The substituent effect on the luminescent properties of a set of 4-amino-4H-1,2,4-triazole: Syntheses, crystal structures and Hirshfeld analyses

Article abstract of DOI:10.1016/j.molstruc.2021.130893

A set of compounds based on 4-amino-4H-1,2,4-triazole group, namely, 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl)dibenzoic acid (1), 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl)dianiline (2), 4,4′-(4-amino-4H-1,2,4-triazole-3,5-diyl)diphenol (3), were obtained

Full text of DOI:10.1016/j.molstruc.2021.130893

Journal of Molecular Structure 1243 (2021) 130893
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
The substituent effect on the luminescent properties of a set of
4-amino-4H-1,2,4-triazole: Syntheses, crystal structures and Hirshfeld
analyses
Yu-Rong Xib, Xu-Kai Chenb, Yong-Tao Wang b, Gui-Mei Tang a,∗, Xiao-Min Chenb,
Yu-Song Wub, Shi-Ning Wang a
a School of Pharmaceutical Sciences, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
b School of Chemistry and Chemical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China
a r t i c l e i n f o
a b s t r a c t
ꢀ
Article history:
A set of compounds based on 4-amino-4H-1,2,4-triazole group, namely, 4,4 -(4-amino-4H-1,2,4-triazole-
Received 1 April 2021
Revised 8 June 2021
Accepted 9 June 2021
Available online 14 June 2021
ꢀ
ꢀ
3,5-diyl)dibenzoic acid (1), 4,4 -(4-amino-4H-1,2,4-triazole-3,5-diyl)dianiline (2), 4,4 -(4-amino-4H-1,2,4-
triazole-3,5-diyl)diphenol (3), were obtained through reacting different aromatic nitrile and hydrazine
under the solvothermal conditions, respectively. The title compounds 1–3 have been characterized by
IR, UV–Vis, 1H NMR, 13 C NMR, element analysis (EA), single crystal X-ray diffraction, and powder X-ray
–
diffraction (PXRD). In these compounds, a plenty of hydrogen bonds (C/N–HꢀO/N) and C H•••π can
Keywords:
4-amino-4H-1,2,4-triazole
Substituent effect
be obviously obtained, through which a three-dimensional framework will be constructed. The solid-
state luminescent spectra of 1–3 show that the emission maxima are observed at 398, 464 and 402 nm,
respectively. The order of maximal peaks is 1<3<2. The Hirshfeld surface analyses confirm that the order
of the contribution of C•••H/H•••C and H•••H contacts is 1<3<2, which is in a good accordance with
that of the luminescent bands.
Crystal structures
Hydrogen bond
Packing interaction
Supramolecular interactions
Hirshfeld surface analyses
© 2021 Elsevier B.V. All rights reserved.
1. Introduction
of luminescent materials with 1,2,4-triazole moieties still remains
sparse. Especially, it is necessary to investigate the 4-amino-1,2,4-
The 1,2,4-triazole is a kind of important five-membered hete-
rocyclic compounds and has attracted considerable interest in the
fields of materials, coordination chemistry and medicine due to
their important biologically activities and strong coordination abil-
ities [1-16]. Typically, the derivatives based on 1,2,4-triazole are
extensively investigated as ligands [17-19] for the design and de-
velopment of novel metal coordination complexes, which exhibit
very interesting physical properties such as magnetism, gas ab-
sorption and optics [20-22]. Recent studies show that a Ir(III)-
based complex consisting of a kind of 1,2,4-triazole displays a sky-
blue emission with high quantum yields, which becomes a type
of potential materials for organic light emitting diodes (OLEDs)
[23]. This heterocyclic compounds have been applied to the field
of material science [24], which plays an important role in energy
materials [25]. Additionally, compounds with 1,2,4-triazole nuclei
have been proved for a broad-spectrum activities such as fungi-
cidal [26], herbicidal [27], anticonvulsant [28] and plant growth
regulatory activities [29]. However, the design and development
triazole based compounds with the controllable photoluminescent
behaviours through the substituents.
Due to 1,2,4-triazoles having the promising functions, different
synthetic approaches have been documented for the preparation
of substituted 1,2,4-triazoles [14,30,31]. The 1,2,4-triazoles is the
reaction of an appropriate aliphatic, aromatic, or heterocyclic pri-
mary amine with diformhydrazide. Despite a positive progress of
the preparation for this heterocyclic compounds has been made
[12], many currently available methods suffer from various lim-
itations, including the use of hazardous and costly materials or
the requirement for harsh reaction conditions [32]. Therefore, the
development of more efficient, convenient and eco-friendly meth-
ods is still desired. On the other hand, solvothermal/hydrothermal
methods have been extensively applied to the field of the coordi-
nation chemistry and materials chemistry [33-39], which is a sim-
ple and available route for the synthesis and preparation of metal
coordination complexes and inorganic materials [40-44]. So far, the
development and investigation of this method remains rare in the
areas of organic chemistry.
Based on these minds mentioned above, herein, we would like
to report an efficient and convenient process for the synthesis
∗
Corresponding authors.
E-mail address: tgm@qlu.edu.cn (G.-M. Tang).
https://doi.org/10.1016/j.molstruc.2021.130893
0022-2860/© 2021 Elsevier B.V. All rights reserved.

