Syntheses, structures and properties of a series of nickel(II) complexes derived from amino-5-mercapto-1,3,4-thiadiazole

Article abstract of DOI:10.1007/s11243-017-0188-y

Abstract: Four complexes possessing photocatalytic activity, namely [Ni(AMT)₂(EDA)₂]₂ (1), [Ni₄(AMT)₆(μ₃-OH)₂(H₂O)₆] (2), [Ni₄(AMT)₆(μ₃-OH)₂(H₂O)₆]·4H₂O (3) and [Ni₄(AMT)₆(μ₃-OH)₂(H₂O)₆]·2H₂O (4) (AMT?=?amino-5-mercapto-1,3,4-thiadiazole and EDA?=?diethanolamine) have been obtained from solvothermal reactions and characterized by physico-chemical and spectroscopic methods. Although complexes 1–4 were prepared from common reactants (nickel nitrate and AMT), the use of different organic amines and reaction conditions lead to the observed differences in their structures. Complex 1 is mononuclear, while complex 2 is a {Ni₄} cluster. Complexes 3–4 are expanded into supramolecular structures by hydrogen bonding interactions, but differences in their lattice water molecules lead to the different supramolecular structures. Photocatalytic studies reveal that complex 4 exhibits good catalytic activity for the degradation of the organic dye methylene blue. Graphical Abstract: Four complexes possessing photocatalytic activity and constructed from the late transition metal Ni(II) and the 2-amino-5-mercapto-1,3,4-thiadiazole ligand have been obtained in solvothermal conditions. Although complexes 1–4 were prepared from common reactants (nickel nitrate and AMT), the use of different organic amines and reaction conditions lead to the observed differences in their structures. Complex 1 is mononuclear, while complex 2 is a {Ni₄} cluster. Complexes 3–4 are expanded into supramolecular structures by hydrogen bonding interactions, but differences in their lattice water molecules lead to the different supramolecular structures. Photocatalytic studies reveal that complex 4 exhibits good catalytic activity for the degradation of the organic dye methylene blue.[Figure not available: see fulltext.].

Full text of DOI:10.1007/s11243-017-0188-y

Transition Metal Chemistry
https://doi.org/10.1007/s11243-017-0188-y
Syntheses, structures and properties of a series of nickel(II) complexes
derived from amino‑5‑mercapto‑1,3,4‑thiadiazole
1
1
1
Yue Ma · Bao Mu · Ru‑Dan Huang
Received: 18 July 2017 / Accepted: 11 October 2017
Springer International Publishing AG 2018
©
Abstract
Four complexes possessing photocatalytic activity, namely [Ni(AMT) (EDA) ] (1), [Ni (AMT) (μ -OH) (H O) ] (2),
2
2 2
4
6
3
2
2
6
[
Ni (AMT) (μ -OH) (H O) ]·4H O (3) and [Ni (AMT) (μ -OH) (H O) ]·2H O (4) (AMT = amino-5-mercapto-1,3,4-thia-
4
6
3
2
2
6
2
4
6
3
2
2
6
2
diazole and EDA = diethanolamine) have been obtained from solvothermal reactions and characterized by physico-chemical
and spectroscopic methods. Although complexes 1–4 were prepared from common reactants (nickel nitrate and AMT), the
use of diꢀerent organic amines and reaction conditions lead to the observed diꢀerences in their structures. Complex 1 is
mononuclear, while complex 2 is a {Ni } cluster. Complexes 3–4 are expanded into supramolecular structures by hydrogen
4
bonding interactions, but diꢀerences in their lattice water molecules lead to the diꢀerent supramolecular structures. Photo-
catalytic studies reveal that complex 4 exhibits good catalytic activity for the degradation of the organic dye methylene blue.
Introduction
coordination polymers which show photocatalytic activities
for the degradation of methylene blue (MB) [20]. Fan et al.
obtained two-dimensional layered complexes that exhibit
preeminent catalytic performance for the homo-coupling of
aryl bromides or iodides without by-products [21]. There-
fore, research into metal organic complexes possessing good
catalytic properties is a current area of interest.
In recent years, much attention has been focused on the
design and construction of novel complexes with interest-
ing properties in the ꢁelds of ꢂuorescence [1–3], catalysis
[
4, 5], magnetism [6–8], electrochemistry [9–11] and gas
adsorption/separation [12, 13]. Among these properties,
photocatalytic complexes have potential applications in the
remediation of environmental pollution [14–16]. Industrial
activity has released many harmful pollutants into the envi-
ronment, which are bad for health and economic develop-
ment [17–19]. As one such class of pollutants, organic dyes
are diꢃcult to remove by conventional methods because
of their stable chemical and non-biodegradable properties.
