A family of mixed-lanthanide metal-organic framework thermometers in a wide temperature range

Article abstract of DOI:10.1039/c8dt03182g

By choosing 2-pyridin-4-yl-4,5-imidazoledicarboxylic acid (H₃PIDC) as the first ligand and sodium oxalate (OX) as the ancillary ligand, a series of mixed-lanthanide metal-organic frameworks (M′LnMOFs) [Tb_1-xEu_x(HPIDC)(ox)_1/2H₂O]·3H₂O (x = 0 1, 0.01 2a, 0.03 2b, 0.05 2c, 0.08 2d, 0.1 2e, 0.3 2f, 0.5 2g, 1 3) have been successfully synthesized via hydrothermal reactions. 2a-2f can serve as ratiometric luminescent sensors for detecting temperature. In this co-doped system, 2d shows an excellent linear response relationship with temperature from 303 to 473 K and exhibits a maximum relative sensitivity (S_r) of 0.60percent K^-1 at 473 K. Furthermore, powder X-ray diffraction (PXRD) experiments indicate that 2d has excellent chemical stability under simulated physiological conditions and alkali-acid solutions with pH ranging from 4 to 11, which makes it suitable to be applied in the physiological environment.

Full text of DOI:10.1039/c8dt03182g

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ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
framework
a Zr-metal–organic
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A family of mixed-lanthanide metal-organic frameworks
thermometer in a wide temperature range
Received 00th January 20xx,
Accepted 00th January 20xx
Yang Yang, Haipeng Huang, Yingzhe Wang, Fangzhou Qiu, Yan Feng, Xuerui Song, Xiaoliang Tang,
Guolin Zhang and Weisheng Liu*
DOI: 10.1039/x0xx00000x
By choosing 2-pyridin-4-yl-4,5-imidazoledicarboxylic acid (H3PIDC) as the first ligand and sodium oxalate (OX) as the
ancillary ligand, a series of mixed-lanthanide metal-organic frameworks (M’LnMOFs) [Tb1-xEux(HPIDC)(ox)1/2H2O]·3H2O (x= 0
1,0.01 2a, 0.03 2b, 0.05 2c, 0.08 2d, 0.1 2e, 0.3 2f, 0.5 2g, 1 3) have been successfully synthesized via hydrothermal
reactions. 2a-2f can serve as ratiometric luminescent sensor for detecting temperature. In this co-doped system, 2d shows
excellent linear relationship response to temperature from 303 to 473 K and exhibits a maximum relative sensitivity (Sr) of
0.60% K-1 at 473 K. Furthermore, Powder X-ray diffraction (PXRD) experiments indicate that 2d has excellent chemical
stability under simulated physiological conditions and alkali-acid solutions with pH ranging from 4 to 11, which makes it
possible to be applied in the physiological environment.
www.rsc.org/
Temperature plays a critical role in scientific research and
people’s daily life. It is an important parameter which needs to
be accurate measured in materials science, biomedicine,
1. Introduction
Due to the advantages of porosity, adjustability of structure
and size, as well as excellent thermal stability and chemical
stability, metal-organic frameworks (MOFs) have been
considered as one of the potential and multifunctional
materials for practical application. In the past two decades,
MOFs have been widely research in energy gas
storage/separation,1 catalysis,2 optics,3-5 electronics,6,7
magnetism8 and biomedicine.9 Rare earth has excellent
electrical, magnetic and optical properties. Among the
research of rare earth materials, luminescence performance is
the most extensive and important content and its emission
range can cover from ultraviolet to near-infrared area
(300~1550 nm).10 Lanthanide metal-organic frameworks (Ln-
MOFs) were constructed by the combination of the intrinsic
spectroscopic properties of lanthanide ions and the
