Coordination-Assembled Lanthanide-Organic Ln3L3 Sandwiches or Ln4L4 Tetrahedron: Structural Transformation and Luminescence Modulation

Article abstract of DOI:10.1002/cjoc.201900101

Photo-functional supramolecular lanthanides assemblies have shown great potential in the materials and biomedical fields. Two new tri(tridentate) ligands (L3 and L4) highlighting small variation of the connection position to the central tridentate linkers have been designed, which leads to the emergent formation of either Ln₃L₃-type sandwich structures or Ln₄L₄-type tetrahedral cages. Moreover, nonlinear enhancement of lanthanide luminescence based on the modulation of inter-ligand charge-transfer states has been revealed on the mix-ligand Ln₃L₃ sandwiches. Our results provide important guidance for structure-design and photoluminescence optimization of supramolecular lanthanide-organic assemblies.

Full text of DOI:10.1002/cjoc.201900101

Accepted Article
Title: Coordination-Assembled Lanthanide-Organic Ln L Sandwiches or Ln L
4 4
3
3
Tetrahedron: Structural Transformation and Luminescence Modulation
Authors: Shao-Jun Hu, Xiao-Qing Guo, Li-Peng Zhou, Li-Xuan Cai, and Qing-Fu Sun*
This manuscript has been accepted and appears as an Accepted Article online.
This work may now be cited as: Chin. J. Chem. 2019, 37, 10.1002/cjoc.201900101.
The final Version of Record (VoR) of it with formal page numbers will soon be
published online in Early View: http://dx.doi.org/10.1002/cjoc.201900101.
ISSN 1001-604X • CN 31-1547/O6
mc.manuscriptcentral.com/cjoc
www.cjc.wiley-vch.de

Coordination-Assembled Lanthanide-Organic Ln L Sandwiches or Ln L
3
3
4 4
Tetrahedron: Structural Transformation and Luminescence Modulation
ab
ac
a
a
,a,b,c
Shao-Jun Hu, Xiao-Qing Guo, Li-Peng Zhou, Li-Xuan Cai, and Qing-Fu Sun*
a
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, PR
China
b
College of Chemistry, Fuzhou University, Fuzhou 350108, PR China
c
University of Chinese Academy of Sciences, Beijing 100049, PR China
Cite this paper: Chin. J. Chem. 2019, 37, XXX—XXX. DOI: 10.1002/cjoc.201900XXX
Photo-functional supramolecular lanthanides assemblies have shown great potential in the materials and biomedical fields. Two new tri(tridentate)
ligands (L3 and L4) highlighting small variation of the connection position to the central tridentate linkers have been designed, which leads to the
emergent formation of either Ln
3
L
3
-type sandwich structures or Ln
4
L
4
-type tetrahedral cages. Moreover, nonlinear enhancement of lanthanide
sandwiches. Our results provide
important guidance for structure-design and photoluminescence optimization of supramolecular lanthanide-organic assemblies.
3 3
luminescence based on the modulation of inter-ligand charge-transfer states has been revealed on the mix-ligand Ln L
Background and Originality Content
been realized by switching the solvents with different polarity.
Moreover, non-linear luminescent enhancement through an
inter-ligand charge transfer sensitization mechanism has been
Coordination-assembled
architectures show many promising applications, such as
[3]
discrete
supramolecular
revealed during the mixed-ligand self-assembly of the Ln
sandwiches.
3 3
L
[
1]
[2]
biomimetic catalysis, molecular sensing, ion extraction,
[
4]
bio-imaging and cancer therapy. In contrast with the intense
reports on metallosupramolecular edifices constructed with
transition metals, multi-nuclear lanthanide-organic architectures
are far less studied. Due to their particular optical, electric and
magnetic characteristics, mononuclear clathrates, bundles or
dinuclear helicates of lanthanides have shown great potential in
the materials and biomedical fields. However, high-nuclear and
sophisticated lanthanide-organic assemblies are still rare because
of the challenges in taming the intrinsic liability and flexibility on
Scheme
1
Coordination-directed self-assembly and structural
transformation of Lanthanide-organic Ln
Tetrahedron.
3
L
3
4 4
sandwiches and Ln L
[
5]
[
6]
[
7]
[
8]
lanthanide coordination.
Supramolecular transformation is an efficient method for the
generation and functionalization of discrete supramolecular
[
9]
assemblies.
In-depth understanding of supramolecular
transformation helps not only in mimicking the biological
transformation processes but also in the design of smart
functional materials. So far, stimuli-responsive supramolecular
[
10]
[11]
[12]
transformations triggered by solvent, concentration, pH,
[
13]
[14]
[15]
light,
metal/ligand ratio,
guests,
and so on have been
accomplished. Recently, our group has reported a systematic
structure evolution of the chiral lanthanide coordination edifices
from helicates and tetrahedrons to cubes via subtle ligand
[
2a, 6a]
variations and concentration effect.
Due to the Laporte symmetry-forbidden 4f-4f transitions on
-1 [16]
2
-1
lanthanides (with molar absorption coefficient ε<10 M cm ),
antenna” sensitization of lanthanide luminescence through the
“
[
17]
adjacent organic chromophores is necessary. To obtain bright
luminescent lanthanide complexes, most efforts have been
focused on designing appropriate ligands with proper energy gap
between the excited state of the donor ligands (usually the triplet Results and Discussion
[18]
state T1) and the accepting emitting states of the lanthanides.
Recently, we found that ligands based on triazole-pyridine-amido
Ligand design and synthesis. Based on geometrical principle,
-symmetry tris-(tridentate) ligands combined with
nine-coordinating C -symmetry Lanthanide nodes usually form
-type tetrahedron.
