Triangular Cd(II)-Sm(III) Schiff Base Complex with Dual Visible and Near-Infrared Luminescent Responses to Nitro Explosives

Article abstract of DOI:10.1021/acs.jpca.0c09758

Two d-4f complexes [Zn2NdL2(OAc)2]·OH (1) and [Cd3Sm3L3(OAc)6(OH)3] (2) with a designed Schiff base ligand N,N′-bis(3-methoxysalicylidene)(binaphthyl)-1,4-diamine (H2L) were synthesized. The Schiff base ligands coordinate with metal ions by μ2(η1:η2:η1:η1:η2:η1) and μ2(η1:η2:η1:η1:η2:η1) modes in the complexes, which show typical lanthanide emissions. The triangular Cd-Sm complex 2 shows both visible and NIR luminescent responses to nitrobenzene explosive 2,4,6-trinitrophenol (PA).

Full text of DOI:10.1021/acs.jpca.0c09758

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Triangular Cd(II)−Sm(III) Schiff Base Complex with Dual Visible and
Near-Infrared Luminescent Responses to Nitro Explosives
Mengyu Niu, Xiaoping Yang,* Yanan Ma, Dongliang Shi, and Desmond Schipper
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ABSTRACT: Two d-4f complexes [Zn2NdL2(OAc)2]·OH (1) and
[Cd3Sm3L3(OAc)6(OH)3] (2) with a designed Schiff base ligand N,N′-bis(3-
methoxysalicylidene)(binaphthyl)-1,4-diamine (H2L) were synthesized. The
Schiff base ligands coordinate with metal ions by μ2(η1:η2:η1:η1:η2:η1) and
μ2(η1:η2:η1:η1:η2:η1) modes in the complexes, which show typical lanthanide
emissions. The triangular Cd−Sm complex 2 shows both visible and NIR
luminescent responses to nitrobenzene explosive 2,4,6-trinitrophenol (PA).
Currently, our research interest has focused on the design of
luminescent lanthanide-based complexes with Schiff base
ligands.25 For example, the flexible Schiff base ligands with
−CH2−CH2− backbones tended to form 30- and 32-nuclear
d-4f complexes,26−28 while the employ of conjugated salen-
type Schiff base ligands such as those with phenylene
backbones gave various “multidecker” lanthanide-based com-
plexes.29−31 Recently, we reported a Sm(III) coordination
polymer with a dual-emissive response to metal ions.32 The
formation of lanthanide Schiff base complexes is usually
affected by some factors, for example, the coordination modes
of ligands and the types of metal ions and anions. As part of
our studies, we report here the results of employing a designed
ligand N,N′-bis(3-methoxysalicylidene)(binaphthyl)-1,4-dia-
mine with a binaphthyl backbone (H2L, Scheme 1). The
purposes of the introduction of a binaphthyl ring into the
Schiff base ligand are that first, a naphthyl ring has a high molar
absorption coefficient, which helps to absorb and transfer more
light energy for lanthanide emission, and second, the large
conjugated aromatic ring can interact with aromatic com-
pounds (e.g., nitrobenzene explosives) by intermolecular π···π
interaction. The reactions of the Schiff base ligand with
lanthanide acetates and ZnCl2/Cd(NO3)2·4H2O gave d-4f
c o m p l e x e s [ Z n 2 N d L 2 ( O A c ) 2 ] · O H ( 1 ) a n d
INTRODUCTION
■
In recent years, the application of fluorescent probes in the
detection of various analytes has been a topic of intense
research activity due to fast response, high sensitivities, and
convenient utilization.1−6 Explosives such as nitroaromatics
have been used in many fields such as mining and military.
Fluorescence-based chemical sensors for the detection of
explosives have attracted much attention since they have
potential applications in national security and environmental
protection.7−9 For the fluorescence-based detection, some
factors (e.g., the concentrations of analytes and the power of
the light source) may disturb the emission intensities of
sensors. To address this deficiency, some fluorescent organic
compounds,10,11 nanoparticles,12,13 and metal complexes14,15
were employed as dual-emissive sensors, which can calibrate
the fluorescence signals by themselves and make the results
more accurate. Recently, Chi et al. first used an Eu-MOF
containing carbon-based dots (CDs) to detect H2O molecules
in organic solvents, where the red light of Eu(III) and the blue
emission of CDs display sensing behavior to H2O molecules.16
In heterometallic d-4f complexes, light-absorbing moieties with
d-block metals (e.g., Zn2+,17 Cd2+,18 Pt2+,19 Ru2+,20 and Cr2+
)
21
may efficiently transfer energy to lanthanide ions. The dual-
emissive detection based on d-4f complexes is achieved mainly
so far by the intensity changes of visible emission of d-block
metal chromophores and luminescence of Ln3+ ions.22−24
Some lanthanide ions (e.g., Sm(III) and Ho(III)) have rich
spectroscopic properties and can show visible and NIR
emissions. However, as we know that there have been very
few reports on dual-emissive sensors based on both visible and
NIR lanthanide emissions.