designability of MOFs and they have unique characteristics
such as long luminescence lifetimes, large Stokes shift,
characteristic emissions and wide emission range. Based on
the above advantages, Ln-MOFs can be widely used in white
LEDs, ion detection, small molecule detection, explosive
detection, pH detection and temperature sensing.11-18
energy science and many other fields.19,20 Compared with the
conventional contact-thermometers, luminescence-based
thermometers have attracted much attention due to the
noninvasiveness, accuracy, high spatial resolution, and
feasibility to work in strong electromagnetic environment and
fast-moving objects.21-26 Early luminescent thermometers for
measuring temperature rely on the luminescent intensity of
single transition, and their accuracy are susceptible by external
factors, such as optical occlusion, sensor material
concentration, excitation power, and the environment-induced
nonradiative relaxation. Due to overcoming the above defects,
ratiometric luminescent thermometers have gradually become
a hot research in the past few years, which using the intensity
ratio of two independent emissions (e.g., Eu3+/Tb3+, Nd3+/Yb3+)
as the ratiometric thermometric parameter. In 2012, Qian’s
group developed the first ratiometric luminescent MOF
thermometer, [(Eu0.0069Tb0.9931)2(DMBDC)3(H2O)4]3DMF3H2O,
which was based on the temperature-dependent
5
luminescence of the D0
→
7F2 transition of Eu3+ at 615 nm and
7F5 transition of Tb3+ at 546 nm. Lian et al. reported
5
the D4
→
the
first near-infrared Ln-MOF thermometer,
Nd0.577Yb0.423BDC-F4, which was based on the intensity ratio
between emissions of Yb3+ at 980 nm and Nd3+ at 1060 nm.21,22
Although these above-mentioned thermometers show
application prospects to some extent, they still have some
shortcomings to restrict the development of luminescent
thermometer, such as low sensitivity, cryogenic and narrow
application temperature range.27,29,30 In addition, pH-stability
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is also a significant factor restricting the development of
luminescent thermometers. Unfortunately, most of the MOF
materials that have been reported are usually unstable under
acid-based solution, which limits their application in
physiological environment. Therefore, a luminescent MOF
thermometer with high chemical stability in a wide pH range is
needed.
MHz, DMSO-d6) δ 151.02, 149.29, 137.64, 123.40, 122.13,
56.57, 19.07. ESI-MS m/z: Calcd. For C12H9N3 195.08, Found:
196.08 [M+H]+.
2 (5 g) was dissolved in 98% H2SO4 (10.0 ml), 30% H2O2
(50.0 ml) was added dropwise and the resulted mixture was
stirred at 383 K. Then the solution gradually heated (388-393-
403-413 K) and reacted at 413 K for 1 h. The solution was
cooled naturally and poured into ice water (200 mL), stirred,
filtered and washed to give H3PIDC as a pale yellow solid
To obtain fresh Ln-MOFs that can work in a wide pH range,
we focused on a dicarboxylic acid, H3PIDC, to construct
isomorphic Ln-MOFs. The imidazole structure can act as a
buffer solution to maintain the structure of Ln-MOFs without
damage, which is readily protonated/deprotonated in acidic or
basic conditions. Based on many rewarding influences, the
introduction of ancillary ligands into Ln-MOFs results in a
significant increase of luminescent intensity.31-33
powder (5.38 g, yield: 80%). 1H NMR (400 MHz, DMSO-d6)
δ
8.91 (d, J = 6.6 Hz, 2H), 8.52 (d, J = 6.7 Hz, 2H). ESI-MS m/z:
Calcd. For C10H7N3O4 233.04, Found: 144.04[M-2CO2-H]−,
188[M-CO2-H]−, 232.02 [M-H]−.