C
3
(
tpa) chelation arms(L1 and L2) could form bright luminescent
[19]
3
lanthanide-organic polyhedra.
Herein, two new tpa-based
[2c, 3, 19-20]
M
4
L
4
Indeed, full-conjugated ligands
tri(tridentate) ligands (L3 and L4) highlighting small variation of
the connection position to the central tridentate linkers have been
designed, which leads to the emergent formation of new
with triphenyl-benzene or triphenyl-triazine cores decorated by
the triazole-pyridine-amido (tpa) chelating arms are known to
3+
self-assemble with Ln (Ln = Eu, Tb, Sm, Dy ) to form bright
Ln
3
L
3
-type sandwich structures or Ln
4
L
4
-type tetrahedral cage
and Ln has also
[19]
luminescent Ln
4
L
4
tetrahedra.
Meanwhile, we also disclosed
(Scheme 1). Transformation between Ln
3
L
3
4 4
L
that the offset arrangement of the chelating groups in the
*E-mail: qfsun@fjirsm.ac.cn
This article has been accepted for publication and undergone full peer review but has not
been through the copyediting, typesetting, pagination and proofreading process, which
may lead to differences between this version and the Version of Record. Please cite this
article as doi: 10.1002/cjoc.201900101
This article is protected by copyright. All rights reserved.

bis-(bidentate) ligands can dictate the final outcomes of the
assembly, where Ln2n 3n (n = 1, 2, 4) could be selectively
This finding persuaded us to check whether the
variation of the connection angles between chelation arm and the
central tridentate spacer has influence on the final product. Bear
this in mind, two new tris-(tridentate) ligands, L3 and L4, where
the connection angle between the chelating arms and the spacer
is changed from 180 to 120 degrees (Scheme 1) have been
designed. Both ligands were synthesized by previously reported
Complex of Eu
3 3 9
(L4) (OTf) . When equimolar amount of
L
Eu(OTf) and L4 were added into a mixed solvent of deuterated
3
[
21]
obtained.
acetonitrile and methanol (v/v, 4:1) and stirred at 50 °C for 1 hour,
the turbid suspension gradually turned into a homogeneous
1
solution. H NMR indicated quantitative formation of a single
product with low symmetry, as roughly two sets of ligand signals
in a 1:2 ratio are observed, except for the further splitting of the
isopropyl groups (Figure 1A, B). Compared with the free ligand,
most signals arising from the assembly are shifted, which can be
[
19]
Ⅲ
method,
high-resolution ESI-MS spectroscopy. (See experimental section
for details.) Surprisingly, L3 and L4 both tend to form Ln
Sandwich structures3 instead of Ln tetrahedron when
self-assemble with Ln . To the best of our knowledge, this is the
first example of lanthanide supramolecular sandwich architecture. High-resolution ESI-TOF-MS clearly confirmed the formation of
which have been fully characterized by NMR and
attributed to paramagnetic Eu centers. All signals could be fully
1
1
assigned with the help of H- H COSY spectra (Figure S12).
1
L
3 3
Diffusion-ordered H NMR (DOSY) also indicated the formation of
4
L
4
a single species in solution, with one diffusion band observed at a
diffusion coefficient of D = 3.55×10
+
-10
2 -1
m s (Figure 1C).
3
+
Moreover, ligand L3 can also self-assemble with Ln to form the
known Ln tetrahedron, where solvent-triggered transformation
between Ln and Ln took place.
the trinuclear supramolecular architecture with a formula of
Eu (L4) (OTf) (Figure 1D). A series of peaks with m/z = 810.1722,
1049.9542, 1449.5897 consistent with the successive loss of OTf-
counter ions on Eu (L4) (OTf) are observed, which can be further
verified by comparing to the isotopic patterns. For example, the
4
L
4
3
3
9
3
L
3
4 4
L
3
3
9
4
+
simulated isotopic pattern for [Eu
3
(L4)
3
(OTf)
5
]
shown in the
insets of Figure 1D perfectly match the experimentally observed
one.
The structure of Eu (L4) (OTf) was ultimately confirmed by
3 3 9
X-ray diffraction analysis. Single crystals were obtained by slow
vapor diffusion of chloroform into the acetonitrile solution of
Eu
diffracts very weakly in nature due to a giant “void” of 25,577 Å
roughly 64.7% of unit cell volume), where highly disordered
charge-balancing counter ions and solvent molecules have been
3 3 9
(L4) (OTf) after weeks. It has to be pointed out this crystal
3
(
[
22]
masked by a Platon/SQUEEZE routine. As shown in Figure 1E,
the discrete Eu (L4) assembly displays a triple-decker sandwich
3
3
structure, where three Eu vertices define a pseudo-regular
triangle with an average Eu···Eu distance measured to be 15.6 Å.
All Eu centers are nine-coordinated with mechanical-coupled
cooperative ΔΔΔ or ΛΛΛ configurations, resulting in the
supramolecular chirality on each complex. However, the
compound crystallized in a P-1 space group, so both ΔΔΔ and ΛΛΛ
enantiomers exist in the same crystal. The intramolecular
distance between adjacent centroids of the triazine rings is
determined to be 3.35 Å (Figure 1F), indicating the existence of
[
14]
strong intra-molecular π-π stacking interactions. As shown in
the asymmetric unit in Figure 1G, two unique Eu (L4) assemblies
3
3
with the same chirality are also closely packed together, giving
rise to a dimeric structure, which is stabilized by multiple
–
hydrogen-bonding interactions through three bridging OTf
anions. Similarly, strong inter-molecular π-π stacking interactions
are observed between the triphenyl-triazine plane, leading to a
sextuple π-π stacked structure in total. The dimeric structures
could also be found in the gas-phase, as assignable peaks
y+
corresponding to [Eu
in the ESI-TOF-MS (Figure 1D).