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Scheme 1. the preparation procedure of compounds 1–3.
of a set of compounds based on 4-amino-4H-1,2,4-triazole group,
cyanobenzoic acid. Yield: 0.686 g, 48.3%. M.p. 212–215 °C. Ele-
mental analysis calcd (%) for C14 H16 N6O (284.33): C, 63.14; H,
5.30; N, 31.56; Found: C, 63.28; H, 5.31; N, 31.50. 1H NMR
ꢀ
namely, 4,4 -(4-amino-4H-1,2,4-triazole-3,5-diyl)dibenzoic acid
ꢀ
ꢀ
(1), 4,4 -(4-amino-4H-1,2,4-triazole-3,5-diyl)dianiline (2), and 4,4 -
(4-amino-4H-1,2,4-triazole-3,5-diyl)diphenol (3), were obtained
through reacting different aromatic nitrile and hydrazine under the
solvothermal conditions, respectively (Scheme 1). The spectra of
FT-IR, UV–Vis, 1H NMR and 13C NMR for 1–3 were studied. Addi-
tionally, the crystal structures of 1–3 have been discussed, and its
fluorescence properties and thermal behaviors were investigated
in details. As we expected, the substituted groups can affect the
luminescent properties of these compounds with amino-triazole
functions, which can be further confirmed by the Hirshfeld surface
analyses.
(400 MHz, DMSO–d6) δ 7.67 (d,
J
=
8.2 Hz, 4H), 6.65 (d,
J = 8.2 Hz, 4H), 5.95 (s, 2H), 5.44 (s, 4H). 13C NMR (101 MHz,
DMSO–d6) δ 154.40, 150.26, 129.56, 115.12, 113.65. IR (KBr, cm–1):
3386(s), 3327(m), 3273(m), 3157(m), 2428(w), 2148(w), 2029(w),
1959(m), 1909(w), 1730(w), 1647(w), 1614(s), 1496(s), 1477(s),
1423(w), 1385(s), 1275(m), 1115(s), 1014(m), 908(w), 837(m),
810(m), 739(w), 694(m), 617(s), 571(m), 532(w), 471(w), 428(w).
2.3. The synthesis of compound 3 (4OH)
The preparation of compound
3 was similar to that of
compound 1 when 4-hydroxyobenzonitrile took place of 4-
2. Experimental
cyanobenzoic acid. Yield: 0.958 g, 71.4%. M.p. 290–292 °C. Elemen-
tal analysis calcd (%) for C14 H12N4O2 (268.28): C, 62.68; H, 4.51;
N, 20.88; Found: C, 62.79; H, 4.50; N, 20.82. 1H NMR (400 MHz,
DMSO–d6) δ 9.88 (s, 2H), 7.84 (d, J = 8.5 Hz, 4H), 6.90 (d,
J = 8.5 Hz, 4H), 6.69 (s, 2H). 13C NMR (101 MHz, DMSO–d6)
δ 159.02, 154.30, 130.48, 130.20, 118.67, 115.94, 115.67. IR (KBr,
cm–1): 3476(br), 3416(w), 3223(w), 2809(w), 2678(w), 2509(w),
2362(w), 1915(w), 1772(m), 1613(s), 1481(s), 1363(w), 1236(s),
1173(s), 1108(s), 979(m), 902(w), 842(s), 744(w), 671(w), 598(m),
534(s), 453(w).
2.1. Materials and measurements
Reagents and solvents were commercially available and not fur-
ther purified. C, H and N microanalyses were carried out with a
Perkin–Elmer 240 elemental analyzer. Thermogravimetric analysis
(TGA) data were collected with a TA SDT Q600 analyzer in N2 at
a heating rate of 10 °C min–1 in the range of 10–600 °C. The FT–
IR spectra were recorded from KBr pellets in the range 400–4000
cm–1 on a Bruker Tensor4 spectrometer. UV–Vis absorption spec-
tra were recorded on a SHIMADZU UV–2600 spectrophotometer
with 0.1 nm resolution. The solution/solid–state fluorescence spec-
tra were recorded on a HITACHI–4500 spectrometer at room tem-
perature.
2.4. Single-crystal structure determination
Single-crystal structures of compounds 1–3 were measured by
a Bruker Smart CCD equipped with graphite–monochromator Mo
˚
Kα radiation (λ = 0.71073 A). The lattice parameters were ob-
2.2. The synthesis of compound 1 (4CA)
tained by a least-squares refinement of the diffraction data. All
the measured independent reflections were used in the structural
analysis, and semi-empirical absorption corrections were applied
using the SADBASE program [45]. The program SAINT was used
for integration of the diffraction profiles [46]. The structure was
solved by direct methods using the SHELXS and OLEX2 program of
the SHELXTL package and refined with SHELXL [47-49]. All non-
hydrogen atoms were located in successive difference Fourier syn-
theses. The final refinement was performed by full-matrix least-
squares methods with anisotropic thermal parameters for all the
non-hydrogen atoms based on F2. The hydrogen atoms were placed
in the calculated sites and included in the final refinement in the
riding model approximation with displacement parameters derived
from the parent atoms to which they were bonded. Special com-
putations for the crystal structure discussions were carried out
with PLATON for Windows [50]. A summary of the crystallographic
data and structure refinements are listed in Table 1. Selected bond
lengths and bond angles are summarized in Tables 2. Correspond-
ing hydrogen bond and packing interactions data for compounds
1–3 are listed in Tables 3 and 4, respectively.
To a mixture solution of ethylene glycol (10 mL) and 85% hy-
drazine hydrate (3.8 mL, 60 mmoL), 4-cyanobenzoic acid (1.470 g,
10 mmoL) were heated at 130 °C for 3 days in a 15 ml Teflon-
lined vessel container. The reacti−on mixture was cooled to room
temperature at a rate of 5 °C h
1. After cooling to room tem-
perature, pure water (30 ml) was poured to the mixture solution
and it was added adjusted to pH 3 by the concentrated HCl so-
lution. Subsequently, the mixture was cooled to room tempera-
ture. Finally, the earthy yellow crystals were collected by vacuum
filtration. Yield (62.5%, 1.013 g). M.p. >300 °C. Elemental analy-
sis calcd (%) for C16 H12N4O4 (324.30): C, 59.26; H, 3.73; N, 17.28;
found: C, 59.42; H, 3.72; N, 17.33. 1H NMR (400 MHz, DMSO–
d6) δ: 13.10 (s, 2H), 8.19 (d, J = 8 Hz, 4H), 8.09 (d, J = 8 Hz,
4H), 6.41 (s, 2H). 13C NMR (100 MHz, DMSO–d6) δ: 166.83,
153.86, 131.57, 130.94, 129.32, 128.37. IR (KBr, cm−1): 3362(m),
3277(w), 3211(w), 2366(w), 1946(w), 1628(m), 1570(m), 1541(m),
1392(m), 1290(m), 1188(m), 1113(m), 1018(m), 966(m), 912(w),
866(m), 783(m), 717(s), 536(m).
2.3. The synthesis of 2 (4NH2)
2.5. Hirshfeld surface analyses
The synthesis procedure of compound 2 was similar to that
of compound 1 when the 4-aminobenzonitrile took place of 4-
The Hirshfeld surface analyses were calculated by the program
of CrystalExploer [51].
2