2.3. Synthesis of 1, 3 and 2a-2g.
The crystal was synthesized according to the literature
procedure.35 Taking
By choosing sodium oxalate (OX) as the ancillary ligand, a
family of M’LnMOFs 2a-2g has been successfully synthesized
via hydrothermal reactions. The temperature-dependent
photoluminescence properties indicate that 2a-2g can be used
as luminescent thermometers, of which 2d shows good linear
relationship response to a relatively wide temperature scope
1 as an example, H3PIDC (0.25 mmol, 58
mg), Tb(NO3)3 (0.2 mmol, 69 mg), sodium oxalate (0.2 mmol,
24 mg), and H2O (6 mL) were sealed into a reactor (23 mL) and
heated at 433 K for four days. Then the mixture was cooled
naturally and yellow block crystals were obtained by filtration
and washed with ethanol. Yield: 50.0%. Calcd (%) for
C11H11N3O9Tb (488.15): C, 27.07; H, 2.27; N, 8.61; found: C,
26.07; H, 2.38; N, 8.76. IR (KBr, cm-1): 3449(m), 3203(w),
1600(s), 1440(s), 1363(s), 1265(m), 1122(m), 985(m), 864(m),
1
from 303 to 473 K and exhibits an excellent Sr of 0.60% K− at
473 K. With 2d as the representative, the article systematically
elaborates the properties and application potential of 2a-2f to
be used as luminescent thermometers.
792(s), 740(m), 665(m), 538(m). The CCDC number for
842720. The Tb/Eu mixed MOFs 2a-2g were obtained similarly
to , except using Tb(NO3)3·6H2O and Eu(NO3)3·6H2O as
1 is
1
2. Experimental section
starting materials. The molar ratios of Tb/Eu salts in 2a-2g
products were showed in Table S1. The yields of 2a-2g were
also showed in Table S1.
2.1. Instruments and measurements
All chemicals were obtained commercially. 1H and 13C NMR
spectra were measured on a JEOLBCS 400M spectrometer with
tetramethylsilane (TMS, 0.00 ppm) as an internal standard.
Mass spectral measurements (ESI) were performed on an LQC
system (Finnigan MAT, USA). Fourier transform infrared (FT-IR)
spectra were recorded on a Burker VERTEX 70 spectrometer
using KBr discs. Elemental analyses (C, H, N) were recorded on
a Vario EL elemental analyzer. The TGA analyses were
measured on a Netzsch STA 449 F3 Jupiter apparatus under an
N2 atmosphere. PXRD data were collected in the 2θ = 5-50°
range using a PANalytical X’Pert Pro diffractometer with CuKα
radiation.
2.4. Luminescence measurements
The temperature measurements (320-473 K) were recorded on
a
high-temperature powder detection accessory. Room-
temperature excitation and emission spectra for the samples
were measured on a Hitachi F-7000 spectrofluorometer, with a
photomultiplier tube voltage of 700 V; a scan speed of 1200
nm/s; and slit widths of 1.0 and 5.0 nm.
3. Results and discussion
3.1. Structural Description
2.2. Synthesis of H3PIDC
Yellow block crystals were successfully synthesized via
hydrothermal reactions, and they are isomorphic and exhibit
As shown in scheme S1, the ligand H3PIDC was obtained
according to the reported article.34 O-Phenylenediamine (1.1
g) and isonicotinic acid (1.23 g) were poured into PPA (13 mL),
and the reaction was performed at 448 K for 4-5 h. Then the
solution was poured into cold water (60 mL). Ammonia
(25~28%) was added slowly and the pH value was adjusted to
7-8. Subsequently, a large amount of white precipitate was
produced. After stirring for 15 min, the mixture was filtered,
washed with water and dried to give 2-(4-Pyridyl)
benzimidazole (2) (1.63 g, yield: 88%).1H NMR (400 MHz,
DMSO-d6) δ 13.28 (s, 1H), 8.78 (d, J = 6.1 Hz, 2H), 8.11 (d, J =
6.1 Hz, 2H), 7.69 (d, J = 48.0 Hz, 2H), 7.29 (s, 2H). 13C NMR (100
the same network. Taking
diffraction analysis demonstrates that
monoclinic space group P21/c. As described in literature 35, the
asymmetric unit of contains one crystallographically
independent Tb3+ ion, a HPIDC2– ligand, half of an oxalate
ligand, and three water molecules. The Tb3+ ion is coordinate
to one N atom from imidazole ring and seven oxygen atoms.