Hence, there is an urgent need to ꢁnd eꢀective methods for
the degradation of these organic pollutants. In recent years,
many research groups have studied photocatalytic degrada-
tion, which has great potential for decomposition of organic
dyes [20–22]. Liu et al. synthesized a variety of cobalt(II)
Transition metal–oxygen clusters have become an
important research ꢁeld in both coordination chemistry and
crystal engineering because of their fascinating structures
and potential applications [23–28]. In these materials, the
organic ligands play a crucial role in their structures. As
functional ligands, thiol-containing azaheterocyclic ligands
have three advantages. Firstly, the thiol group allows for con-
formational rotation, allowing for ꢂexible complex geom-
etries. Secondly, these ligands have multiple coordination
sites, due to the two nitrogen atoms of the thiadiazole group
and the thiolate sulfur atom. Hence, they are likely to have
a wealth of chemical properties [29–31].
In this work, we selected the late transition
metal nickel(II), together with 2-amino-5-mer-
capto-1,3,4-thiadiazole (AMT) to obtain four new
mononuclear and tetranuclear clusters, namely
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11243-017-0188-y) contains
supplementary material, which is available to authorized users.
[
(
[
Ni(AMT) (EDA) ] (1), [Ni (AMT) (μ -OH) (H O) ]
2
2 2
4
6
3
2
2
6
*
Ru-Dan Huang
2), [Ni (AMT) (μ -OH) (H O) ]·4H O (3) and
4
6
3
2
2
6
2
huangrd@bit.edu.cn
Ni (AMT) (μ -OH) (H O) ]·2H O (4). The influence
4
6
3
2
2
6
2
1
Key Laboratory of Cluster Science of Ministry of Education,
School of Chemistry and Chemical Engineering, Beijing
Institute of Technology, Beijing 100081, China
of organic amines and diꢀerent reaction temperatures on
the products is discussed. In addition, the photocatalytic
Vol.:(0
1
123456789)
3

Transition Metal Chemistry
properties of complex 4 have been investigated, revealing
that complex 4 is able to degrade MB.
Synthesis of complex 1
A mixture of Ni(NO ) ·6H O (0.2908 g, 1.00 mmol), AMT
3
2
2
(
0.1332 g, 1.00 mmol), distilled water (4 mL) and ethanol
Experimental
(4 mL) was transferred to a 25-mL Teꢂon-lined reactor.
Ethylenediamine (1.5 mL) was then added to the reaction
solution under stirring, keeping the mixture at 110 °C for
Materials and methods
3
days. After cooling the autoclave to room temperature,
All reagents were purchased commercially and used with-
out further puriꢁcation. Elemental analyses (C, H, N) were
obtained with a PerkinElmer 2400 CHN elemental analyzer.
FTIR spectra (KBr pellets) were taken on a Nicolet 170SX
spectrophotometer. Thermogravimetric (TG) analyses were
carried out on an Exstar SII TG/DTA 7200 integration ther-
mal analyzer. Powder X-ray diꢀraction (PXRD) patterns
were measured on a Siemens D5005 diꢀractometer (Cu Ka
radiation, λ = 1.5410 Å). UV–vis absorption spectra were
recorded on a TU-1901 UV–vis spectrophotometer.
green block crystals were obtained, but with poor reproduc-
ibility and crystallinity. Yield 15% based on Ni(II). Elemen-
tal analysis (%) calcd for C H N Ni S : C, 21.68; H, 4.55;
16
40 20
2 8
N, 31.60%. Found: C, 21.64; H, 4.53; N, 31.58%. IR (KBr
−
1
pellet, cm ): 3225(m), 1596(s), 1514(s), 1454(m), 1374(s),
1326(s), 1263(m), 1117(w), 1008(s), 947(s), 872(w), 755(s),
673(s), 614(w), 594(w), 576(w), 517(m).
Synthesis of complex 2
The synthesis of complex 2 was similar to that of 1, except
that the ethylenediamine was replaced by triethanolamine.