Complexes of Eu (L3) (OTf)
complex was synthesized in the same method as for Eu
6
(L4)
6
(OTf)18-y
]
(y=5,6,7) were also observed
3
3
9
and Eu
4
(L3)
4
(OTf)12. The Eu
3
(L3)
by
3
3
(L4)
3
III
using the corresponding L3 and Eu salts. Due to the co-existence
[23]
of potential ΔΔΔ, ΔΔΛ, ΔΛΛ and ΛΛΛ isomers, it is difficult to
fully assign the H NMR spectrum of this complex in this case
1
1
Figure 1 Characterization of the self-assembly of L4 with Eu(OTf)
3
: H NMR
(
Figure 2A). Nonetheless, DOSY (Figure 2B) and ESI-TOF-MS
(
(
(
400 MHz, 293 K) spectra of (A) free ligand L4 (in CDCl
B) the Eu (L4) (OTf) complex (in CD NO /CD OD=4:1); (C) H DOSY and
D)ESI-TOF-MS spectra of the Eu (L4) (OTf)12 complex with insets showing
3 3
/CD OD = 4:1) and
1
(Figure 2G) clearly confirmed the formation of the trinuclear
3
3
9
3
2
3
Ⅲ
Eu
L3 were self-assembled in nitromethane with a lower polarity, the
Eu (L3) tetrahedral complex was obtained. This was firstly
indicated by a totally different H NMR spectrum (Figure 2C) from
the Eu (L3) complex. Secondly, DOSY (Figure 2D) also indicated
the formation of a single species with a different size (diffusion
3 3 9
(L3) (OTf) structures in solution. Interestingly, when Eu and
3
3
the observed (Obs) and simulated (Sim) isotopic patterns of the peaks
5
+
4
4
corresponding to [Eu
3
(L4)
3
(OTf)
4
] . X-ray crystal structure of the Eu
(L4) assembly;
dimeric structure refined in the asymmetric unit
Color mode: Eu, purple sphere; C, green; N, dark blue; O, red; F,
3
(L4)
3
1
complex: Side view (E) and top view (F) of the discrete Eu
3
3
3
3
3 3 3 2
(G) (OTf) @[Eu (L4) ]
(
-10
2 -1
coefficient of D = 3.98×10 m s for Eu
diameter of 16.8 Å), which is similar to the Eu L
4
(L3)
4
, corresponding to a
-type complexes
gray-green; S, yellow).
4 4
2
T hw i sw aw r. tc i jcc l. ew ii lse yp - rv oc ht e. dc et ed by c o© p 2y 0r i1g 9h St .I OA Cl ,l Cr iAg Sh ,t Ss h ra en sg eh ar vi , e&d W. ILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2019, 37, XXX－XXX

[
19]
chelates connection angle, where analogous Ф (56% vs. 52%)
[19] III
4
4
were obtained. Similar characteristic Eu emission bands were
also observed for Eu (L3) , but the excitation band shows a little
blue shifting. Under the same measurement conditions (0.3v%
-
4
4
tetranuclear
(OTf)
MeNO
measured for Eu
2
/MeCN),
a
(L3)
smaller quantum yield (Ф=15.7%) was
than Eu (L3) (Ф=23.2%).( See experimental
4
(OTf)
4
4
3
3
(L3)
4
(OTf)
section for details) This implies that the unique π-π stacked
conformation of the ligands on the sandwich complexes
dramatically enhanced the sensitization ability toward lanthanide
luminescence. In our previous study, we have demonstrated that
intra-ligand charge-transfer state provides a good alternative
Figure 2H).
Attempts to crystallize Eu
(L3) (OTf)12 tetrahedron were unsuccessful possibly due to the
existence of complicated isomers. Thus, their structures were
simulated by molecular mechanic modeling. The optimized
[2c]
sensitization pathway toward bright luminescent cages.
strong inter-ligand π-π stacking interactions observed on the
triple-decker Ln sandwich motivated us to further modulate its
The
structure of ΔΔΔ-Eu
E and 2F, respectively. The average distance of Eu···Eu of the
ΔΔΔ-Eu (L3) are similar to Eu (L4) . For Eu (L3) , it is worth to
3 3 4 4
(L3) and ΔΔΔΔ-Eu (L3) are shown in Figure
3 3
L
luminescence based on a mixed ligands strategy.
mention that there are 25 possible isomeric structures by the
3 x
Nonlinear enhanced luminescence on Eu (L3) (L4)3-x.
combination of chirality at metal centers (Δ/Λ) and clockwise or
Luminescence modulation by doping of different organic ligands
[
24]
[25]
anticlockwise orientation of ligands (A/C).
Solvent-triggered transformation between Eu (L3)
was then studied. When the nitromethane solution of Eu
(Table S2)
has been studied in MOFs and other nanomaterials. However,
[
26]
3
3
and Eu
4
(L3)
(L3)
4
such a doping has seldom been tested on the molecular level.