Four oxygen atoms comes from HPIDC2– ligand, two oxygen
atoms comes from oxalate ligand and the last oxygen atom
comes from the water molecule (Figure 1a). Two adjacent Tb3+
ions are connected by HPIDC2– ligands and assembled into the
[Tb2] units, which further expanded into 1D chain
1
as an example, X-ray single crystal
1
crystallizes in the
1
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Figure 1. (a) Coordination environment of Tb3+. (b) 1D Tb2 chain motif showing
the coordination polyhedral of the Tb atoms. (c) Perspective view of the 2D
framework. (d) View of the 3D framework.
Figure 3. Power XRD of 2d after being immersed in the solutions of pH= 4-11 for
three days.
acid-base stability was also conducted. The solid powder of 2d
was successively immersed in the solutions of pH= 4-11 for
three days, then separated by filtration and dried. The Powder
XRD spectra of 2d in solutions of pH = 4-11 shows slight
changes, suggesting that 2d has excellent stability in wide pH
range (Figure 3). Encouraged by the outstanding pH stability,
the luminescent spectrum of 2d in solution of different pH was
studied. The powder sample of 2d was immersed in a 5 mL
solution of different pH and ultrasonicated for 30 min to form
emulsion, and then the luminescent spectrum was performed.
The luminescent spectrum was in good agreement with PXRD,
indicating that 2d has excellent thermal and acid-base stability
(Figure S3).
–Tb–O–C–O–Tb– geometrical patterns (Figure 1b). The
adjacent 1D chain geometrical patterns are extended into the
2D metal–organic layers by the second coordination site of
HPIDC2– ligands (Figure 1c). A 3D metal-organic framework is
generated by adjacent layers (Figure 1d). The final
coordination polyhedral of Tb3+ can be best described as a
bicapped trigonal prism. PXRD experiments indicate that the
M’LnMOFs is isostructural to the reported 1 (Figure 2).
3.2. Framework Stability
Stability is a limiting factor in the practical application of MOFs
material, and high thermal stability is the primary condition to
fabricate luminescent thermometers with a wide temperature
range. The TGA analyses demonstrate that 2d has high thermal
stability with a decomposition temperature approximately
high up to 400 °C, which is attributed to the tight 3D polymeric
structure (Figure S1 and S2).
3.3. Temperature-Dependent Photoluminescent Properties
Because of they are almost insoluble in most solvents such as
DMSO, CH3CN, DMF, EtOH, THF, MeOH, and H2O, powder
samples of 2a-2g were used for all tests. The excitation and
To further determine the potential applications of 2d, the
emission spectra of ligand H3PIDC, 1, 3 and 2a-2g were
investigated (Figure 4). The ligand of H3PIDC exhibits a broad
emission band at 408 nm under 422 nm excitation, which is
presumably belong to the π
excitation at 333 nm, and
and Eu3+ emission bands, respectively, with a dominating
intensity at 549 nm (5D4 7F5) and 618 nm (5D0 7F2) (Figure
→
π* transitions (Figure S4). Upon
1
3
exhibit the characteristic Tb3+
→
→
S5). As we expected, 2a-2g simultaneously exhibit the typical
Eu3+ (618 nm) and Tb3+ (549 nm) emission, implying efficient
energy transfer from ligand H3PIDC to the Eu3+ and Tb3+ ions
(Figure S6-S8). Subsequently, the temperature-dependent
photoluminescence properties of
investigated from 320-473 K. As shown in Figure 5,
luminescent intensities of Tb3+ and Eu3+ in
and decreases
1, 3 and 2a-2g were
1
3
drastically when the temperature increases, which is usually
ascribed to the thermal activation of nonradiative-decay
processes.36-38 Although the non-radiative process produces a
certain amount of heat, which doesn’t affect the temperature
of the sample in the process of measurement. Therefore, the
Figure 2. Powder XRD patterns of 1, 3 and 2a-2g.
