Diastereoselective self-assembly of a triple-stranded europium helicate with light modulated chiroptical properties

Article abstract of DOI:10.1039/d1dt00251a

Chiroptical photoswitches are of increasing interest for their potential in advanced information technologies. Herein, an achiral bis-β-diketonate ligand (o-L) with a photoresponsive diarylethene moiety as a linker was designed, which co-assembled with Eu³⁺ions andR- andS-bis(diphenylphosphoryl)-1,10-binaphthyl (R/S-BINAPO) as chiral ancillaries to form dinuclear triple-stranded helicates, [Eu₂(o-L)₃(R/S-BINAPO)₂]. The helicates in the enantiopure form were confirmed by¹H,¹⁹F,³¹P NMR and DOSY NMR analyses. Furthermore, the mirror-image CD and CPL spectra also demonstrate the existence of stable ground- and excited-state chiralities in solution. When exposed to alternate ultraviolet and visible light, the helicates showed reversible color variations from colorless to purple, followed by the presence of light-triggered quadruple optical and chiroptical outputs, named CD, PL, CPL andg_lumswitches. With these light-modulated optical outputs, the possibility for the fabrication of IMPLICATION and INHIBIT logic gates was discussed.

Full text of DOI:10.1039/d1dt00251a

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Diastereoselective self-assembly of a triple-
stranded europium helicate with light modulated
chiroptical properties†
Cite this: Dalton Trans., 2021, 50,
4604
Zhihui Zhang, Yanyan Zhou, Ting Gao,
Hongfeng Li
Pengfei Yan,
Xiaoyan Zou* and
*
Chiroptical photoswitches are of increasing interest for their potential in advanced information techno-
logies. Herein, an achiral bis-β-diketonate ligand (o-L) with a photoresponsive diarylethene moiety as a
3
+
linker was designed, which co-assembled with Eu ions and R- and S-bis(diphenylphosphoryl)-1,10-
binaphthyl (R/S-BINAPO) as chiral ancillaries to form dinuclear triple-stranded helicates, [Eu (o-L) (R/
]. The helicates in the enantiopure form were confirmed by H, F, P NMR and DOSY NMR
2
3
1
19 31
S-BINAPO)
2
analyses. Furthermore, the mirror-image CD and CPL spectra also demonstrate the existence of stable
ground- and excited-state chiralities in solution. When exposed to alternate ultraviolet and visible light,
the helicates showed reversible color variations from colorless to purple, followed by the presence of
light-triggered quadruple optical and chiroptical outputs, named CD, PL, CPL and glum switches. With
these light-modulated optical outputs, the possibility for the fabrication of IMPLICATION and INHIBIT
logic gates was discussed.
Received 25th January 2021,
Accepted 22nd February 2021
DOI: 10.1039/d1dt00251a
rsc.li/dalton
lanthanide compounds with magnetic dipole transition
Introduction
usually showed obviously higher g
values (typically with
lum
−
2
9
Chiroptical photoswitches are highly beneficial for raising the
glum = 10 –0.5). Therefore, the employment of chiral lantha-
dimensions of optical output signals and increasing the infor- nide complexes as CPL photoswitches seemed to be more
mation storage density. Circularly polarized luminescence promising to realize effective photomodulation. Diarylethenes
(CPL) and circular dichroism (CD) spectroscopy were usually (DAEs) are regarded as the most widely used light-responsive
employed to probe the chiroptical outputs of optically active constituents in optical switches because of their excellent
1
10
compounds. In recent years, chiroptical photoswitches based fatigue resistance and thermal stability. In 2018, Kawai
on CPL have been developed. Although seldom reported, a few reported a dynamic CPL optical switch based on a dinuclear
examples that enable chiral luminophores to switch the CPL europium complex with tetrathiazole as the photocontrolled
2
3
4,7,11
11
by various external stimuli, such as pH, chemicals, light,
heat and mechanical force, have been reported. Among these responsive CPL switch based on a dinuclear europium
stimuli, light was one of the most favorable stimuli due to its helicate.
convenient operation and waste free characteristic. For Lanthanide helicates have attracted increasing attention as
unit. More recently, we reported another example of a light-
5
6
1
2
instance, Akagi et al. reported the first photoresponsive CPL chiral luminescent materials because of their supramolecular
switch based on a diarylethene conjugated polymer, which chirality and higher luminescence quantum yields. To get a
7
showed PL, UV, CD and CPL quadruple optical outputs.
preferred-handed helicate, the introduction of a chiral center
To facilitate CPL determination, the materials should into the molecular strand was the general strategy, although
1
3
combine the high luminescence efficiency with a large lumine- the synthetic processes were complicated and high cost.
scence dissymmetry factor (glum value). In comparison with Another strategy was the employment of chiral counterions
pure organic luminophores (generally with glum = 10 –10 ),
1
4
−
5
−3
8
15
or chiral ancillary ligands to regulate the diastereoselective
self-assembly of metal helicates. Recently, we reported two
examples of the formation of lanthanide podates and helicates
with CPL properties using the chiral ancillary ligand induced
Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education;
School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080,
China. E-mail: zxy_18889@126.com, lihongfeng@hlju.edu.cn
16
strategy.
1
19
Herein, we designed and synthesized an achiral bis-
†
Electronic supplementary information (ESI) available: H NMR, F NMR,
β-diketonate ligand (o-L) with a photoresponsive diarylethene
moiety as a spacer, which co-assembled with Eu ions and S-
ESI-TOF-MS, thermal stability, fatigue resistant property spectra, emission
3
+
spectra and the method for Φo–c and Φc–o. See DOI: 10.1039/d1dt00251a
4604 | Dalton Trans., 2021, 50, 4604–4612
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and R-bis(diphenylphosphoryl)-1,10-binaphthyl (R/S-BINAPO)
to form a pair of homochiral lanthanide triple-stranded heli-
cates, ΛΛ-[(Eu
2
L
3
)(S-BINAPO)
2
2 3 2
] and ΔΔ-[(Eu L )(R-BINAPO) ].
The NMR and chiroptical characterization studies demon-
strated that the chiral S- and R-BINAPO enabled the effective
regulation of the diastereoselectivity of these photochromic
lanthanide helicates during the self-assembly process. Upon
alternate ultraviolet and visible light irradiation, the two enan-
tiomers showed light-switching absorption and emission pro-
perties. Finally, two logic gates, IMPLICATION and INHIBIT
were realized based on UV, PL, ECD and CPL outputs.