Received: October 29, 2020
Revised: December 17, 2020
Published: January 4, 2021
https://dx.doi.org/10.1021/acs.jpca.0c09758
© 2021 American Chemical Society
J. Phys. Chem. A 2021, 125, 251−257
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refined isotropically. For 1 and 2, their CCDC numbers of
crystal structures are 2031776 and 2031777, respectively (see
www.ccdc.cam.ac.uk/data_request/cif). The bond lengths and
angles selected are displayed in Tables S1 and S2 (SI).
For 1: C78H66N4O17Zn2Nd, monoclinic (Cc), a = 33.516(8),
b = 14.576(3), c = 17.164(4) Å, α = 90°, β = 109.594(4)°, γ =
90°, V = 7900(3) Å3, Dc = 1.351 g cm−3, Z = 4, μ(Mo Kα) =
1.316 mm−1, T = 190 K, F(000) = 3372. R1 = 0.0721, wR2 =
0.2138, GOF = 1.009.
Scheme 1. Structure Diagram of the Designed Schiff Base
Ligand
For 2: C123H111Cd3N6O31Sm3, hexagonal (R3), a =
19.273(3), b = 19.273(3), c = 31.065(11) Å, α = 90°, β =
90°, γ = 120°, V = 9993(4) Å3, Dc = 1.474 g cm−3, Z = 3,
μ(Mo Kα) = 1.842 mm−1, T = 190 K, F(000) = 4407. R1 =
0.0867, wR2 = 0.1875, GOF = 1.144.
[Cd3Sm3L3(OAc)6(OH)3] (2). The Cd−Sm complex 2 shows
a triangular structure with 12 electron-rich groups such as
naphthyl and phenyl rings from H2L, which is beneficial to
forming π···π interactions with aromatic compounds. Interest-
ingly, 2 exhibits both visible and NIR lanthanide luminescent
responses to nitrobenzene explosives, especially to 2,4,6-
trinitrophenol (PA) with high sensitivity.
RESULTS AND DISCUSSION
■
Synthesis and Characterization. According to well-
established procedures,34 H2L was obtained from the
condensation reaction of 1,1′-binaphthyl-2,2′-diamine and 2-
hydroxy-3-methoxybenzaldehyde (Figure S1), with a yield of
97%. The yellow crystalline solid of 1 was achieved by the
reaction of the Schiff base ligand with ZnCl2 and Nd(OAc)3·
4H2O in a EtOH/MeOH solution. As shown in Figure 1, two
EXPERIMENTAL SECTION
■
Synthesis of the Schiff Base Ligand H2L. To a 15 mL
EtOH solution of 2-hydroxy-3-methoxybenzaldehyde (20.0
mmol, 3.04 g), 1,1′-binaphthyl-2,2′-diamine (10.0 mmol, 2.84
g) in 20 mL of EtOH was added slowly in 20 min. The mixture
was heated for 3.5 h under reflux with stirring. It was cooled to
room temperature to give a yellow solid product, which was
then filtered, washed three times using 5 mL of ethanol, and
dried overnight in air. Yield: (calculated from 1,1′-binaphthyl-
2,2′-diamine): 5.3607 g (97%). EA: Found: C, 78.31%; H,
5.13%; N, 5.12%. Calcd for C36H28N2O4: C, 78.24%; H,
1
5.11%; N, 5.07%. H NMR (CD3Cl3, 500 MHz): 12.18 (2H),
8.46 (2H), 7.85 (4H), 7.42 (2H), 7.27 (2H), 7.09 (2H), 7.03
(2H), 6.63 (2H), 3.63 (6H). IR (KBr, cm−1): 1613 (w), 1458
(m), 1251 (s), 1074 (m), 982 (s), 814 (s), 742 (s), 629 (s).
Synthesis of [Zn2NdL2(OAc)2]·OH (1). To a 20 mL MeOH
solution of ZnCl2 (0.20 mmol, 0.0272 g), Nd(OAc)3·4H2O
(0.20 mmol, 0.0642 g), and H2L (0.20 mmol, 0.1104 g),
triethylamine in 1 mL of a EtOH solution (1.0 mol/L) was
added. The mixture was heated for 3 h under reflux with
stirring. A clear solution was obtained after filtration, and slow
diffusion of ether into the solution for 2 weeks gave a yellow
crystalline product of 1. Yield (calculated from ZnCl2): 0.0778
g (49%). EA: Found: C, 58.52; H, 4.51; N, 3.34%. Calcd for
C78H66N4NdO17Zn2: C, 58.32; H, 4.14; N, 3.49%. IR (KBr,
cm−1): 1616 (s), 1543 (s), 1436 (s), 1233 (s), 1195 (s), 1075
(m), 972 (s), 701 (s), 659 (s). mp > 179.85 °C (decompose).