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Δ
=1.91473-0.00299T
with a correlation coefficient (R2) of 0.999, where T is the given
temperature of 2d demonstrating 2d is an excellent
(1)
,
luminescent thermometer in relatively wide temperature
scope from 303 to 473 K (Figure 6c). In order to further
evaluate the performance of 2d, the sensitivity was calculated
according to equation (2) and (3), which is an important
parameter for thermometer applications. The absolute
sensitivity (Sab) of luminescent thermometers can be defined
as the change in the intensity ratio with temperature, as
shown in equation (2):39
∂Δ
∂T
Sab
=
(2)
and the relative sensitivity (Sr), which is usually more
significative for practical applications, can be defined as in
equation (3):40
(∂Δ/∂T)
Sr =
(3)
Δ
Figure 4. Excitation and emission spectra of 2d at room temperature.
where
ꢀ
represents the ITb/IEu and
T
represents the
temperature. According to the equation (2), the Sab of 2d is
0.003 K−1. The Sr of 2d increases gradually from 303 to 473 K,
1
and reaches its maximum values of 0.6 % K− at 473 K (Figure
6d). The value of Sr is 4.3 times larger than that of the
M
’
LnMOF luminescent thermometer Tb0.99Eu0.01(BDC)1.5(H2O)2
reported by Carlos and 1.6 times larger than that of the first
LnMOF ratiometric luminescent thermometer
Eu0.0069Tb0.9931-DMBDC reported by Cui.27,41 Compared to
previously reported M LnMOF luminescent thermometers,
M
’
’
although the Sr of 2d is not very prominent, a thermometer
with a wide temperature range from 303 to 473 K is extremely
rare (Table. 1). Furthermore, as shown in Figure 7, the samples
2d of different batches basically show the same temperature-
dependent photoluminescence emission spectrum and exhibit
1
the same sensitivity of 0.6 % K− at 473 K. The temperature-
dependent photoluminescence emission spectra of other
M’LnMOF were also performed to evaluate the influences of
Figure 5. Emission spectra of (a)
excited at 333 nm. Normalized emission intensities of (b) 5D0
Eu3+ (618 nm) and (d) 5D4 7F5 transition of Tb3+ (549 nm).
3
and (c)
1
recorded between 303 and 473 K
→
7F4 transition of
→
non-radiative process will not have an impact on the
temperature-dependent photoluminescence tests. As shown
in Figure 6a, although the luminescent intensities of both Tb3+
and Eu3+ in 2d decrease when the temperature increases, the
luminescent intensity of Tb3+ reduces at a faster rate and the
Eu3+ reduces at a slower rate compared with
1 and 3 (Figure
6b). When the temperature is 473 K, the intensity of Eu3+
occupies most of the spectrum. The same phenomenon was
also observed in other materials, which is due to the energy
transfer from the Tb3+ to Eu3+.
We choose the intensity ratio of Tb3+ (549 nm) to Eu3+ (618
nm) (ITb/IEu) as the parameter in the temperature sensing
process. The advantage of choosing this parameter is being a
self-alignment dimension of the temperature from the
luminescent intensity. The intensity ratio of 2d as a function of
temperature shows a good linear relationship in the range
from 303 to 473 K that can be fitted as a function of
Figure 6. (a) Emission spectra of 2d recorded between 303 and 473 K excited at 333 nm.
(b) The normalized intensities of Eu3+/618 nm (red) and Tb3+/549 nm(green) in 2d; inset:
the calibrated intensities of ITb/IEu. (c) Temperature-dependent normalized intensity
ratio of Eu3+ (618 nm) to Tb3+ (549 nm) and the fitted curve for 2d. (d) Temperature-
dependent relative sensitivity (Sr) of 2d.
4 | J. Name., 2012, 00, 1-3
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Table 1. Composition, working ranges (K), maximum relative In the M’LnMOFs system, the mechanism of temperature-
sensitivity values (Sm, % K−1), and the temperature at which Sm dependent luminescent responses has been clearly and
is maximum (Tm, K) of ratiometric luminescent MOF systematically elucidated by the previous researchers, which is
thermometers.