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Table 1
Crystal data and structure refinement parameters for compounds 1–3.
Compound reference
1
2
3
Chemical formula
Formula Mass
C
16H12N4O4
C14H16N6O
284.33
Orthorhombic
10.9651(5)
16.5655(9)
7.1492(4)
90
C14H12N4O2
268.28
Monoclinic
9.4502(17)
7.5947(15)
18.190(4)
90
324.30
Orthorhombic
3.7674(9)
11.271(3)
33.244(9)
90.00
Crystal System
˚
a/A
˚
b/A
˚
c/A
α/°
β/°
γ /°
90.00
90
102.089(6)
90
90.00
90
3
˚
Unit cell volume/A
Temperature/K
Space group
1411.7(6)
296(2)
Pbcm
1298.60(12)
100.00(10)
Pna21
1276.6(4)
100(2)
P21/n
No. of formula units per unit cell, Z
4
4
4
Radiation type
Mo Kα
0.113
Mo Kα
0.099
Mo Kα
0.098
Absorption coefficient, μ/mm−1
No. of reflections measured
No. of independent reflections
Rint
7346
5826
10,616
2960
1271
2807
0.0601
0.0418
0.0994
0.0811
0.1207
1.015
0.1632
0.0379
0.0889
0.0573
0.1043
1.116
0.0618
0.0525
0.1388
0.0646
0.1467
1.056
Final R1 values (I > 2σ(I))
Final wR(F2) values (I > 2σ(I))
Final R1 values (all data)
Final wR(F2) values (all data)
Goodness of fit on F2
CCDC number
1,422,655
2,067,982
2,067,983
aR1= ꢁFo|-|Fcꢁ/ |Fo|. bwR2=[ [w(Fo2-Fc2)2] / [w(Fo2)2]]1/2
.
3. Results and discussion
space group. The asymmetric unit contains one 4NH2 molecule
and one free water molecule (Fig. 2a). The bond distances among
˚
3.1. Description of the crystal structures
the triazole ring fall in the range of 1.308(6)−1.453(10) A, which
can be found in other amino-triazole compounds. Two dihedral an-
gles between the phenyl rings and the triazole ring are 37.3 and
35.2°, being obviously smaller than that of compound 1.
In supramolecular structures, hydrogen bonds and stacking in-
teractions can often be observed. As shown in Fig. 2 and Table 3,
3.1.1. Structure of 1 (4CA)
Single X-ray analysis for the compound 4CA reveals that it crys-
tallizes in the form of centrosymmetric space group Pbcm with
the orthorhombic system. There exists half molecule of 44CA in
a symmetric unit (Fig. 1a). The dihedral angle between the central
triazole ring and the phenyl ring is 40.6°, being obviously higher
than those found in other amino-triazole-based compounds. The
three types of hydrogen bonds were observed in compound 1, such
as: (a) The N–H•••N (N1–H1A•••N2 3.114(3) A, a-1/2 + x,1/2-
a
˚
b
y,z; N5–H5A•••N6 3.197(4) A, b1/2-x,−1/2
+
y,−1/2
+
z;
˚
bond distances of N N, C N and C = N range from 1.316(3) to
N5–H5B•••N1 3.406(4) A, c1/2-x,1/2
+ y,−1/2 +
z; N6–
c
˚
–
–
d
˚
˚
1.417(4) A, being similar to those in other compounds with amino-
H6B•••N3 3.047(3) A, D-1/2 + x,3/2-y,z) intermolecular hydro-
triazole functional group. It is worthy to mention that the free
ligand 4CA does not form molecular zwitterions, which is differ-
ent from that found in 2-(1H-benzotriazol-1-yl) acetic acid [52-
53]. Each 4CA molecule making using of the carboxylate group in
gen bonds occur among different nitrogen atoms of different 4NH2
molecules. (b) The N–H•••O (N1–H1B•••O1 3.024(3) A, b1/2-
b
˚
x,−1/2 + y,−1/2 + z; O1–H1D•••N1 3.065(3) A, a-1/2 + x,1/2-
a
˚
y,z; N6–H6A•••O1 3.158(3) A, c1/2-x,1/2 + y,−1/2 + z) inter-
c
˚
the formation of head-tail forms a type of intermolecular hydrogen
molecular hydrogen bonds originate from the nitrogen atoms of
the 4NH2 molecule and the oxygen atoms of the crystallized
water molecules. (c) The hydrogen bond of O1–H1D•••N1a (a-
a
bonds (O(1)–H(1)•••O(2) , 1.83 A, a-x,1-y,1-z) (Table 2). Through
˚
the hydrogen bond interactions, 4CA molecules are linked into a
1-D wave-like chain along the crystallographic c axis (Fig. 1b).
Additionally, the triazole groups of two 4CA molecules form an-
other kind of intermolecular hydrogen bonds (N(3)–H(3B)•••N(2)b,
˚
1/2 + x,1/2-y,z) with the distance of 3.065(3) A can be found
between the oxygen atom of water molecular and the nitrogen
atom of phenylamino group of 4NH2. Except from these hydrogen
2.15 A, 1-x,1/2 + y,3/2-z; N(3)–H(3B)•••N(2) , 2.53 A, c-1 + x,y,z)
(Table 2). These hydrogen bonds lie parallel to each other result-
ing in a two-dimensional (2D) supramolecular layer along the bc
plane. It is interestingly observed in the 2D array, there are two
types of hydrogen-bonded patterns A–D, noted asR22(8) (Fig. 5c(A))
andR36(40) (Fig. 1c(B)), respectively. These 2D layers are further ex-
tended into a three-dimensional (3D) supramolecular framework
through two kinds of offset π•••π packing interactions between
aromatic rings. One originates from two triazole groups (3.7674(18)
bonds, the π•••π and C H•••π packing interactions can be found
b
c
˚
˚
–
in compound 2. For example, there exist the interactions such
as Cg1•••Cg1a(a1-x,1-y,−1/2 + z), Cg1•••Cg1b(b1-x,1-y,1/2 + z),
C2–H2•••Cg3c(c1/2-x,−1/2
+
y,1/2
+
z), C5–H5•••Cg3d(d1-x,1-
y,−1/2
+
z), C11–H11•••Cg2e(e1/2-x,1/2
+
y,1/2
+
z) as well
as C14–H14•••Cg2a with the distances of 3.6405(18), 3.6404(18),
˚
3.388(3), 3.343(3), 3.345(3) and 3.515(3) A, respectively . The Cg1
and Cg2 and Cg3 represent the centers of N2–N3–C8–N4-C7, C1–
C2–C3–C4–C5–C6 and C9–C10–C11–C12 –C13–C14, respectively.
In Fig. 2b, through the N1–H1B•••O1b intermolecular hydrogen
bonds, the crystallized water molecules and the 4NH2 molecules
alternatively link to supramolecular congregation. Further, through
the hydrogen bonds of N6–H6A•••O1c, the adjacent congrega-
tion can be expanded to a supramolecular 1D chain along the
crystallographic b direction. Then, the hydrogen bonds of N1–
H1AꢀN2a and N6–H6BꢀN3d make the adjacent 1D chains ex-
˚
˚
A) and another does from two phenyl groups (3.7675(17) A)
(Fig. 1d).
3.1.2. Structure of 2 (4NH2)
When 4-amine phenyl nitrile replaced the 4-cyanobenzoic acid,
a new compound 2 can be obtained under the similar reaction
conditions. Single-crystal X–ray diffraction analysis reveals that
compound 2 belongs to the orthorhombic system with the Pna21
3