Synthesis of [Cd3Sm3L3(OAc)6(OH)3] (2). The synthesis
process of 2 was the same as that of 1 with the use of
Cd(NO3)2·4H2O (0.20 mmol, 0.0472 g), Sm(OAc)3·6H2O
(0.20 mmol, 0.0654 g), and H2L (0.20 mmol, 0.1104 g). Yield:
0.0713 g (35%). EA: Found: C, 49.51; H, 3.76; N, 2.87%.
Calcd for C123H111Cd3N6O31Sm3: C, 49.95; H, 3.78; N, 2.84%.
IR (KBr, cm−1): 1609 (s), 1386 (s), 1212 (m), 1071 (m), 966
(m), 748 (w), 624 (m). mp > 172.83 °C (decompose).
X-ray Single Crystal Diffraction. A Smart APEX CCD
diffractometer (Mo Kα radiation) was employed for the
collection of X-ray data of the single crystals. The crystal
structures of 1 and 2 have been solved by SHELX 97 program
using a direct method.33 SADABS program was used for the
empirical absorption correction. Non-hydrogen atoms were
refined anisotropically and located from trial structures, and
hydrogen atoms were calculated by geometrical methods and
Figure 1. Structure of the trinuclear Zn−Nd complex 1 (Zn2+: green;
Nd3+: blue).
Zn(II) ions have a square-based pyramidal geometry, located
in the inner N2O2 cavities of two L2− ligands. The Nd(III) ion
is ten-coordinated and shows a coordination geometry of
bicapped tetragonal antiprism, bound to the O2O2 donor sets
of two L2− ligands. The Nd(III) and Zn(II) ions are linked
together through two OAc− anions and four phenolic oxygen
atoms of the L2− ligands. The average Zn(II)···Nd(III)
distance is 3.542 Å. In 1, each Schiff base ligand coordinates
with one Zn(II) and one Nd(III) and displays a coordination
mode of μ2(η1:η2:η1:η1:η2:η1), while the OAc− anion exhibits a
μ2 coordination mode with the metals. The bond lengths of
Nd−O, Zn−N, and Zn−O in the structures are 2.400−2.880,
1.980−2.130, and 1.980−2.080 Å, respectively.
The formation of d-4f complexes depends on the d-metal
ions used, and the reaction of Schiff base ligand with
Sm(OAc)3·6H2O and Cd(NO3)2·4H2O gave 2 under the
same experimental conditions as above. The hexanuclear Cd−
Sm complex 2 shows an interesting triangular structure, which
has a C3 symmetry axis through the center of the molecule
(Figure 2). Different from those in 1, two benzene rings of the
L2− ligand are more distorted in 2. Thus, the L2− ligand can
coordinate with three metal ions (one Cd(II) and two
Sm(III)), resulting in a coordination mode of
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Figure 4. Absorption bands of the Schiff base ligand, 1, and 2 in
CH3CN.
Figure 2. Triangular structure of the hexanuclear Cd−Sm complex 2
(Cd2+: green; Sm3+: blue).
μ3(η1:η2:η1:η1:η2:η1). The Cd(II) ions are bound to the O2O2
donor sets of Schiff base ligands, while the Sm(III) ions are
coordinated with the O atoms of L2− ligands. The Sm(III) ions
are nine-coordinated and show a distorted tricapped trigonal
prism geometry. All Cd(II) and Sm(III) ions are connected
through three μ3-L2− ligands, three μ2-OH−, and six μ2-OAc−
anions. The average Cd(II)···Sm(III) distance is 3.759 Å, and
the bond lengths of Sm−O, Cd−N, and Cd−O are 2.370−
2.871, 2.269−2.363, and 2.240−2.339 Å, respectively. In
Figure 3, an image of scanning electron microscopy (SEM)
Figure 5. Lanthanide luminescence of 1 in CH3CN (C = 40 μM).
Figure 3. SEM image (a) and EDX spectroscopy (b) of 2.
exhibits the crystalline nature of 2, and the molar ratio of Cd/
Sm in its energy-dispersive X-ray spectroscopy (EDX) is found
to be 1, consistent with the crystal structure. For 1 and 2, their
power XRD spectra are similar to those generated from their
crystal data (Figure S3). Melting point measurements and
thermogravimetric analyses show that 1 and 2 are stable before
170 °C (see Experimental Section and Figure S4).