Results and discussion
Synthesis and characterization of L and the complexes
Achiral bis-β-diketone (o-L) with a photoresponsive diaryl-
ethene moiety as the spacer was prepared by a multi-step pro-
cedure as shown in Scheme 1. Both 3 and 4 were synthesized
1
7,18
according to the reported procedures.
The following
Suzuki coupling of with 3-acetylbenzeneboronic acid
4
afforded the intermediate, 5. Finally, the ligand (o-L) was pre-
pared through a step of Claisen condensation of 5 with ethyl
trifluoroacetate. The corresponding intermediates and ligands
1
1
were confirmed by H NMR and MS (Fig. S1–S6†). From the H
NMR spectra of L, the existence of parallel (p) and antiparallel
(
ap) conformations could be confirmed by two observable CH
3
2 3 2
Fig. 1 (a) ESI-TOF-MS spectrum of Eu (o-L) (R-BINAPO) with the inset
resonances, H and H .
The helicates Eu
BINAPO)
I
I′
representing the simulated (Sim.) and observed (Obs.) isotopic distri-
2
(o-L)
3
(S-BINAPO)
2
and Eu
2
(o-L)
3
(R-
1
butions. (b) H NMR (400 MHz) spectra of o-L, R-BINAPO and the
were isolated by the co-assembly of o-L, chiral
1
2
complex Eu
2
(o-L)
3
(R-BINAPO)
2
in THF-d
8
. (c) H DOSY spectrum of
S/R-BINAPO and EuCl ·6H O with the molar ratios of 3 : 2 : 2. Eu (o-L) (R-BINAPO) (THF-d ).
3
2
2
3
2
8
The high-resolution ESI-TOF-MS analyses affirmed the success-
ful preparation of the triple-stranded helicates. For instance,
Fig. 1a displays two clusters of peaks that are attributed to the
comparing the isotopic distributions of the experimental
results with the simulated results.
+
+
single charged [M + H] and [M + Na] species of Eu
BINAPO) at m/z 4297.5678 and 4320.5576, respectively. The
mass spectra of Eu (o-L) (S-BINAPO) and the corresponding
2 3
(o-L) (R-
2
1
31
19
The H, P, and F NMR and DOSY NMR results also sup-
2
3
2
ported the successful preparation of Eu (o-L) (S-BINAPO) and
3
+
2
3
2
Gd complexes also showed the expected molecular ion peaks
Fig. S7 and S8†). The assignments were further affirmed by
Eu
2 3 2
(o-L) (R-BINAPO) and their integrality in THF (Fig. S9–
(
1
S12†). As shown in Fig. 1b, the H NMR of Eu
2
3
(o-L) (R-
BINAPO) showed broadening and indistinguishable signals in
2
the range of 6.5–8.5 ppm. It could be rationally explained as
the loss of the C
number of aromatic rings in one helicate. However, fortu-
nately, the CH groups on the reactive carbon atoms only
showed a single peak at 2.2 ppm. It implied that all the reso-
3
symmetry and the presence of a large
3
1
9
31
nances belong to one single species. In F and P NMR, CF3
presents a singlet peak at 0 ppm, while the P atom in BINAPO
also gave a singlet peak at −133 ppm (Fig. S10 and S11†).
These results further supported that only one diastereoisomer
was formed in the assembly process. In addition, the single
diffusion rate (D = 3.07 × 10− cm
6
2
s
−1
) of the H NMR
1
diffusion ordered spectroscopy (DOSY) of Eu (o-L) (R-
2
3
2
BINAPO) also indicated the presence of a single species in
THF (Fig. 1c). Additionally, the only single peak attributed to
Scheme 1 Synthetic routes of o-L and the complexes Eu
2 3
(o-L) (R/
1
S-BINAPO)
2
.
CH resonance present in the H NMR of the complex demon-
3
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strated the formation of a helicate breaking conformer equili-
brium of L, with an antiparallel (ap) conformer isomer already
existing in the helicate.
1
9
As in our previous work and other published results, the
chiral ancillary ligands could induce the metal supramolecular
assemblies to produce single diastereoisomers. To better
understand this kind of chiral induction, several methods
have been tried to grow single crystals of complexes, but all the
efforts failed. Herein, we resorted to a semiempirical mole-
cular mechanics modeling fabricated by the LUMPAC 3.0 soft-
ware with a Sparkle/AM1 model to optimize the possible struc-
20
ture. As can be seen in Fig. S13,† the right-handed helical
conformation ΔΔ-Eu (o-L) ligated with the R-BINAPO and
S-BINAPO isomers and both were considered in the structu-
rally optimized process. The result showed Eu (o-L)
BINAPO) having a relatively lower system energy than the
S-BINAPO complex. Consequently, it was proposed that
R-BINAPO could induce Eu (o-L)
to form a P helical confor- lizing at the thionaphthene group and BINAPO. Upon
mation helicate and endow the metal center with the ΔΔ con- irradiation by 275 nm ultraviolet light, the colorless solutions
2
3
Fig. 3 UV-vis absorption spectra of L (1.0 × 10− M) and Eu
5
2
L
3
(R-
2
BINAPO) (ΔΔ-1). Inset: ΔΔ-1 after irradiation with UV and visible light
6
(R- (3.3 × 10− M, THF, 293 K).
3
2
2
2
3
figuration (Fig. 2).
of L and complexes both gradually became purple in color,
and a new band presented at 390 and 548 nm, which could be
ascribed to the absorbances of closed-ring isomers. It was
noticed that the molar extinction coefficient (Δε) for the
complex at 548 nm was not three times larger than that for L,
although one helicate was comprised of three photochromic
ligands. It indicated that the complexes should have a lower
conversion ratio between the open-ring and closed-ring forms
than the free ligand. We suggested that this decrease should
arise from the restriction of the rotation free degree of ligands
in the helicate, and thus influenced the close ring efficiency.
The conversion ratio between the closed-ring and open-ring
forms can be determined from the H NMR of L and com-
plexes in their photostationary state (PSS). According to the
3
integration area of the CH group (Fig. S14 and S15†), the con-
version ratios were calculated to be 20.1% and 6.4% for L and
the complex, respectively. On the basis of the conversion ratios
and the plots of irradiation time dependence on absorbance at
Optical switch by ground-state absorption
3
+
The UV-vis absorption spectra of L and the corresponding Eu
complex before and after UV irradiation are shown in Fig. 3. In
the open-ring form of DAE, L and Eu (o-L) (R-BINAPO)
2
2
3
showed similar spectral patterns in the range of 250–400 nm
with the maxima absorbance at about 280 nm. The spectra
seem to be complicated and exhibit several unobvious
shoulder peaks. It could be explained by the vibrational pro-
gressions of the π–π* transitions considering the presence of
multiple alkyl groups in one ligand. The strong absorbance at
about 320 nm was ascribed to the π–π* charge transfer tran-
sition (ILCT) from the alkyl group to the β-diketonate units.
