Two luminescent cobalt(II) coordination polymers for selective sensing of MnO4? in water

Article abstract of DOI:10.1007/s11243-018-0248-y

Two luminescent Co(II)-based coordination polymers (CPs) with the formulae of [Co(L1)(1,4-ndc)·H₂O]_n (CP 1) and [Co₂(L2)(1,4-chdc)₂]_n (CP 2) (L1 = 1,1′-(1,4-butanediyl)bis(5,6-dimethylbenzimidazole), 1,4-H₂ndc = 1,4-naphthalenedicarboxylic acid, L2 = 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole), 1,4-H₂chdc = 1,4-cyclohexanedioic acid) have been synthesized. Both CPs were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, elemental analysis, IR spectroscopy, and powder X-ray diffraction. CP 1 reveals a 2D 3,5L2 framework, while CP 2 has a 2D (4,5)-connected 4,5L51 network. Both CPs are luminescent and can be employed for the selective detection of free MnO₄^? in water.

Full text of DOI:10.1007/s11243-018-0248-y

Transition Metal Chemistry
https://doi.org/10.1007/s11243-018-0248-y
Two luminescent cobalt(II) coordination polymers for selective sensing
−
of MnO in water
4
1
1
1
1
Xiao‑Xue Zhao · Zhan‑Bin Qin · Yue‑Hua Li · Guang‑Hua Cui
Received: 21 April 2018 / Accepted: 16 May 2018
©
Springer International Publishing AG, part of Springer Nature 2018
Abstract
Two luminescent Co(II)-based coordination polymers (CPs) with the formulae of [Co(L1)(1,4-ndc)·H O] (CP 1) and
2
n
[
Co (L2)(1,4-chdc) ] (CP 2) (L1=1,1′-(1,4-butanediyl)bis(5,6-dimethylbenzimidazole), 1,4-H ndc=1,4-naphthalenedi-
2
2 n
2
carboxylic acid, L2=1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole), 1,4-H chdc=1,4-cyclohexanedioic acid) have been
2
synthesized. Both CPs were characterized by single-crystal X-ray diꢀraction, thermogravimetric analysis, elemental analysis,
IR spectroscopy, and powder X-ray diꢀraction. CP 1 reveals a 2D 3,5L2 framework, while CP 2 has a 2D (4,5)-connected
−
4
,5L51 network. Both CPs are luminescent and can be employed for the selective detection of free MnO in water.
4
Introduction
the synthesis of CPs, on account of the free rotation of the
benzimidazole units around the alkyl spacers, which allow
varying coordination modes to suit the coordination geom-
etry of the metal centers [8–12].
As a member of the family of porous solid materials, coor-
dination polymers (CPs) have attracted much attention in
the ꢁelds of supramolecular and materials chemistry. Due
to their structural and chemical tunability, as well as high
surface areas, CPs are widely used in gas storage and separa-
tion, drug delivery, environmental monitoring, ion exchange,
proton conduction, and chemical sensing [1–5]. However,
the rational construction of CPs with speciꢁc properties
remains a challenge. The architecture of CPs is inꢂuenced
by many factors, which include the ꢂexibility or rigidity of
the bridging ligand, coordination preferences of the metal,
and other reaction conditions (ligand-to-metal ratio, pH, sol-
vent) [6, 7]. In general, the structures and properties of CPs
can be adjusted through rational selection of organic ligands.
In particular, the bis(benzimidazole) ligands with ꢂexible
spacers are widely employed as typical N-donor ligands in
Permanganate has found widespread use for the puriꢁca-
tion of drinking water from contamination by microorgan-
isms [13]. However, residual permanganate in the treated
water can cause stomach upsets, hypotension, kidney injury,
and cardiovascular collapse [14, 15]. Conventional methods
for the detection of permanganate, which include atomic
absorption spectrometry (AAS), spectrophotometry, vol-
tammetry, chromatography, and inductively coupled plasma
(ICA), need expensive instrumentation and complicated
methodology [16–20]. Hence, chemical sensors based
on luminescent CPs have received considerable attention
because of their low cost, high selectivity, quick response,
and good reversibility [21, 22]. For instance, Yan and co-
workers reported a CP whose ꢂuorescence emission could
−
be selectively quenched by MnO [23].