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Fig. 1. (a) A perspective view of 1. (b) The 1D chain through hydrogen bonds along the c axis. (c) The 2D supramolecular network formed by hydrogen bonds in 1. (d) The
packing diagram of 1.
4

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Table 2
˚
Selected bond lengths (A) and angles (°) for complexes 1–3.
˚
˚
Bond lengths/bond angles
Bond lengths (A)/Bond angles (°)
Bond lengths/bond angles
Bond lengths (A)/Bond angles (°)
1
O1-C7
N1-C8
N2-N3
N2-C8a
C1-C6
C2-C3
C4-C5
C5-C6
1.289(3)
1.316(3)
1.417(4)
1.368(3)
1.387(3)
1.378(3)
1.393(3)
1.380(3)
O2-C7
N1-N1a
N2-C8
C1-C2
C1-C7
C3-C4
C4-C8
1.243(3)
1.392(3)
1.368(3)
1.392(3)
1.487(3)
1.395(3)
1.468(3)
C8-N1-N1a
N3-N2-C8a
C2-C1-C6
C6-C1-C7
C2-C3-C4
C3-C4-C8
C4-C5-C6
O1-C7-O2
O2-C7-C1
N1-C8-C4
2
107.54(19)
126.25(13)
119.6(2)
121.4(2)
119.7(2)
121.5(2)
120.5(2)
123.9(2)
120.4(2)
125.3(2)
N3-N2-C8
C8-N2-C8a
C2-C1-C7
C1-C2-C3
C3-C4-C5
C5-C4-C8
C1-C6-C5
O1-C7-C1
N1-C8-N2
N2-C8-C4
126.25(13)
106.0(2)
119.0(2)
120.7(2)
119.5(2)
119.0(2)
120.0(2)
115.7(2)
109.4(2)
125.3(2)
N1-C1
1.402(3)
1.319(3)
1.433(3)
1.364(3)
1.395(3)
1.381(4)
1.395(4)
1.380(4)
1.397(3)
1.381(4)
1.398(3)
N2-N3
N3-C8
N4-C7
N6-C12
C1-C6
1.385(3)
1.312(3)
1.367(3)
1.394(3)
1.403(3)
1.398(3)
1.467(4)
1.469(3)
1.400(3)
1.400(4)
1.376(4)
N2-C7
N4-N5
N4-C8
C1-C2
C2-C3
C3-C4
C4-C5
C4-C7
C5-C6
C8-C9
C9-C10
C10-C11
C12-C13
C9-C14
C11-C12
C13-C14
N3-N2-C7
N5-N4-C7
C7-N4-C8
N1-C1-C6
C1-C2-C3
C5-C4-C7
C1-C6-C5
N2-C7-C4
N3-C8-N4
N4-C8-C9
C8-C9-C14
C9-C10-C11
N6-C12-C11
C11-C12-C13
C9-C14-C13
3
107.8(2)
126.7(2)
106.3(2)
121.0(2)
120.7(2)
119.5(2)
120.5(2)
125.2(2)
109.4(2)
126.1(2)
118.2(2)
120.4(2)
121.0(2)
118.1(2)
121.1(2)
N2-N3-C8
N5-N4-C8
N1-C1-C2
C2-C1-C6
107.7(2)
126.5(2)
120.4(2)
118.6(2)
120.8(2)
121.0(2)
108.9(2)
125.8(2)
124.5(2)
123.1(2)
118.4(2)
121.2(2)
120.8(2)
120.8(2)
C2-C3-C4
C4-C5-C6
N2-C7-N4
N4-C7-C4
N3-C8-C9
C8-C9-C10
C10-C9-C14
C10-C11-C12
N6-C12-C13
C12-C13-C14
O1-C1
1.354(2)
1.3884(19)
1.316(2)
1.370(2)
1.393(2)
1.380(2)
1.395(2)
1.380(2)
1.388(2)
1.384(2)
1.388(2)
O2-C12
N1-C7
N3-N4
N3-C8
C1-C6
1.358(2)
1.311(2)
1.408(2)
1.363(2)
1.391(2)
1.392(2)
1.462(2)
1.467(2)
1.394(2)
1.393(2)
1.379(2)
N1-N2
N2-C8
N3-C7
C1-C2
C2-C3
C3-C4
C4-C5
C4-C7
C5-C6
C8-C9
C9-C10
C9-C14
C11-C12
C13-C14
C10-C11
C12-C13
N2-N1-C7
N4-N3-C7
C7-N3-C8
O1-C1-C6
C1-C2-C3
107.99(13)
128.64(13)
106.55(13)
121.08(14)
119.52(15)
118.88(15)
121.49(14)
120.23(15)
126.56(14)
109.06(14)
125.39(14)
121.76(14)
121.06(15)
117.89(14)
119.85(15)
120.54(15)
N1-N2-C8
N4-N3-C8
O1-C1-C2
C2-C1-C6
107.56(12)
123.93(13)
119.06(14)
119.86(15)
121.12(15)
119.63(14)
120.37(15)
108.83(14)
124.60(14)
125.54(14)
119.39(14)
118.85(15)
119.43(14)
122.20(15)
120.13(15)
C2-C3-C4
C3-C4-C5
C3-C4-C7
C5-C4-C7
C4-C5-C6
C1-C6-C5
N1-C7-N3
N3-C7-C4
N2-C8-C9
C8-C9-C10
C10-C9-C14
C10-C11-C12
O2-C12-C13
C12-C13-C14
N1-C7-C4
N2-C8-N3
N3-C8-C9
C8-C9-C14
C9-C10-C11
O2-C12-C11
C11-C12-C13
C9-C14-C13
Symmetry codes: axe,y,3/2-z for 1.
5