due to a typical process of energy transfer from one rare earth
ion to another.27,42-45 With the change of temperature, the
process of energy transfer from one rare earth ion to another
is the basis to design ratiometric luminescent thermometer. To
further verify the mechanism of the energy transfer from Tb3+
to Eu3+, the photoluminescence emission spectra of 2d were
Luminescent MOF
Range (K)
303-473
50 - 200
290-320
100-300
100-450
293-353
283-333
40-300
Sm (% K-1)
0.6
Tm
Tb0.92Eu0.08-HPIDC-OX
Eu0.0069Tb0.9931-DMBDC 14
473
200
318
300
450
293
333
300
275
250
313
300
150
1.15
0.31
3.27
0.11
1.28
2.53
16
28
Tb0.99Eu0.01(BDC)1.5·(H2O)2
Tb0.9Eu0.1PIA 29
30
[Eu0.7Tb0.3(cam)(Himdc)2(H2O)2]3
ZJU-88⊃perylene 31
Eu3+0.5%/Tb3+99.5%@In(OH)(bpydc) 32
Tb0.957Eu0.043cpda 27
Tb0.98Eu0.02(OA)0.5(DSTP) ·3H2O 33
Eu0.0878Tb0.9122L 34
carried out at room temperature upon excitation at 488 nm,
7F6 transition of the Tb3+ ion. As
5
which is belongs to the D4
→
shown in Figure S23, the photoluminescence emission spectra
of 2d exhibits the characteristic Eu3+ emission bands at 618 nm
77-275
2.4
(5D0
→ →
7F2 transition) and Tb3+ emission bands at 549 nm (5D4
75-250
4.9
7F5 transition), respectively. The results fully illustrate that the
process of energy transfer from Tb3+ to Eu3+ actually happened.
Similarly, the mechanism has also been proved by the
photoluminescence emission spectra of other M’LnMOF at
room temperature upon excitation at 488 nm (Figure S24-S29).
Tb0.80Eu0.20BPDA 17
Eu0.2 Tb0.8 L 35
298-318
40-300
1.19
0.15
0.12
16
{[Eu2(L)3·(H2O)2·(DMF)2]·16H2O}n
10-150
3.5. MTT and Biocompatibility Assay
To assess the potential of 2d in biological applications, the
stability and toxicity was preliminarily investigated under
simulated physiological conditions. We immersed the solid
powder of 2d in the phosphate buffered saline (PBS) solutions
for 24 h, filtered and dried naturally to give sample powder,
followed by XRD experiment. The XRD profile shows slight
changes, suggesting that 2d has excellent stability under
simulated physiological conditions (Figure 8). Furthermore, the
cytotoxicity of 2d was performed by MTT assay. Baby hamster
kidney (BHK) cells were selected as the model and seeded in a
12-well culture plates. A various concentrations of 2d (0, 10,
20, 50, 100 and 200 μg/mL) were added to the wells and
incubated for 48 h. As shown in Figure S30, the cells still
maintain high viability (
＞95%) after incubation with high
concentration (200 μg/mL) of 2d, which suggests that 2d has
Figure 7. Temperature dependent intensity ratio of Tb3+ (549 nm) to Eu3+ (618
nm) in different batches of 2d samples recorded between 303 and 473 K.
no obvious toxicity to living cells. The results clearly
different proportions of Eu3+ and Tb3+, suggesting that other
M’LnMOF also have potential applications in temperature
sensing (Figure S9-S15). Therefore, a better performance
luminescent thermometer could be acquired by adjust the
ratio of Eu3+ and Tb3+.
In
photoluminescence emission spectrum of 2d is illustrated by
Commission Internationale de L Eclairage (CIE) chromaticity
addition,
the
temperature-dependent
’
diagram coordinates (Figure S16). The color of 2d can slowly
change from yellow to red, as the corresponding CIE
coordinates change from (0.37, 0.4532) at 303 K to (0.3273,
0.3165) at 473 K, which can be expressly noticed by naked eye
and camcorder. The CIE chromaticity diagrams of other
thermometers are shown in Figure S17-S22. Therefore, 2d can
be used as a sensitive luminescent colorimetric thermometer
in relatively wide temperature scope from 303 to 473 K.
Figure 8. PXRD patterns of 2d and 2d immersed in PBS solution for 24 h.
3.4. Energy Transfer Mechanism
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biocompatibility.
