Effective luminescence sensing of Fe3+, Cr2O72-, MnO4- and 4-nitrophenol by lanthanide metal-organic frameworks with a new topology type

Article abstract of DOI:10.1039/c9dt01907c

Lanthanide MOFs (Ln-MOFs), {[Ln₂(L)₂(H₂O)₂]·5H₂O·6DMAC}_n, [Ln = Eu(1) and Tb(2); H₃L = 4,4′-(((5-carboxy-1,3-phenylene)bis(azanediyl))bis(carbonyl)) dibenzoic acid, DMAC = N,N′-d

Full text of DOI:10.1039/c9dt01907c

View Article Online
View Journal
Dalton
Transactions
An international journal of inorganic chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: J. Ma and W. Liu,
Dalton Trans., 2019, DOI: 10.1039/C9DT01907C.
Volume 46
Number 10
14 March 2017
Pages 3073-3412
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Dalton
Transactions
An international journal of inorganic chemistry
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
rsc.li/dalton
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
ISSN 0306-0012
COMMUNICATION
Douglas W. Stephen et al.
shall the Royal Society of Chemistry be held responsible for any errors
N-Heterocyclic carbene stabilized parent sulfenyl, selenenyl,
and tellurenyl cations (XH+, X = S, Se, Te)
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
rsc.li/dalton

Please do not adjust margins
Page 1 of 9
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT01907C
ARTICLE
Effective Luminescence Sensing of Fe3+, Cr2O7 , MnO4 and 4-
nitrophenol by A New Topology Type of Lanthanide Metal-organic
Frameworks
2-
-
Received 00th January 20xx,
Accepted 00th January 20xx
Jing-Jing Ma a and Wei-sheng Liu a
DOI: 10.1039/x0xx00000x
A new topology type of lanthanide MOFs (Ln-MOFs), {[Ln2(L)2(H2O)2]·5H2O·6DMAC}n, [Ln||| =Eu(1) and Tb(2); H3L = 4,4`-(((5-
carboxy-1,3-phenylene)bis(azanediyl))bis(carbonyl)) dibenzoic acid, DMAC = N,N′-dimethylacetamide], have been isolated.
Single crystal X-ray diffraction indicate that complexes1−2 are isostructural with binuclear [Eu2(COO)7]n secondary building
units as 7-connected nodes and H3L ligands as 3-connected nodes, can be viewed as a (5,7)-connected 3D framework with
a new topological point symbol of { 32 · 44 · 54 } { 34 · 46 · 56 · 65 }. Complexes1-2 exhibit an excellent luminescent sensing
response to inorganic ions Fe3+, Cr2O72-, MnO4- and 4-nitrophenol, with low detection limit and high Ksv value. Interestingly,
-
when the MnO4 ions are detected, the color of the solid sample is observed to change from yellow to brown, visually
-
indicating luminescence induction, which makes the process of detecting MnO4 ions simpler and more practical.
Moreover, by using time-resolved photoluminescence techniques, complexe1 can effectively eliminate background
fluorescence interference during detection and improve detection accuracy. Solvent luminescence studies, pH stability and
PXRD data indicate that complexes1-2 can be used as an excellent water-stable multi-response luminescence sensor for
detecting a wide variety of toxic substances. In addition, the mechanism of selective detection is explained by the energy
competition between the excitation of complexes1-2 and the ultraviolet absorption of responsive substance.
sensor, Ln-MOFs have made great progress in sensing a wide
variety of materials in many fields, such as illuminating devices,
biomedical imaging, smart light probes and sensors.1 The potential
Introduction
Metal organic frameworks (MOFs), also known as pore-coordinating
polymers (PCP), are a new class of porous crystalline materials that
are formed by the coordination of metal ions with organic ligands.1
Compared with traditional inorganic and organic polymers, MOFs
have more porosity and controllable specific surface area, especially
the adjustable pore size and variable functional groups of highly
regular pores.2 So MOFs are received more and more attention and
research from research teams,3-5 and achieved great results in
hydrogen storage,1 catalysis,6-9 optical materials,10-19 drug
delivery,20,21 magnetic,22-24 gas adsorption and separation.25-27 We
all know that lanthanide ions have excellent fluorescence
luminescence properties, for example, a long fluorescence lifetime,
large Stokes shift values, narrow emission bands and absorption
bands.28-34 The unique luminescence properties of the high
recognition ability of the guest molecule make Ln-MOFs as an
excellent candidate for fluorescence sensor, including the detection
of toxic inorganic ions and small organic molecules. As a fluorescent
of Ln-MOFs can be further exploited using time-resolved photo
luminescent technique (TRPT), which provides spectral and
temporal evolution of samples emitted after short-light pulse
illumination and is widely used as a clinical diagnostic, biomarker
and luminescent probe.35-37 By applying an appropriate time delay
using TRPT, long-lifetime luminescent Ln-MOFs can be effectively
eliminated from background interference in biological samples and
the environment, including scattered light and undesired short-
lived autofluorescence.38-41 Therefore, Ln-MOFs have
a good
application prospect in time-resolved luminescence detection.
Issues such as industrial waste discharge and water pollution have
become one of the problems that must be solved when protecting
the environment, because these harmful pollutants seriously
damage sustainable development and human health.31-33 Current
technical methods for effective detection of environmental
pollution are time consuming and expensive.42 Therefore, there is
an urgent need for a new material to quickly and effectively detect
environmental pollutants. The harm of iron and manganese
pollution to drinking water sources is a problem in many areas of
China.31-33 Excessive iron harms the human liver, iron-contaminated
a. Lanzhou University, Key Laboratory of Nonferrous Metals Chemistry and
Resources Utilization of Gansu Province and State Key Laboratory of Applied
Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou
730000, China
-
areas are often high-risk areas of liver disease, and excess MnO4
† Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
can cause liver and kidney damage, cancers and even deformities.