4
4
We designed the following experiments to confirm that
intra-ligand charge-transfer state can be used to enhance the
luminescence of the lanthanide-organic edifices. Firstly, when
was evaporated and re-dissolved in acetonitrile by heating at 60°C
1
for 1.5 h, both H NMR (Figure S24) and ESI-TOF-MS (Figures S25,
equimolar amount of Eu(OTf)
was self-assembled, formation of heteroligand Eu
3
and mixed L4/L3 (2:1 molar ratio)
(L4) (L3)3-x (x =
3
x
0, 1, 2, 3) sandwiches was confirmed by ESI-TOF-MS (Figure S35).
The emission spectra (λex = 298 nm) were collected with the
gradually increased fraction of the L4 content [f = L4/(L3+L4)]. As
shown in Figure 3C, the emission intensity at 615 nm shows a
nonlinear enhancing trend with two maxima appeared at f = 0.4
investigated. Similar to the reported ligands, both L3 and L4 in
and 0.7, respectively. These are the ratios where Eu
(L4) (L3) are preferably formed (Figures S51-S54). As a control,
the emission intensity (615 nm) shows a linear change by
systemically mixing of the preformed Eu (L3) and Eu (L4)
complexes (Figure S54-S59). We speculate that the formation of
A-D-A or D-A-D type π-π stackings between the triphenylbenzene
(Donor, D) and triphenyltriazine (Acceptor, A) aromatic panels on
the ligands accounts for the bactrian-shape of the emission
enhancement. This was further supported by the UV-vis spectrum,
3 1 2
(L4) (L3) or
CH
3
CN solution show strong absorptions in the 235−320 nm range, Eu
3
2
1
respectively (Figure 3A). Upon excitation at 298 nm in the ligand
level, Eu
3
(L4)
3
3
3
3
3
5
7
5
80, 593, 615, 650 and 702 nm, corresponding to D
transitions of Eu
performance of L4 and L3 were apparently different, with
photoluminescent quantum yields Ф of Eu (L4) and Eu (L3)
3
3
3
3
measured to be 55.3% and 34.7% in acetonitrile solution,
respectively (Figure S28, S29). This is a little different from the
where heteroligand complexes of Eu
3 x
(L4) (L3)3-x (x= 1 and 2)
previous report of Eu
4
L
4
built from L1 and L2 with different
showed slightly enhanced absorption at 300 nm compared to the
1
Figure 2 Self-assembly of L3 with Eu(OTf)
Eu (L3) (OTf) complexes (in CD NO /CD
minimized structure of (E) Eu (L3) and (F) Eu
and simulated isotopic patterns of the peaks corresponding to [Eu
3
. H NMR (400 MHz, 293 K) spectra of (A)the Eu
3
(L3)
complexes and (D) the Eu
(L3) and (H) the Eu (L3) , with insets showing the observed
and [Eu (L3) ] , respectively. For clarity, only the tetrahedral
3
(OTf)
9
complexes (in CD
3
CN/CD
3
OD) and (C) the
1
4
4
9
3
2
3
OD); H DOSY spectra of (B) the Eu
3
(L3)
3
(OTf)
9
4
(L3) (OTf)
4
9
complexes; Energy
3
3
4
(L3) . ESI-TOF-MS spectra of (G) the Eu
4
3
3
4
4
5+
5+
3 3
(L3) (OTf)
4
]
4
4 7
(OTf)
Chin. J. CT hhe i ms .a2r 0t i1c 9l e, 3i 7s , pX rX oX t－e cX t Xe Xd by co p©y r 2i g0 h1 9t . SAI Ol lCr,i gC hA tS s, Sr he as ne gr hv ae i ,d &. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
framework is shown. Eu, purple sphere; C, green; N, dark blue; O, red; H, white.
www.cjc.wiley-vch.de
3

Report
First author et al.
mix-complex solutions (Eu
Figure 3 (A) UV-Vis absorption of L3, L4 and Eu
3
(L3)
3
/Eu
3
(L4)
3
=1/2 or 2/1) (Figure S33).
Our results provide important guidance for structure-design and
3 3
(L4) , Eu
3
(L3)
3
and Eu
4
(L3)
4
photoluminescence
optimization
of
supramolecular
lanthanide-organic assemblies.
Experimental
Materials and Methods. Unless otherwise stated, all
chemicals and solvents were purchased from commercial
companies and used without further purification. Anhydrous
solvents were distilled according to standard procedures. The
solvents used for photophysical measurements were of HPLC
grade. Deuterated solvents were purchased from Admas, J&K
scientific and Sigma-Aldrich. 1D and 2D-NMR spectra were
measured on a Bruker Biospin Avance III (400 MHz) spectrometer.
1
H-NMR chemical shifts were determined with tetramethylsilane
(TMS) or respect to residual signals of the deuterated solvents
used. ESI-TOF-MS mass spectra were recorded on Impact II
UHR-TOF from Bruker, with tuning mix as the internal calibrant.
Data analysis was conducted with the Bruker Data Analysis
software (Version 4.3) and simulations were performed with the
Bruker Isotope Pattern software. UV-Vis spectra were recorded on
UV-2700 spectrometer from SHIMADZU. Excitation and emission
spectra were recorded on FS5 and FLSP920 spectrofluorometer
from Edinburg Photonics. Spectra were corrected for the
experimental functions. The emission quantum yields in solution
and solid state were measured by FS5 spectrofluorometer from
Edinburg Photonics with integrating sphere.