Photophysical Properties. The emission and excitation
spectra of the lanthanide complexes were investigated in
CH3CN. The free H2L displays UV−vis absorption bands at
233, 285, and 319 nm, which are all shifted in 1 and 2 (Figure
4). Under excitation at 373 nm, the H2L ligand has an emission
Figure 6. Lanthanide luminescence of 2 in CH3CN (C = 5 μM).
ions (LMET) happens in the complexes.35 The fluorescence
data of the free Schiff base ligand and complexes can be found
in Table 1.
Sensing Behavior of Complexes to Explosives. The
luminescence sensing behavior of 1 and 2 to nitrobenzene
Table 1. Fluorescence Data of the Free H2L and Complexes
1 and 2
Φem
λex (nm)/ε (×105 M−1cm−1
)
λem (nm)
τ (μs)
(%)
band at 621 nm (Figure S5). As shown in Figures 5 and 6, the
4
typical Nd(III) luminescence of 1 (NIR: F3/2
→
4Ij/2
H2L
373/0.01
621
transitions, j = 9, 11, and 13) and Sm(III) emissions of 2
1
374/0.045
871, 906, 1063,
1327
5.81
0.32
4
6
(visible: G5/2 → Hj/2 transitions, j = 5, 7, 9, and 11; NIR:
6
4G5/2 → Fj/2 transitions, j = 1, 3, 5, 7, and 9) are detected
2
Vis: 283/0.15, 373/0.05
NIR: 277/0.16, 373/0.05
598, 646, 709
899, 950, 1028,
1178, 1244
16.57
7.64
upon excitations at the absorption bands of ligands, indicating
that the energy transfer from Schiff base ligands to lanthanide
0.12
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explosives (Scheme S1) was investigated in CH3CN. The NIR
luminescence of 1 can be quenched by the addition of
explosives. As shown in Figure 7, with the addition of 60 μM
much lower compared to those required for other explosives,
demonstrating the high sensitivity of 2 to PA by both visible
and NIR luminescent responses.
The luminescence quenching is linear with the increase of
the concentrations of explosives (Figures S7 and S8). Thus, the
visible (or NIR) luminescence quenching constants (Ksv) of 2
to explosives can be estimated by the Stern−Volmer equation
Io/I = 1 + Ksv[A],36 in which Io and I are the luminescence
intensities at 646 nm (or 950 nm) in the absence and presence
of the explosive, respectively, and [A] represents its added
concentration (M) (Figures 8 and 9). For 2, the quenching
constants of visible and NIR luminescent responses to PA are
4.62 × 104 and 1.81 × 104 M−1, respectively, which are among
the highest values so far reported for the fluorescent detection
41
of explosives.37−40 The limits of detection (LOD = 3σ/Ksv
)
of 2 to PA by the visible and NIR luminescent responses are
estimated to be 1.1 × 10−6 and 2.1 × 10−5 M, respectively.
These results demonstrate that 2 exhibits visible and NIR
luminescence sensing to PA with high sensitivity.
Figure 7. Quenching percentages of the lanthanide emission of 1 (40
μM) to the addition of 60 μM explosives in CH3CN.
The stability of 2 during the response experiments is
checked by powder X-ray diffraction (PXRD). The PXRD
pattern of 2 after treated with PA is similar to that treated
before, indicating that the structure of the Cd(II)−Sm(III)
complex is not changed during the experiments (Figure S9).
Thus, the luminescence quenching of 2 with the addition of
PA is not due to the decomposition of the complex or the
coordination of PA with Sm(III) ions in 2. For luminescent
lanthanide complexes, the organic ligands are able to absorb
and transfer light energy to Ln(III) ions (“antenna effect”).42,43
Thus, if the added explosives have high molar absorption
coefficients at the λex of 2, they may quench lanthanide
luminescence by the “inner filter effect” (Scheme 2).44 As
PA, the luminescence quenching percentage of 1 is 82%, which
is much higher than those caused by the addition of other
explosives with the same concentration (less than 40%). It is
noticeable that the added explosives can decrease the
lanthanide luminescence of 2 in either visible or NIR range
(Figures 8,9, S7, and S8), indicating that 2 shows dual
Scheme 2. “Antenna Effect” of Schiff Base Ligands and the
“Inner Filter Effect” of Explosives to the Lanthanide
Luminescence of 2
Figure 8. Ksv values of 2 to explosives for the visible luminescence
quenching. The inset shows the visible emission quenching of 2 (5
μM) to the addition of PA.
Figure 9. Ksv values of 2 to explosives for the NIR luminescence
quenching. The inset shows the NIR emission quenching of 2 (50
μM) to the addition of PA.
shown in Figure 10, the absorption coefficient of PA at λex
=
373 nm is 1.6 × 104 M−1 cm−1, which is higher than that of 2
at the excitation wavelength (0.5 × 104 M−1 cm−1; Table 1).
