 1,2,3‒triazole‒based sulfonamide 3f.
Empirical formula
Formula weight (gmolꢂ1
T(K)
Mu (MoK⍺) [/mm]
Crystal system
Space group
C
25H25BrN4O2S
a(Å)
b(Å)
5.8743 (12)
14.560 (3)
28.662 (6)
2451.5 (9)
4
Unambiguous evidence for the structure of 3f was obtained
)
525.45
293
1.791
Orthorhombic
P212121
€
from a single-crystal X-ray analysis. Rontgen crystal structure of 3f
c(Å)
V (Å3)
is shown in Fig. 1. X-ray diffraction intensity data for a single-crystal
of 3f (0.40 ꢁ mm 0.13 mm ꢁ 0.10 mm) were collected at 293 K on a
crystal diffractometer STOE-IPDS 2T equipped with graphite
Z
Dcalc (g cmꢂ3
)
1.424
H3C
H3C
H3C
H3C
H3C
O
O
O
O
O
S
S
S
S
S
CH3
O
O
O
O
N
N
N
N
N
O
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
H2C
H3C
CH3
3e (89%)
3a (91%)
3b (88%)
3c (63%)
3d (66%)
Br
H3C
H3C
H3C
O
S
N
O
CH3
S
CH3
O
O
O
O
O
S
CH3
S
CH3
S
CH3
N
N
N
N
O
N
O
O
N
N
N
N
N
N
N
N
N
N
N
N
N
N
H3C
H2C
3i (61%)
CH3
3k (68%)
3h (64%)
3f (87%)
3g (61%)
Br
Br
Scheme 2. The synthesized structures of a variety of 1,2,3‒triazole‒based sulfonamides 3a-k.

76
H. Saeidian et al. / Journal of Molecular Structure 1131 (2017) 73e78
3.3. Theoretical studies on 1,2,3‒triazole‒based sulfonamide 3f
Quantum calculation chemistry has been quite successful in
providing theoretical background of popular qualitative chemical
concepts [15]. Quantum chemical calculations help chemist to
calculate the structural and physicochemical properties of the
molecule. With the encouraging experimental data of 1,2,3‒tri-
azole‒based sulfonamides 3, our attention was focused on calcu-
lations for investigation of physicochemical properties of 3f such as
structural data, NMR data, FT-IR frequencies, Mulliken charge dis-
tribution and electrophilicity index.
Fig. 2. Optimized geometry for the B3LYP/631þþG (d, p) of 3f.
3.3.1. Benchmarking of methods
As one of our goals is to find an accurate method that is
computationally efficient, we have focused on two methods HF and
DFT with different basis sets. The representative structural pa-
rameters for 3f via X-ray diffraction are: C1-Br1 1.887 Å, C15-C22
1.581 Å, C8-S11.787 Å, N1-N2 1.352 Å and N4-S11.634 Å, N4C15C22
107.2ꢀ, N4C7C6 115.3ꢀ, N1C5C4 112.0ꢀ, Br1C1C2 120.2ꢀ and
Br1C1C25 120.5ꢀ. These structural data can help to find the optimal
method for calculations. The correlation coefficient for the bond
lengths and bond angles along error in data for HF and DFT with
different basis sets for 3f are available in supporting information
(Table S1, and Fig. 26S). Calculations show that B3LYP with basis set
6-31þþG (d, p) gave satisfactory results and structural parameters
have good agreement with experimental data (Table 2). The opti-
mized geometric parameters in Table 2 are in good agreement with
the X-ray experimental results. The differences between the two
values are within normal ranges.
The experimental N1-N2, and C8-S1 distances of 1.352 and 1.787
are very accurately regenerated by B3LYP/6-31þþG (d, p) with
values of 1.351 and 1.798 Å, respectively for 3f. On the other hand
BrlC1C2 bond angle of 120.20ꢀ, is well represented by this
computational method, 119.48ꢀ. Thus, the highest level of theory
used here, B3LYP/6-31þþG (d, p), produces calculated bond lengths
and bond angles that are in good agreement with the experimental
values (Fig. 2).
