Circularly Polarized Luminescence from Enantiopure C2-Symmetrical Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide Complexes

Article abstract of DOI:10.1021/acs.inorgchem.0c00628

We report the synthesis and characterization of C₂-symmetrical lanthanide complexes supported by enantiopure hexadentate ligands derived from 1,2-diaminocyclohexane. Coordination of (R,R)- or (S,S)-N,N,N′,N′-tetrakis(2-pyridylmethyl)-trans-1,2-

Full text of DOI:10.1021/acs.inorgchem.0c00628

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Article
Circularly Polarized Luminescence from Enantiopure C2‑Symmetrical
Tetrakis(2-pyridylmethyl)-1,2-diaminocyclohexane Lanthanide
Complexes
̈
Kaitlynn M. Ayers, Nathan D. Schley, and Gael Ung*
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ABSTRACT: We report the synthesis and characterization of C2-sym-
metrical lanthanide complexes supported by enantiopure hexadentate
ligands derived from 1,2-diaminocyclohexane. Coordination of (R,R)- or
(S,S)-N,N,N′,N′-tetrakis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane
(tpdac) to samarium, europium, terbium, and dysprosium generates the
corresponding C2-symmetrical (tpdac)Ln(OTf)3 complexes in high yields.
The tpdac ligands are competent sensitizers for lanthanide luminescence,
yielding modest emissions (Φ of ≤28%). Additionally, the complexes exhibit
strong circularly polarized luminescence (|glum| values of up to 0.13, 0.09,
0.22, and 0.15 for Sm, Eu, Tb, and Dy, respectively) in solution. We also
observed that some transitions typically associated with small dissymmetry
factors exhibit unusually high |glum| values and, therefore, should not be overlooked in future studies.
and lack only the ability to form a chiral geometry to
potentially enable CPL. The chiral trans-1,2-diaminocyclohex-
ane moiety has recently been shown to enable strong CPL with
lanthanides using an N,N′-bis(2-pyridylmethyl)-trans-1,2-dia-
minocyclohexane-N,N′-diacetic acid ligand (bpcd in Figure
1).14 This dianionic ligand affords Tb and Eu complexes with
glum values of ≤|0.11| and ≤|0.2|, respectively. Inspired by our
previous work and these contributions, we report herein the
synthesis and circularly polarized luminescence of visible
emitting lanthanide complexes (Sm, Eu, Tb, and Dy)
supported by a chiral derivative of the neutral tpen
[N,N,N′,N′-tetrakis(2-pyridylmethyl)-trans-1,2-diaminocyclo-
hexane (tpdac in Figure 1)]. These complexes are modestly
luminescent with quantum yields ranging from 0.2% to 28%
and display strong CPL activity with glum values of ≤|0.22|.
INTRODUCTION
■
Circularly polarized luminescence (CPL) is the emission of
light where one circular polarization (left or right) is more
intense than the other (right or left, respectively). Growing
interest in the field of CPL has been justified by promising
applications of CPL emitters for three-dimensional displays,1
spintronic devices,2 information storage,3 and optical sensors.4
CPL is quantified by luminescence dissymmetry factors {glum
=
(IL − IR)/[1/2(IL + IR)], where IL and IR are the intensities of
the left- and right-polarized emission, respectively}. To date,
the most efficient CPL emitters are lanthanide-based
coordination complexes with glum values ranging from 0.1 to
1,5 although recent advances in CPL-emitting small molecules
(glum ∼ 10−2)6 and transition metal complexes (glum values of
≤0.2) have been made.7−11 Due to the fact that their
luminescence arises from f−f transitions, lanthanide complexes
are ideal for CPL emission. For the same reason, however,
lanthanide light absorption is weak and therefore requires the
coordination of organic ligand sensitizers to enable their
emission (the so-called “antenna effect”).12 In the concluding
remarks of their review on lanthanide CPL, Zinna and Di Bari
stated that optimum ligands for lanthanide-based CPL should
(1) form a stable/inert lanthanide complex, (2) be a good
sensitizer, (3) form a complex with chiral geometry that can
give rise to strong CPL, and (4) form a complex with good
solubility.5a We have recently reported that simple N,N,N′,N′-
tetrakis(2-pyridylmethyl)ethylenediamine (tpen in Figure 1)
forms stable lanthanide complexes, exhibiting only one C2-
symmetrical species in solution.13 These lanthanide complexes
are modestly luminescent and soluble in polar organic solvents
RESULTS AND DISCUSSION
■
Synthesis and Characterization. The enantiopure
ligands (R,R)-tpdac and (S,S)-tpdac were synthesized from
enantiopure (R,R)-1,2-diaminocyclohexane and (S,S)-1,2-dia-
minocyclohexane, respectively, using a method similar to that
used for the preparation of tpen (Scheme 1).13 Recrystalliza-
Received: February 27, 2020
https://dx.doi.org/10.1021/acs.inorgchem.0c00628
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Figure 1. Previously reported luminescent lanthanide complexes supported by neutral (tpen) and dianionic (bpcd) hexadentate ligands (left) and
neutral hexadentate ligand (tpdac) complexes discussed in this work (right).