4
Based on the above considerations, we synthesized
two new Co(II) CPs based on ꢂexible bis(benzimidazole)
ligands, namely [Co(L1)(1,4-ndc)·H O] (CP 1) and
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s11243-018-0248-y) contains
supplementary material, which is available to authorized users.
2
n
[
Co (L2)(1,4-chdc) ] (CP 2) (L1 = 1,1′-(1,4-butanediyl)
2
2 n
bis(5,6-dimethylbenzimidazole), L2=1,1′-(1,4-butanediyl)
*
Guang-Hua Cui
tscghua@126.com
bis(2-methylbenzimidazole), 1,4-H ndc = 1,4-naphtha-
2
lenedicarboxylic acid, 1,4-H chdc = 1,4-cyclohexanedioic
1
2
College of Chemical Engineering, Hebei Key
Laboratory for Environment Photocatalytic
and Electrocatalytic Materials, North China University
of Science and Technology, No. 21 Bohai Road,
Caofeidian New-City, Tangshan, Hebei 063210,
People’s Republic of China
acid). Both of these CPs proved to be eꢀective luminescent
−
sensors toward MnO anion. Their thermal stabilities have
4
also been investigated.
Vol.:(0
1
123456789)
3

Transition Metal Chemistry
Experimental
mixture was heated at 140 °C for 72 h. After cooling to
room temperature, red block crystals of CP 1 were col-
lected in 44.1% yield based on Co. Elemental analysis (%)
for C H CoN O (F =637.58): calcd, C, 64.1; H, 5.4; N,
Materials and methods
3
4
34
4
5
w
−
1
The proligands L1 and L2 (Scheme 1) were synthesized
according to the literature procedures [24, 25]. Other starting
materials were purchased from Beijing InnoChem Science
and Technology Co., Ltd and used without further puriꢁca-
tion. IR spectra were obtained on an Avatar 360 (Nicolet)
8.8%. Found: C, 63.9; H, 5.2; N, 8.6%. IR (KBr, cm ):
3427 s. 1607 s, 1575 s, 1539 m, 1510 s, 1459 w, 1404 s,
1363 s, 1261 w, 1208 w, 802 m.
Synthesis of [Co2(L2)(1,4‑chdc)2]n
−
1
spectrophotometer in the range of 400–4000 cm . PXRD
measurements were obtained on a PANalytical Empyrean
diꢀractometer at 40 mA, 40 kV with Cu-target radiation
Co(OAc)2·4H2O (0.2 mmol, 49.8 mg), L2 proligand
(0.1 mmol, 33 mg), 1,4-H2chdc (0.2 mmol, 32.4 mg), and
NaOH (0.2 mmol, 8.0 mg) were mixed with distilled water
(10 mL) and heated at 140 °C for 72 h. Pink crystals of
CP 2 were obtained with 47.5% yield (based on Co). Anal.
Calcd for C18H21CoN2O4 (Fw =388.30): C, 55.7; H, 5.5; N,
(
λ=1.5418 Å) over the 2θ range of 5°–50°. Elemental analy-
ses for C, H and N were obtained with on a Perkin-Elmer
40C instrument. Thermogravimetric analysis (TGA) was
2
−
1
carried out under a nitrogen gas ꢂow of 30 mL min with a
−
1
−1
heating rate of 10 °C min on a Netzsch STA449 F1 ther-
mogravimetric analyzer. Luminescence spectra were meas-
ured at room temperature with an FS5 Edinburgh lumines-
cence spectrometer in the solid state.
7.2%. Found: C, 55.6; H, 5.6; N, 7.3%. IR (KBr, cm ):
1589 s, 1509 m, 1451 w, 1409 s, 1292 w, 768 m, 737 s.