The maxima at 280 nm was attributed to the transitions loca-
1
548 nm, the photocyclization (Φo–c) and photocycloreversion
(
Φc–o) quantum yields were estimated to be 0.27% and 3.3%
for the complexes, while L showed the higher values with Φo–c
and Φc–o reaching to 1.5% and 19%, respectively (Fig. S16–
S19†).
In view of the introduction of chiral R/S-BINAPO and the
above spectral analyses, it was inferred that chiral ancillary
could successfully control the diastereoselective self-assembly
of a triple-stranded helicate. Therefore, the chirality of the heli-
cate before and after UV irradiation was characterized by CD
spectroscopy. As shown in Fig. 4, the two complexes Eu
2 3
L (S-
BINAPO) and Eu (R-BINAPO) displayed the mirror-image
2
2
L
3
2
Cotton effects in the range of 250–650 nm. In the open-ring
form, the complexes showed the expected chiroptical signals
in the UV absorption region of 250–400 nm. After exposure to
UV light, some new bands appeared in the 400–650 nm visible
spectra region, corresponding to the photochromic bands pre-
senting in the UV-vis absorption spectra. The observed chirop-
tical signals that ranged from 300 to 650 nm arose from the
Fig. 2 Sparkle/AM1 ground state geometries of Eu
ΔΔ-1) before (upper graph) and after (lower graph) irradiation with UV
light.
2 3 2
(o-L) (R-BINAPO)
(
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Fig. 4 CD spectra of Eu
(
2
L
3
(R-BINAPO)
2 2 3 2
(ΔΔ-1) and Eu L (S-BINAPO)
ΛΛ-1) (3.3 × 10− M, THF, 293 K).
6
Fig. 5 PL (lower curve, right axis) and CPL spectra (upper curves, left
axis) of Eu
2
L
3
(R-BINAPO)
2
(ΔΔ-1) and Eu
2
L
3
(S-BINAPO)
2
(ΛΛ-1) in the
−6
open-ring and PSS states (3.3 × 10 M, THF, 293 K).
achiral L. This result demonstrated that the chiralities of R-
and S-BINAPO have been transferred to L through the for-
mation of a homochiral helicate, and thus a chiroptical switch-
ing based on CD signals was achieved. The gabs values of the
corresponding bands in the open-ring form and photostation-
ary state (PSS) have been calculated from the CD spectra and
summarized in Table S1.†
In addition, L and complexes also showed excellent fatigue
resistant properties during light irradiation. In a fatigue-resist-
ant experiment, L and complexes did not show any obvious
decrease in absorbances after five successive reversible cycles.
Additionally, the thermal stabilities were proved to be excel-
lent. After heating the complexes in their photostationary state
5
Fig. 5, five mirror-image CPL emission peaks ascribed to D
0
7
→
F (J = 0–4) transitions were observed in their open-ring
J
5
7
form and PSS. In these bands, the ΔI attributed to D → F
0
1
5
7
and
D
0
→
F
2
transitions showed larger polarized emitting
intensities than the other deactivated ground states, F0,3,4
The large ΔI at 612 nm was due to the strongest PL intensity of
0 1
this transition. In contrast, the D → F transition at 595 nm
also displayed a relatively large intensity, although its total
emitting intensity was low. This was mainly benefiting from its
magnetic dipole transition characteristic. From the CPL
spectra, it could be seen that ΔI also showed decreases similar
to that observed in the PL spectra. This was easily understood
from the drop in the total emission intensity. The lumine-
scence dissymmetry factor, glum value (−2 ≤ glum ≤ 2) is a stan-
7
.
5
7
(
(
PSS) for 2 h at 55 °C, no obvious spectral change was observed
Fig. S20–S22†).
dard to evaluate the degree of CPL, where glum = 2(I
L
− I
R L
)/(I +
Optical switch by excited-state emission
5
7
I
R
). The |glum| values for the D
0 J
→ F (J = 0–4) transitions are
From the UV and CD spectra, it was demonstrated that the
photoisomerization of DAE units in helicates had influenced
the ground state electron transitions. Therefore, we inferred
that photoisomerization would also affect the optical and chir-
optical properties of their excited states. Fig. 5 displays the
emission spectra of Eu L (R/S-BINAPO) in THF. Upon exci-
5
7
listed in Table 1. It showed that the D → F transition at
0
1
595 nm gave the largest |glum| value of 0.099 in the open-ring
forms. Unexpectedly, this value increased to 0.133 in the
photostationary state (PSS).
The decrease in PL and increase in CPL intensities were the
results of the photocyclization of DAE moieties, which modu-
lated the excited state energy level of the ligand and the coordi-
2
3
2
tation at 350 nm (excitation spectra provided in Fig. S23†), the
complexes showed five sharp emission bands at 580, 594, 612,
3
+
nation environment around the Eu ions. In photochromic
fluorescence switches, luminescence quenching usually obeys
5
7
6
50 and 702 nm, corresponding to the D → F (J = 0–4) tran-
0 J
sitions. In PSS, the emission intensity at 612 nm decreases to
0% of its initial value. The luminescence quantum yields
4
were measured to be 8.0% in the open-ring form, which was
about 2.5 times higher than that in PSS (ΦEu = 3.2%).
5
7
Table 1 The glum values of the
0 J
D → F (J = 0–4) transition for
Moreover, the emission lifetimes also showed an observable Eu L (S-BINAPO) and Eu L (R-BINAPO)
2
3
2
2
3
2
decrease from one single exponential lifetime of 778 μs to two
lower double exponential lifetimes of 442 and 669 μs (Fig. S24–
S26†). The observed two lifetimes arose from the part photoi-
5
7
g
lum 0 J
D → F (J = 0, 1, 2, 3, 4)
Complexes
J = 0
J = 1
0.099
−0.099
J = 2
J = 3
0.005
−0.005
0.050
J = 4
3
+
somerization of the ligand, which make the Eu ion sites in
o-ΔΔ-1
o-ΛΛ-1
pss-ΔΔ-1
−0.052
0.054
0.077
−0.005
0.003
−0.063
0.067
−0.022
0.023
0.025
two different coordination environments.