Eu
3
(L4)
3
(OTf)
.0310 mmol, 1 equiv) and Eu(OTf)
.1 equiv) in 1 mL MeCN at 25°C for 1 h, the turbid suspension of
9
: To a suspension of ligand L4 (3.03 mg,
-
3
-3
3
1
3
(2.19 mg, 3.1610 mmol,
ligands gradually turned clear. The solid progressively dissolved to
1
give a resulting homogeneous yellow solution. H NMR showed
1
the quantitative formation of Eu
3
(L4)
3
(OTf)
9
. m.p.>300 °C. H NMR
(
3
CD CN , 400 MHz) δ 9.91 (s, 1H), 8.46 (d, J = 11.4 Hz, 2H), 8.39 (s,
1
7
7
1
H), 8.24 (d, J = 7.8 Hz, 1H), 7.88 (d, J = 7.1 Hz, 1H), 7.65 (s, 1H),
.56 (d, J = 6.2 Hz, 1H), 7.47 (d, J = 7.8 Hz, 1H), 7.37 (dd, J = 12.9,
.4 Hz, 2H), 7.25 (t, J = 7.4 Hz, 1H), 7.10 (s, 2H), 7.01 (t, J = 8.1 Hz,
H), 6.92 (d, J = 7.9 Hz, 2H), 6.61 (t, J = 7.6 Hz, 1H), 6.29 (d, J = 7.3
Hz, 1H), 6.19 (t, J = 7.8 Hz, 1H), 5.78 (s, 1H), 5.36 (d, J = 7.1 Hz, 1H),
5
1
=
.17 (d, J = 7.1 Hz, 1H), 4.83 (d, J = 7.5 Hz, 1H), 4.50 (d, J = 7.8 Hz,
H), 4.03 (s, 1H), 3.66 (s, 1H), 3.23 (s, 1H), 2.21 (s, 3H), 1.27 (dd, J
10.5, 5.4 Hz, 6H), 1.10 (d, J = 4.9 Hz, 3H), 0.29 (dd, J = 12.7, 5.5
Hz, 6H). HRMS for Eu
those at the high intensities. m/z calcd for [M-3(CF
1
1
3
(L4)
3
(OTf)
9
: The following picked signals are
–
–
–
3+
4+
5+
3
SO
3
SO
3
SO
3
3
3
)]
)]
)]
447.2414, found 1447.2412; calcd for [M-4(CF
found 1047.9420; calcd for [M-5(CF
08.5637, found 808.5632; calcd for [M-6(CF SO )] 649.1445,
047.9427,
– 6+
8
3 3
–
7+
3 3
found 649.1445; calcd for [M-7(CF SO )] 534.9877, found
5
34.9883.
Eu (L3)
procedure as Eu
3
3
(OTf)
9
: Eu
3
(L3)
3
(OTf)
9
was prepared by a same
1
3
(L4) (OTf)
3
9
. m.p.>300 °C. H NMR (CD CN/CD OD
3 3
-
5
v/v = 4:1,400 MHz, 298 K) δ 9.78 (s, 2H), 8.73 (s, 1H), 8.48 (s, 1H),
8.41 (d, J = 7.9 Hz, 1H), 8.20 (s, 1H), 8.01 (s, 1H), 7.94 (d, J = 5.5 Hz,
1H), 7.91 (d, J = 10.2 Hz, 2H), 7.83 (d, J = 5.3 Hz, 2H), 7.75 (d, J =
in CH
3
CN (c = 1x10 M) (B) Excitation and emission of Eu
3
(L4)
CN (c = 1x10 M). (C) The emission spectra(CH
x10 M, λex = 298 nm) of the mixed-ligand Eu (L4) (L3)3-x (x =0-3)
3
, Eu
3 3
(L3)
-5
and Eu
4
(L3)
4
in CH
3
3
CN, c =
-5
1
3
x
8
5
7
.8 Hz, 1H), 7.60 (d, J = 10.2 Hz, 1H), 7.55 (s, 1H), 7.46 (dd, J = 15.0,
.9 Hz, 2H), 7.26 (t, J = 6.7 Hz, 2H), 7.19 (d, J = 9.1 Hz, 1H), 7.13 –
.07 (m, 1H), 6.99 (d, J = 7.2 Hz, 1H), 6.90 (d, J = 8.1 Hz, 1H), 6.80
complexes with increasing content of L4 [f = L4/(L3+L4)] (Inset shows the
changes of the emission intensity at 615 nm at different f values with two
schematic diagrams of the dominate species of Eu
Eu (L4) (L3) at f = 0.4 and 0.7, respectively.
3 1 2
(L4) (L3) and
(t, J = 6.4 Hz, 1H), 6.73 – 6.67 (m, 1H), 6.59 (d, J = 12.4 Hz, 1H),
3
2
1
6
3
3
.25 – 6.14 (m, 2H), 5.79 (d, J = 7.2 Hz, 1H), 5.35 – 5.22 (m, 3H),
.57 (d, J = 16.2 Hz, 1H), 2.78 (d, J = 5.6 Hz, 3H), 2.16 (d, J = 5.7 Hz,
H), 1.74 (d, J = 5.9 Hz, 3H), 1.48 (d, J = 5.5 Hz, 3H), 1.03 (d, J = 6.1
Conclusions
Unprecedented supramolecular lanthanide-organic sandwich
complexes were obtained by a small variation of ligand
conformations, and the first example of sandwich-to-tetrahedron
transformation was observed based on solvent effect. Moreover,
nonlinear enhancement of lanthanide luminescence based on the
3 3 9
Hz, 3H), 0.58 (d, J = 5.6 Hz, 3H) ; HRMS for Eu (L3) (OTf) : The
following picked signals are those at the highest intensities. m/z
–
3+
calcd for [M–3(CF
3
SO
3
)] 1444.2558, found 1444.2544; calcd for
–
4+
[M–4(CF
3
SO
)]
)]
3
)] 1045.7019, found 1045.7035; calcd for [M–
806.7713, found 806.7723; calcd for [M–
647.6513, found 647.6517; calcd for [M–
–
5+
6+
5(CF
3
SO
SO
3
–
modulation of inter-ligand charge-transfer state has been realized. 6(CF
3
3
4
T hw i sw aw r. tc i jcc l. ew ii lse yp - rv oc ht e. dc et ed by c o© p 2y 0r i1g 9h St .I OA Cl ,l Cr iAg Sh ,t Ss h ra en sg eh ar vi , e&d W. ILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2019, 37, XXX－XXX

Running title
Chin. J. Chem.