X‑ray crystallography
X-ray single-crystal diꢀraction data for CPs 1 and 2 were
Synthesis of [Co(L1)(1,4‑ndc)·H O]
collected on a Bruker SMART 1000 CCD diꢀractometer at
2
n
2
96 K with Mo-K radiation (λ=0.71073 Å) by the mode
α
Co(OAc) ·4H O (0.2 mmol, 49.6 mg), 1,4-H ndc (0.2 mmol,
of ω scan. Empirical absorption corrections were applied to
raw intensities with the SADABS program, and the SAINT
program was used for integration of the diꢀraction proꢁles
[26, 27]. Both structures were solved by direct methods
2
2
2
4
3.2 mg), the L1 proligand (0.1 mmol, 34.6 mg), and NaOH
(
0.2 mmol, 8.0 mg) were added to distilled water (10 mL)
and sealed in a 25 mL Teꢂon lined steel container. The
Scheme 1 Structural formulae of L1, L2, 1,4-H ndc and 1,4-H chdc
2
2
1
3

Transition Metal Chemistry
using the SHELXT-2016 program and subsequently reꢁned
Results and discussion
2
by full-matrix least-squares techniques based on F with
the SHELXTL crystallographic software package [28]. The
hydrogen atoms of the water molecules were located from a
diꢀerence Fourier map and reꢁned with constraints, while
the hydrogen atoms of the organic ligands were associated
with their parent atoms and reꢁned isotropically with ꢁxed
thermal factors. The relevant crystallographic data for CPs 1
and 2 is given in Table 1. Selected bond lengths and angles
are provided in Table 2. In CP 1, two carbon atoms (C23,
C24) were both disordered over two sites; the occupancies
have been freely reꢁned, but constrained to equal 1. Values
are approximately 68 and 32%.
Crystal structure of CP 1
The crystal structure of CP 1, formulated as [Co(L1)
(1,4-ndc)·H O] , with the atom labeling is shown in Fig. 1a.
2
n
CP 1 crystallizes in the monoclinic system with the space
group P2 /n. There are one Co(II) center, one L1 ligand,
1
2
−
one 1,4-ndc ligand and one coordinated water ligand in
the asymmetric unit of CP 1. Each Co(II) center is six coor-
dinated by four oxygen atoms (O1A, O2, O3B, O1W, sym-
metry code: A=−x, −y+1, −z; B=x, y, z+1) from three
2−
diꢀerent 1,4-ndc anions plus one coordinated water ligand,
as well as two nitrogen atoms (N1, N4C, symmetry code:
C=x−1/2, −y+3/2, z−1/2) from two separate L1 ligands,
in a distorted octahedral geometry. The Co–O bond lengths
vary from 2.053(3) to 2.272(3) Å, while the Co–N bond dis-
tances are 2.125(3) and 2.130(3) Å; these values are similar
to those found in related cobalt(II) CPs [29, 30].
Fluorescence quenching experiments
The inorganic salts were dissolved in deionized water
−
3
(
100 mL) to aꢀord 2 × 10 M aqueous solutions. Anion
solutions were obtained from K CO , KCl, K S O , KBr,
2
3
2
2
8
2
−
KClO , KBrO , KIO , and KMnO in deionized water. Sam-
As shown in Figure S1a and S1b, each 1,4-ndc dianion
coordinates to three Co(II) atoms, with its deprotonated car-
3
3
3
4
ples of CP 1 and CP 2 (4 mg) were ground into powders and
suspended in 4 mL of the aqueous salt solutions, exposed
to ultrasonic radiation for 30 min, and then aged for 10 h to
generate stable suspensions.