3
+
The chiroptical switching properties of Eu ions in the
0.133
excited state can be reflected by the CPL spectra. As shown in pss-ΛΛ-1
−0.075
−0.132
−0.053
−0.029
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the Förster resonance energy transfer (FRET) mechanism,
where energy could transfer from the fluorophores to DAE
2
1
units. In this work, the absorbance edge of the helicates
extended to 650 nm, which covered the whole transition emis-
3
+
sion region of Eu ions. It indicated the FRET participation in
3
+
the quenching of Eu ion emission. In luminescent lantha-
nide complexes, the Dexter electron exchange mechanism
should not be excluded. Within this mechanism, the energy
1
transfer from the triplet state (T ) of the ligand to the excited
3
+
3+
state of Ln is the predominant pathway. For Eu complexes,
5
−1
the energy gap ΔE (T – D ) in the range of 2500–5000 cm
1
0
was proposed to be more effective for improving energy trans-
2
2
fer. By virtue of the phosphorescence spectra of the corres-
3
+
ponding Gd complex (Fig. S27†), ΔE was estimated to be
702 cm− and −1899 cm for the open-ring and closed-ring
1
−1
2
isomers, respectively. In the open-ring form, ΔE was located
just at the proposed energy gap range. Whereas, in the situ-
ation of PSS, the triplet state of the closed-ring form dropped
to 15 600 cm− and lower than the D
1
5
energy level of Eu ion.
3+
0
3
+
It implied that energy transfer from the ligand to Eu ions
was impossible. We suggested the FRET and Dexter energy
transfer mechanisms would coexist in the sensitization
Fig. 6 The symbolic representation and truth table of the logic circuit.
The two trigger wavelengths are denoted as input, I1 (275 nm) and I2
3
+
process of Eu ion luminescence.
(
526 nm). The output is defined as OCD (CD signal at 548 nm), OCPL (CPL
signal at 612 nm), OPL (PL signal at 612 nm), and Oglum (glum signal at
95 nm).
Application in logic circuit
5
From the above results, it was noticed that the chiral helicates
could realize reversible photomodulation to the ground- and
excited-state optical and chiroptical properties by light stimuli. light response DAE units, the europium helicates showed
Therefore, the helicates could be exploited to fabricate a mole- light-triggered optical and chiroptical switching properties.
cular logic gate (MLG) by employing UV and visible lights as Upon the alternative stimuli of UV and visible lights, the heli-
inputs and the spectral variations from CD, PL, CPL and glum cates realized reversible spectral changes from UV, CD, PL,
as the outputs. To fabricate a logic gate, the input and output CPL and glum. On the basis of these multiple optical responses,
conditions must be defined first. Here, we designated the two classes of logic gates, IMPLICATION and INHIBIT, were
open-ring form of the helicate as an initial state of MLG and successfully fabricated. This work demonstrated that the
1
UV light (λ = 275 nm) was defined as input (I ) and visible employment of the supramolecular co-assembly strategy to
light (λ = 526 nm) as input (I ); without and with light stimuli integrate the multiple functional building blocks into one heli-
2
were defined as logical inputs 0 and 1, respectively. For the cate could construct complicated light-modulation optical and
logic outputs, CD, PL, CPL and glum at λ = 548, 612, 612 and chiroptical switches and design the desired molecule logic
5
95 nm were designated as the detectable signals and named gates.
as OCD, OPL, OCPL and Oglum, respectively. On the basis of these
limitations, two classes of logic gates were fabricated by moni-
toring the variations in the CD, PL, CPL and glum values
Experimental
Materials and instruments
(Fig. 6). The INHIBIT logic gate was realized by employing the
CD and glum values, where the inputs were I = 1 and I = 0 and
1
2
Ethyl trifluoroacetate, benzo[b]thiophene, (R/S)-BINAPO and
LnCl ·6H O salts (Ln = Eu and Gd) were purchased from
3 2
the outputs (OCD and Oglum) were to be 1. When PL and CPL
were considered as outputs, an IMPLICATION logic gate was
Chembee Chemical Reagent Co., Ltd (China). The other
chemicals are of analytical reagent grade and used without
further purification.
1 2
fabricated, where the only inputs were I = 1 and I = 0 and the
outputs (OPL and OCPL) could be 0.
The NMR experiments were performed using a Bruker
Avance III 400 MHz spectrometer. Elemental analyses were per-
formed using an Elementar Vario EL cube. The EI-MS for
Conclusions
In summary, a pair of chiral triple-stranded helicates, [Eu (o- small molecule mass was recorded using an Agilent 5975N,
2
3 2 2 3 2
L) (S-BINAPO) ] and [Eu (o-L) (R-BINAPO) ] have been success- while the mass spectra of the ligand and complexes were
fully constructed using the chiral ancillary ligand induced recorded using a Bruker maXis ESI-TOF mass spectrometer.
strategy. Upon the combination of molecular chirality with the The UV-vis spectra were recorded using a PerkinElmer Lambda
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2
5 spectrometer. The CD and CPL spectral data were recorded ring at room temperature overnight, 20 mL of water was
using an Olis DM245 spectrofluorimeter. The photo- dropped into the mixture to quench the reaction and extracted
luminescence spectra containing the emission, excitation and with Et O (20 mL). The organic layer was then separated and
luminescence lifetime measurements were recorded using an washed with water two times and dried over Na SO . The
2
2
4
Edinburgh FLS 1000 spectrophotometer, and the lumine- required product was obtained as a pale yellow solid and puri-
scence quantum yield (Φ) was estimated by an integrating fied by chromatography on silica gel (with hexane as eluting).
1
sphere equipped on this instrument. The Φ values were calcu- Yield, 47%. H NMR (400 MHz, CDCl
3
): antiparallel confor-
lated using the following equation:
mer: δ 2.19 (s, 3H); parallel conformer: δ 2.47 (s, 3H), 7.14–7.38
+
Ð
(
m, 8H). EI-MS m/z = 468.12 M .