Thus, the added PA can compete for the light energy with the
Schiff base ligands in 2, resulting in the lanthanide emission
quenching of the complex. In addition, the absorption
coefficient of 2-NP at 373 nm is found to be 0.2 × 104 M−1
cm−1, which is lower than that of PA but much higher than
those of other explosives that almost show no absorption at
this wavelength (Figure 10). As a result, 2 has the second
luminescent response properties to explosives. Compared with
other explosives, the low concentration of PA can quench the
luminescence rapidly. For example, the most intense
lanthanide emissions of 2 at 646 and 950 nm are decreased
about a half, with the addition of 21.8 and 39.3 μM PA,
respectively (Figures S7 and S8). These two concentrations are
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Figure 10. UV−vis spectra of nitrobenzene explosives in CH3CN at
room temperature.
Figure 12. NIR lanthanide emission quenching of 2 (50 μM) in
CH3CN caused by the step-by-step addition of explosives (10 μM).
highest visible and NIR luminescence quenching constants to
2-NP (0.65 × 104 and 0.18 × 104 M−1; Figures 8 and 9),
confirming the inner filter effect of explosives to the lanthanide
emission quenching.
cycles of the additions of another explosive and PA, suggesting
the high selectivity of 2 to the latter.
For the visible (or NIR) luminescence of 2, besides the
excitation wavelength at 373 nm, another excitation wave-
length is at 283 nm (or 277 nm), where the absorption
coefficient of PA is 0.27 × 104 M−1 cm−1 (or 0.26 × 104 M−1
cm−1). The absorption coefficients of 2 at 277 and 283 nm are
1.6 × 104 and 1.5 × 104 M−1 cm−1, respectively, which are
higher than those of PA at these two excitation wavelengths.
When the excitation wavelengths of the visible and NIR
luminescence are changed to 283 and 277 nm, the Ksv values of
2 to PA are 0.82 × 104 and 0.77 × 104 M−1, respectively
(Figure S10), which are lower than those obtained with the
excitation wavelength at 373 nm. This is due to the higher
absorption coefficients of 2 at 283 and 277 nm. These results
further demonstrate that the inner filter effect of PA plays an
important role in the lanthanide emission quenching of 2.
As shown in Figures 11 and 12, the step-by-step addition of
nitrobenzene explosives has been employed to study the effect
CONCLUSIONS
■
In brief, two Zn−Nd and Cd−Sm complexes 1 and 2 were
synthesized from a designed Schiff base ligand H2L that has a
binaphthyl backbone and coordinates with metal ions by
μ2(η1:η2:η1:η1:η2:η1) and μ2(η1:η2:η1:η1:η2:η1) modes. The
Schiff base ligands can transfer light energy to lanthanide
ions, resulting in the typical Nd(III) and Sm(III) emissions of
the complexes. The triangular Cd−Sm complex 2 exhibits
interesting dual visible and NIR emissive responses to
nitrobenzene explosives and shows high sensitivity and
selectivity to PA. The quenching constants to PA for the
visible and NIR lanthanide emissions of 2 are 4.62 × 104 and
1.81 × 104 M−1, respectively.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.jpca.0c09758.
■
sı
General procedures; 1H NMR spectra of H2L; IR spectra
of H2L and complexes 1 and 2; powder XRD patterns of
1 and 2; thermogravimetric analysis of 1 and 2; chemical
structures of nitro explosives; NIR luminescence sensing
of 2 to nitro explosives; powder XRD patterns of 2
before and after treated with PA; and CCDC numbers
for 1 and 2 are 2031776 and 2031777, respectively
(PDF)
AUTHOR INFORMATION
Corresponding Author
■
Xiaoping Yang − Zhejiang Key Laboratory of Carbon
Materials, College of Chemistry and Materials Engineering,
Wenzhou University, Wenzhou 325035, China;
orcid.org/0000-0002-4370-517X; Email: xpyang@
wzu.edu.cn
Figure 11. Visible lanthanide emission quenching of 2 (5 μM) in
CH3CN caused by the step-by-step addition of nitrobenzene
explosives (10 μM).
Authors
of other explosives on the emission sensing of 2 to PA. The
emission quenching of 2 to PA and other explosives shows that
the visible (or NIR) luminescence was not reduced rapidly
when another explosive such as 1,3-DNB was added twice first,
while it was decreased much fast with the subsequent addition
of PA. This phenomenon can be found again in the following
Mengyu Niu − Zhejiang Key Laboratory of Carbon Materials,
College of Chemistry and Materials Engineering, Wenzhou
University, Wenzhou 325035, China
Yanan Ma − Zhejiang Key Laboratory of Carbon Materials,
College of Chemistry and Materials Engineering, Wenzhou
University, Wenzhou 325035, China
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dynamic tracing in living cells. J. Am. Chem. Soc. 2014, 136, 14237−
14244.