a
Scheme 1. Synthesis of (S,S)-tpdac and Coordination to Lanthanides
a
The syntheses of the (R,R)-tpdac enantiomer and its corresponding complexes were performed analogously using (R,R)-1,2-diaminocyclohexane
as starting material.
tion from hexanes yielded colorless blocks that were ground
and dried; this purification step was essential for obtaining
good luminescence from the subsequent coordination
complexes. Coordination of tpdac ligands to lanthanide
trifluoromethanesulfonate salts yielded complexes (tpdac)Ln-
(OTf)3 (Ln = Sm, Eu, Tb, or Dy) in good yields after
1
recrystallization (Scheme 1). The H NMR spectra of each
enantiomer of the metal complexes were taken and, as
expected, were identical. For the weakly paramagnetic ((S,S)-
tpdac)Sm(OTf)3 complex, two independent sets of peaks
attributed to the pyridines were observed (Figure S1). The
europium, terbium, and dysprosium complexes were highly
paramagnetically shifted but exhibited the expected number of
peaks (Figures S3, S6, and S8, respectively).
Figure 2. Solid state structures of ((R,R)-tpdac)Eu(OTf)3 (left) and
((S,S)-tpdac)Eu(OTf)3 (right). Hydrogen atoms, noncoordinated
trifluoromethanesulfonate, and co-crystallized 1,2-dimethoxyethane
have been omitted for the sake of clarity. Thermal ellipsoids are drawn
at the 50% probability level.
Solid State Structures. Recrystallization of both enan-
tiomers ((R,R)-tpdac)Eu(OTf)3 and ((S,S)-tpdac)Eu(OTf)3
yielded single crystals suitable for X-ray diffraction studies. As
expected, both enantiomers crystallized as single enantiomers
in the noncentrosymmetric P212121 space group [Flack
parameters15 of −0.017(2) and 0.028(6) for ((R,R)-tpdac)-
Eu(OTf)3 and ((S,S)-tpdac)Eu(OTf)3, respectively]. The solid
state structure of ((R,R)-tpdac)Eu(OTf)3 showed the
hexadentate coordination of the (R,R)-tpdac ligand to the
lanthanide ion, as well as two bound trifluoromethanesulfo-
nates and a third trifluoromethanesulfonate out of sphere
(Figure 2, left). The eight-coordinate geometry around the
lanthanide can be best described as a bisdisphenoid (or
dodecahedral deltahedron),16 where a C2 symmetry axis
crosses the vertex formed by the oxygen atoms of the
trifluoromethanesulfonate ligands (Figure S45). This structure
contrasts with the previously reported (tpen)Eu(OTf)3
complex, which is best described as a distorted square
antiprism.13 This slight change in geometry is possibly due
to the increased rigidity of the cyclohexane backbone. As
expected, the solid state structure of ((S,S)-tpdac)Eu(OTf)3 is
a perfect mirror image of the one previously described for the
((R,R)-tpdac)Eu(OTf)3 complex (Figure 2, right).