1
1
1
0
boxylate groups adopting (κ −κ )−(κ −κ )−μ coordina-
3
tion mode, generating a 1D inꢁnite ladder chain along the b
2
−
axis. Two pairs of 1,4-ndc ligands are linked together by
Table 1 Crystallographic data
CPs
1
2
and experimental details for
CPs 1 and 2
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C H CoN O
637.58
Monoclinic
P2 /n
13.686(3)
11.349(2)
18.915(3)
90
C H CoN O
4
388.3
Monoclinic
P2 /c
10.6347(10)
8.7996(7)
17.570(2)
90
3
4
34
4
5
18 21
2
1
1
α (°)
β (°)
γ (°)
V (Å )
93.599(4)
90
2932.1(9)
4
1.444
0.636
101.353(3)
90
1612.0(2)
4
1.600
1.092
3
Z
Dcalcd (g/cm3)
Absorption coeꢃcient (mm−1)
F(000)
1332
808
Crystal size (mm)
θ range (deg)
Index range h, k, l
Reꢂections collected
Independent reꢂections (Rint)
Data/restraint/parameters
0.27×0.25×0.23
2.333–24.999
−16/16, −13/13, −22/22
41,105
5165 (0.1582)
5165/37/421
0.24×0.22×0.18
2.755–28.340
−14/14, −11/11, −23/18
24,939
4020 (0.0900)
4020/0/227
2
Goodness-of-ꢁt on F
1.008
1.096
Final R , wR (I>2σ(I))
Largest diꢀ. peak and hole
0.0619, 0.1227
0.551, −0.462
0.0619, 0.1212
0.975, −0.540
1
2
1
3

Transition Metal Chemistry
Table 2 The selected bond lengths (Å) and angles (°) for CP 1 and
CP 2
CP 1
Co1-O1A
Co1-O2
2.073(3)
2.053(3)
Co1-O1W
Co1-N1
2.272(3)
2.125(3)
Co1-O3B
2.062(3)
Co1-N4C
2.130(3)
O2-Co1-O3B
O2-Co1-O1A
O3B-Co1-O1A
O2-Co1-N1
O1A-Co1-N4C
O2-Co1-O1W
O1A-Co1-O1W
N4C-Co1-O1W
166.42(11)
96.04(10)
96.86(10)
88.93(11)
89.85(12)
82.04(10)
176.25(11)
93.55(12)
O3B-Co1-N1
O1A-Co1-N1
O2-Co1-N4C
O3B-Co1-N4C
N1-Co1-N4C
O3B-Co1-O1W
N1-Co1-O1W
86.92(11)
89.62(12)
95.96(12)
88.31(12)
175.11(12)
84.84(10)
87.13(12)
CP 2
Co1-O1
2.031(2)
2.034(2)
Co1-N1
Co1-O3B
2.067(3)
2.214(3)
Co1-O2A
Co1-O4D
2.060(3)
Co1-O3D
2.393(3)
O1-Co1-O2A
O2A-Co1-O4
O2A-Co1-N1
O1-Co1-O3B
O4D-Co1-O3B
O1-Co1-O3D
O4-Co1-O3D
O3B-Co1-O3D
162.05(11)
91.03(11)
99.96(11)
82.13(11)
161.66(11)
85.74(10)
58.49(10)
103.18(9)
O1-Co1-O4D
O1-Co1-N1
O4D-Co1-N1
O2A-Co1-O3B
N1-Co1-O3B
O2A-Co1-O3D
N1-Co1-O3D
96.11(11)
93.45(11)
108.14(12)
85.92(10)
90.19(11)
84.00(10)
166.33(11)
Symmetry codes for CP 1: A=−x, −y+1, −z; B=x, y, z+1;
C=x−1/2, −y+3/2, z−1/2. Symmetry codes for CP 2: A=−x+1,
−
y+2, −z+1; B=−x+1, −y+1, −z+1; D=x, y+1, z
two Co(II) centers to form a binuclear [Co (COO) ] cluster,
2
2
with a Co···Co distance of 4.721(1) Å. The L1 ligands adopt
3
3
a trans-conformation, with a N
···N–C ···C torsion angle
donor
sp
sp
of 177.52(3)°, and bridge Co(II) centers to form a zigzag
chain with a Co···Co distance of 11.61(2) Å (Figure S1c).