.
u
¼
m2
2h
where
m
and h are the chemical potential and chemical hardness,
respectively given by:
m
¼ ðELUMO þ EHOMOÞ=2 and
h
¼ ðELUMO ꢂ EHOMOÞ=2
ELUMO is the energy of the lowest unoccupied molecular orbital and
EHOMO is the energy of the highest occupied molecular orbital.
HOMO and LUMO as main orbitals are responsible for reactivity of
compounds [19]. The HOMO (
an electron and the LUMO (
obtain an electron. The HOMO and LUMO energy calculated by
B3LYP/6-31þþG (d, p) for 3f is shown in Fig. 3. The HOMO orbital is
mainly located on the aryl ring bearing bromine atom, while the
LUMO orbital is localized on the sulfonamide moiety as well as the
aryl ring bearing methyl group.
p
p
donor) represents the ability to give
acceptor) represents the ability to
3.3.3. FT-IR spectrum study of 3f
A main important goal of this part is to assign the experimental
frequencies to the computed vibrational modes of 3f properly. The
experimental and the calculated infrared spectra of 3f by the DFT
method at the B3LYP/6-31þþG (d, p) level are shown in Fig. 4. The
3.3.2. Calculation of electrophilicity index of 3f (HOMO-LUMO
analysis)
Many of the organic reactions can be described in terms of the
electrophilic and nucleophilic reactions. Electrophilicity is relative
reactivity of a molecule that is sufficient to describe the reactivity of
compounds [16]. Based on the work of Parr et al. the electrophilicity
index is calculated according to the equation [17,18].
Table 2
Computed structural parameters and error percent with respect to experimental
data for the B3LYP/6-31þþG (d, p) of 3f.
Geometrical parameters
Experimental
Theoretical
Error in data
Bond lengths (Å)
C1-Br1
C15-C22
C8-S1
N1-N2
1.8870
1.5810
1.7870
1.3520
1.6340
1.9020
1.5360
1.7982
1.3512
1.6981
0.7042
ꢂ2.8495
0.6267
ꢂ0.0607
3.9217
N4-S1
Bond angles (ꢀ)
N4-C15-C22
N4-C7-C6
N1-C5-C4
Br1-C1-C2
Br1-C1-C25
107.20
115.30
112.00
120.20
120.50
112.7502
114.7572
113.8292
119.4826
119.5368
5.1774
ꢂ0.4708
1.6332
ꢂ0.5968
ꢂ0.7993
Fig. 3. The HOMO and LUMO gap for 3f.

H. Saeidian et al. / Journal of Molecular Structure 1131 (2017) 73e78
77
Fig. 4. Experimental (top) and calculated (down) FT-IR spectra of 3f.
vibrational band assignments have been made by using GaussView
molecular visualization program [20]. It should be noted that the
scaling factors 0.98 and 0.99 for below 1800 cmꢂ1 and above
1800 cmꢂ1 were applied for calculated frequencies, respectively. In
general, there was a good agreement between experimental and
calculated frequencies. The aromatic CeH stretching vibrations are
presented in the region 3225e3112 cmꢂ1. In obtained experimental
IR spectrum, due to the low dipole moment changes in aromatic
rings, the intensities of aromatic CeH bond stretching are weak and
it is hard to assign the peaks to each aromatic ring separately.
Aliphatic CH, CH2 and CH3 asymmetric and symmetric calculated
stretching vibrations mainly are observed in the region 2976-
3087 cmꢂ1 and its experimental counterpart appear in the region
asymmetric and symmetric S]O stretching band for sulfonamide
group were observed at 1339 and 1155 cmꢂ1 and their calculated
counterparts appear at 1270 and 1067 cmꢂ1, respectively.