(12) Ma, H.; Song, B.; Wang, Y.; Cong, D.; Jiang, Y.; Yuan, J. Dual-
emissive nanoarchitecture of lanthanide-complex-modified silica
particles for in vivo ratiometric time-gated luminescence imaging of
hypochlorous acid. Chem. Sci. 2017, 8, 150−159.
(13) Zhang, K. Y.; Zhang, J.; Liu, Y.; Liu, S.; Zhang, P.; Zhao, Q.;
Tang, Y.; Huang, W. Core−shell structured phosphorescent nano-
particles for detection of exogenous and endogenous hypochlorite in
live cells via ratiometric imaging and photoluminescence lifetime
imaging microscopy. Chem. Sci. 2015, 6, 301−307.
(14) Zhang, K. Y.; Liu, H.; Tang, M.; Choi, A. W.; Zhu, N.; Wei, X.;
Lau, K.; Lo, K. K. Dual-emissive cyclometalated Iridium(III)
polypyridine complexes as ratiometric biological probes and
organelle-selective bioimaging reagents. Inorg. Chem. 2015, 54,
6582−6593.
Dongliang Shi − Zhejiang Key Laboratory of Carbon
Materials, College of Chemistry and Materials Engineering,
Wenzhou University, Wenzhou 325035, China
Desmond Schipper − Department of Chemistry and
Biochemistry, The University of Texas at Austin, Austin,
Texas 78712-0165, United States
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.jpca.0c09758
Author Contributions
The manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript.
Notes
(15) Yoshihara, T.; Yamaguchi, Y.; Hosaka, M.; Takeuchi, T.;
Tobita, S. Ratiometric molecular sensor for monitoring oxygen levels
in living cells. Angew. Chem., Int. Ed. 2012, 51, 4148−4151.
(16) Dong, Y.; Cai, J.; Fang, Q.; You, X.; Chi, Y. Dual-emission of
lanthanide metal−organic frameworks encapsulating carbon-based
dots for ratiometric detection of water in organic solvents. Anal.
Chem. 2016, 88, 1748−1752.
(17) Wong, W.-K.; Liang, H.; Wong, W.-Y.; Cai, Z.; Li, K.-F.; Cheah,
K.-W. Synthesis and near-infrared luminescence of 3d-4f bi-metallic
Schiff base complexes. New J. Chem. 2002, 26, 275−278.
(18) Chi, Y.-X.; Niu, S.-Y.; Jin, J.; Wang, R.; Li, Y. Syntheses,
structures and photophysical properties of tetranuclear Cd−Ln
coordination complexes. Dalton Trans. 2009, 7653−7659.
(19) Xu, H.-B.; Shi, L.-X.; Ma, E.; Zhang, L.-Y.; Wei, Q.-H.; Chen,
Z.-N. Diplatinum alkynyl chromophores as sensitisers for lanthanide
luminescence in Pt2Ln2 and Pt2Ln4 (Ln = Eu, Nd, Yb) arrays with
acetylide-functionalized bipyridine/phenanthroline. Chem. Commun.
2006, 1601−1603.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (No. 21771141) and Key Foundation for
High-level Talents Innovation Technology Projects of
Wenzhou (2019).
REFERENCES
■
(1) Shi, P.; Hu, H.; Zhang, Z.; Xiong, G.; Zhao, B. Heterometal−
organic frameworks as highly sensitive and highly selective
luminescent probes to detect I− ions in aqueous solutions. Chem.
Commun. 2015, 51, 3985−3988.
(2) Xu, Y.-Y.; Sun, O.; Xie, B.-Y.; Gao, T.; Qi, Y. Enhanced
luminescence for detection of small molecules based on doped
lanthanide compounds with a dinuclear double-stranded helicate
structure. New J. Chem. 2019, 43, 16706−16713.
(3) Guo, Z.; Xu, H.; Su, S.; Cai, J.; Dang, S.; Xiang, S.; Qian, G.;
Zhang, H.; O’Keeffe, M.; Chen, B. A robust near infrared luminescent
ytterbium metal-organic framework for sensing of small molecules.
Chem. Commun. 2011, 47, 5551−5553.
(4) Hou, S.-L.; Dong, J.; Tang, M.-H.; Jiang, X.-L.; Jiao, Z.-H.; Zhao,
B. Triple-interpenetrated lanthanide-organic framework as dual wave
bands self-calibrated pH luminescent probe. Anal. Chem. 2019, 91,
5455−5460.
(5) Kang, X.-M.; Fan, X.-Y.; Hao, P.-Y.; Wang, W.-M.; Zhao, B. A
stable zinc-organic framework with luminescence detection of
acetylacetone in aqueous solution. Inorg. Chem. Front. 2019, 6,
271−277.