Green block crystals were obtained. Yield 23% based on
Ni(II). Elemental analysis (%) calcd for C H N Ni O S :
12
26 18
4
8 12
Table 1 Crystal data and
Complex
1
2
3
4
structure reꢁnements for
complexes 1–4
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C H N Ni S C H N Ni O S
C H N Ni O S
1242.13
C H N Ni O S
12 30 18 4 10 12
1206.08
1
6
40 20
2
8
12 26 18
4
8
12
12 34 18
4
12 12
886.58
Monoclinic
P2(1)/c
8.6276(11)
10.1567(12)
11.3063(15)
90
1170.07
Monoclinic
P2(1)/n
10.5052(11)
9.5476(9)
19.780(2)
90
Monoclinic
P2(1)/n
13.4656(11)
9.6485(6)
17.2696(12)
90
Monoclinic
P2(1)/n
10.4245(6)
9.4637(6)
19.7434(10)
90
α (°)
β (°)
γ (°)
V (Å )
99.458(13)
90
977.3(2)
1
1.506
1.432
95.356(9)
90
1975.3(3)
2
1.967
2.575
90.0890(10)
90
2243.7(3)
2
1.839
2.279
95.0900(10)
90
1940.09(19)
4
2.061
2.628
3
Z
Dc (g cm−3)
μ (mm−
F (000)
1
)
460
1184
1264
1220
Reꢂection collected 6056
8405
3488
244
0.0762
1.045
0.0543
0.0923
5698
3398
262
0.0408
1.036
0.0639
0.1682
11,092
3423
253
0.0556
1.068
0.0367
0.0930
Unique reꢂections
Parameters
Rint
1724
106
0.0554
1.045
0.0424
0.1130
GOF
a
R [I > 2σ(I)]
1
b
wR (all data)
2
a
R = Σ||Fo|–|Fc||/Σ|Fo|
1
b
2
2 2
2 2 1/2
wR = Σ[w(Fo –Fc ) ]/Σ[w(Fo ) ]
2
1
3

Transition Metal Chemistry
Table 2 Selected bond distances
Complex 1
Ni(1)–N(5)#1
Ni(1)–N(5)
(
Å) and angles (deg) for
2.098(3)
2.098(3)
2.111(3)
180.0(2)
Ni(1)–N(4)#1
Ni(1)–N(1)#1
Ni(1)–N(1)
2.111(3)
2.132(3)
2.132(3)
90.55(13)
89.45(13)
91.09(12)
88.91(12)
89.45(13)
90.55(13)
180.0(3)
complexes 1–4
Ni(1)–N(4)
N(5)#1–Ni(1)–N(5)
N(5)#1–Ni(1)–N(4)
N(5)–Ni(1)–N(4)
N(5)#1–Ni(1)–N(4)#1
N(5)–Ni(1)–N(4)#1
N(4)–Ni(1)–N(4)#1
N(5)#1–Ni(1)–N(1)#1
N(5)–Ni(1)–N(1)#1
Symmetry codes for 1: #1 − x + 1, − y, − z
Complex 2
N(4)–Ni(1)–N(1)#1
82.31(13) N(4)#1–Ni(1)–N(1)#1
97.69(13) N(5)#1–Ni(1)–N(1)
97.69(13) N(5)–Ni(1)–N(1)
82.31(13) N(4)–Ni(1)–N(1)
180.00(18) N(4)#1–Ni(1)–N(1)
88.91(12) N(1)#1–Ni(1)–N(1)
91.09(12)
Ni(1)–O(1)
Ni(1)–O(1)#1
Ni(1)–N(7)
Ni(1)–N(1)
Ni(1)–N(5)
Ni(1)–O(2)
2.028(4)
2.038(4)
2.099(5)
2.101(5)
2.102(5)
2.120(4)
82.06(16) O(1)–Ni(2)–N(2)
92.86(18) O(1)–Ni(2)–N(4)
93.24(18) N(2)–Ni(2)–N(4)
88.50(18) O(1)–Ni(2)–O(4)
89.46(18) N(2)–Ni(2)–O(4)
177.1(2)
89.56(18) O(1)–Ni(2)–O(3)
171.45(19) N(2)–Ni(2)–O(3)
88.9(2)
88.6(2)
Ni(2)–O(1)
Ni(2)–N(2)
Ni(2)–N(4)
Ni(2)–O(4)
Ni(2)–O(3)
Ni(2)–S(6)#1
2.009(4)
2.095(5)
2.098(5)
2.105(4)
2.170(4)
2.4707(19)
90.84(18)
85.19(18)
89.4(2)
89.93(17)
179.22(19)
90.6(2)
173.58(16)
94.91(19)
92.00(18)
84.32(16)
94.82(12)
91.62(15)
178.97(16)
88.32(13)
87.88(13)
O(1)–Ni(1)–O(1)#1
O(1)–Ni(1)–N(7)
O(1)#1–Ni(1)–N(7)
O(1)–Ni(1)–N(1)
O(1)#1–Ni(1)–N(1)
N(7)–Ni(1)–N(1)
O(1)–Ni(1)–N(5)
O(1)#1–Ni(1)–N(5)
N(7)–Ni(1)–N(5)
N(1)–Ni(1)–N(5)
O(1)–Ni(1)–O(2)
O(1)#1–Ni(1)–O(2)