–
7+
7
(CF
Eu
3
SO
4
3
)] 533.7084, found 533.7081.
(OTf)12: To a suspension of ligand L3 (4.01 mg,
7001-7045; (d) Fujita, M.; Tominaga, M.; Hori, A., Therrien, B. Coordination
assemblies from a Pd(II)-cornered square complex, Acc. Chem. Res. 2005, 38,
369-378; (e) Yoshizawa, M.; Klosterman, J.K., Fujita, M. Functional molecular
flasks: new properties and reactions within discrete, self-assembled hosts,
Angew. Chem. Int. Ed. 2009, 48, 3418-3438; (f) Holliday, B.J., Mirkin, C.A.
Strategies for the Construction of Supramolecular Compounds through
Coordination Chemistry, Angew. Chem. Int. Ed. 2001, 40, 2022-2043; (g)
Smulders, M.M.; Riddell, I.A.; Browne, C., Nitschke, J.R. Building on
architectural principles for three-dimensional metallosupramolecular
construction, Chem. Soc. Rev. 2013, 42, 1728-1754; (h) Chen, L.; Chen, Q.; Wu,
M.; Jiang, F., Hong, M. Controllable coordination-driven self-assembly: from
discrete metallocages to infinite cage-based frameworks, Acc. Chem. Res.
(L3)
4
-
3
-3
4
1
.0210 mmol, 1 equiv.) and Eu(OTf)
3
(2.89 mg, 4.8310 mmol,
.2 equiv) in 1 mL MeNO at 50°C for 1.5 h, the turbid suspension
of ligands gradually turned clear. The solid progressively dissolved
to give a resulting homogeneous yellow solution. H NMR showed
the quantitative formation of Eu
spectra could not be assigned due to the poor solubility of this
complex. m.p.>300 °C. HRMS for Eu (L3) (OTf)12: The following
2
1
4 4
(L3) (OTf)12. However, its NMR
4
4
picked signals are those at the high intensities. m/z calcd for
–
–
–
–
–
4+
5+
6+
7+
8+
[
[
[
[
M-4(CF
M-5(CF
M-6(CF
M-7(CF
M-8(CF
3
3
3
3
3
SO
SO
SO
SO
SO
3
3
3
3
3
)]
)]
)]
)]
1444.2558, found 1444.2545; calcd for
1125.4139, found 1125.4129; calcd for
913.1864, found 913.1853; calcd for
761.3093, found 761.3083; calcd for
2015, 48, 201-210.
[6] (a) Li, X.Z.; Zhou, L.P.; Yan, L.L.; Yuan, D.Q.; Lin, C.S., Sun, Q.F. Evolution of
–
9+
[
)] 647.6517, found 647.6509; [M-9(CF
3
SO
3
)]
Luminescent Supramolecular Lanthanide M2nL3n Complexes from Helicates
and Tetrahedra to Cubes, J. Am. Chem. Soc. 2017, 139, 8237-8244; (b) Jing, X.;
He, C.; Yang, Y., Duan, C. A metal-organic tetrahedron as a redox vehicle to
encapsulate organic dyes for photocatalytic proton reduction, J. Am. Chem.
Soc. 2015, 137, 3967-3974; (c) Hamacek, J.; Poggiali, D.; Zebret, S.; El Aroussi,
B.; Schneider, M.W., Mastalerz, M. Building large supramolecular
nanocapsules with europium cations, Chem. Commun. 2012, 48, 1281-1283.
–
10+
5
59.0289, found 559.0286; calcd for [M-10(CF
found 488.2311.
3
SO
3
)] 488.2308,
Supporting Information
The supporting information for this article is available on the
WWW under https://doi.org/10.1002/cjoc.2018xxxxx.
[
7] (a) Bünzli, J.-C.G., Piguet, C. Lanthanide-Containing Molecular and
Supramolecular Polymetallic Functional Assemblies, Chem. Rev. 2002, 102,
897-1928; (b) Butler, S.J., Parker, D. Anion binding in water at lanthanide
Acknowledgement (optional)
1
centres: from structure and selectivity to signalling and sensing, Chem. Soc.
Rev. 2013, 42, 1652-1666; (c) Barry, D.E.; Caffrey, D.F., Gunnlaugsson, T.
Lanthanide-directed synthesis of luminescent self-assembly supramolecular
structures and mechanically bonded systems from acyclic coordinating organic
ligands, Chem. Soc. Rev. 2016, 45, 3244-3274; (d) Sabbatini, N.; Guardigli, M.,
Lehn, J.M. Luminescent Lanthanide Complexes as Photochemical
Supramolecular Devices, Coordin. Chem. Rev. 1993, 123, 201-228.
This work was supported by the NSFC (Grant Nos.
2
1825107, 21601183, 2017J05037), the Strategic Priority
Research Program of the Chinese Academy of Sciences
Grant No. XDB20000000).