The two kinds of chains are linked together by shared Co(II)
centers, yielding a 2D layer (Fig. 1b). To further describe the
structure of CP 1, the topological analysis approach has been
applied by using TOPOS 4.0 software [31]. The network of
CP 1 can be represented as a (3,5)-connected 3,5L2 topol-
2
7
2
ogy with the point symbol (4 .6 .8)(4 .6) by denoting the
2
−
1
,4-ndc ligands as three-connected nodes and the Co(II)
center as ꢁve-connected nodes (Fig. 1c).
Fig. 1 a The coordination environment of the Co(II) center in CP 1
with 30% thermal ellipsoids. Hydrogen atoms are omitted for clar-
ity (symmetry codes: A=−x, −y+1, −z; B=x, y+1, z; C=x−1/2,
Crystal structure of CP 2
−
y+3/2, z−1/2); b view of 2D framework of CP 1; c The 2D
CP 2 [Co (L2)(1,4-chdc) ] crystallizes in the mono-
2
2 n
2 7 2
(
3,5)-connected (4 .6 .8)(4 .6) 3,5L2 sheet of CP 1
clinic space group P2 /c. The asymmetric unit contains
1
one independent Co(II) center, one fully deprotonated
2
−
2−
1
,4-chdc ligand, and half of an L2 ligand. As shown in
four different 1,4-chdc ligands (Co1–O1 = 2.031(2),
Co1–O2A = 2. 034(2), Co1–O3D = 2. 214(3),
Co1–O4D = 2.060(3), Co1–O3B = 2.214(3), symmetry
Fig. 2a, the Co(II) center has a distorted octahedral coor-
dination geometry, provided by ꢁve oxygen atoms from
1
3

Transition Metal Chemistry
2−
In CP 2, the fully deprotonated, anionic 1,4-chdc ligand
1
1
2
1
adopts a (κ −κ )−(κ −κ )−μ coordination mode (Figure
4
S2a). As illustrated in Figure S2b, the carboxylate groups
2
−
of the 1,4-chdc ligands bridge two Co(II) centers into a
binuclear [Co (COO) ] secondary building unit (SBU) with
2
4
a Co···Co separation of 2.866(8) Å. These SBUs link to each
2−
other via 1,4-chdc ligands, resulting in an inꢁnite 1D chain
Figure S2c). The adjacent nonbonding Co···Co distances
(
are 8.799(9) Å between neighboring [Co (COO) ] SBUs.
2
4
The L2 ligands, in a trans-conformation, bridge the Co(II)
centers to propagate the chains in a linear manner, which
2
−
are in turn connected through 1,4-chdc ligands to gener-
ate a 2D network (Fig. 2b). From the topological viewpoint,
the network of CP 2 is constructed from the 4-connected
2−
1
,4-chdc ligand nodes and 5-connected Co(II) nodes. This
net can be classiꢁed as a 4,5-connected layer of the 4,5L51
topological framework (Fig. 2c).
IR spectra and PXRD patterns
The main features of the IR spectra of CPs 1 and 2 are asso-
ciated with the N-donor ligands and the carboxylate groups
2
−
2−
of the 1,4-ndc or 1,4-chdc ligands. For CP 1, the strong
−
1
peak at 3425 cm is attributed to the O–H stretching of
−
1
the coordinated water. Peaks around 1700 cm are not
observed, conꢁrming that all carboxylate groups of both
CP 1 and CP 2 are fully deprotonated. Strong characteristic
−
1
bands at 1607 and 1404 cm for CP 1 and 1589, 1348 and
−
1
1
478 cm for CP 2 belong to the asymmetric and sym-
metric vibrations of the carboxylate groups. The separa-
tions ∆ν[ν (COO)–ν (COO)] of these bands are typical of
as
s
−
1
monodentate carboxylate coordination for CP 1 (203 cm )
−
1
and chelate/monodentate coordination (111 and 241 cm )
−1
for CP 2. The characteristic peaks at 1510 cm for CP 1 and
−
1
1
509 cm for CP 2 are assigned to the ν(C=N) stretching
vibrations of the benzimidazole rings [32, 33].