N(7)–Ni(1)–O(2)
N(1)–Ni(1)–O(2)
N(5)–Ni(1)–O(2)
Symmetry codes for 2: #1 − x + 1, − y + 1, − z + 1
Complex 3
N(4)–Ni(2)–O(4)
N(4)–Ni(2)–O(3)
O(4)–Ni(2)–O(3)
177.06(16) O(1)–Ni(2)–S(6)#1
95.15(15) N(2)–Ni(2)–S(6)#1
88.24(18) N(4)–Ni(2)–S(6)#1
90.52(18) O(4)–Ni(2)–S(6)#1
93.19(19) O(3)–Ni(2)–S(6)#1
Ni(1)–O(1)
Ni(1)–O(1)#1
Ni(1)–N(7)#1
Ni(1)–N(4)
Ni(1)–O(2)
Ni(1)–N(2)
O(1)–Ni(1)–O(1)#1
O(1)–Ni(1)–N(7)#1
O(1)#1–Ni(1)–N(7)#1
O(1)–Ni(1)–N(4)
O(1)#1–Ni(1)–N(4)
N(7)#1–Ni(1)–N(4)
O(1)–Ni(1)–O(2)
O(1)#1–Ni(1)–O(2)
N(7)#1–Ni(1)–O(2)
2.047(5)
2.051(5)
2.091(6)
2.094(6)
2.115(5)
2.139(7)
83.0(2)
92.9(2)
91.6(2)
88.5(2)
90.5(2)
177.7(3)
177.5(2)
94.5(2)
87.0(2)
Ni(2)–O(1)
Ni(2)–N(1)
Ni(2)–N(5)
Ni(2)–O(3)
Ni(2)–O(4)
Ni(2)–S(6)
O(1)–Ni(2)–N(1)
O(1)–Ni(2)–N(5)
N(1)–Ni(2)–N(5)
O(1)–Ni(2)–O(3)
N(1)–Ni(2)–O(3)
N(5)–Ni(2)–O(3)
O(1)–Ni(2)–O(4)
N(1)–Ni(2)–O(4)
N(5)–Ni(2)–O(4)
2.008(5)
2.102(7)
2.108(6)
2.125(5)
2.148(5)
2.474(2)
86.4(2)
91.6(2)
88.3(3)
173.8(2)
93.0(2)
94.5(2)
88.1(2)
90.2(2)
178.5(2)
1
3

Transition Metal Chemistry
Table 2 (continued)
N(4)–Ni(1)–O(2)
O(1)–Ni(1)–N(2)
O(1)#1–Ni(1)–N(2)
N(7)#1–Ni(1)–N(2)
N(4)–Ni(1)–N(2)
O(2)–Ni(1)–N(2)
Symmetry codes for 3: #1 − x + 1, − y + 1, − z + 1
Complex 4
91.7(2)
88.8(2)
171.8(2)
89.1(3)
89.1(3)
93.7(2)
O(3)–Ni(2)–O(4)
85.7(2)
93.93(16)
178.69(18)
93.02(19)
86.59(17)
88.52(17)
O(1)–Ni(2)–S(6)
N(1)–Ni(2)–S(6)
N(5)–Ni(2)–S(6)
O(3)–Ni(2)–S(6)
O(4)–Ni(2)–S(6)
Ni(1)–O(1)
Ni(1)–O(1)#1
Ni(1)–N(7)
Ni(1)–N(4)
Ni(1)–O(2)
Ni(1)–N(2)
2.042(3)
2.048(3)
2.086(4)
2.088(4)
2.111(3)
2.122(4)
83.33(13) O(1)–Ni(2)–N(1)
91.98(14) O(1)–Ni(2)–O(4)
93.14(13) N(1)–Ni(2)–O(4)
88.96(13) O(1)–Ni(2)–N(5)
89.46(13) N(1)–Ni(2)–N(5)
177.32(13) O(4)–Ni(2)–N(5)
177.37(12) O(1)–Ni(2)–O(3)
94.04(12) N(1)–Ni(2)–O(3)
88.04(14) O(4)–Ni(2)–O(3)
91.14(14) N(5)–Ni(2)–O(3)
88.96(13) O(1)–Ni(2)–S(6)#1
171.96(14) N(1)–Ni(2)–S(6)#1
89.40(14) O(4)–Ni(2)–S(6)#1
88.10(14) N(5)–Ni(2)–S(6)#1
93.67(14) O(3)–Ni(2)–S(6)#1
Ni(2)–O(1)
Ni(2)–N(1)
Ni(2)–O(4)
Ni(2)–N(5)
Ni(2)–O(3)
Ni(2)–S(6)#1
2.009(3)
2.090(4)
2.099(3)
2.104(4)
2.160(3)
2.4723(13)
84.89(13)
89.40(13)
91.03(14)
91.42(14)
89.24(15)
179.16(14)
173.05(13)
92.66(14)
84.13(12)
95.06(14)
94.57(9)
O(1)–Ni(1)–O(1)#1
O(1)–Ni(1)–N(7)
O(1)#1–Ni(1)–N(7)
O(1)–Ni(1)–N(4)
O(1)#1–Ni(1)–N(4)
N(7)–Ni(1)–N(4)
O(1)–Ni(1)–O(2)
O(1)#1–Ni(1)–O(2)
N(7)–Ni(1)–O(2)
N(4)–Ni(1)–O(2)
O(1)–Ni(1)–N(2)
O(1)#1–Ni(1)–N(2)
N(7)–Ni(1)–N(2)
N(4)–Ni(1)–N(2)
O(2)–Ni(1)–N(2)
Symmetry codes for 4: #1 − x + 1, − y + 1, − z + 1
179.23(11)
88.41(9)
91.33(10)
87.81(9)
C, 12.32; H, 2.24; N, 21.55%. Found: C, 12.29; H, 2.22; N,
−
1
2
2
1
1.53%. IR (KBr pellet, cm ): 3515(m), 3435(m), 3139(s),
361(w), 1597(s), 1522(s), 1402(s), 1355(m), 1309(w),
053(s), 933(m), 718(m), 624(w), 557(w).