At the same time, due to Cr(VI) is widely used in industry, it is
also toxic pollutants in the environment.48-55 The US Environmental
43-47
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 2 of 9
ARTICLE
Journal Name
2-
Protection Agency classifies Cr2O7 (a potent carcinogen) as a According to the reference to synthesis of the ligand H3L (4, 4’-(((5-c
View Article Online
serious pollutant.56,57 Therefore, it is important to quickly and arboxy-1,3-phenylene)bis(azanediyl))bis(carbonyl))dibenzoicacid),
DOI: 10.1039/C9DT01907C
sensitively detect harmful ions in water. Similar works have been and sufficiently characterized(see the ESI†).68
reported. Yao et al. reported two Zn2+-based luminescent metal-
Synthesis of complexes1-2.
organic frameworks. They can effectively detect antibiotics ion and
nitro aromatic (NAC) compounds.58 Tao et al. reported a new Ln-
MOF, which can be used to detect acetone, Fe3+, Cr2O7 and 4-
nitrophenol in aqueous solutions.59 Yang et al. reported a micro
porous europium metal-organic framework (Eu-MOF), which exhibit
effective recognition of Cr2O72−, MnO4 , and Cr3+ ions and SDBS.60
Zhang et al. reported a novel UIO-66-type MOF doped with Eu3+. It
can specifically recognize Hg2+ with a detection limit of 8.26nM.61
However, the study of water-stable Ln-MOFs systems for efficient
multi-response detection of toxic contaminants is very rare.
Therefore, more research on water-stable Ln-MOFs is urgently
needed to accelerate the development of effective detection of
pollutants.16, 62-66
A mixture of La(NO3)3·6H2O (0.0112g, 0.024mmol), H3L (0.0112g,
0.023mmol), N,N-dimethylacetamide (DMAC, 4mL) and H2O (1mL)
were sealed in a Teflon-lined stainless steel container, stirred for 30
minutes to clarify the mixture, then heated at 90°C for 5 days.
Centrifuge to obtain pale yellow crystals and wash several times
with ethanol. The yield was 61%, 68% for complexes1-2,
respectively (based on H3L).
2−
−
{[Eu2(L)2(H2O)2]n·(5H2O)·(6DMAC)}n (1). Elementalanalysis (%): Calcd
for C70H94Eu2N10O29 (1843.47), C 46.28, H 5.1, N 7.6%; Found: C
45.76, H 4.599, N 7.41%. IR (KBr, cm-1): 3336 (s), 1593 (vs), 1544
(vs), 1396 (vs), 1262 (s), 1016 (w), 733 (w), 561 (w).
Our group has long been committed to study the structure and
luminescence detection properties of water-stable Ln-MOFs, and
design a new topology type of Ln-MOFs luminescence sensor. The
aromatic polycarboxylic acid organic ligand 4,4’-(((5-carboxy-1,3-
{[Tb2(L)2(H2O)2]n·(5H2O)·(6DMAC)}n (2). Elementalanalysis (%): Calcd
for C70H94Tb2N10O29 (1855.851), C 45.26, H 5.1, N 7.5%; Found: C
45.48, H 4.806, N 7.45%. IR (KBr, cm-1): 3324 (s), 1606 (vs), 1519
(vs), 1409 (vs), 1262 (s), 1006 (w), 721 (w), 587 (w).
phenylene)bis(azanediyl))bis(carbonyl))dibenzoicacid
and
La(NO3)3·6H2O are reacted by solvothermal method to obtain the
equivalent structure 3D Ln-MOFs, {[Ln2(L)2(H2O)2]·5H2O·6DMAC}n,
[Ln = Eu(1) and Tb(2); H3L = 4,4’-(((5-carboxy-1,3phenylene)bis
Solvent, pH and water stability.
|||
Disperse of 3mg ground complexes1-2 in 2mL solvent (DMAC, tert-
butanol, methanol, DMF, ethanol, isopropanol / acetonitrile, H2O)
or in 2mL aqueous solutions with different pH in the range of 4-11.
Sonicate for 30 minutes to obtain a uniformly dispersed suspension,
and perform fluorescence measurements. PXRD measurement was
performed after the samples were allowed to stand for 3 days (Fig.
S1-S4).
(azanediyl))bis(carbonyl))dibenzoic
acid,
DMAC
=
N,N′-
dimethylacetamide], have been isolated. The structure and
luminescent sensing properties of water-stable complexes1-2 are
investigated in detail. Moreover, complexe1 can effectively remove
badly scattered light and short-lived fluorescent background
interference by time-resolved photoluminescence (TRPT), and has a
good application prospect in time-resolved luminescence detection.
This work provides a very valuable basis for realizing the application
of water-stable Ln-MOFs in actual production and life.
Disperse of 3mg ground complexes1-2 in 2mL aqueous solutions.
PXRD measurement was performed after the samples were allowed
to stand for 1, 3, 5, 8 and 10 days respectively (Fig. S4).
Experimental section
Cation and anion sensing.
Materials and physical measurements
Disperse of 3mg ground complexes1-2 in 2mL aqueous solution of
M(NO3)χ (Mχ+ = Mg2+, Ag+, Ni2+, Na+, Zn2+, K+, Cu2+,Co2+, Cr3+, Ca2+,
All materials were purchased commercially. Single-crystal X-ray
diffraction data were collected on a Bruker SMART 1000 CCD
diffractometer. The structures were solved by direct methods using
SHELXTL-2017 and refined by Olex2 program.67 X-ray powder
diffraction data were obtained by PAN type X'Pert Pro
diffractometer. By using GmbH instrument to get the elemental
analyses. Luminescence properties were measured using a FSL920
-
Al3+ or Fe3+, 1×10-3mol/L) or NaX (KX) (X= I-,Ac-, SO32-,Br-, NO3 , Cl-,
CO32-,PO43-, CH3COO-, S2O32-, BO3 , C2O42-, H2PO2 , SO42-, HSO3 , CNS-,
-
-
-
MnO4 , CrO42-,or Cr2O72-, 1×10-3mol/L). Sonicate for 30 minutes to
-
obtain a uniformly dispersed suspension, and perform fluorescence
measurements.
Nitro aromatic compounds sensing
fluorescence spectrometer. By
a Bruker VERTEX 70 FTIR
spectrometer to record IR spectra. TGA analysis was performed
under a N2 atmosphere using a Netzsch STA 449 F3 Jupiter analyzer.
Disperse of 3mg ground complexes1-2 in 2mL aqueous solution of
PA, NB, 2, 4-DNT, 1, 3-DNB, 4-NP or 4-NT (1×10-3mol/L). Sonicate
for 30 minutes to obtain a uniformly dispersed suspension, and
perform fluorescence measurements.