Lemission
Φ ¼ Ð
Ð
1,2-Bis(6-iodo-2-methyl-1-benzothiophen-3-yl)hexafluorocyclo-
pentene (4). A 250 mL Schlenk flask filled with 3 (2.00 g,
Ereference ꢀ Esample
where Ereference is the emission spectrum of the excitation light 4.3 mmol), sulfuric acid (3 mL), water (7 mL), and AcOH
as only the reference in the sphere, Esample is the emission (150 mL) was heated to 65 °C. Iodine (1.20 g, 4.9 mmol) and
spectrum of the excitation light as only the sample in the
sphere, Lemission is the emission spectrum of the sample. The tion and reacted for 3 h. Then the mixture was poured into
H IO (0.39 g, 1.7 mmol) were added to the above clear solu-
5 6
method is accurate within 10%.
150 mL of water and extracted three times with Et
). The combined organic layer was concentrated and purified
by chromatography on silica gel and eluted with hexane to give
2
O (20 mL ×
3
Synthetic procedures
1
4
3
in 73% yield. H NMR (400 MHz, CDCl ) parallel conformer:
2
-Methylbenzo[b]thiophene (1). Benzo[b]thiophene (5.10 g, δ 2.17 (s, 6H), 7.35–7.37 (d, J = 8 Hz, 2H), 7.64–7.64 (d, J = 8
8.0 mmol) was dissolved in 100 mL of THF and then cooled Hz, 2H), 8.04 (s, 2H); antiparallel conformer: δ 2.46 (s, 6H),
to −78 °C under the protection of a N atmosphere. 7.25–7.26 (d, J = 4 Hz, 2H), 7.47–7.49 (d, J = 8 Hz, 2H), 7.96 (s,
n-Butyllithium (1.6 M, 30.27 mL, 49.4 mmol) was then added 2H). ESI-TOF-MS m/z = 719.83.
3
2
dropwise slowly in one hour. The resulting solution gradually
1,2-Bis[6-(5-acetylphenyl)-2-methyl-1-benzothiophen-3-yl]hexa-
became yellow, followed by the presence of a white suspension. fluorocyclopentene (5). Compound 4 (3.00 g, 4.2 mmol) and
After being warmed to r.t., iodomethane (4.64 mL, 76.0 mmol) 3-formylphenylboronic acid (2.50 g, 15.0 mmol) were added
was added into the above solution and stirred for 6 h, forming into a 250 mL Schlenk flask containing 100 mL of THF. Under
a colourless solution. The reaction was finally ended by adding the protection of a N
0 mL of water into the reaction solution. The water layer was 0.5 mmol) was added to the mixture and heated to reflux for
then separated and extracted with CH Cl for two times. The 24 h. The yellow reaction solution gradually changed to deep
2 3 4
atmosphere, [Pd(PPh ) ] (0.63 g,
5
2
2
combination of the organic layers was dried with anhydrous red. After returning to room temperature, 50 mL of water was
Na SO . The evaporation of the solvent gave a white solid in added and then extracted with Et O (20 mL × 3). The com-
2
4
2
1
8
1
1
9% yield. H NMR (400 MHz, CDCl
3
2 4
): δ 2.57 (s, 3H), 6.96 (s, bined organic layer was then dried with Na SO . Concentration
H), 7.20–7.36 (m, 2H), 7.63 (d, J = 8 Hz, 1H), 7.74 (d, J = 8 Hz, and purification by chromatography on silica (eluting with
+
1
H). EI-MS m/z = 148.16 M .
-Bromo-2-methylbenzo[b]thiophene (2).
7.5 mmol) was added into AcOH/CHCl (100 mL v/v = 1 : 1) 6H), 7.84–7.86 (m, 2H), 8.32 (s, 2H); antiparallel conformer: δ
hexane) gave 5 as a white solid in 66% yield. H NMR
3
1
(10.00 g, (400 MHz, CDCl ) parallel conformer: δ 2.37 (s, 6H), 2.77 (s,
3
6
3
and stirred for 5 min at 0 °C. N-Bromosullirimide (13.20 g, 2.64 (s, 3H), 2.73 (s, 3H), 7.73–7.76 (m, 2H), 8.22 (s, 1H);
7
4
4.3 mmol) was added to the above solution and stirred for 7.56–7.68 (m, 6H), 7.92–8.00 (m, 6H). ESI-TOF-MS m/z = 727.74
h; the reaction solution then changed from yellow to deep [M + Na] .
+
red. The reaction was finally ended by adding 50 mL of water
into the reaction solution. The water layer was then separated and ethyl trifluoroacetate in 1,2-dimethoxyethane (DME).
and extracted with CH Cl for two times. The combined Freshly prepared sodium methoxide (0.09 g, 1.7 mmol) and
organic layer was washed with water and dried with anhydrous ethyl trifluoroacetate (0.20 mL, 1.7 mmol) were added into a
Na SO . A pale pink solid was obtained by recrystallization of Schlenk flask containing 30 mL of DME and stirred until the
the coarse product from n-hexane, 92% yield. H NMR solution became clear and transparent. Then 5 (0.20 g,
Ligand, L. L was prepared by the Claisen condensation of 5
2
2
2
4
1
(
(
400 MHz, CDCl ): δ 2.54 (s, 3H), 7.24–7.53 (m, 2H), 7.68–7.72 0.3 mmol) was added, and then the solution was stirred for
3
+
m, 2H). EI-MS m/z = 227.11 M .
,2-Bis(2-methylbenzo[b]thiophen-3-yl)hexafluorocyclopentene quenched with ice-water, acidified to pH 2–3 using 2.0 M HCl
3). A 250 mL Schlenk flask was charged with 2 (10.00 g, solution, and the resulting yellow precipitate was filtered and
4.0 mmol) and dry THF (100 mL) and cooled to −78 °C under recrystallized from ethyl acetate solvents to give white flake
24 hours at room temperature. The final reaction solution was
1
(
4
1
a N
6.0 mmol) was added dropwise at −78 °C in one hour. After δ 2.29 (s, 6H), 8.19 (s, 2H); antiparallel conformer: δ 2.56 (s,
stirring for another 1 h, octafluorocyclopentene (2.95 mL, 3H), 8.09 (s, 1H); 7.45–7.48 (m, 3H), 7.59–7.69 (m, 6H),
2.0 mmol) was slowly added dropwise. During this addition, 7.77–7.79 (m, 3H), 7.87–7.96 (m, 3H). ESI-TOF-MS m/z = 912.98
2 8
atmosphere. Then n-butyllithium (1.6 M, 41.00 mL, crystals (55%). H NMR (400 MHz, THF-d ) parallel conformer:
6
2
−
the pale-yellow suspension changed to deep brown. After stir- [M + OH] .