Table 3 Data of hydrogen bounds for complexes 3–4
D–H···A
D–H
H···A
D···A
D–H···A
Synthesis of complex 3
Complex 3
N(3)–H(3B)···O(5W)
O(4W)–H(3D)···O(2W)
O(3W)–H(4B)···O(5W)
O(3W)–H(4C)···O(3W)
O(4W)–H(5A)···N(9)d
O(4W)–H(5C)···O(4W)
a
0.86
0.85
0.85
0.85
0.85
0.85
2.11
2.26
2.14
2.25
2.20
2.01
2.9360
3.0647
2.9777
3.0772
2.9172
2.8193
162
157
168
164
142
159
The synthetic method for complex 3 was similar to that of
b
1
, except that the ethylenediamine was replaced by trieth-
ylamine/ethanolamine in 4:1 ratio (v/v). Green block crys-
tals were obtained. Yield 28% based on Ni(II). Elemental
analysis (%) calcd for C H N Ni O S : C, 11.60; H,
c
b
12 34 18
4
12 12
2
.76; N, 20.30%. Found: C, 11.57; H, 2.74; N, 20.33%. IR
Symmetry codes for 3: a 1/2 − x, 1/2 + y, 1/2 – z; b 1 − x, 1 − y,
−
1
(
KBr pellet, cm ): 3567(m), 3412(m), 3147(s), 1615(s),
574(m), 1532(s), 1421(s), 1372(m), 1066(m), 916(w),
723(m), 673(m), 661(w), 624(w), 531(m), 508(w).
−
z; c − x, 1 − y, − z; d 1/2 − x, − 1/2 + y, 1/2 − z
1
Complex 4
a
O(1W)–H(2B)···O(3W)
0.85
0.86
2.55
2.22
3.0237
2.9803
117
147
N(9)–H(9A)···O(4W)b
Symmetry codes for 4: a x, − 1 + y, z; b 1 − x, 1 − y, 1 − z
1
3

Transition Metal Chemistry
Synthesis of complex 4
The synthetic method for complex 4 was similar to that
of 3, except that the reaction temperature was maintained
at 130 °C for 3 days. Green block crystals were obtained.
Yield 25% based on Ni(II). Elemental analysis (%) calcd
for C H N Ni O S : C, 11.95; H, 2.51; N, 20.90%.
1
2
30 18
4
10 12
−1
Found: C, 11.97; H, 2.54; N, 20.93%. IR (KBr pellet, cm ):
3
1
6
523(m), 3446(m), 3158(s), 1603(s), 1560(m), 1527(s),
410(s), 1358(m), 1053(m), 927(w), 716(m), 665(m),
56(w), 613(w), 561(m), 511(w).
X‑ray crystallographic studies
Single-crystal X-ray diꢀraction data collections for com-
plexes 1–4 were carried on a Bruker APEX diꢀractom-
eter with Mo Kα radiation (graphite monochromator,
λ = 0.71073 Å) at 298 K. The structures were solved by
direct methods using the SHELXTL crystallographic
software package and reꢁned by full-matrix least squares
2
methods on F with SHELXL [32]. In ꢁnal reꢁnements for
complexes 1–4, all nonhydrogen atoms were reꢁned aniso-
tropically. The carbon, nitrogen and oxygen-bound hydrogen
atoms were generated theoretically onto the speciꢁc atoms
and reꢁned isotropically using ꢁxed thermal factors. Sum-
maries of the crystallographic data and structure reꢁnement
parameters for complexes 1–4 are listed in Table 1. Selected
bond distances and angles are given in Table 2. The hydro-
gen bond parameters are summarized in Table 3. The CCDC
numbers are 1470863–1470866 for complexes 1–4.