(6) Kang, X.-M.; Hu, H.-S.; Wu, Z.-L.; Wang, J.-Q.; Cheng, P.; Li, J.;
Zhao, B. An ultrastable matryoshka [HF13] nanocluster as a
luminescent sensor for concentrated alkali and acid. Angew. Chem.,
Int. Ed. 2019, 58, 16610−16616.
(7) Qi, X.; Jin, Y.; Li, N.; Wang, Z.; Wang, K.; Zhang, Q. A
luminescent heterometallic metal−organic framework for the naked-
eye discrimination of nitroaromatic explosives. Chem. Commun. 2017,
53, 10318−10321.
(8) Sun, X.; Wang, Y.; lei, Y. Fluorescence based explosive detection:
from mechanisms to sensory materials. Chem. Soc. Rev. 2015, 44,
8019−8061.
(9) Hu, Z.; Deibert, B. J.; Li, J. Luminescent metal−organic
frameworks for chemical sensing and explosive detection. Chem. Soc.
Rev. 2014, 43, 5815−5840.
(10) Takahashi, S.; Piao, W.; Matsumura, Y.; Komatsu, T.; Ueno, T.;
Terai, T.; Kamachi, T.; Kohno, M.; Nagano, T.; Hanaoka, K.
Reversible off−On fluorescence probe for hypoxia and imaging of
hypoxia−normoxia cycles in live cells. J. Am. Chem. Soc. 2012, 134,
19588−19591.
(11) Huang, C.; Jia, T.; Tang, M.; Yin, Q.; Zhu, W.; Zhang, C.;
Yang, Y.; Jia, N.; Xu, Y.; Qian, X. Selective and ratiometric fluorescent
trapping and quantification of protein vicinal dithiols and in situ
(20) Baca, S. G.; Adams, H.; Grange, C. S.; Smith, A. P.; Sazanovich,
I.; Ward, M. D. [Os(bipy)(CN)4]2− and Its relatives as components
of polynuclear assemblies: Structural and photophysical properties.
Inorg. Chem. 2007, 46, 9779−9789.
(21) Torelli, S.; Imbert, D.; Cantuel, M.; Bernardinelli, G.; Delahaye,
S.; Hauser, A.; Bunzli, J.-C. G.; Piguet, C. Tuning the decay time of
̈
lanthanide-based near infrared luminescence from micro- to milli-
seconds through d→f energy transfer in discrete heterobimetallic
complexes. Chem. - Eur. J. 2005, 11, 3228−3242.
(22) Boulay, A.; Deraeve, C.; Elst, L. V.; Leygue, N.; Maury, O.;
́
Laurent, S.; Muller, R. N.; Mestre-Voegtle, B.; Picard, C. Terpyridine-
based heteroditopic ligand for RuIILn3III metallostar architectures (Ln
= Gd, Eu, Nd, Yb) with MRI/optical or dual-optical responses. Inorg.
Chem. 2015, 54, 1414−1425.
(23) Nonat, A. M.; Quinn, S. J.; Gunnlaugsson, T. Mixed f−d
coordination complexes as dual visible- and near-Infrared-emitting
probes for targeting DNA. Inorg. Chem. 2009, 48, 4646−4648.
(24) Comby, S.; Tuck, S. A.; Truman, L. K.; Kotova, O.;
Gunnlaugsson, T. New trick for an old ligand! the sensing of Zn(II)
using a lanthanide based ternary Yb(III)-cyclen-8-hydroxyquinoline
system as a dual emissive probe for displacement assay. Inorg. Chem.
2012, 51, 10158−10168.
(25) Yang, X.; Jones, R. A.; Huang, S. Luminescent 4f and d-4f
polynuclear complexes and coordination polymers with flexible salen-
type ligands. Coord. Chem. Rev. 2014, 273−274, 63−75.
(26) Yang, X.; Schipper, D.; Jones, R. A.; Lytwak, L. A.; Holliday, B.
J.; Huang, S.-M. Anion dependent self-Assembly of NIR luminescent
24- and 32-metal Cd-Ln complexes with drum-like architectures. J.
Am. Chem. Soc. 2013, 135, 8468−8471.
(27) Yang, X.; Schipper, D.; Zhang, L.; Yang, K.; Huang, S.; Jiang, J.;
Su, C.; Jones, R. A. Anion dependent self-assembly of 56-metal Cd-Ln
nanoclusters with enhanced near-infrared luminescence properties.
Nanoscale 2014, 6, 10569−10573.
(28) Wang, C.; Yang, X.; Wang, S.; Zhu, T.; Bo, L.; Zhang, L.; Chen,
H.; Jiang, D.; Dong, X.; Huang, S. Anion dependent self-assembly of
256
https://dx.doi.org/10.1021/acs.jpca.0c09758
J. Phys. Chem. A 2021, 125, 251−257

The Journal of Physical Chemistry A
pubs.acs.org/JPCA
Article
drum-like 30- and 32-metal Cd-Ln nanoclusters: visible and NIR
luminescent sensing of metal cations. J. Mater. Chem. C 2018, 6, 865−
874.