Synthesis of H3L.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 9
Dalton Transactions
Please do not adjust margins
Journal Name
ARTICLE
Fluorescence titration studies
The emission can be attributed to the π* / n or π* / VπietwraAnrtiscilteioOnnlinine
the ligand.69-71
DOI: 10.1039/C9DT01907C
The titration experiments were carried out in this way. Ultrasonic
for 30 minutes, 3mg ground complexes1-2 were dispersed in 2mL
-
aqueous solution, and Fe3+, Cr2O72-, MnO4 or 4-NP were gradually
added to the system in an incremental manner. For all experiments
performed on complexe1, fluorescence emission data were
collected at λex = 394nm and emission wavelengths at 550~700nm;
for complexe2, fluorescence emission data were collected at λex
=
339nm and emission wavelengths at 450~650nm. When Fe3+,
-
2-
MnO4 , Cr2O7 or 4-NP was gradually added, the fluorescence
emission intensity of complexes1-2 was gradually quenched, but
the shape of the emission spectrum was not any change.
Time-Resolved Luminescence Detection
Time-resolved emission spectrum (TRES) was performed by using a
FLS920 instrument. Luminescence signals from 500 to 700nm were
collected and recorded in 5nm steps using a R928-P instrument. 59
Rhodamine 6G was added as a typical fluorescent interference with
a short emission life of 6.77ns to a solution containing Complexe1
(1mg / 2mL) in DMAC buffer (3μM). The TRES experiments before
and after the addition of 4-NP (1×10-3mol/L) were selected and
compared with 0 and 2ms delayed photoluminescence spectra.
Results and discussion
Crystal Structure
X-ray crystallographic analysis indicates that complexes1-2 are
isomorphic to the P-1 space group. As a typical example of
complexe1,
each
asymmetric
unit
consists
of
one
crystallographically independent Eu3+ ion, one deprotonated L3-
ligand, and one coordinated H2O molecule (Fig. S5). Each Eu3+ ion is
nine-coordinated by two oxygen atoms from two H2O molecules
and seven oxygen atoms from carboxyls of five H3L ligands. In the
meantime, the neighboring Eu3+ ions are bridged through oxygen
atoms from the carboxylate groups of branched organic ligand and
further form the [Eu2(COO)7]n secondary building units (SBUs) (Fig.
1a). Three carboxylate groups from L3- can coordinate to five Eu
atoms (Fig. 1b). Adjacent binuclear [Eu2(COO)7]n units are
connected by L3− to form a 1D chain, and adjacent 1D chains are
linked by ligand L3− to form a 2D network (Fig. 1c, 1d). Furthermore,
adjacent networks are further accumulated in the vertical direction
to obtain a 3D framework (Fig. 1e, S5). In this work, we have
obtained a new topology, and the 3D framework can be viewed as
(5, 7)-connected, which with a new topological point symbol of {32 ·
44 · 54} {34 · 46 · 56 · 65} (Fig. 1f).
Figure1. (a) Coordination environment of central Eu3+ ions in
complexe1 with hydrogen atoms omitted for clarity. (b)
Coordination sites of L3-. (c)1D chain. (d) 2D layer. (e) 3D
framework.
(f)
Topology.
The excitation spectrum of complexe1 is obtained by monitoring
the emission of Eu3+ ion at 619nm. In the excitation spectrum, there
is a broad excitation band of 300 to 400nm, which is designated as
the π→ π* transition of the ligands.72 Complexe1 displays
characteristic emissions at 590 and 619nm, which attribute to the
5D0 →7FJ (J =1-3) transitions of the Eu3+ ion, when excited at 394nm
Luminescent properties
5
(Fig. 2a). The emission intensity of the D0 → 7F2 transition is much
5
7
stronger than the D0→ F1 transition, which indicates that Eu3+ is
located at a low-symmetry environment.73 Because of the antenna
effect of organic ligands, energy can be well transferred from the
The solid luminescent properties of organic ligand H3L and
complexes1-2 are studied in detail. When excited at 353nm, the
organic ligand H3L show a broad emission band at 464nm (Fig. S6).
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 4 of 9
ARTICLE
Journal Name
74
ligand to the Eu3+ center.29,
The ligand-based emission band the complexes1-2. The characteristic peaks of cVoimewpAlretixcelesO1n-l2in'es
-1
DOI: 10.1039/C9DT01907C
around 550nm was not observed in complexe1 suggesting an carboxylic acid groups respectively shit to 1593, 1396cm and 1606,
efficient energy transfer from the ligand-centered excited states to 1409cm-1 belonging to the asymmetric and symmetric stretching
the Eu3+ excited states. The quantum yield and solid fluorescence vibration of the carboxylic acid group participating in the
lifetime of complexe1 were measured to provide luminescence coordination. Furthermore, it is found by comparison that the
decay of Eu3+. The luminescence quantum yield is 2.12% and the diffraction peaks observed in the PXRD pattern of the simulated
lifetime value is 341.46 µs (Fig. S7a, Table S2). When excited at λex
=
single crystal closely matched the diffraction peaks of the sample
339nm, the emission spectrum of complexe2 displays four typical XRD data, indicating that the complexes1-2 have excellent relative
Tb3+ bands at 494, 548, 588 and 624nm (Fig. 2b). These emissions purity (Fig. S9). Complexes1-2 remove the lattice water in the range
are due to the transitions 5D4→7F6, 5D4→7F4 and 5D4→7F3, of 50-110°C with
a weight loss of 6.3% (calcd.4.9%), 7.1%
correspondingly. An intense band at 548nm corresponds to a (calcd.4.8%). On heating to 200°C, further release of DMAC moieties
hypersensitive 5D4→7F5 transition due to antenna effect from results in a weight loss of 24.9% (calcd.28.4%), 26.5% (calcd.28.2%).
MOF.29, 74 The luminescence quantum yield of complexe2 is 11.61% And the organic ligand began to decompose, when the temperature
and lifetime value is 668.29μs (Fig. S7b, Table S2). rose
to
380°C
(Fig.
S10).
Figure3. (a) Luminescence intensity at 619nm of complexe1
dispersed in the aqueous solutions of different cations, when
excited at 394nm. (b) Cations selectivity of complexe1 (I0 / I) in H2O.