Fig. 1 a Coordination environment of the Ni atom in complex 1 (#1
−
x + 1, − y, − z). b The mononuclear structure for 1
Fig. 2 Coordination environment of Ni atom in complex 2 (#1 –x + 1, –y + 1, –z + 1)
1
3

Transition Metal Chemistry
Fig. 3 a Unit of binuclear for 2. b The tetranuclear clusters for 2
Results and discussion
groups of two separate AMT ligands, one sulfur atom
(
S6) from one thiol group of an AMT ligand, one oxygen
Crystal structure of [Ni(AMT) (EDA) ] (1)
atom (O1) of a μ3-bridging hydroxyl group and two water
ligands (O2W and O3W) (Fig. 2b). The Ni–O, Ni–N and
Ni–S bond lengths are in the ranges of 2.009(4)–2.170(4) Å,
2.095(5)–2.102(5) Å and 2.4707(19) Å, respectively. The
AMT ligands display two types of coordination patterns. In
the ꢁrst, two nitrogen atoms of the 1,3,4-thiadiazole groups
are coordinated to the metal. In the second, one nitrogen
atom of a 1,3,4-thiadiazole group and one thiolate sulfur
atom are coordinated. Four AMT ligands serve to connect
two Ni atoms, forming a binuclear structure, in which the
two metal Ni atoms exhibit vertices sharing (Fig. 3a). Pairs
of binuclear units are interconnected by hydroxylic oxygen
atoms to form a tetranuclear cluster, exhibiting side-sharing
(Fig. 3b).
2
2 2
The single-crystal X-ray diꢀraction study shows that com-
plex 1 crystallizes in the monoclinic P2(1)/c space group.
The asymmetric unit contains two crystallographically inde-
pendent nickel atoms, four AMT ligands and four ethylene-
diamine ligands. The Ni1 is located in an octahedral conꢁgu-
ration, being coordinated by two nitrogen atoms (N1, N1#1)
from the 1,3,4-thiadiazole groups of the AMT ligands, plus
four nitrogen atoms (N4, N5, N4#1 and N5#1) of two ethyl-
enediamine ligands (Fi. 1a). The Ni–N bond lengths are in
the range of 2.098(3)–2.132(3) Å. Complex 1 has a mono-
nuclear structure (Fig. 1b), which can be explained by the
chelating ability of the ethylenediamine ligands.
Crystal structure of [Ni (AMT) (μ ‑OH) (H O) ] (2)
4
6
3
2
2
6
Crystal structure of [Ni (AMT) (μ ‑OH) (H O) ]·4H O
4
6
3
2
2
6
2
Complex 2 crystallizes in the monoclinic P2(1)/n space
(3)
group. The asymmetric unit includes two nickel atoms, three
AMT ligands, one μ -bridging hydroxyl group and three
Although the core structure of complex 3 is the same as
that of complex 2, the tetranuclear clusters are expanded
into a 3D supramolecular framework by hydrogen bond-
ing interactions in complex 3. Thus, 2D layers are formed
through three kinds of O–H···O hydrogen bonding inter-
actions, between the neighboring lattice water molecules
(O4W), between the lattice water molecules (O4W)
and the water ligands (O2W), and between the water
3
water ligands. The Ni centers all have octahedral geometries,
with two kinds of coordination environment. Ni1 is coor-
dinated by three nitrogen atoms (N2, N4 and N7) from the
1
,3,4-thiadiazole groups of three separate AMT ligands, two
oxygen atoms (O1 and O1#1) of μ -bridging hydroxyl groups
3
and one water ligand (O1W) (Fig. 2a). Ni2 is coordinated by
two nitrogen atoms (N1 and N5) from the 1,3,4-thiadiazole
1
3

Transition Metal Chemistry
Fig. 4 a 2D structure of com-
plex 3. b View of 3D supramo-
lecular framework of 3
1
3

Transition Metal Chemistry
Fig. 5 a 1D chain of complex 4.
b The 2D network of 4
ligands (O3W) (Fig. 4a) [O(4W)–H(5C)···O(4W) = 2.8
Crystal structure of [Ni (AMT) (μ ‑OH) (H O) ]·2H O
4
6
3
2
2
6
2
1
93 Å, O(4W)–H (3D)···O(2W) = 3.0647 Å, O(3W)–H
(4)
(
4C)···O(3W) = 3.0772 Å]. The adjacent 2D supramolecu-
lar layers are extended into a 3D supramolecular frame-
work by hydrogen bonding interactions from the water
ligand (O3W) and the lattice water molecules (O5W)
with a distance of 2.9777 Å. The other hydrogen bond-
ing interactions are between the nitrogen atoms (N3 and
N9) of the AMT ligands and the lattice water molecules
In contrast to complex 3, in complex 4 the tetranuclear
clusters are extended into a 2D supramolecular network by
hydrogen bonding interactions. The adjacent tetranuclear
clusters are interconnected by hydrogen bonding interac-
tions between two water ligands (O1W and O3W), with
an O(1W)–H(2B)···O(3W) distance of 3.0237 Å, to form a
1D supramolecular chain. Neighboring chains are assem-
bled into a 2D supramolecular network through hydrogen
bonding interactions between the lattice water molecules
(
O5W and O4W) [N(3)–H(3B)···O(5W) = 2.9360 Å and
N(9)–H(5A)···O(4W) = 2.9172 Å] (Fig. 4b).