(
References
[
1] (a) Fiedler, D.; Leung, D.H.; Bergman, R.G., Raymond, K.N. Selective
[8] El Aroussi, B.; Zebret, S.; Besnard, C.; Perrottet, P., Hamacek, J. Rational
design of a ternary supramolecular system: self-assembly of pentanuclear
lanthanide helicates, J. Am. Chem. Soc. 2011, 133, 10764-10767.
[9] Wang, W.; Wang, Y.X., Yang, H.B. Supramolecular transformations within
discrete coordination-driven supramolecular architectures, Chem. Soc. Rev.
2016, 45, 2656-2693.
Molecular Recognition, C−H Bond Activation, and Catalysis in Nanoscale
Reaction Vessels, Acc. Chem. Res. 2005, 38, 349-358; (b) Wiester, M.J.;
Ulmann, P.A., Mirkin, C.A. Enzyme mimics based upon supramolecular
coordination chemistry, Angew. Chem. Int. Ed. 2011, 50, 114-137.
[2] (a) Liu, C.L.; Zhou, L.P.; Tripathy, D., Sun, Q.F. Self-assembly of stable
luminescent lanthanide supramolecular M cages with sensing properties
4
L
6
[10] Zarra, S.; Clegg, J.K., Nitschke, J.R. Selective assembly and disassembly of
toward nitroaromatics, Chem. commun. 2017, 53, 2459-2462; (b) Zhang, K.;
Xie, X.; Li, H.; Gao, J.; Nie, L.; Pan, Y.; Xie, J.; Tian, D.; Liu, W.; Fan, Q.; Su, H.;
Huang, L., Huang, W. Highly Water-Stable Lanthanide–Oxalate MOFs with
Remarkable Proton Conductivity and Tunable Luminescence, Adv.Mater. 2017,
a water-soluble Fe10L15 prism, Angew. Chem. Int. Ed. 2013, 52, 4837-4840.
[11] Stephenson, A.; Argent, S.P.; Riis-Johannessen, T.; Tidmarsh, I.S., Ward,
M.D. Structures and dynamic behavior of large polyhedral coordination cages:
an unusual cage-to-cage interconversion, J. Am. Chem. Soc. 2011, 133,
858-870.
29, 1701804; (c) Liu, C.L.; Zhang, R.L.; Lin, C.S.; Zhou, L.P.; Cai, L.X.; Kong, J.T.;
Yang, S.Q.; Han, K.L., Sun, Q.F. Intraligand Charge Transfer Sensitization on
Self-Assembled Europium Tetrahedral Cage Leads to Dual-Selective
Luminescent Sensing toward Anion and Cation, J. Am. Chem. Soc. 2017, 139,
[12] Lusby, P.J.; Muller, P.; Pike, S.J., Slawin, A.M. Stimuli-responsive reversible
assembly of 2D and 3D metallosupramolecular architectures, J. Am. Chem. Soc.
2009, 131, 16398-16400.
1
2474-12479.
[13] Han, M.; Michel, R.; He, B.; Chen, Y.S.; Stalke, D.; John, M., Clever, G.H.
Light-triggered guest uptake and release by a photochromic coordination cage,
Angew. Chem. Int. Ed. 2013, 52, 1319-1323.
[14] Sorensen, A.; Castilla, A.M.; Ronson, T.K.; Pittelkow, M., Nitschke, J.R.
Chemical signals turn on guest binding through structural reconfiguration of
triangular helicates, Angew. Chem. Int. Ed. 2013, 52, 11273-11277.
[15] Scherer, M.; Caulder, D.L.; Johnson, D.W., Raymond, K.N. Triple
Helicate—Tetrahedral Cluster Interconversion Controlled by Host–Guest
Interactions, Angew. Chem. Int. Ed. 1999, 38, 1587-1592.
[3] Li, X.Z.; Zhou, L.P.; Yan, L.L.; Dong, Y.M.; Bai, Z.L.; Sun, X.Q.; Diwu, J.; Wang,
S.; Bunzli, J.C., Sun, Q.F. A supramolecular lanthanide separation approach
based on multivalent cooperative enhancement of metal ion selectivity, Nat.
Commun. 2018, 9, 547-556.
[4] (a) Bunzli, J.C. Lanthanide luminescence for biomedical analyses and
imaging, Chem. Rev. 2010, 110, 2729-2755; (b) Zhou, Z.; Liu, J.; Rees, T.W.;
Wang, H.; Li, X.; Chao, H., Stang, P.J. Heterometallic Ru-Pt metallacycle for
two-photon photodynamic therapy, PNAS. 2018, 115, 5664-5669; (c) Stang,
P.J.,
Olenyuk,
B.
Self-Assembly,
Symmetry,
and
Molecular
[16] Georges, J. Lanthanide-sensitized luminescence and applications to the
determination of organic analytes. A review, Analyst. 1993, 118, 1481-1486.
[17] Ma, Y., Wang, Y. Recent advances in the sensitized luminescence of
organic europium complexes, Coordin. Chem. Rev. 2010, 254, 972-990.
[18] (a) Bünzli, J.-C.G. On the design of highly luminescent lanthanide
complexes, Coordin. Chem. Rev. 2015, 293-294, 19-47; (b) Amoroso, A.J., Pope,
S.J. Using lanthanide ions in molecular bioimaging, Chem. Soc. Rev. 2015, 44,
4723-4742.
Architecture: Coordination as the Motif in the Rational Design of
Supramolecular Metallacyclic Polygons and Polyhedra, Acc. Chem. Res. 1997,
3
[
1
0, 502-518.