Luminescence Properties. The emissive properties of the
recrystallized complexes (tpdac)Ln(OTf)3 (Ln = Sm, Eu, Tb,
or Dy) were investigated. Acetonitrile solutions of both
enantiomers of the complexes were excited at 280 nm; their
emission spectra were recorded, and as expected, each
enantiomer gave identical data (Figure 3). The expected
sharp transitions were observed for all visible emitting
lanthanides.12a Specific analysis of the ((R,R)-tpdac)Eu(OTf)3
emission spectrum can provide additional information about
the number of species in solution and the symmetry of the
complex.17 A unique and sharp 5D0 → 7F0 transition (577 nm)
5
7
was observed, as well as three components in the D0 → F1
transition (591 nm), indicative of a single species in solution
(Figure 3, top right). The presence of the 5D0 → 7F0 transition,
combined with the 1H NMR and single-crystal X-ray
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Figure 3. Emission spectra of (tpdac)Ln(OTf)3 [Ln = Sm(S,S) (top left), Eu(R,R) (top right), Tb(S,S) (bottom left), and Dy(R,R) (bottom
right)] complexes emitting in the visible region (∼4.5 × 10−6 mol L−1 in acetonitrile). Excitation at 280 nm. Slit widths (nm): 20/5, 20/1, 10/1,
and 20/10 for Ex/Em for Sm, Eu, Tb, and Dy, respectively.
diffraction data, is consistent with a C2 symmetry of the
complex in solution. An unusually strong 5D0 → 7F4 transition
is observed at 699 nm. Because this region is often corrected
for the low sensitivity of the detector, we also collected
noncorrected data (Figure S42).
Table 1. Compiled Photophysical Data for ((R,R)-
tpdac)Ln(OTf)3 and ((S,S)-tpdac)Ln(OTf)3
a
lifetimes and CPL
glum
The quantum yields are 0.17%, 1.8%, 28.4%, and 0.43% for
the samarium, europium, terbium, and dysprosium complexes,
respectively. These quantum yields are lower than those of the
comparable (tpen)Ln(OTf)3 complexes,13 likely due to the
increased number of C−H bonds present from the cyclo-
hexane backbone and the resulting loss of sensitization energy
through C−H vibrations.18 Utilizing the analogous gadolinium
complex, the triplet energy of the tpdac ligand was determined
to be around 24150 cm−1 (Figure S18), which is consistent
with the energy levels of the emissive lanthanide states (17700
cm−1,19 17300 cm−1,17 20500 cm−1,20 and 21000 cm−1,
respectively)21 and the respective quantum yields observed.
As expected for lanthanide-based emitters, long luminescence
lifetimes were observed for the strong emitters (0.95 and 3.3
ms for Eu and Tb, respectively), while shorter lifetimes were
obtained for the weakly luminescent complexes (25 and 20 μs
for Sm and Dy, respectively). Photophysical data are compiled
in Table 1. Using the lifetimes and quantum yields, the
sensitization efficiency was determined to be 12.1% for the
europium complexes (see pages S23 and S24 of the Supporting
Information).
Ln
Φ (%)
wavelength (nm)
τ (ms)
R,R
S,S
Sm
0.17
563
597
643
577
591
615
648
690
489
542
582
622
650
479
575
665
0.025
0.025
0.023
0.90
0.95
0.96
0.95
0.95
3.3
3.3
3.4
3.4
3.3
+0.12
−0.06
−0.13
+0.05
−0.05
+0.05
b
b
Eu
Tb
Dy
1.8
28.4
0.43
nd
nd
−0.06
−0.06
+0.09
+0.07
+0.02
−0.17
−0.07
+0.10
−0.22
−0.05
−0.01
−0.15
+0.06
+0.06
−0.09
−0.07
−0.02
+0.16
+0.07
−0.10
+0.21
+0.05
+0.02
+0.14
0.020
0.021
na
a
CPL was measured at ∼1 × 10−3 mol L−1. The lifetime was
b
measured to be ∼4 × 10−6 mol L−1. Not detectable.
Circularly Polarized Luminescence. The relatively good
circularly polarized luminescence studies. Circularly polarized
luminescence of all complexes made them available for
luminescence spectra of both enantiomers ((R,R)-tpdac)Sm-
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Figure 4. Normalized CPL spectra of ((R,R)-tpdac)Sm(OTf)3 (red) and ((S,S)-tpdac)Sm(OTf)3 (blue) in acetonitrile solutions (1.12 × 10−3 mol
L−1) at room temperature. The intensity of each transition has been normalized to the largest CPL signal (see Figure S10 for the glum plot). The
total luminescence is traced in the background. Excitation at 280 nm. Slit widths: 13 nm (Ex/Em).