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Fig. 2. (a) A perspective view of 2. (b) The 1D supramolecular chain along the crystallographic b direction. (c) The 2D supramolecular network formed by hydrogen bonds
along the crystallographic ab plane in 2. (c) The packing diagram of 2 along the crystallographic a axis.
6

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Table 3
the monoclinic system, being different from the reported com-
pound in the literature [54]. The asymmetric unit is comprised of
one 4OH molecule (Fig. 3a). The bond lengths among the triazole
Hydrogen bond geometries in the crystal structure of compounds 1–3, respectively.
a
˚
˚
•••
•••
•••
•••
D–H A (°)
Compounds
D–H
A
H
A (A)
D
A (A)
˚
ring range from 1.311(2) to 1.3884(19) A, which can be observed in
a
•••
1
O1-H1
O2
1.83
2.15
2.53
2.26
2.643(3)
3.176(4)
3.288(4)
3.114(3)
3.024(3)
3.065(3)
3.197(4)
3.406(4)
3.158(3)
3.047(3)
3.314(2)
2.8362(19)
2.806(2)
3.282(2)
3.275(2)
159
161
122
176
b
literature. Two dihedral angles with 38.5 and 41.6° can be observed
between the phenyl rings and the triazole ring, which are compa-
rable to that found in compound 1 and obviously larger than that
observed in compound 2.
•••
•••
N3-H3A
N3-H3B
N1–H1A
N1–H1B
O1–H1D
N5–H5A
N5–H5B
N6–H6A
N6–H6B
N1
c
N2
a
•••
•••
2
N2
b
O1
2.06(4)
2.17(4)
2.33(4)
2.60(4)
2.30
174(3)
167(4)
159(3)
143(3)
172
a
•••
•••
•••
N1
–
It often happen the hydrogen bonds and C Hꢀπ stacking inter-
actions in the supramolecular structures. In compound 3, it occurs
N H•••O intermolecular hydrogen bonds: (a) The N4-H4A•••O1
(c1-x,-y,-z) and N4-H4B•••O2d (d-1/2-x,1/2
b
N6
c
c
d
N1
c
•••
•••
O1
–
N3
2.25
153
+
y,−1/2-z) hydro-
a
•••
3
O1-H1
O1-H1
O2-H2
N1
2.61
142
gen bond comes from the amino-nitrogen atoms of triazole ring
and the hydroxyl oxygen atoms, where the bond distance are
a
b
ꢀ
•••
N2
N1
2.00
173
•••
2.00
162
170
146
c
˚
•••
•••
N4-H4A
O1
2.41
3.282(2) and 3.275(2) A, respectively. (b) The hydrogen bonds of
d
N4-H4B
O2
2.50
–
O H•••N can be observed among the hydroxyl oxygen atoms and
the triazole-yl nitrogen atoms. For instances, it occur the hydrogen
bonds of O1-H1•••N1a (a1/2 + x,1/2-y,1/2 + z), O1-H1•••N2a and
O2-H2•••N1b (b-1 + x,y,z), where the bond lengths are 3.314(2),
Symmetry codes:.
a-x,1-y,1-z.
b1-x,1/2 + y,3/2-z.
c-1 + x,y,z for 1. a-1/2 + x,1/2-y,z.
b1/2-x,−1/2 + y,−1/2 + z.
c1/2-x,1/2 + y,−1/2 + z.
˚
2.8362(19) and 2.806(2) A, respectively. Apart from these hydr-
–
gogen bonds, we can find the C H•••π packing interactions such
as C10-H10•••Cg2a (a1/2-x,−1/2 + y,−1/2-z) and C14-H14•••Cg3b
(b-1/2-x,1/2 + y,−1/2-z), where the bond distances are 3.3198(18)
d-1/2 + x,3/2-y,z for 2. a1/2 + x,1/2-y,1/2 + z.
b-1 + x,y,z.
c1-x,-y,-z.
˚
and 3.5925(19) A, respectively. The rings of Cg2 and Cg3 indicate
d-1/2-x,1/2 + y,−1/2-z for 3.
two phenyl centers.
As shown in Fig. 3b, a supramolecular 1D chain can be formed
Table 4
along the crystallographic a direction through the hydrogen bonds
of O2-H2•••N1b. Through the hydrogen bonds of N4-H4B•••O2d
πꢀπ and C–Hꢀπ geometries in the crystal structure of compounds 1–3.
˚
˚
Compounds
CgꢀCg
πꢀπ (A)
C–HꢀCg
C–Hꢀπ (A)
a
and C H•••π stacking interactions of C10-H10•••Cg2 and C14-
–
a
b
c
H14••• Cg3b, the adjacent supramolecular 1D chains can be ex-
panded to a supramolecular 2D sheet along the crystallographic
ab plane (Fig. 2c). Then, the O1-H1•••N1a, O1-H1•••N2a and