(c) Luminescence responses of complexe1 toward different
concentrations of Fe3+ (0-1.0mM) in H2O (λex = 394nm). (d) Stern-
Volmer plot of I0 / I versus increasing concentrations of Fe3+.
Figure2. (a) Excitation (λex = 394nm) and emission (λem = 619nm)
spectra of complexe1 at room temperature. (b) Excitation (λex
Selective sensing of cations
=
339nm) and emission (λem = 548nm) spectra of complexe2 at room
temperature.
In order to further explore the excellent photoluminescence
properties and stability of complexes1-2, we conducted a sensing
application based on the emission of Eu3+ / Tb3+ in water systems.
For example, samples of complexe1 (3mg) are separately added to
an aqueous solution of M(NO3)x and sonicated for 30 minutes to be
uniformly dispersed. Fluorescence luminescence data of the
aqueous solution of complexe1 were collected by excitation at λex
=394nm. When Fe3+ ions were added to the aqueous solution, the
characteristic emission peak of Eu3+ at 619nm was rapidly
quenched, while the other cations showed little or slight
FT-IR, PXRD analysis and Thermal stability
The FT-IR spectrum of the organic ligand H3L shows a significant
absorption broad band in the 3200-3000cm-1 region, which
corresponds to the characteristic peak of the carboxylic acid group.
By comparing the FT-IR spectra of complexes1-2, it is found that the
broadband disappeared significantly in the region of 3200-3000cm-
1, which means that Eu3+ / Tb3+ is coordinated with the carboxylic
acid group (Fig. S8). Analysis the FT-IR spectrum of H3L reveals a
strong absorption peak at 1715cm-1, which can be attributed to the
asymmetric stretching vibration of the carbonyl group. When Eu3+/
Tb3+ is coordinated to the oxygen atom of the carbonyl group, the
absorption peak at 1715cm-1 disappears in the infrared spectrum of
interference. Therefore, the complexe1 can be used as
a
fluorescence sensor to detect Fe3+ ions with high selectivity and
sensitivity, which is not interfered by other cations (Fig. S11).
Further, by comparing the PXRD spectra of the sample dispersed in
Fe3+ ions and the simulated single crystal, it is found that the peak
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 9
Dalton Transactions
Please do not adjust margins
Journal Name
ARTICLE
2-
positions of the diffraction peaks are consistent, indicating that the fluorescence titration experiment of Cr2O7 was performed. As the
View Article Online
2-
DOI: 10.1039/C9DT01907C
framework of the complexe1 remain intact during the detection to Cr2O7 (0.1mM - 10.0mM) gradually increased, the fluorescence
determine its stability (Fig. S12).
A fluorescence titration luminescence intensity of the complexe1 at 619nm gradually
experiment was performed of Fe3+. As the Fe3+ (0.1mM - 10.0mM) decreased. It is indicate that there is a good linear correlation
2-
gradually increased, the luminescence intensity of the complexe1 at between the amount of Cr2O7 and the relative fluorescence
619nm gradually decreased. It is indicate that there is a good linear intensity in a low linear range of 0-1.0mM (R2 = 0.9752). The Stern-
correlation between the amount of Fe3+ and the relative Volmer constant KSV is calculated to be 1052M-1 and the detection
fluorescence intensity in a low linear range of 0-1.0mM (R2
=
limit for Cr2O72- is 8.94×10-5M, which is at a relatively high level than
0.9021). The quenching efficiency can be quantitatively analysed the work reported in the past (Fig. 4, Table S5).51,60,62
using the Stern-Volmer (SV) equation, (I0/I)=KSV[M] + 1 where I0 and
The fluorescence emission spectrum of the complexe2 was
collected by excitation at λex = 339nm. When MnO4 ions were
I are the fluorescence intensities before and after the additions of
the analyte, respectively, KSV is the quenching constant, and [M] is
the concentration of the analyte. KSV calculated by SV equation is
5941M-1 and the detection limit of Fe3+ is 10-5mM, which is at a
relatively high level than the work reported in the past (Fig. 3, Table
S4). Complexe2 can also be effectively detected Fe3+ (Fig. S13, S14).
-
added to the system, the characteristic emission peak of Tb3+ at
548nm was significantly quenched, while the other anions showed
little or slight interference. It is obvious that complexe2 can
-
effectively detect MnO4 , which is not interfered by other anions
(Fig. S16). By comparing the PXRD patterns, it is found that the
peak positions of the diffraction peaks are uniform, indicating that
the skeleton of the complexe2 remain intact during the detection to
determine its stability (Fig. S17).
A
fluorescence titration
-
-
experiment of MnO4 was performed. As the MnO4 (0.1mM -
10.0mM) gradually increased, the fluorescence luminescence
intensity of the complexe2 at 548nm gradually decreased. It is
indicate that there is a good linear correlation between the amount
-
of MnO4 and the relative fluorescence intensity in a low linear
range of 0-1.0mM (R2 = 0.9937). The calculated detection limit of
-
MnO4 is 4.48×10-5mM and KSV is 1200M-1, which is at a relatively
high level than the work reported in the past (Fig. 5, Table S6).
Figure4. (a) Luminescence intensity at 619nm of complexe1
dispersed in the aqueous solutions of different anions, when
excited at 394nm. (b) Anions selectivity of complexe1 (I0 /I) in H2O.
(c) Luminescence responses of complexe1 toward different
concentrations of Cr2O72- (0-1.0mM) in H2O (λex = 394nm). (d) Stern-
2-
Volmer plot of I0 / I versus increasing concentrations of Cr2O7
.
Selective sensing of anions
The anions detection experiments of complexes 1-2 were carried
-
2-
out in NaX aqueous solutions (X= I-,Ac-, SO32-,Br-, NO3 , Cl-, CO3
,PO43-, CH3COO-, SO32-, S2O32-,BO3 ,C2O42-, H2PO2 , SO42-, HSO3 , CNS-,
MnO4 ,CrO42-,or Cr2O72-, 1 × 10-3M). Analysis of the emission
-
-
-
-
Figure5. (a) Luminescence intensity at 548nm of complexe2
dispersed in the aqueous solutions of different anions, when
spectrum reveals that different anions have different effects on the
fluorescence intensity of complexes1-2. It is obvious that
complexe1 can effectively detect Cr2O72-, which is not interfered by
other anions (Fig. S15). Further, by comparing the PXRD spectra of
excited at 339nm. (b) Anions selectivity of complexe2 (I0 / I) in H2O.