(
[
O4W) and the nitrogen atoms (N9) from the AMT ligands
N(9)–H(9A)···O(4W) = 2.9803 Å] (Fig. 5).
1
3

Transition Metal Chemistry
Fig. 6 Summary vision of structure for complexes 1–4
Inꢀuence of amines and reaction temperature
Although the syntheses of all four complexes use nickel
nitrate and AMT, diꢀerent organic amines and reaction
temperatures were used. These diꢀerences determine the
structures of complexes (Fig. 6). Firstly, in the syntheses of
complexes 1–3, the amines were ethylenediamine, trietha-
nolamine and a mixture of triethylamine and ethanolamine,
respectively. Complex 1 is a mononuclear structure; it
appears that the strong chelating eꢀect of ethylenediamine
restricts further expansion of the structure. Complexes 2
and 3 are both tetranuclear clusters, but with diꢀerences in
the lattice water molecules. Thus, there are no weak inter-
actions in complex 2 because of the absence of the lattice
water. However, in complex 3, there are four lattice water
molecules around each tetranuclear cluster, leading to forma-
tion of the ꢁnal 3D supramolecular framework by hydrogen
bonding interactions.
Fig. 7 TG curves of the complexes 1–4 under N atmosphere
2
For complexes 3 and 4, the organic amines were the same,
but the diꢀerent reaction temperatures led to diꢀerences in
1
3

Transition Metal Chemistry
Fig. 8 Absorption spectra of the MB solution during the decomposition reaction with the presence of complex 4
X‑ray powder diꢁraction and thermal stabilities
The X-ray powder diꢀraction (XRPD) patterns for com-
plexes 1–4 were obtained at room temperature. As shown
in Fig. S2, the patterns for the experimental samples match
with the simulated ones, conꢁrming the phase purities of the
samples. The diꢀerences of intensity may be caused by the
preferred orientation of the crystals [33].
In order to investigate the thermal stabilities of the com-
plexes, TG analyses were carried out in a ꢂowing nitrogen
atmosphere between 30 and 800 °C, at a heating rate of
−
1
1
0 °C min (Fig. 7). Complex 1 only displays one weight
loss step, while complexes 2–4 show two weight loss steps.
For complex 1, the main skeleton began to collapse at
2
20 °C, with a total weight loss of 74.47%. The ꢁrst weight
losses for the other complexes are 11.64% at 150–220 °C for
Fig. 9 Photocatalytic decomposition rates of MB solution under vis-
ible light irradiation with the use of the complex 4 and the control
experiment without any catalyst
2
4
, 8.66% at 130–210 °C for 3 and 12.10% at 120–225 °C for
. These can be assigned to the loss of hydroxyl groups and/
or water ligands and/or lattice water molecules (calc. 12.13%
for 2, 8.53% for 3 and 11.94% for 4). The second weight
losses of 59.85% at 220–700 °C for 2, 63.09% at 260–750 °C
for 3 and 59.67% at 230–750 °C for 4 are attributed to col-
lapse of the frameworks (calc. 62.34% for 2, 67.42% for
3 and 63.29% for 4). The residual weights (28.51% for 2,
28.25% for 3 and 28.23% for 4) correlate with NiO (calcd
25.53% for 2, 24.05% for 3 and 24.77% for 4).
the ꢁnal supramolecular structures. Complex 3 was obtained
at 110 °C and complex 4 at 130 °C. Although both com-
plexes are tetranuclear clusters, there is only one lattice
water molecule for each tetranuclear cluster of complex 4,
which aꢀects the further expansion of the 2D supramolecu-
lar structure.
1
3

Transition Metal Chemistry
2
3
.
.
Ye JW, Zhao LM, Bogale RF, Gao Y, Wang XX, Qian XM, Guo
S, Zhao JZ, Ning GL (2015) Chem Eur J 21:2029
Yu Y, Zhang XM, Ma JP, Liu QK, Wang P, Dong YB (2014)
Chem Commun 50:1444
Photocatalytic activities
Organic dyes are harmful pollutants. Their high water
solubilities make them diꢃcult to degrade by conven-
tional methods. Photocatalytic degradation is an eꢀective
method for the gradual decomposition of organic dyes into
non-polluting organic acids and carbon dioxide. Insoluble
homometallic nanoscale clusters can be eꢀective photo-
catalysts for the degradation of organic complexes [25].
Therefore, we have tested complex 4 as a representative
photocatalyst for the degradation of methyl orange (MO),
methylene blue (MB) and rhodamine B (RhB) as model
pollutants.
4. Ma Z, Wei LJ, Alegria ECBA, Martins LMDRS, Silva MFC,
Pombeiro AJL (2014) Dalton Trans 43:4048
5
6
7
8
.
.
.