N4-H4A•••O1c hydrogen bonds make the adjacent layers form a
suprmolecular 3D framework along the crystallographic a direction
•••
1
Cg1
Cg1
Cg1
Cg1
Cg2
Cg2
Cg1
Cg1
Cg1
Cg1
Cg2
Cg2
3.7674(18)
3.7674(18)
3.7674(18)
3.7674(18)
3.7675(17)
3.7673(17)
3.6405(18)
3.6404(18)
•••
•••
•••
•••
•••
d
a
b
2
3
Cg1••• Cg1a
C2–H2•••Cg3c
C5–H5•••Cg3d
C11–H11•••Cg2e
C14–H14•••Cg2a
3.388(3)
3.343(3)
3.345(3)
3.515(3)
˚
(Fig. 3d). Notably, the shortest stacking distances (3.841 A) can be
Cg1•••Cg1b
observed between two phenyl rings.
The superposition of the moieties containing bis-phenyl amino-
triazole group in compounds 1–3 is shown in Fig. S1. As shown
in Fig. S1, in compounds 1 and 3, all atoms are not located in the
same plane, revealing that it does happen the obvious dihedral an-
gles between the triazole group and phenyl ring. However, there
does exist a small dihedral angle between the same aromatic rings
in compound 2. The present results may be responsible for the lu-
minescent properties mentioned below.
a
•••
•••
3.841
C10-H10
C14-H14
Cg2
3.3198(18)
3.5925(19)
Cg3b
Symmetry codes: a-1 + x,y,z.
b1+x,y,z.
c-1 + x,y,3/2-z.
d1+x,y,3/2-Z for 1. a1-x,1-y,−1/2 + z.
b1-x,1-y,1/2 + z.
c1/2-x,−1/2 + y,1/2 + z.
d1-x,1-y,−1/2 + z.
3.3. IR spectra
e1/2-x,1/2 + y,1/2 + z for 2. a1/2-x,−1/2 + y,−1/2-z.
b-1/2-x,1/2 + y,−1/2-z for 3. Cg1 = N1-C8-N2-C8a-N1a; Cg2= C1-C2-C3-C4-C5-C6
for 1. Cg1 = N2–N3–C8–N4; Cg2 = C7 C1–C2–C3–C4–C5–C6; Cg3 = C9–C10–C11–
C12 –C13–C14 for 2. Cg2 = C1-C2-C3-C4-C5-C6; Cg3 = C9-C10-C11-C12-C13-C14 for
3.
The IR spectra of compounds 1–3 containing amine-triazole
moieties are shown in Fig. S2. As shown in Fig. S2, the character-
istic bands of the carboxylate group in the usual region at 1628
cm−1 for the asymmetric stretching and at 1392 cm−1 for the
symmetric stretching. The moderate peak at 1290 cm−1 suggests
the presence of vC–O stretching vibration of the 1. The peak of
937 cm−1 is attributed to δO–H bending vibration. The bands are
located at 1650 cm−1 and 1450 cm−1 for 1, which suggests the
tend to
a
supramolecular 2D sheet along the crystallographic
–
ab plane (Fig. 2c). Finally, there exist the π•••π and C H•••π
packing interactions (Cg1•••Cg1a, Cg1•••Cg1b, C2–H2•••Cg3c, C5–
H5•••Cg3d and C11–H11•••Cg2e) and hydrogen bonds such as N5–
H5AꢀN6b, N5–H5BꢀN1c as well as O1–H1DꢀN1a. Based on these
supramolecular interactions, a supramolecular 3D architecture can
be generated along the crystallographic c direction (Fig. 2d).
vC=N stretching vibrations of the aromatic rings of 1. The bend-
/C
–
ing vibration of C N can be observed at the range of 1392–1188.
The peak located at 783 cm−1 indicates the existence of the ben-
zene ring. The band located at 3211 cm−1 can be ascribed to the
vC–H stretching vibration of phenyl rings.
3.3. Structure of 3 (4OH)
For compound 2, the strong band located at 3386 cm−1 can be
ascribed to the characteristic v-OH stretching vibration of the wa-
ter molecule. The characteristic vibration peak of νNH can be ob-
served at 3327 cm−1, suggesting that there exist the amino groups
in the skeleton. The bands can be observed at the range of 1614–
When 4–hydroxyl phenyl nitrile took place of 4-cyanobenzoic
acid, a new compound 3 can be obtained under the similar re-
action conditions. The results of X–ray crystal diffraction analysis
show that compound 3 belongs to the space group of P21/n with
1477 cm−1, which can be assigned to the vC=C stretching vibra-
/N
7