(c) Luminescence responses of complexe2 toward different
concentrations of MnO4- (0-1.0mM) in H2O (λex = 339nm). (d) Stern-
2-
the sample dispersed in Cr2O7 ions and the simulated single
-
Volmer plot of I0 / I versus increasing concentrations of MnO4 .
crystal, it is found that the peak positions of the diffraction peaks is
consistent, indicating that the framework of the complexe1 remain
intact during the detection to determine its stability (Fig. S12). A
Selective sensing of nitro aromatic compounds
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 6 of 9
ARTICLE
Journal Name
-
Aromatic compounds are a class of compounds with a benzene ring complexes1-2 before and after Fe3+, Cr2O72-, MnO4 , 4-NP treatment
View Article Online
DOI: 10.1039/C9DT01907C
structure. They are structurally stable, are not easily decomposed, confirmed that the framework of complexes1-2 remained intact (Fig.
and are highly toxic, causing serious pollution to the environment S12, S17, S18). Therefore, luminescence quenching is not caused by
and causing great harm to the human body, so we explore the the collapse of a crystal structure. Then, according to the static
ability of complexes1-2 to detect nitro aromatic compounds. quenching mechanism, the static quenching does not change the
Analysis of the emission spectrum reveals that different nitro lifetime. In contrast, the dynamic quenching will cause
a
aromatic compounds have different effects on the fluorescence comparable decrease in lifetime.75-77 Comparing the fluorescence
-
intensity of complexes1-2. Taking the effect of nitro aromatic lifetimes of complexes1-2 before and after Fe3+, Cr2O72-, MnO4 , 4-
compounds on complexe1 as an example, it is found that 4-NP can NP treatment, it is found that the average fluorescence lifetime
significantly quench the complexe1. By comparing the PXRD spectra remained almost unchanged, which means that there is no
of the sample dispersed in 4-NP aqueous solution and the simulated interaction between them (Table S3). And last, UV-visible
single crystal, which show that the frame of the complexe1 is not absorption experiments were carried out in aqueous solutions of
destroyed upon detection (Fig. S18). As the 4-NP (0.1mM - different cations, anions and nitro aromatic compounds.78,79 UV-
10.0mM) gradually increased, the fluorescence luminescence visible absorption spectra indicate that the absorption band of Fe3+
2-
-
intensity of the complexe1 at 619nm gradually decreased. It is ions is 260nm to 370nm; Cr2O7 ions is 250nm to 400nm; MnO4
indicate that there is a good linear correlation between the amount ions is 270nm to 370nm and 4-NP is 250nm to 350nm (Fig. S22). By
-
of 4-NP and the relative fluorescence intensity in a low linear range comparing the UV-visible absorption spectra of Fe3+, Cr2O72-, MnO4
of 0-1.0mM (R2 = 0.9819). The calculated detection limit of 4-NP is and 4-NP with the excitation spectra of complexes1-2 (394nm,
7.6 × 10-5M and KSV is 5352M-1, which is at a relatively high level 339nm), it is found that there is a significant overlap between the
than the work reported in the past (Fig. 6, Table S7). So complexe1 absorption peaks and the excitation peaks. Therefore, the
can achieve high sensitivity and rapid detection of 4-NP, which is quenching effect of complexes1-2 on them may be attributed to
not interfered by other nitro aromatic compounds (Fig. S19). their energy competition with complexes1-2. A similar fluorescence
52, 53, 60, 79-81
Complexe2 also can detect 4-NP with high selectivity and sensitivity quenching mechanism has been reported.49,
For
-
(Fig.
S20,
S21). example, a solid sample immersed in an aqueous solution of MnO4
from light yellow
luminescence induction, which makes the detection process of
→
brown (Fig. S23), visually indicating
-
-
MnO4 more convenient and practical. It confirms that MnO4
effectively absorbs /excited energy from the organic linker, while
reducing energy transfer to the metal-center, reducing complexes1-
2
luminescence
emission.8
Figure6. (a) Luminescence intensity at 619nm of complexe1
dispersed in the aqueous solutions of different nitro aromatic
compounds, when excited at 394nm. (b) Nitro aromatic compounds
selectivity of complexe1 (I0 / I) in H2O. (c) Luminescence responses
of complexe1 toward different concentrations of 4-NP (0-1.0mM) in
H2O (λex = 394nm). (d) Stern-Volmer plot of I0 / I versus increasing
concentrations
of
4-NP.
Luminescence quenching mechanism
Figure7. Original and quenched luminescence intensity (619nm) of
2-
complexe1 recycled after sensing experiments for Fe3+ (a1), Cr2O7
To explore the luminescence quenching mechanism of inorganic
(a2) and 4-NP (a3); five recycling tests were investigated. Original
and quenched luminescence intensity (548nm) of complexe2
2-
-
ions Fe3+, Cr2O7
, MnO4 and 4-NP on complexes1-2, some
necessary measures were performed. First, the PXRD spectra of
2-
recycled after sensing experiments for Fe3+ (a1), Cr2O7 (a2) and 4-
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 9
Dalton Transactions
Please do not adjust margins
Journal Name
ARTICLE
NP
(a3);
five
recycling
tests
were
investigated. (b) Time-gated photoluminescence spectrum obtained after the
View Article Online
DOI: 10.1039/C9DT01907C
addition of the complexe1 + Rhodamine 6G mixture before and
after 4-NP was delayed by 2ms. (c, d) Time-resolved
Recycling of complexes1-2
photoluminescence spectra of complexe1 + Rhodamine 6G mixture
before(c) and after (d) the addition of 4-NP.Conditions: complexe1=
1mg / 2mL, Rhodamine 6G = 3μM, 4-NP = 1 × 10-3mol/ L.
In order to achieve the recyclability of complexe1-2 in practical
applications, we investigated its cycle performance as
a
2-
luminescent probe for Fe3+, Cr2O7 and 4-NP. Hence, we
respectively dispersed complexes1-2 in the H2O solution (1×10−3M)
of Fe3+, Cr2O72- and 4-NP to obtain the 1-Fe3+, 1-Cr2O72-, 1-4-NP and
2-Fe3+, 2-Cr2O72-, 2-4-NP samples. In the next step, the resulting
solids were treated multiple times with H2O to completely wash
Figure 8a shows the steady-state photoluminescence spectrum.