This journal is © The Royal Society of Chemistry 2021
Dalton Trans., 2021, 50, 4604–4612 | 4609

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Paper
Dalton Transactions
Synthesis of [Eu
NEt3 (0.04 mL, 0.30 mmol) and (R/S)-BINAPO (0.07 g,
2
(o-L)
3
](R/S-BINAPO)
2
. L (0.10 g, 0.1 mmol),
J. Autschbach and J. Crassous, Chem. – Eur. J., 2015, 21,
1673–1681.
0
5
.1 mmol) were dissolved in 30 mL of methanol and stirred for
min. Then LnCl ·6H O (0.03 g, 0.07 mmol) in 5 mL of
3 (a) Z.-H. Zhao, X. Liang, M.-X. He, M. Y. Zhang and
C.-H. Zhao, Org. Lett., 2019, 21, 9569–9573; (b) F. Wang,
W. Ji, P. Yang and C.-L. Feng, ACS Nano, 2019, 13, 7281–
7290; (c) D. Niu, Y. Jiang, L. Ji, G. Ouyang and M. Liu,
Angew. Chem., Int. Ed., 2019, 58, 5946–5950; (d) Y. Imai and
J. Yuasa, Chem. Commun., 2019, 55, 4095–4098; (e) J. Gong,
M. Yu, C. Wang, J. Tan, S. Wang, S. Zhao, Z. Zhao, A. Qin,
B. Tang and X. Zhang, Chem. Commun., 2019, 55, 10768–
10771; (f) J. Chen, Y. Chen, L. Zhao, L. Feng, F. Xing,
C. Zhao, L. Hu, J. Ren and X. Qu, J. Mater. Chem. C, 2019, 7,
13947–13952; (g) P. Reiné, A. M. Ortuño, S. Resa, L. Álvarez
de Cienfuegos, V. Blanco, M. J. Ruedas-Rama, G. Mazzeo,
S. Abbate, A. Lucotti, M. Tommasini, S. Guisán-Ceinos,
M. Ribagorda, A. G. Campaña, A. Mota, G. Longhi,
D. Miguel and J. M. Cuerva, Chem. Commun., 2018, 54,
13985–13988; (h) P. Reiné, J. Justicia, S. P. Morcillo,
S. Abbate, B. Vaz, M. Ribagorda, Á. Orte, L. Álvarez de
Cienfuegos, G. Longhi, A. G. Campaña, D. Miguel and
J. M. Cuerva, J. Org. Chem., 2018, 83, 4455–4463; (i) H. Ito,
H. Sakai, Y. Okayasu, J. Yuasa, T. Mori and T. Hasobe,
Chem. – Eur. J., 2018, 24, 16889–16894; ( j) A. Homberg,
E. Brun, F. Zinna, S. Pascal, M. Górecki, L. Monnier,
C. Besnard, G. Pescitelli, L. Di Bari and J. Lacour, Chem.
Sci., 2018, 9, 7043–7052; (k) H. Maeda, Y. Bando,
K. Shimomura, I. Yamada, M. Naito, K. Nobusawa,
H. Tsumatori and T. Kawai, J. Am. Chem. Soc., 2011, 133,
3
2
methanol was added, which was accompanied by the presence
of a large amount of precipitation. The mixture was then
refluxed for 12 h. After cooling to room temperature, the pre-
cipitate was filtered and washed with 10 mL of CH OH and
3
1
0 mL of H
Eu (o-L)
C217H130Eu F O P S (4297.5678): C, 48.32; H, 2.53; S, 6.23.
2
O, respectively, and then dried under vacuum.
[
2
3
](R-BINAPO) Yield: 75.30% anal. calc. for
2
.
2
36 16 4 6
Found: C, 48.25; H, 2.77; S, 6.09. ESI-TOF-MS: m/z = 4298.5678
+
[M + H] .
[
Eu (o-L) ](S-BINAPO) . Yield: 76.35% anal. calc. for
2
3
2
C
217
H130Eu
2
F
36
O
16
P
4
S
6
(4297.4685): C, 48.33; H, 2.52; S, 6.25.
Found: C, 48.19; H, 2.69; S, 6.17. ESI-TOF-MS: m/z = 4298.4587
+
[M + H] .
[
Gd (o-L)
2
3
](R-BINAPO)
2
.
Yield: 79.52% anal. calc. for
C
217 2 36 16 4 6
H130Gd F O P S (4308.1059): C, 53.06; H, 2.28; S, 6.59.
Found: C, 53.01; H, 2.32; S, 6.35. ESI-TOF-MS: m/z = 4308.1392
+
[M + H] .
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
9
266–9269.
(a) W. Miao, S. Wang and M. Liu, Adv. Funct. Mater., 2017,
7, 1701368; (b) H. Jiang, Y. Jiang, J. Han, L. Zhang and
M. Liu, Angew. Chem., Int. Ed., 2019, 58, 785–790;
c) Y. Hashimoto, T. Nakashima, D. Shimizu and T. Kawai,
4
This work is financially supported by the National Natural
Science Foundation of China (No. 520730805, 51872077 and
2
5
1773054).
(
Chem. Commun., 2016, 52, 5171–5174; (d) X. Jin, D. Yang,
Y. Jiang, P. Duan and M. Liu, Chem. Commun., 2018, 54,
References
4513–4516; (e) Y. Wang, Y. Jiang, X. Zhu and M. Liu, J. Phys.
1
(a) G. Longhi, E. Castiglioni, J. Koshoubu, G. Mazzeo and
S. Abbate, Chirality, 2016, 28, 696–707; (b) H. G. Brittain,
Chirality, 1996, 8, 357–373; (c) J. P. Riehl and
F. S. Richardson, Chem. Rev., 1986, 86, 1–16; (d) G. Muller
and J. P. Riehl, in Comprehensive Chiroptical Spectrometry:
Instrumentation, Methodologies, and Theoretical Simulations,
Wiley, 2012, pp. 65–90; (e) F. S. Richardson and J. P. Riehl,
Chem. Rev., 1977, 77, 773–792; (f) F. Zinna and L. Di Bari,
Chirality, 2015, 27, 1–13; (g) H. C. Aspinall, Chem. Rev.,
Chem. Lett., 2019, 10, 5861–5867.
5 (a) Z.-B. Sun, J.-K. Liu, D.-F. Yuan, Z.-H. Zhao, X.-Z. Zhu,
D.-H. Liu, Q. Peng and C.-H. Zhao, Angew. Chem., Int. Ed.,
2019, 58, 4840–4846; (b) K. Hirano, T. Ikeda, N. Fujii,
T. Hirao, M. Nakamura, Y. Adachi, J. Ohshita and T. Haino,
Chem. Commun., 2019, 55, 10607–10610; (c) Q. Ye, D. Zhu,
H. Zhang, X. Lu and Q. Lu, J. Mater. Chem. C, 2015, 3,
6997–7003.