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Fig. 3. (a) A perspective view of 3. (b) The 1D chain through hydrogen bonds along the a axis. (c) The 2D supramolecular network formed by hydrogen bonding interactions
in 3. (d) The packing diagram of 3.
8

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Scheme 2. The structure of the 1.
tion of the phenyl and the triazole-yl rings. The bands range from
1385 to 1115 cm−1, indicating the existence of the bending vibra-
tions of aromatic C–N. The bands located at the range of 908–617
cm−1 can be assigned to the in-plane and out-plane bending vi-
bration of γ (CH) and δ(CH) modes of aromatic rings.
For compound 3, we can find the broad band located at 3476
cm−1, which can bs attributed to the hydroxylic and amino stretch-
–
ing vibration. The aromatic C H stretching vibration can be ob-
served at 3223 cm−1. The bands 1613 and 1481 cm−1 can be as-
signed to the vC=C and vC=N stretching vibration of the aromatic
rings. The bending vibrations of aromatic C–N change from 1363
to 1173 cm−1. The bands can be found in the range of 979–671
cm−1, indicating the existence of C H from the phenyl groups.
–
3.4. UV–Vis spectra
The electronic spectral data of 1, 2 and 3 at 2.08×10−5 mol
−
1
L
in dimethyl sulfoxide (DMSO) as solution have been exam-
ined (Fig. S3). The UV–vis spectra of the compounds 1–3 show that
there exists one strong absorption band at 293, 295 and 295 nm,
respectively. The present results may be assigned to π∗ → π elec-
tronic transition of the aromatic rings [55-57].
3.5. NMR spectra
The 1H and 13C NMR spectra for the target compounds were
recorded in DMSO–d6 as solvent and the data are given in the ex-
perimental section, which are shown in Fig. S4 and S5, respectively.
The atomic labels of the title compounds are shown in Scheme 2.
As shown in Fig. S4, there are four types of hydrogen atoms in
compounds 1–3. For compound 1, the single peak for the car-
boxylic -OH group occurs at 13.10 ppm (Fig. S4a). For compounds
2 and 3, the single signals for the -NH2 and -OH groups bonded to
the phenyl ring can be observed at 5.44 and 9.88 ppm, respectively
(Fig. S4b and S4c). Two doublet signals with the coupling constant
of 8 Hz at 8.20 and 8.10 ppm are assigned to aromatic protons in
the 1H NMR spectrum of 1. The phenyl protons can be observed
with the doublet signals located at 7.67 and 6.65 ppm (both cou-
pling constant are 8.2 Hz), 7.84 and 6.90 ppm with both coupling
Fig. 5. Hirshfeld surface mapped with dnorm (a), shape index (b) and curvedness (c)
of compound 1.
constant are 8.5 Hz for compounds 2 and 3, respectively. The pro-
tons of -NH2 group connected to triazole ring give a single peak at
6.41, 5.95 and 6.69 ppm for compounds 1–3, respectively.
The structures of compounds 1–3 can be further confirmed by
13C NMR data, which are in a good agreement with those of the 1H
NMR, IR and crystal structures (Fig. S5). The carboxylic carbons (C1
and C1ꢀ ) occur at 166.83 ppm in compound 1. The signal observed
at 153.86, 154.40 and 159.02 ppm can be attributed to the triazole
carbons (C6 and C6ꢀ ) for compounds 1–3, respectively. Additionally,
the signals appeared at the range of 131.57–128.37, 150.26–113.65,
and 154.30–115.67 ppm are assigned to phenyl carbons (C5, C5ꢀ
;
C2, C ; C , C , C , C
and C4, C , C , C4ꢀ’’) for compounds 1–
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
4 ’
3
2
3
3 ’
3 ’’
4
3, respectively. Thus, the structures for 1–3 were identified by the
spectra of 1H and 13C NMR, which is in a good accordance with
the crystal structures mentioned above.
3.6. Powder X-ray diffraction
In order to confirm the pure phase of 1–3, the powder X-ray
diffraction (PXRD) were investigated. As illustrated in Fig. S6, the
peak positions of the simulated and experimental PXRD patterns
are in a good accordance with each other. The present results show
that there exists a pure phase for the target products [58].
3.7. Thermogravimetric analysis
To evaluate the thermal stable properties of these compounds,
the primarily thermogravimetric experiment on samples contain-
Fig. 4. Fluorescent emission spectra of compounds 1–3 in the solid state at room
temperature.
9

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
Fig. 7. Hirshfeld surface mapped with dnorm (a), shape index (b) and curvedness (c)
of compound 3.
Table 5
Bonding contacts of compounds 1–3.
Fig. 6. Hirshfeld surface mapped with dnorm (a), shape index (b) and curvedness (c)
of compound 2.
1
2
3
H•••H (%)
32.2
12.9
22.8
12.3
41.0
16.2
6.5
33.5
16.0
14.3
29.0
ing powdered crystals was taken under N2 atmosphere with heat
rate of 10 °C min–1 [59]. The thermogravimetric analysis (TGA) re-
sults are shown in Fig. S7. The TGA curve of 1 shows that there ex-
ists a platform until 318 °C, indicating that compound 1 has high
thermal stability. After that, it suffers a sharp weight loss up to
600 °C. For compound 2, it occurs a plateau from room temper-
ature to 110 °C. After that, the loss weight occurs at the range
of 110 °C −145 °C, suggesting the loss of the crystallized water
molecules (cald. 6.3% and obsd. 6.3%). Then, a second platform
can be observed between 145 °C and 318 °C. Then, there exists a
weight loss, being corresponded to the decomposition of the or-
ganic compound. For compound 3, we can find a platform between
the room temperature and 322 °C, suggesting that compound 3 has
a high thermal stability. Then, the loss weight occurs, which can be
assigned to the decomposition of organics.
H•••N/N•••H (%)
H•••O/O•••H (%)
C•••H/H•••C (%)
30.2
temperature [38-39]. As shown in Fig. 4, the spectra of compounds
1–3 show that the maximal emission peaks occur at 398, 464 and
402 nm with an excitation wavelength of 290, 350 and 295 nm,
respectively. Notably, we can find that there exists an order of
the maximal bands for these compounds as the following: 1<3<2.
Compared the maximal peak of compound 1, those of compounds
2 and 3 show obvious red-shift phenomena. The red-shifted val-
ues are about 74 and 4 nm for compounds 2 and 3, respectively.
The observed phenomena can be ascribed to the difference of
electron-accept/donor groups. There exists the order of electron-
donor groups: -COOH<-OH<-NH2, which is in a good agreement
with that of the maximal peaks. The present luminescent results
reveal that the optic property can be easily tuned by the sub-
stituents.
3.8. Luminescent properties
To examine the optic properties of the title compounds, the
solid-state photoluminescence of 1–3 was investigated at room
10