Powder X-ray diꢀraction (PXRD) patterns for the as-
synthesized CP 1 and CP 2 are consistent with the simu-
lated patterns except for intensity diꢀerences, which can be
ascribed to the diꢀerent orientations of the crystals in the
powder samples. Hence, bulk samples of both CPs show
good phase purity (Figure S3).
Fig. 2 a Coordination environment of the Co(II) center in CP 2
with 30% thermal ellipsoids. Hydrogen atoms are omitted for clar-
ity, (symmetry codes: A=−x+1, −y+2, −z+1, B=−x+1, −y+1,
−
z+1, C=−x, −y+1, −z+1, D=x, y+1, z); b 2D layer of CP 2
Thermal stability
2
−
constructed by Co(II) centers, 1,4-chdc ligands, and L2 ligands; c
schematic representation of (4,5)-connected 4,5L51 topology frame-
work for the CP 2
Thermogravimetric analysis (TGA) of both CPs was carried
out. As shown in Fig. 3, the TGA curves show that CPs 1
and 2 are stable up to 81 and 417 °C, respectively. For CP
1, the ꢁrst weight loss of 2.7% in the range of 81–373 °C
corresponds to gradual removal of a water molecule (calcd:
2.8%). The host framework subsequently decomposed at
373–723 °C (calcd: 85.4%, obsd: 84.7%), leaving a resi-
due of CoO 12.6% (calcd. 11.8%). For CP 2, the L2 and
code: A=−x+1, −y+2, −z+1; B=−x+1, −y+1, −z+1;
D=x, y+1, z) together with one nitrogen atom from an L2
ligand (Co1–N1=2.067(3)). The bond distances are all in
the normal ranges, and comparable to those found in similar
cobalt CPs [29, 30].
1
3

Transition Metal Chemistry
Compared with the L1 and L2 proligands, the obvious red-
shift of 49 nm for CP 1 and blue-shift of 10 nm for CP 2 may
be attributed to LMCT and π*→π, respectively [34, 35].
−
MnO sensing properties
4
The evident luminescent properties of CPs 1 and 2 prompted
us to investigate their possible application for the detection
of anions in aqueous solution. The luminescence quenching
behavior of CP 1 and CP 2 was investigated in the presence
2
−
−
2−
−
of a range of anions, speciꢁcally CO , Cl , S O , Br ,
3
2
8
−
−
−
−
MnO , ClO , BrO , and IO . The luminescence inten-
4
3
3
3
sities of both CPs in response to various anions in aqueous
solution are shown in Fig. 5. Obviously, most anions show
a negligible inꢂuence on the emission intensity. However,
−
the addition of MnO anion has a distinct quenching eꢀect
Fig. 3 TGA curves of CPs 1 and 2
4
2
−
1
4
2
,4-chdc ligands decomposed in the temperature range of
17 – 680 °C (calcd: 80.7%, obsd: 78.9%). The residue of
1.1% (calcd: 19.3%) matched with CoO.
Luminescence properties
The luminescence of CPs 1 and 2, as well as the free pro-
ligands L1, L2, 1,4-H ndc, and 1,4-H chdc were studied in
2
2
the solid state at room temperature (Fig. 4). L1 and L2 gave
maximum emission peaks at 316 and 306 nm upon excita-
tion at 279 and 284 nm, respectively. For free 1,4-H cndc,
2
the main emission peak was at 326 nm (λ =296 nm), while
ex
free 1,4-H ndc gave a maximum at 492 nm (λ =297 nm);
2
ex
these can be assigned to n → π* or π → π* transitions.