6 (a) W. Shang, X. Zhu, T. Liang, C. Du, L. Hu, T. Li and
M. Liu, Angew. Chem., Int. Ed., 2020, 59, 12811–12816;
(b) Z. Shen, T. Wang, L. Shi, Z. Tang and M. Liu, Chem. Sci.,
2015, 6, 4267–4272.
2
002, 102, 1807–1850.
2
(a) A. H. G. David, R. Casares, J. M. Cuerva, A. G. Campaña
and V. Blanco, J. Am. Chem. Soc., 2019, 141, 18064–18074;
(
2
b) K. Takaishi, M. Yasui and T. Ema, J. Am. Chem. Soc.,
018, 140, 5334–5338; (c) D. Han, J. Han, S. Huo, Z. Qu,
T. Jiao, M. Liu and P. Duan, Chem. Commun., 2018, 54,
630–5633; (d) T. Otani, A. Tsuyuki, T. Iwachi, S. Someya,
7 H. Hayasaka, T. Miyashita, K. Tamura and K. Akagi, Adv.
Funct. Mater., 2010, 20, 1243–1250.
8 (a) K. Takaishi, K. Iwachido and T. Ema, J. Am. Chem. Soc.,
2020, 142, 1774–1779; (b) S. Lee, K. Y. Kim, S. H. Jung,
J. H. Lee, M. Yamada, R. Sethy, T. Kawai and J. H. Jung,
Angew. Chem., Int. Ed., 2019, 58, 18878–18882;
(c) J.-R. Jiménez, B. Doistau, C. M. Cruz, C. Besnard,
J. M. Cuerva, A. G. Campaña and C. Piguet, J. Am. Chem.
5
K. Tateno, H. Kawai, T. Saito, K. S. Kanyiva and T. Shibata,
Angew. Chem., Int. Ed., 2017, 56, 3906–3910; (e) N. Saleh,
B. Moore, M. Srebro, N. Vanthuyne, L. Toupet,
J. A. Williams, C. Roussel, K. K. Deol, G. Muller,
4610 | Dalton Trans., 2021, 50, 4604–4612
This journal is © The Royal Society of Chemistry 2021

View Article Online
Dalton Transactions
Paper
Soc., 2019, 141, 13244–13252; (d) Y. Li, A. Yagi and K. Itami,
J. Am. Chem. Soc., 2020, 142, 3246–3253; (e) N. Hellou,
M. Srebro-Hooper, L. Favereau, F. Zinna, E. Caytan,
L. Toupet, V. Dorcet, M. Jean, N. Vanthuyne,
J. A. G. Williams, L. Di Bari, J. Autschbach and J. Crassous,
Angew. Chem., Int. Ed., 2017, 56, 8236–8239; (f) R. Aoki,
F. Zinna, L. Di Bari and M. Seitz, Chem. – Eur. J., 2018, 24,
13556–13564; (i) Y. Hasegawa, Y. Miura, Y. Kitagawa,
S. Wada, T. Nakanishi, K. Fushimi, T. Seki, H. Ito, T. Iwasa,
T. Taketsugu, M. Gon, K. Tanaka, Y. Chujo, S. Hattori,
M. Karasawa and K. Ishii, Chem. Commun., 2018, 54,
10695–10697.
R. Toyoda, J. F. Kögel, R. Sakamoto, J. Kumar, Y. Kitagawa, 14 (a) I. Regeni, B. Chen, M. Frank, A. Baksi, J. J. Holstein
K. Harano, T. Kawai and H. Nishihara, J. Am. Chem. Soc.,
017, 139, 16024–16027.
(a) M. Leonzio, A. Melchior, G. Faura, M. Tolazzi, F. Zinna,
L. Di Bari and F. Piccinelli, Inorg. Chem., 2017, 56, 4413–
and G. H. Clever, Angew. Chem., Int. Ed., 2020, 1–9;
(b) N. Ousaka, S. Yamamoto, H. Iida, T. Iwata, S. Ito,
Y. Hijikata, S. Irle and E. Yashima, Nat. Commun., 2019,
10, 1457; (c) T. Haino, H. Shio, R. Takano and
Y. Fukazawa, Chem. Commun., 2009, 2481–2483;
(d) R. M. Yeh, M. Ziegler, D. W. Johnson, A. J. Terpin and
K. N. Raymond, Inorg. Chem., 2001, 40, 2216–2217;
(e) R. M. Yeh and K. N. Raymond, Inorg. Chem., 2006, 45,
1130–1139.
2
9
4
422; (b) J. Zhang, L. Dai, A. M. Webster, W. T. K. Chan,
L. E. Mackenzie, R. Pal, S. L. Cobb and G.-L. Law, Angew.
Chem., Int. Ed., 2021, 60, 1004–10102; (c) D. E. Barry,
J. A. Kitchen, L. Mercs, R. D. Peacock, M. Albrecht and
T. Gunnlaugsson, Dalton Trans., 2019, 48, 11317–11325;
(
d) T. Wu and P. Bouř, Chem. Commun., 2018, 54, 1790– 15 (a) Y. Zhou, H. Li, T. Zhu, T. Gao and P. Yan, J. Am. Chem.
1
792; (e) L. Armelao, D. B. D.′. Amico, L. Bellucci,
Soc., 2019, 141, 19634–19643; (b) Y. Furusho, T. Kimura,
Y. Mizuno and T. Aida, J. Am. Chem. Soc., 1997, 119, 5267–
5268.
G. Bottaro, L. Di Bari, L. Labella, F. Marchetti,
S. Samaritani and F. Zinna, Inorg. Chem., 2017, 56, 7010–
7
018; (f) J. Gregoliński, P. Starynowicz, K. T. Hua, 16 (a) S. Bi, Y. Zhou, Y. Yao, Z. Cheng, T. Gao, P. Yan and
J. L. Lunkley, G. Muller and J. Lisowski, J. Am. Chem. Soc.,
008, 130, 17761–11777; (g) M. Seitz, E. G. Moore,
A. J. Ingram, G. Muller and K. N. Raymond, J. Am. Chem.
H. Li, Aust. J. Chem., 2021, 74, 145–150; (b) D. Liu, Y. Zhou,
Y. Zhang, H. Li, P. Chen, W. Sun, T. Gao and P. Yan, Inorg.
Chem., 2018, 57, 8332–8337.