Excited at λex = 394nm, the maximum emission at 572nm can be
assigned to Rhodamine 6G, and the peak appearing at ~ 619nm can
be attributed to the fluorescence emission of complexe1. When 4-
NP (1 × 10-3mol/L) was added, the fluorescence interference
generated by Rhodamine 6G at 572nm still existed, and the
luminescence intensity did not change significantly, but the
characteristic emission peak intensity of complexe1 decreased
significantly, which proved to be quenched by 4-NP, indicating
background fluorescence produced a strong interference with the
detection of 4-NP by complexe1. Then, TRES was measured at room
2-
away Fe3+, Cr2O7 ions and 4-NP. The emission intensity of the
untreated sample is equivalent to the emission intensity of the
recovered MOF-1 and MOF-2 (Fig. 7). The same behaviors were
observed for the same sample after five cycles of repeated cycles,
indicating that complexes1-2 is a recyclable luminescent probe for
sensitive and rapid detection of Fe3+, Cr2O72- ions and 4-NP.
Application in time-resolved luminescence measurement
temperature, with
a mixture of complexe1 (1mg/2mL) and
Rhodamine 6G dye (3μM) before and after the addition of 4-NP
(Fig. 8c, 8d). The Time-gated photoluminescence spectra obtained
after the 2ms delay of the mixture effectively removed the
background fluorescence of Rhodamine 6G. After the addition of 4-
NP, the emission intensity of TRES was significantly attenuated,
which achieved a time resolved luminescence on response of 4-NP
(Fig. 8b). Despite the low intensity of this technique, these results
indicate that Ln-MOFs with long fluorescence lifetime has
significant advantages in eliminating background interference and
improving signal to noise ratio.
It is well known that lanthanide ions have a long fluorescence
emission lifetime. Therefore, complexe1 has a good potential
application prospect in time-resolved luminescence detection, and
can effectively remove badly scattered light or short-lived
fluorescent background interference. In DMAC and ambient
temperature, the average emission lifetime of complexe1
monitored at 619nm was 1.12ms, showing a sufficiently long
fluorescence characteristic, which is sufficient for TRES
experiments. The typical fluorescent dye Rhodamine 6G was used
as the signal interference. Short emission lifetime of Rhodamine 6G
in DMAC was 6.77ns (3μM), and its emission range overlapped with
the characteristic fluorescence emission of complexe1 (Fig. S24,
Table S2). The TRES experiments before and after the addition of 4-
NP (1×10-3mol/ L) was selected and compared with 0 and 2ms
Conclusions
In summary, we have successfully obtained a 3D water-stable Ln-
MOFs with
a new topology type by solvothermal method.
Complexes1-2 can be one of the examples of a very stable multi-
responsive luminescence sensor. It is capable of detecting toxic
inorganic ions and nitro aromatic explosives selectively, stably,
highly sensitivity in water systems. This work highlights the
application of water-stable Ln-MOFs as a luminescence sensor for
the detection of toxic substances and extends the range of
applications for such porous materials with unique structural types.
More importantly, the time-resolved photoluminescence
technology of complexe1 is successfully used to detect 4-NP, which
effectively eliminates short-lived fluorescence interference and
significantly improves signal-to-noise ratio. It is useful for TRES
probe designs. Our next step will focus on water-stable
complexes1-2’s effective application in a wider range of areas.
Typical applications are adsorption in the gas or liquid phase for
proton conduction, sensing and catalysis in a wading environment.
In addition, the assembly of water-stable Ln-MOFs into thin film
have great potential for improving the efficiency of many industrial
processes such as water separation and wastewater purification.
delayed
photoluminescence
spectra
(Fig.
8).
Conflicts of interest
Figure8. (a) Steady-state photoluminescence of a mixture of
complexe1 + Rhodamine 6G before and after the addition of 4-NP.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 8 of 9
ARTICLE
Journal Name
There are no conflicts to declare.
24.
T.-F. Zheng, S.-L. Yao, C. Cao, S.-J. Liu, H.-K.VHiewu,ArTti.clZehOannlinge,
H.-P. Huang, J.-S. Liao, J.-L. Chen DaOndI: 1H0..-1R0.39W/Ce9nD,TN0e19w0.7CJ.
Chem., 2017, 41, 8598-8603.
25.
26.
27.
L.-J. Murray, M. Dinca and J.-R. Long, Chem. Soc. Rev.,
2009, 38, 1294-1314.
S. Qiu, M. Xue and G. Zhu, Chem. Soc. Rev., 2014, 43,
6116-6140.
D.-X. Xue, A.-J. Cairns, Y. Belmabkhout, L. Wojtas, Y. Liu,
M.-H. Alkordi and M. Eddaoudi, J. Am. Chem. Soc., 2013,
135, 7660-7667.
Acknowledgements
This work was supported by NSFC (Grant 21431002, 21871122)
and Fundamental Research Funds for the Central Universities
(No. lzujbky-2018-kb12).
28.
29.
L. Armelao, S. Quici, F. Barigelletti, G. Accorsi, G. Bottaro,
M. Cavazzini and E. Tondello, Coord. Chem. Rev., 2010,
254, 487-505.
J.-C.-G. Bünzli and S.-V. Eliseeva, Chem. Sci., 2013, 4,
1939-1949.
S.-I. Weissman, J. Chem. Phys., 1942 , 10, 214-217.
M.-E. Germain and M.-J. Knapp, Chem. Soc. Rev., 2009,
38,2543-2555.
S.-A. Boyd, G. Sheng, B.-J. Teppen and C.-T. Johnston,
Environ. Sci. Technol., 2001, 35, 4227-4234.
X. Zhou, H. Li, H. Xiao, L. Li, Q. Zhao, T. Yang, J. Zuo and W.
Huang, Dalton. Trans., 2013, 42, 5718-5723.
H. Wang, S.-J. Liu, D. Tian, J.-M. Jia and T.-L. Hu, Cryst.
Growth Des., 2012, 12, 3263-3270.