3.3.4. NMR spectral studies of 3f
The NMR computations were performed using the gauge-
independent atomic orbital (GIAO) method [16]. Chemical shifts
were reported in parts per million relative to tetramethylsilane
(TMS) for 1H NMR and 13C NMR spectra. Relative chemical shifts
were calculated by using the corresponding TMS shielding calcu-
lated at the same theoretical level as the reference. Computed
B3LYP/6-311þþG (d, p) 1H and 13C chemical shifts for 3f are listed
in supporting information (Table 2S). Computed and experimental
aliphatic 1H and 13C chemical shifts of 3f is presented at Table 3.
According to the comparison between experimental and calculated
data, the calculated 1H and 13C chemical shifts are in acceptable
agreement with the experimental results.
2930-2957 cmꢂ1
.
For aromatic rings, the bands are observed at 1530, 1490 and
1453 cmꢂ1 are assigned to the CeH in-plane rocking vibrations of
aromatic rings. The calculated values of this mode were somewhat
shifted to the lower frequencies appearing at 1513, 1467 and
1421 cmꢂ1. Triazole ring CeC stretching band for the titled com-
pound in calculated IR spectrum appears at 1569 cmꢂ1. Strong
The most deviation is observed in the 13C chemical shift of
carbon-27 of 3f, 16.91 ppm, whereas it was calculated as 13.58 ppm.

78
H. Saeidian et al. / Journal of Molecular Structure 1131 (2017) 73e78
Table 3
affords 10 novel analogues of 1,2,3-triazole-based sulfonamides as
fine chemicals in good yields (61e91%). The structure of the syn-
thesized compounds were fully determined by X-ray, NMR, CHN
and ESI-MS analysis. The optimized bond lengths, bond angles,
calculated frequencies and chemical shifts (NMR) for 3f showed the
agreement with the experimental results. HOMO-LUMO analysis
pointed that the HOMO orbital is mainly located on the aryl ring
bearing bromine atom, while the LUMO orbital is localized on the
sulfonamide moiety as well as the aryl ring bearing methyl group.
Computed B3LYP/6-31þþG (d, p) and experimental aliphatic 1H and13C chemical
shifts of 3f.
Atoma
Theoretical chemical
shift/ppm
Experimental chemical
shift/ppm
׀dexp-dB3LYP׀
H8
5.72
3.76
4.64
1.23
5.33
4.40
5.23
1.38
0.39
0.64
0.59
0.15
0.07
1.35
3.14
0.57
3.33
0.29
H22
H26
H30
H47
C7
C21
C25
C27
C44
2.52
2.45
54.68
35.91
56.49
13.58
21.30
53.33
39.05
55.92
16.91
21.59
Acknowledgments
We are grateful to Dr. S. Taheri and Dr. M. R. Halvagar for X-ray
analysis. We also are thankful to Mr. Biglari for NMR spectral
support.
a
For numbering of atoms refer Fig. 2.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.molstruc.2016.11.027.
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3.3.5. Mulliken analysis of 3f
Atomic charge in molecules has been used to describe the pro-
cesses of electronegativity equalization and charge transfer in
chemical reactions. Mulliken atomic charge affect electronic
structure, dipole moment, and molecular polarizability [21]. The
Mulliken charge distribution structure of 3f is shown in Fig. 5. All
the hydrogen atoms exhibit a net positive charge in Mulliken
analysis. These magnitudes are changing between 0.226 and 0.368
in Mulliken analysis. The oxygen and nitrogen atoms on sulfon-
amide moiety in 3f exhibit a negative charge and sulfur atom a
positive charge.
4. Conclusions
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Shawnee Mission, KS, 2007.
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In summary, we have developed a convenient and green 1,3-
dipolar cycloaddition reaction involving N-propargyl sulfon-
amides and alkyl azides in the mixed solvent EtOH/H2O, which