2
Soc., 2007, 129, 15468–15470; (h) L. Dai, W.-S. Lo, 17 (a) Y. Ushiogi, T. Hase, Y. Iinuma, A. Takata and J. Yoshida,
I. D. Coates, R. Pal and G.-L. Law, Inorg. Chem., 2016, 55,
065–9070.
0 (a) H. Al Sabea, N. Hamon, O. Galangau, L. Norel,
Chem. Commun., 2007, 2947–2949; (b) J. Mamiya,
A. Kuriyama, N. Yokota, M. Yamada and T. Ikeda, Chem. –
Eur. J., 2015, 21, 3174–3177.
9
1
O. Maury, F. Riobé, R. Tripier and S. Rigaut, Inorg. Chem. 18 Y. Zhang, Y. Zhou, T. Gao, P. Yan and H. Li, Chem.
Front., 2020, 7, 2979–2989; (b) H. Al Sabea, L. Norel, Commun., 2020, 56, 13213–13216.
O. Galangau, H. Hijazi, R. Métivier, T. Roisnel, O. Maury, 19 (a) F. Zinna, L. Arrico and L. Di Bari, Chem. Commun.,
C. Bucher, F. Riobé and S. Rigaut, J. Am. Chem. Soc., 2019,
41, 20026–20030; (c) L.-X. Cai, L.-L. Yan, S.-C. Li,
L.-P. Zhou and Q.-F. Sun, Dalton Trans., 2018, 47, 14204–
4210; (d) R. Kashihara, M. Morimoto, S. Ito, H. Miyasaka
and M. Irie, J. Am. Chem. Soc., 2017, 139, 16498–16501;
e) M. Irie, T. Fukaminato, K. Matsuda and S. Kobatake,
Chem. Rev., 2014, 114, 12174–12277.
1 Y. Hashimoto, T. Nakashima, M. Yamada, J. Yuasa,
G. Rapenne and T. Kawai, J. Phys. Chem. Lett., 2018, 9,
2019, 55, 6607–6609; (b) T. Harada, Y. Nakano, M. Fujiki,
M. Naito, T. Kawai and Y. Hasegawa, Inorg. Chem., 2009, 48,
11242–11250; (c) M. Leonzio, M. Bettinelli, L. Arrico,
M. Monari, L. Di Bari and F. Piccinelli, Inorg. Chem., 2018,
57, 10257–10264; (d) J. Yuasa, T. Ohno, K. Miyata,
H. Tsumatori, Y. Hasegawa and T. Kawai, J. Am. Chem. Soc.,
2011, 133, 9892–9902; (e) M. Górecki, L. Carpita, L. Arrico,
F. Zinna and L. Di Bari, Dalton Trans., 2018, 47, 7166–7177;
(f) T. Y. Bing, T. Kawai and J. Yuasa, J. Am. Chem. Soc.,
2018, 140, 3683–3689; (g) N. Koiso, Y. Kitagawa,
T. Nakanishi, K. Fushimi and Y. Hasegawa, Inorg. Chem.,
2017, 56, 5741–5747; (h) T. Harada, H. Tsumatori,
K. Nishiyama, J. Yuasa, Y. Hasegawa and T. Kawai, Inorg.
Chem., 2012, 51, 6476–6485; (i) Y. Nishioka, T. Yamaguchi,
M. Kawano and M. Fujita, J. Am. Chem. Soc., 2008, 130,
8160–8161.
1
1
(
1
2
151–2157.
1
2 J. Zhang, Y. Zhou, Y. Yao, Z. Cheng, T. Gao, H. Li and
P. Yan, J. Mater. Chem. C, 2020, 8, 6788–6796.
3 (a) K. Wydra, M. J. Kobyłka, T. Lis, K. Ślepokura and
J. Lisowski, Eur. J. Inorg. Chem., 2020, 2020, 2096–2104;
1
(b) Y. B. Tan, Y. Okayasu, S. Katao, Y. Nishikawa,
F. Asanoma, M. Yamada, J. Yuasa and T. Kawai, J. Am.
Chem. Soc., 2020, 142, 17653–17661; (c) M. Deng, 20 J. Diogo, L. Dutra, T. D. Bispo and R. O. Freire, J. Comput.
N. D. Schley and G. Ung, Chem. Commun., 2020, 56, 14813– Chem., 2014, 35, 772–775.
4816; (d) L.-J. Chen, H.-B. Yang and M. Shionoya, Chem. 21 (a) M. D. Johnstone, C.-W. Hsu, N. Hochbaum,
1
Soc. Rev., 2017, 46, 2555–2576; (e) J. W. Canary, Chem. Soc.
Rev., 2009, 38, 747–756; (f) V. Y. Chang, K. U. D. Calvinho,
R. C. Tovar, V. A. Johnson, D. A. Straus and G. Muller,
Eur. J. Inorg. Chem., 2020, 2020, 3815–3828; (g) L. Arrico,
C. De Rosa, L. Di Bari, A. Melchior and F. Piccinelli, Inorg.
Chem., 2020, 59, 5050–5062; (h) E. Kreidt, L. Arrico,
J. Andréasson and H. Sundén, Chem. Commun., 2020, 56,
988–991; (b) N. Yano, M. Yamauchi, D. Kitagawa,
S. Kobatake and S. Masuo, J. Phys. Chem. C, 2020, 124,
17423–17429; (c) H.-B. Cheng, G.-F. Hu, Z.-H. Zhang,
L. Gao, X. Gao and H.-C. Wu, Inorg. Chem., 2016, 55, 7962–
7968.
This journal is © The Royal Society of Chemistry 2021
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View Article Online
Paper
Dalton Transactions
2
2 (a) M. W. Mara, D. S. Tatum, A.-M. March, G. Doumy,
E. G. Moore and K. N. Raymond, J. Am. Chem. Soc., 2019,
J. Am. Chem. Soc., 1995, 117, 9408–9414; (c) M. Latva,
H.
Takalo,
V.-M.
Mukkala,
C.
Matachescu,
1
41, 11071–11081; (b) F. J. Steemers, W. Verboom,
J. C. Rodriguez-Ubis and J. Kankare, J. Lumin., 1997, 75,
149–169.
D. N. Reinhoudt, E. B. van der Tol and J. W. Verhoeven,
4612 | Dalton Trans., 2021, 50, 4604–4612
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