Intense emission bands were found at 365 (at λ =302 nm)
ex
and 296 nm (at λ =257 nm) for CPs 1 and 2, respectively.
ex
Fig. 5 a The luminescent intensities of CP 1 on addition of diꢀerent
Fig. 4 Solid-state emission spectra of CPs 1–2 and L1 as well as L2
anions in H O solution; b the luminescent intensities of CP 2 on addi-
2
ligands at room temperature
tion of diꢀerent anions in H O solution
2
1
3

Transition Metal Chemistry
on the luminescence of both CPs, such that the quenching
between quenching efficiency and the concentration
−
eꢃciency reaches 99.4% for CP 1 and 98.7% for CP 2. To
of MnO (Fig. 7). The quenching efficiency was well
4
−
investigate the selectivity of MnO over the other anions,
described by the Stern–Volmer equation;
4
anti-interference sensing experiments were carried out in
the presence of other anions. The quenching efficiency
was found to be unaꢀected by any other anions (Figure
I ∕I = 1 + K M
0
(1)
sv
where K is the quenching constant, M is the concentration
sv
−
of MnO anion, and I and I are the luminescence intensities
S4). These results suggest that both of these CPs can act as
4
0
−
of each CP before and after exposure to the anion, respec-
luminescent probes for the detection of MnO even in the
4
5
−1
tively [36]. The K values were obtained as 2.83×10 M
presence of other anions.
sv
4
−1
for CP 1 and 1.63 × 10 M for CP 2. The detection lim-
In order to examine the sensitivities of the CPs for
−
−
−
its for MnO were calculated by the equation: detection
the MnO anion, diꢀerent concentrations MnO anion
4
4
4
limit=3σ/k (k: slope, σ: stand) and the limits of detection
from 0.1 to 0.6 mM were investigated. The results dem-
−
−4
for the MnO anion were obtained as 1.4×10 M for CP
onstrated that the luminescent intensities of CPs 1 and 2
4
−
4
−
1 and 1.2×10 M for CP 2.
both decreased gradually with increasing MnO anion
4
PXRD and UV–vis spectroscopy were employed in
order to study the possible sensing mechanism. Firstly, the
PXRD spectra (Figure S5) of both CPs dispersed in aqueous
concentration (Fig. 6). There is a good linear relationship
Fig. 6 a Emission spectra of CP 1 dispersed in various concentrations
Fig. 7 a Linear Stern–Volmer curve in the low concentration range of
−
−
of MnO ions; b emission spectra of CP 2 dispersed in various con-
the MnO ion for CP 1; b linear Stern–Volmer curve in the low con-
4
4
−
−
centrations of MnO ion
centration range of the MnO ion for CP 2
4
4
1
3

Transition Metal Chemistry
−
solutions of MnO were measured. The results showed that
7. Wang SL, Hu FL, Zhou JY, Zhou Y, Huang Q, Lang JP (2015)
Cryst Growth Des 15:4087–4097
4
the 2D networks of both CPs were stable in the presence of
8
.
Yu XY, Fu Y, Fu JT, Xu JN, Luo YN, Yang YY, Qu XS, Zhang J,
Lu SL (2018) J Mol Struct 1157:530–535
−
MnO . Next, UV–vis spectra of aqueous suspensious of
4
−
both CPs in the presence of MnO were recorded (Figure
9. Hao JM, Yu BY, Van Hecke K, Cui GH (2015) CrystEngComm
17:2279–2293
4
−
S6). There were overlaps between MnO and CPs 1 and
4
1
0. Jiao CH, He CH, Geng JC, Cui GH (2011) Transit Metal Chem
2
in the ranges of 265–320 and 230–290 nm, respectively,
3
7:17–23
which suggests that eꢃcient quenching occurs by com-
1
1. Huan DH, Yu YM, Wang SC, Dong GY (2015) Z Anorg Allg
Chem 641:1899–1905
petitive absorption of the excitation wavelength energy by
−
MnO anion versus CP 1 and CP 2 [37–39].