4. Conclusions
Temperature plays an important role in many intracellular
chemical reactions and physiological processes, such as cell
division, gene expression, and enzyme reaction. Therefore, a
series of ratiometric luminescent thermometers were 16 J.-P. Zhao, J. Xu, S.-D. Han, Q.-L. Wang and X.-H. Bu., Adv.
Mater., 2017, 29, 1606966.
synthesized and they have excellent stability in wide pH range
from 4 to 11. Compared with pure inorganic or organic
thermometers, which are based on gold-CdTe nanoparticles,
quantum dot clusters, organic dye molecule, rare-earth doped
17 H. Wang, J. Xu, D.-S. Zhang, Q. Chen, R.-M. Wen, Z. Chang
and X.-H. Bu., Angew. Chem. Int. Edit., 2015, 54, 5966.
18 Q. Gao, J. Xu, D. Cao, Z. Chang and X.-H. Bu., Angew. Chem.
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materials and NIPAM materials,46-48 the ratiometric 19 W. Zhuopeng, A. Duarte, C.-S. Arnau, B. C. D. S., I. Inhar, M.
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,
luminescent thermometers is generally concerned by the
researchers as an organic-inorganic hybrid materials due to the
accuracy, noninvasiveness, and the ability to work in fast-
moving objects and strong electromagnetic environment.
Preliminary studies prove that 2d has excellent stability, low 22 F. Jiao, T. Kaijun, H. Dehui, W. Shuangqing, L. Shayu, Z. Yi, L.
Yi and Y. Guoqiang, Angew. Chem., 2011, 123, 8222.
23 C. D. S. Brites, P. P. Lima, N. J. O. Silva, A. Millán, V. S. Amaral,
F. Palacio and L. D. Carlos, New. J. Chem., 2011, 35, 1177.
24 X. Meng, S.-Y. Song, X.-Z. Song, M. Zhu, S.-N. Zhao, L.-L. Wu
toxicity and good biocompatibility under simulated
physiological conditions. Furthermore, based on the signal-to-
noise ratios of spectrometer, the theoretical temperature
sensing resolution of 2d is found to be 0.012 K,30 which is
and H.-J. Zhang., Inorg. Chem. Front., 2014, 1, 757.
accurate enough to monitor the tiny temperature change of 25 S.-N. Zhao, X.-Z. Song, M. Zhu, X. Meng, L.-L. Wu, J. Feng, S.-Y.
pathological and normal cells.49 Therefore, we believe that 2d
Song and H.-J. Zhang, Chem – Eur. J., 2015, 21, 9748.
26 M. Zhu, X. Z. Song, S. Y. Song, S. N. Zhao, X. Meng, L. L. Wu, C.
can be used as a practical temperature sensing materials for
Wang and H. J. Zhang., Adv. Sci., 2015, 2, 1500012.
the disease diagnosis in the near future.
27 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.
28 X. Lian, D. Zhao, Y. Cui, Y. Yang and G. Qian, Chem. Commun.,
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29 D. Wang, Q. Tan, J. Liu and Z. Liu, Dalton. T., 2016, 45, 18450.
30 D. Zhao, X. Rao, J. Yu, Y. Cui, Y. Yang and G. Qian, Inorg.
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Conflicts of interest
There are no conflicts to declare.
31 Y. Wei, Q. Li, R. Sa and K. Wu, Chem. Commun., 2014, 50
1820.
32 A. Fratini, G. Richards, E. Larder and S. Swavey, Inorg. Chem.,
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33 S. V. Eliseeva, D. N. Pleshkov, K. A. Lyssenko, L. S. Lepnev, J.-C.
G. Bünzli and N. P. Kuzmina, Inorg. Chem., 2010, 49, 9300.
34 S. Ting, M. Jian-Ping, H. Ru-Qi and D. Yu-Bin, Acta. Crystallogr.
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35 S. Lin, L. Gui-Zhu, X. Mei-Hua, L. Xiao-Jian, L. Jian-Rong and D.
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,
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Grants 21431002).
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Table of Contents
A family of mixed-lanthanide metal-organic frameworks thermometer in a wide temperature range.