5] (a) Caulder, D.L., Raymond, K.N. Supermolecules by Design, Acc. Chem. Res.
999, 32, 975-982; (b) Chakrabarty, R.; Mukherjee, P.S., Stang, P.J.
Supramolecular coordination: self-assembly of finite two- and
three-dimensional ensembles, Chem. Rev. 2011, 111, 6810-6918; (c) Cook,
T.R., Stang, P.J. Recent Developments in the Preparation and Chemistry of
Metallacycles and Metallacages via Coordination, Chem. Rev. 2015, 115,
[19] Guo, X.Q.; Zhou, L.P.; Cai, L.X., Sun, Q.F. Self-assembled bright
luminescent lanthanide-organic polyhedra for ratiometric temperature
Chin. J. CT hhe i ms .a2r 0t i1c 9l e, 3i 7s , pX rX oX t－e cX t Xe Xd by co p©y r 2i g0 h1 9t . SAI Ol lCr,i gC hA tS s, Sr he as ne gr hv ae i ,d &. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
5

Report
First author et al.
sensing, Chem. Eur. J. 2018, 24, 6936-6940.
[
20] (a) Hamacek, J.; Bernardinelli, G., Filinchuk, Y. Tetrahedral assembly with
lanthanides: Toward discrete polynuclear complexes, Eur. J. Inorg. Chem. 2008,
008, 3419-3422; (b) Yan, L.L.; Tan, C.H.; Zhang, G.L.; Zhou, L.P.; Bunzli, J.C.,
2
Sun, Q.F. Stereocontrolled self-assembly and self-sorting of luminescent
Europium tetrahedral cages, J. Am. Chem. Soc. 2015, 137, 8550-8555.
[21] Caulder, D.L.; Powers, R.E.; Parac, T.N., Raymond, K.N. The Self-Assembly
4 6
of a Predesigned Tetrahedral M L Supramolecular Cluster, Angew. Chem. Int.
Ed. 1998, 37, 1840-1843.
[
22] Spek, A.L. Single-crystal structure validation with the programPLATON, J.
Appl. Crystallogr. 2003, 36, 7-13.
23] Hong, C.M.; Kaphan, D.M.; Bergman, R.G.; Raymond, K.N., Toste, F.D.
[
Conformational Selection as the Mechanism of Guest Binding in a Flexible
Supramolecular Host, J. Am. Chem. Soc. 2017, 139, 8013-8021.
[24] Qu, H.; Tang, X.; Wang, X.; Li, Z.; Huang, Z.; Zhang, H.; Tian, Z., Cao, X.
Chiral molecular face-rotating sandwich structures constructed through
restricting the phenyl flipping of tetraphenylethylene, Chem. Sci 2018, 9,
8814-8818.
[25] (a) Chen, C.X.; Qiu, Q.F.; Pan, M.; Cao, C.C.; Zhu, N.X.; Wang, H.P.; Jiang,
J.J.; Wei, Z.W., Su, C.Y. Tunability of fluorescent metal-organic frameworks
through dynamic spacer installation with multivariate fluorophores, Chem.
Commun. 2018, 54, 13666-13669; (b) Zhang, X.; Wang, W.; Hu, Z.; Wang, G.,
Uvdal, K. Coordination polymers for energy transfer: Preparations, properties,
sensing applications, and perspectives, Coordin. Chem. Rev. 2015, 284,
206-235.
[26] (a) Yuasa, J.; Ohno, T.; Miyata, K.; Tsumatori, H.; Hasegawa, Y., Kawai, T.
Noncovalent ligand-to-ligand interactions alter sense of optical chirality in
luminescent tris(beta-diketonate) lanthanide(III) complexes containing a chiral
bis(oxazolinyl) pyridine ligand, J. Am. Chem. Soc. 2011, 133, 9892-9902; (b)
Koizuka, T.; Yanagisawa, K.; Hirai, Y.; Kitagawa, Y.; Nakanishi, T.; Fushimi, K.,
Hasegawa, Y. Red luminescent Eu(III) coordination bricks excited on nlue LED
chip, Inorg. Chem. 2018, 57, 7097-7103.
(The following will be filled in by the editorial staff)
Manuscript received: XXXX, 2019
Manuscript revised: XXXX, 2019
Manuscript accepted: XXXX, 2019
Accepted manuscript online: XXXX, 2019
Version of record online: XXXX, 2019
6
T hw i sw aw r. tc i jcc l. ew ii lse yp - rv oc ht e. dc et ed by c o© p 2y 0r i1g 9h St .I OA Cl ,l Cr iAg Sh ,t Ss h ra en sg eh ar vi , e&d W. ILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2019, 37, XXX－XXX

Entry for the Table of Contents
Page No.
Title
Coordination-Assembled
Lanthanide-Organic
Tetrahedron:
Ln Sandwiches or Ln L
3
L
3
4 4
Structural Transformation and Luminescence
Modulation
Shao-Jun Hu, Xiao-Qing Guo, Li-Peng Zhou,
Li-Xuan Cai and Qing-Fu Sun*
a
c
State Key Laboratory of Structural Chemistry, Fujian Institute of Research University of Chinese Academy of Sciences, Beijing 100049, PR China
on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, E-mail:
PR China
E-mail:
b
College of Chemisity, Fuzhou University, Fuzhou 350108, PR China
E-mail:
Chin. J. TC hh ei sm a. 2r t0i c1 l8e , ti es mp pr ol a ttee cted by copy ©r ig 2h0 t 1. 8A Sl lI Or iCg , hC t As S r, eS sh ea nr vg eh ad i ., & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
7