Fig. 8. Finger print plots (a, b and c) of compounds 1–3, resepectively.

Y.-R. Xi, X.-K. Chen, Y.-T. Wang et al.
Journal of Molecular Structure 1243 (2021) 130893
4. Conclusion
In summary, we have successfully synthesized
a
set of
3,5-disubstituent-4-amine-1,2,4-triazole with different functional
groups through a convenient method under the solvothermal re-
action conditions. The title compounds are characterized by EA, IR,
NMR, UV–Vis spectra, single-crystal X-ray diffraction, and powder
X-ray diffraction. The photoluminescent properties can not only be
mediated through the substituents, but also the maximal peaks
are proportional to the electron-donor capacities of the substi-
tuted groups. The Hirshfeld surface analyses further reveal that
there exists the same order of the H•••H and C•••H/H•••C bond-
ing contacts, which are in a good accordance with the lumines-
cent order. The present strategy gives us a platform to develop
and design the novel luminescent materials. Currently, 4-amine-
1,2,4-triazole based compounds displaying the promising photo-
luminescent materials are explored.
Fig. 9. Bonding contacts of compounds 1–3.
Author statement
Yu-Rong Xi: Data curation, Writing-Original draft preparation.
Xu-Kai Chen: Data Curation, Investigation, Resources
Yong-Tao Wang: Supervision, Writing - Review & Editing
Gui-Mei Tang: Conceptualization, Methodology, Project admin-
istration
3.9. Hirshfeld surface analyses
To evaluate the relationship between the intermolecular inter-
actions and the luminescent properties, the Hirshfeld surface anal-
yses were performed. The Hirshfeld surface and the correspond-
ing two-dimension fingerprint plots visualize the intermolecular
interactions. The distances de and di are on behalf of the clos-
est atom from the Hirshfeld surface outside and inside, respec-
tively, which can be enabled to analysis the intermolecular con-
tacts by mapping of dnorm (distance equal to the Vander Waals
radii) . As shown in Fig. 5a, the deep red spots describe the
H•••H (32.2%) and O•••H/O•••H (22.8%) bonding contacts con-
tribution, represent the carboxylic bonding contact (Fig. 8a). Fur-
thermore, the H•••N/N•••H and C•••H/H•••C weak contacts con-
tribute 12.9% and 12.3%, respectively, which were described in
blue regions in Fig. 5a. Three circles in compound 1 described
in red areas in shape index represent the hollows and the bump
shown in blue (Fig. 5b) [60]. As the curvedness expressed (Fig. 5c),
all atoms are located in a plane. In compound 2, the type of
H•••H (41.0%), C•••H/H•••C (30.2%), N•••H/H•••N (16.2%) and
O•••H/H•••O (6.5%) bonding contacts contribute the most inter-
actions of total molecule (Fig. 8b) and show in the red spots
(Fig. 6a). The contribution of other weak contacts is listed as the
following: C•••N/N•••C (3.9%), C•••O/O•••C (0.0%), N•••N (1.8%),
O•••N/N•••O (0.0%), O•••O (0.0%) and C•••C (0.2%) (Fig. S8). As
shown in Fig. 7a, in compound 3, the bright red spots in the
Hirshfeld surface indicate the strong connections of H•••O/O•••H,
N•••H/H•••N and C•••H/H•••C, which contribute 14.3%, 16.0% and
29.0% to the whole interactions, respectively. They show two sharp
spikes (Fig. 8c and Fig. 9). Notably, the H•••H contribution can be
found to be 33.5%. The bonding contacts of compounds 1–3 are
collected in Table 5 and Fig. 9.
Xiao-Min Chen: Data Curation
Yu-Song Wu: Investigation, Validation
Shi-Ning Wang: Visualization, Investigation
Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
Acknowledgments
This work was financially supported by Shandong Distinguished
Middle-aged Young Scientist Encouragement and Reward Foun-
dation (BS2011CL034), Shandong Provincial Natural Science Foun-
dation (ZR2017MB041), and College Student Innovation and En-
trepreneurship Training Program (S201910431065, S202010431073
and S202010431001).
Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2021.130893.
References
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Exploring the Effects of Synthetic and Postsynthetic Grinding on
the Properties of the Spin Crossover Material Fe(atrz)(3) (BF4)(2)
(atrz = 4-Amino-4H-1,2,4-Triazole), in: Magnetochemistry, 6, 2020, p. 44.
[2] E.S. Bazhina, A.A. Bovkunova, A.V. Medved’ko, N.N. Efimov, M.A. Kiskin, I.L. Ere-
As shown in Table 5, Fig. 8 and Fig. 9, we can find that the
H•••H contribution with 32.2%, 41.0% and 33.5% can be observed
for compounds 1–3, respectively. Obviously, the order of H•••H
contribution is following: 1<3<2. Notably, the difference of H•••H
contribution between compounds 1 and 3 is 1.3%, while that be-
tween compounds 1 and 2 is 8.8%. Obviously, the difference value
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