S.-W. Botchway, M. Charnley, J.-W. Haycock, A.-W.
Parker, D.-L. Rochester, J.-A. Weinstein and J.-A.-G.
Williams, PNAS., 2008, 105, 16071-16076.
Notes and references
1.
C. Wang, X. Liu, N. Keser Demir, J.-P. Chen and K. Li, Chem.
Soc. Rev., 2016, 45, 5107-5134.
2.
3.
B. Yan, Acc. Chem. Res., 2017, 50, 2789-2798.
S.-L. Yao, S.-J. Liu, X.-M. Tian, T.-F. Zheng, C. Cao, C.-Y. Niu,
Y.-Q. Chen, J.-L. Chen, H. Huang and H.-R. Wen, Inorg.
Chem., 2019, 58, 3578-3581.
30.
31.
4.
5.
S.-L. Yao, S.-J. Liu, C. Cao, X.-M. Tian, M.-N. Bao and T.-F.
Zheng, J. Solid State Chem., 2019, 269, 195-202.
S.-L. Yao, T.-F. Zheng, X.-M. Tian, S.-J. Liu, C. Cao, Z.-H.
Zhu, Y.-Q. Chen, J.-L. Chen and H.-R. Wen,
CrystEngComm., 2018, 20, 5822-5832.
32.
33.
34.
35.
6.
7.
E. Coronado and G. Minguez Espallargas, Chem. Soc. Rev.,
2013, 42, 1525-1539.
J.-M. Falkowski, T. Sawano, T. Zhang, G. Tsun, Y. Chen, J.-
V. Lockard and W. Lin, J. Am. Chem. Soc., 2014, 136, 5213-
5216.
8.
J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang and C.-Y. Su,
Chem. Soc. Rev., 2014, 43, 6011-6061.
9.
S.-S. Wang and G.-Y. Yang, Chem. Rev., 2015, 115, 4893-
4962.
P. Horcajada, R. Gref, T. Baati, P.-K. Allan, G. Maurin, P.
Couvreur, G. Ferey, R.-E. Morris and C. Serre, Chem. Rev.,
2012, 112, 1232-1268.
K.-M.-L. Taylor Pashow, J.-D. Rocca, Z. Xie, S. Tran and W.
Lin, J. Am. Chem. Soc., 2009, 131, 14261-14263.
D. Liu, K. Lu, C. Poon and W. Lin, Inorg. Chem., 2014, 53,
1916-1924.
S.-L. L. and Q. Xu, Energy. Environ. Sci., 2013, 6, 1656-
1683.
N. Busschaert, C. Caltagirone, W. Van Rossom and P.-A.
Gale, Chem. Rev., 2015, 115, 8038-8155.
Y. Cui, H. Xu, Y. Yue, Z. Guo, J. Yu, Z. Chen, J. Gao, Y. Yang,
G. Qian and B. Chen, J. Am. Chem. Soc., 2012, 134, 3979-
3982.
36.
37.
D. Jin and J.-A. Piper, Anal. Chem., 2011, 83, 2294-2300.
E.-A. Weitz, J.-Y. Chang, A.-H. Rosenfield and V.-C. Pierre,
J. Am. Chem. Soc., 2012, 134, 16099-16102.
K. Huang and A.-A. Marti, Anal. Chem., 2012, 84, 8075-
8082.
H. Shi, H. Sun, H. Yang, S. Liu, G. Jenkins, W. Feng, F. Li, Q.
Zhao, B. Liu and W. Huang, Adv. Funct. Mater., 2013, 23,
3268-3276.
Y. Tang, H.-R. Yang, H.-B. Sun, S.-J. Liu, J.-X. Wang, Q.
Zhao, X.-M. Liu, W.-J. Xu, S.-B. Li and W. Huang, Chem.
Eur. J., 2013, 19, 1311-1319.
Y. You, S. Lee, T. Kim, K. Ohkubo, W.-S. Chae, S. Fukuzumi,
G.-J. Jhon, W. Nam and S.-J. Lippard, J. Am. Chem. Soc.,
2011, 133, 18328-18342.
10.
38.
39.
11.
12.
13.
14.
15.
40.
41.
16.
17.
18.
Y. Cui, Y. Yue, G. Qian and B. Chen, Chem. Rev., 2012, 112,
1126-1162.
Z. Hu, B.-J. Deibert and J. Li, Chem. Soc. Rev., 2014, 43,
5815-5840.
L.-E. Kreno, K. Leong, O.-K. Farha, M. Allendorf, R.-P. Van
Duyne and J.-T. Hupp, Chem. Rev., 2012, 112, 1105-1125.
Y. Lu and B. Yan, Chem. Commun., 2014, 50, 13323-13326.
J.-S. Qin, D.-Y. Du, W.-L. Li, J.-P. Zhang, S.-L. Li, Z.-M. Su, X.-
L. Wang, Q. Xu, K.-Z. Shao and Y.-Q. Lan, Chem. Sci., 2012,
3, 2114-2118.
H. Tao, T.-D. Bennett and Y. Yue, Adv. Mater., 2017, 29,
1601705.
S.-J. Liu, C. Cao, S.-L. Yao, T.-F. Zheng, Z.-X. Wang, C. Liu,
J.-S. Liao, J.-L. Chen, Y.-W. Li and H.-R. Wen, Dalton.
Trans., 2016, 46, 64-70.
42.
43.
M. Tian and H. Ihmels, Chem. Commun., 2009, 3175-3177.
H.-B. Gray and J.-R. Winkler, Annu. Rev. Biochem., 1996,
65, 537-556.
X. Liu and E.-C. Theil, Acc. Chem. Res., 2005, 38, 167-175.
M. Elavarasi, A. Rajeshwari, S.-A. Alex, D. Nanda Kumar, N.
Chandrasekaran and A. Mukherjee, Anal. Methods., 2014,
6, 5161-5167.
H. He, S.-H. Chen, D.-Y. Zhang, R. Hao, C. Zhang, E.-C. Yang
and X.-J. Zhao, Dalton. Trans., 2017, 46, 13502-13509.
L. Li, L. Fan, M. Sun, H. Qiu, X. Li, H. Duan and C. Luo,
Colloids. Surf B. Biointerfaces., 2013, 107, 76-83.