12. Li LL, Li HX, Ren ZG, Liu D, Chen Y, Zhang Y, Lang JP (2009)
Dalton Trans 40:8567–8573
4
1
1
1
1
3. Lalezary S, Pirbazari M, Mcguire MJ (1986) J Am Water Works
Assoc 78:62–69
4. Korkut E, Saritas A, Aydin Y, Korkut S, Kandis H, Baltaci D
(2013) World J Emerg Med 4:73–74
Conclusions
5. Ong KL, Tan TH, Cheung WL (1997) J Accid Emerg Med
1
4:43–45
Two new 2D coordination polymers [Co(L1)
6. Ding B, Liu SX, Cheng Y, Guo C, Wu XX, Guo JH, Liu YY, Li
Y (2016) Inorg Chem 55:4391–4402
(
1,4-ndc)·H O] (CP 1) and [Co (L2)(1,4-chdc) ] (CP
2
n
2
2 n
2
) were synthesized and characterized. Both CPs shows
17. Song EJ, Kang J, You GR, Park GJ, Kim Y, Kim SJ, Kim C, Har-
rison RG (2013) Dalton Trans 42:15514–15520
−
selective detection capability toward MnO . The selectiv-
4
1
8. Tesfaldet ZO, Van Staden JF, Stefan RI (2004) Talanta
ity is ascribed to the competitive absorption of the excit-
6
4:1189–1195
ing radiation. The detection limits for CPs 1 and 2, of
19. Ganjali MR, Gupta VK, Hosseini M, Rafiei-Sarmazdeh Z,
Faridbod F, Goldooz H, Badiei AR, Norouzi P (2012) Talanta
−
4
−4
1
.4 × 10 M and 1.2 × 10 M, respectively, suggest that
8
8:684–688
they could ꢁnd application as luminescence sensing probes
for permanganate ion.
2
2
2
0. Yang YJ, Wang M, Zhang KL (2016) J Mater Chem
:11404–11418
1. Lustig WP, Mukherjee S, Rudd ND, Desai AV, Li J, Ghosh SK
4
(
2017) Chem Soc Rev 46:3242–3285
2. Wang L, Yao ZQ, Ren GJ, Han SD, Hu TL, Bu XH (2016) Inorg
Chem Commun 65:9–12
Supplementary data
2
2
3. Wu JX, Yan B (2017) J Colloid Interface Sci 504:197–205
4. Wang XX, Hao JM, Li GY, Cui GH (2015) J Chem Crystallogr
45:77–85
CCDC 1811517 and 1811518 contains the supplementary
crystallographic data for the CP 1 and CP 2. These data
can be obtained free of charge via http://www.ccdc.cam.
ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge CB2
2
2
5. Hao SY, Hao ZC, Liu YG, Dong GY (2017) Chinese J Struct
Chem 36:118–126
6. Slagle JR (1963) J ACM 10:507–520
27. Sheldrick GM (1996) Tammanstrasse 4:1999–2003
28. Sheldrick GM (2015) Acta Crystallogr Sect A: Found Crystallogr
7
1:3–8
1
EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@
2
3
9. Shao ZC, Huang C, Han X, Wang HR, Li AR, Han YB, Li K, Hou
HW, Fan YT (2015) Dalton Trans 44:12832–12838
0. Qin L, Wang ZJ, Wang T, Zheng HG, Chen JX (2014) Dalton
Trans 43:12528–12535
ccdc.cam.ac.uk.
Acknowledgements The project was supported by the National Natural
Science Foundation of China (51474086), Natural Science Founda-
tion—Steel and Iron Foundation of Hebei Province (B2015209299).
31. Blatov VA, Shevchenko AP, Proserpio DM (2014) Cryst Growth
Des 14:3576–3586
3
3
3
2. Qin L, Li GY, Zheng J, Xiao SL, Cui GH (2013) J Inorg Orga-
nomet Polym Mater 23:1266–1273
3. Zhang X, Dong GY, Liu YG, Cui GH (2015) J Inorg Organomet
Polym Mater 26:62–68
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