(29) Yang, X.; Jones, R. A. Anion dependent self-assembly of ″tetra-
decker″ and ″triple-decker″ luminescent Tb(III) salen complexes. J.
Am. Chem. Soc. 2005, 127, 7686−7689.
(30) Yang, X.; Jones, R. A.; Wong, W.-K. Pentanuclear tetra-decker
luminescent lanthanide Schiff base complexes. Dalton Trans. 2008,
1676−1678.
(31) Wong, W. K.; Yang, X.; Jones, R. A.; Rivers, J.; Lynch, V.; Lo,
W. K.; Xiao, D.; Oye, M. M.; Holmes, A. Multinuclear luminescent
Schiff-base Zn-Nd sandwich complexes. Inorg. Chem. 2006, 45, 4340−
4345.
(32) Liu, J.; Zhu, T.; Yang, X.; Chen, H.; Shi, D.; Zhu, C.; Schipper,
D.; Jones, R. A. Construction of a 1-D Sm(III) coordination polymer
with long-chain Schiff base ligand: Dual-emissive response to metal
ions. Inorg. Chem. Front. 2020, 7, 464−469.
(33) Sheldrick, G. H. SHELX 97, A Software Package for the Solution
̈
̈
and Refinement of X-ray Data; University of Gottingen: Gottingen,
Germany, 1997.
(34) Lam, F.; Xu, J. X.; Chan, K. S. Binucleating ligands: synthesis of
acyclic achiral and chiral Schiff base-pyridine and Schiff base-
phosphine ligands. J. Org. Chem. 1996, 61, 8414−8418.
(35) Petoud, S.; Cohen, S. M.; Bunzl, J.-C. G.; Raymond, K. N.
̈
Stable lanthanide luminescence agents highly emissive in aqueous
solution: Multidentate 2-hydroxyisophthalamide complexes of Sm3+,
Eu3+, Tb3+, Dy3+. J. Am. Chem. Soc. 2003, 125, 13324−13325.
(36) Xiao, Y.; Cui, Y.; Zheng, Q.; Xiang, S.; Qian, G.; Chen, B. A
microporous luminescent metal−organic framework for highly
selective and sensitive sensing of Cu2+ in aqueous solution. Chem.
Commun. 2010, 46, 5503−5505.
(37) Liu, C.; Zhou, L.; Tripathy, D.; Sun, Q. Self-assembly of stable
luminescent lanthanide supramolecular M4L6 cages with sensing
properties toward nitroaromatics. Chem. Commun. 2017, 53, 2459−
2462.
(38) Nagarkar, S. S.; Joarder, B.; Chaudhari, A. K.; Mukherjee, S.;
Ghosh, S. K. Highly selective detection of nitro explosives by a
luminescent metal-organic framework. Angew. Chem., Int. Ed. 2013,
52, 2881−2885.
(39) Nagarkar, S. S.; Desai, A. V.; Ghosh, S. K. A fluorescent metal−
organic framework for highly selective detection of nitro explosives in
the aqueous phase. Chem. Commun. 2014, 50, 8915−8918.
(40) Qin, J.-H.; Ma, B.; Liu, X.-F.; Lu, H.-L.; Dong, X.-Y.; Zang, S.-
Q.; Hou, H.-W. Aqueous- and vapor-phase detection of nitroaromatic
explosives by a water-stable fluorescent microporous MOF directed
by an ionic liquid. J. Mater. Chem. A 2015, 3, 12690−12697.
(41) Qi, X.; Jin, Y.; Li, N.; Wang, Z.; Wang, K.; Zhang, Q. A
luminescent heterometallic metal-organic framework for the naked-
eye discrimination of nitroaromatic explosives. Chem. Commun. 2017,
53, 10318−10321.
(42) Sabbatini, N.; Guardigli, M.; Lehn, J. M. Luminescent
lanthanide complexes as photochemical supramolecular devices.
Coord. Chem. Rev. 1993, 123, 201−228.
(43) Piguet, C.; Bunzli, J.-C. G. Mono- and polymetallic lanthanide-
̈
containing functional assemblies: a field between tradition and
novelty. Chem. Soc. Rev. 1999, 28, 347−358.
(44) Tian, D.; Li, Y.; Chen, R. Y.; Chang, Z.; Wang, G. Y.; Bu, X. H.
A luminescent metal−organic framework demonstrating ideal
detection ability for nitroaromatic explosives. J. Mater. Chem. A
2014, 2, 1465−1470.
257
https://dx.doi.org/10.1021/acs.jpca.0c09758
J. Phys. Chem. A 2021, 125, 251−257