Z. Chen, Y. Sun, L. Zhang, D. Sun, F. Liu, Q. Meng, R. Wang
and D. Sun, Chem. Commun., 2013, 49, 11557-11559.
44.
45.
19.
20.
46.
47.
48.
21.
22.
23.
S.-J. Liu, J.-P. Zhao, W.-C. Song, S.-D. Han, Z.-Y. Liu and X.-
H. Bu, Inorg. Chem., 2013, 52, 2103-2109.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 9
Dalton Transactions
Please do not adjust margins
Journal Name
ARTICLE
49.
C.-S. Cao, H.-C. Hu, H. Xu, W.-Z. Qiao and B. Zhao, Cryst. 77.
Eng. Comm., 2016, 18, 4445-4451.
C. Zhang, S. Huang, D. Yang, X. Kang, M. SVhieawngAr,ticCle. OPnelninge
DOI: 10.1039/C9DT01907C
and J. Lin, J. Mater. Chem., 2010, 20, 6674-6680.
50.
51.
P.-P. Jana and S. Lidin, Inorg. Chem., 2015, 54, 713-721.
G.-P. Li, G. Liu, Y.-Z. Li, L. Hou, Y.-Y. Wang and Z. Zhu,
Inorg. Chem., 2016, 55, 3952-3959.
78.
Q. Zhang, J. Wang, A.-M. Kirillov, W. Dou, C. Xu, C. Xu, L.
Yang, R. Fang and W. Liu, ACS. Appl. Mater. Interfaces.,
2018, 10, 23976-23986.
52.
53.
54.
55.
56.
Y.-T. Liang, G.-P. Yang, B. Liu, Y.-T. Yan, Z.-P. Xi and Y.-Y. 79.
Wang, Dalton. Trans., 2015, 44, 13325-13330.
X.-Y. Xu and B. Yan, ACS. Appl. Mater. Interfaces., 2015, 7, 80.
721-729.
F.-Y. Yi, J.-P. Li, D. Wu and Z.-M. Sun, Chem. Eur. J., 2015, 81.
21, 11475-11482.
M. Zheng, H. Tan, Z. Xie, L. Zhang, X. Jing and Z. Sun, ACS. 82.
Appl. Mater. Interfaces., 2013, 5, 1078-1083.
L. Aviva and P.-A. Lay, Coord. Chem. Rev., 2005, 249, 281-
298.
Y. Liu, J.-J. Ma, C. Xu, Y. Yang, M. Xia, H. Jiang and W.-S.
Liu, Dalton. Trans., 2018, 47, 13543-13549.
R.-M. Wen, S.-D. Han, G.-J. Ren, Z. Chang, Y.-W. Li and X.-
H. Bu, Dalton. Trans., 2015, 44, 10914-10917.
X.-L. Zhao, D. Tian, Q. Gao, H.-W. Sun, J. Xu and X.-H. Bu,
Dalton. Trans., 2016, 45, 1040-1046.
B. Ding, S.-X. Liu, Y. Cheng, C. Guo, X.-X. Wu, J.-H. Guo, Y.-
Y. Liu and Y. Li, Inorg. Chem., 2016, 55, 4391-4402.
57.
58.
A. Zhitkovich, Chem. Res. Toxicol., 2005, 18, 3-11.
X.-Q. Yao, G.-B. Xiao, H. Xie, D.-D. Qin, H.-C. Ma, J.-C. Liu
and P.-J. Yan, CrystEngComm., 2019, 21, 2559-2570.
Y. Tao, P. Zhang, J. Liu, X. Chen, X. Guo, H. Jin, J. Chai, L.
Wang and Y. Fan, New J. Chem., 2018, 42, 19485-19493.
S.-L. Yang, Y.-Y. Yuan, P.-P. Sun, T. Lin, C.-X. Zhang and Q.-
L.Wang, New. J. Chem., 2018, 42, 20137-20143.
X. Zhang, W. Zhang, C. Li, X. Qin and C. Zhu, Inorg. Chem.,
2019, 58, 3910-3915.
X.-Y. Guo, F. Zhao, J. Liu, Z.-L. Liu and Y.-Q. Wang, J.
Mater. Chem. A., 2017, 5, 20035-20043.
J. Liu, G. Ji, J. Xiao and Z. Liu, Inorg. Chem., 2017, 56, 4197-
4205.
T.-Y. Gu, M. Dai, D.-J. Young, Z.-G. Ren and J.-P. Lang,
Inorg. Chem., 2017, 56, 4669-4679.
F.-Y. Yi, W. Yang and Z.-M. Sun, J. Mater. Chem., 2012, 22,
23201-23209.
B. Chen, S. Xiang and G. Qian, Acc. Chem. Res., 2010, 43 ,
1115-1124.
C. Glidewell and G.-M. Sheldrick, J.C.S. Dalton., 1792,
2409-2411.
Y.-H. He, Y.-L. Feng, Y.-Z. Lan and Y.-H. Wen, Cryst.
Growth Des., 2008, 10, 3586-3594.
X.-X. Wang, X.-Q. Wang, X.-Y. Niu and T.-P.Hu*,
CrystEngComm., 2016, 18, 7471-7477.
L.-L. Wen, Z.-D. Lu, J.-G. Lin, Z.-F. Tian, H.-Z. Zhu and Q.
Meng, Cryst. Growth Des., 2007, 7, 93–99.
D. Niu, J. Yang, J. Guo, W.-Q. Kan, S.-Y. Song, P. Du and J.-
F. Ma, Cryst. Growth Des., 2012, 12, 2397−2410.
H.-H. Li, S. Inoue, K.-I. Machida and G.-Y. Adachi, Chem.
Mater., 1999, 11, 3171-3176.
T.-F. Liu, W. Zhang, W.-H. Sun and R. Cao, Inorg. Chem.,
2011, 50, 5242-5248.
M.-L. Ma, C. Ji and S.-Q. Zang, Dalton. Trans., 2013, 42,
10579-10586.
H. He, Y. Song, F. Sun, N. Zhao and G. Zhu, Cryst. Growth
Des., 2015, 15, 2033-2038.
X. Wang, P. Yan, Y. Li, G. An, X. Yao and G. Li, Cryst.
Growth Des., 2017, 17, 2178-2185.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
Please do not adjust margins