.
Draksharapu A, Boersma AJ, Leising M, Meetsma A, Browne
WR, Roelfes G (2015) Dalton Trans 44:3647
Miura A, Nagao M, Takei T, Watauchi S, Mizuguchi Y, Takano
Y, Tanaka I, Kumada N (2015) Cryst Growth Des 15:39
Liu JL, Yuan K, Leng JD, Ungur L, Wernsdorfer W, Guo FS,
Chibotaru LF, Tong ML (2012) Inorg Chem 51:8538
Ghoshal D, Maji TK, Mostafa G, Sain S, Lu TH, Ribas J, Zan-
grandoe E, Chaudhuri NR (2004) DaltonTrans 11:1687
9. Nomura M (2011) Dalton Trans 40:2112
1
0. Cruz H, Gallardo I, Guirado G (2011) Green Chem 13:2531
1. Zhao Q, Liu SJ, Shi M, Li FY, Jing H, Yi T, Huang C (2007)
Organometallics 26:5922
1
1
Under visible light irradiation, no signiꢁcant degrada-
tion of MO could be observed upon adding complex 4 or
without any catalyst (Fig. S3a, b). When the dye was MB,
the degradation rate was increased from 25.2% (without
any photocatalyst) to 31.6% after 180 min of photoirradia-
tion. Hence, complex 4 exhibits a limited photocatalytic
activity for the degradation of MB (Figs. 8a, b, 9). When
the dye was RhB, the degradation rate of RhB increased
from 14.6% (without any photocatalyst) to 15.8% after
2. Xiong SS, He YB, Krishna R, Chen BL, Wang Z (2013) Cryst
Growth Des 13:2670
1
1
3. Yang XC, Xu Q (2017) Cryst Growth Des 17:1450
4. Mu B, Li CX, Song M, Ren YL, Huang RD (2016) CrystEng-
Comm 18:3086
1
5. Guo J, Yang J, Liu YY, Ma JF (2012) CrystEngComm 14:6609
16. Wang HH, Yang J, Liu YY, Song S, Ma JF (2015) Cryst Growth
Des 15:4986
1
7. Adeyemo AA, Adeoye IO, Bello OS (2012) Toxicol Environ
Chem 94:1846
1
80 min of photoirradiation, which is within the experi-
1
8. Levec J, Pintar A (2007) Catal Today 124:172
mental error (Figs. S3c, d, S4).
19. Ali I, Asim M, Khan TA (2012) J Environ Manage 113:170
2
0. Wang XL, Sui FF, Lin HY, Zhang JW, Liu GC (2014) Cryst
Growth Des 14:3438
XRPD tests showed that the pattern for complex 4 was
unchanged after the photocatalytic experiment, indicating
that the complex has good photocatalytic stability (Fig.
S2).
2
1. Guo LA, Huang C, Liu L, Shao ZC, Tong Y, Hou HW, Fan YT
(
2016) Cryst Growth Des 16:4926
22. Wang CC, Li JR, Lv XL, Zhang YQ, Guo GS (2014) Energy
Environ Sci 7:2831
2
3. Chen L, Gao Y, Cheng YK, Li HC, Wang ZG, Li ZQ, Zhang RQ
(
2016) Nanoscale 8:4086
2
4. Bi YF, Wang ST, Liu M, Duab SC, Liao WP (2013) Chem Com-
mun 49:6785
Conclusion
2
2
5. Mu B, Wang Q, Huang RD (2016) RSC Adv 6:12114
6. Gong WJ, Liu YY, Yang J, Wu H, Ma JF, Xie TF (2013) Dalton
Trans 42:3304
In summary, the one-pot solvothermal system was used to
prepare four diꢀerent complexes of metal Ni(II) with AMT.
Complex 4 shows limited photocatalytic selectivity for the
degradation of some organic dyes.
2
2
7. He KH, Li YW, Chen YQ, Song WC, Bu XH (2012) Cryst
Growth Des 12:2730
8. Chen WC, Yan LK, Wu CX, Wang XL, Shao KZ, Su ZM, Wang
EB (2014) Cryst Growth Des 14:5099
2
3
9. Maiti N, Chadha R, Das A, Kapoor S (2016) RSC Adv 6:62529
0. Huang L, Tang F, Hu BX, Shen J, Yu T, Meng QJ (2001) J Phys
Chem B 105:7984
Acknowledgements This work was supported by the Program for
National Nature Science Foundation of China (Nos. 21271024 and
2
0971014) and Foundation the 111 Project (B07012) in China.
3
3
1. Farias RF, Nunes LM (2001) Transition Met Chem 26:477
2. Sheldrick GM (2008) Acta Crystallogr Sect A: Found Crystallogr
6
4:112
3
3. Wu BL, Wang S, Wang RY, Xu JX, Yuan DQ, Hou HW (2013)
Cryst Growth Des 13:518
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