Figure 5. Normalized CPL spectra of ((R,R)-tpdac)Eu(OTf)3 (red) and ((S,S)-tpdac)Eu(OTf)3 (blue) in acetonitrile solutions (9.27 × 10−4 mol
L−1) at room temperature. The intensity of each transition has been normalized to the largest CPL signal (see Figure S13 for the glum plot). The
total luminescence is traced in the background. Excitation at 280 nm. Slit widths: 5 nm (Ex/Em).
(OTf)3 and ((S,S)-tpdac)Sm(OTf)3 were obtained in
acetonitrile. Perfect mirror image CPL spectra were recorded
and display rich features (Figure 4). The most CPL-active
band originates from the 4G5/2 → 6H5/2 transition, displaying a
The CPL spectra of both enantiomers ((R,R)-tpdac)Eu-
(OTf)3 and ((S,S)-tpdac)Eu(OTf)3, obtained in acetonitrile,
also displayed perfect mirror images (Figure 5). As expected,
5
7
no detectable CPL signals are observed from the D0 → F0
transition. Modestly CPL-active signals were observed for the
bisignate pattern with maximum glum values of |0.12|. For the
7
5
7
5D0 → F1 and D0 → F2 at 593 and 615 nm, respectively,
with a maximum glum value of ∼|0.06|. Surprisingly, marginally
stronger CPL signals (∼|0.08|) were observed from the 5D0 →
7F3 and 5D0 → 7F4 at 650 and 701 nm, respectively. The latter
transitions are not typically reported or do not exhibit stronger
4
emission centered at 601 nm corresponding to the G5/2
→
6H7/2, a more complex tetrasignate pattern is observed with
maximum glum values around |0.05|. The last observable
6
transition (4G5/2 → H9/2) is weaker in both intensity and
5
7
5
glum (|0.01|) and follows a bisignate pattern. Those
CPL signals than the typically studied D0 → F1 and D0 →
7F2 transitions.
observations are consistent with the expected rotatory
strengths of the transitions, where R(4G5/2
→
6H5/2) ≈
The two enantiomers ((R,R)-tpdac)Tb(OTf)3 and ((S,S)-
tpdac)Tb(OTf)3 also showed mirror image CPL spectra
R(4G5/2 → H7/2) > R(4G5/2 → H9/2).22
6
6
D
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Figure 6. Normalized CPL spectra of ((R,R)-tpdac)Tb(OTf)3 (red) and ((S,S)-tpdac)Tb(OTf)3 (blue) in acetonitrile solutions (9.22 × 10−4 mol
L−1) at room temperature. The intensity of each transition has been normalized to the largest CPL signal (see Figure S15 for the glum plot). The
total luminescence is traced in the background. Excitation at 280 nm. Slit widths: 5 nm (Ex/Em).
Figure 7. Normalized CPL spectra of ((R,R)-tpdac)Dy(OTf)3 (red) and ((S,S)-tpdac)Dy(OTf)3 (blue) in acetonitrile solutions (9.19 × 10−4 mol
L−1) at room temperature. The intensity of each transition has been normalized to the largest CPL signal (see the Figure S17 for the glum plot). The
total luminescence is traced in the background. Excitation at 280 nm. Slit widths: 13 nm (Ex/Em).
(Figure 6). As observed in other reported CPL-active terbium
complexes, the 5D4 4F5, 5D4 4F4, and 5D4 4F3
crystal field is significantly perturbing the system into
generating stronger dissymmetry factors.
→
→
→
Because of the unusually strong CPL signals observed in
some transitions of both europium and terbium species, we
also investigated the dysprosium complexes ((R,R)-tpdac)Dy-
(OTf)3 and ((S,S)-tpdac)Dy(OTf)3. Both enantiomers dis-
played mirror image CPL spectra (Figure 7), and the most
transitions (545, 585, and 624 nm, respectively) exhibit
trisignate patterns with strong dissymmetry factors (glum
= |0.16|, |0.07|, and |0.10|, respectively). Drastically lower glum
values (∼|0.02|) are observed for the 5D4 → 4F6 and 5D4 → 4F1
transitions at 491 and 670 nm, respectively. More surprisingly,
the weakly emissive 5D4 → 4F2 transition at 653 nm exhibits a
very strong CPL signal following a trisignate pattern with a glum
of |0.22|. The stronger CPL signal is not consistent with the
transition rules described by Richardson,22 because the 5D4 →
4F2 transition should be of the same type as the weakly CPL-
6
CPL-active transition was the 4F9/2 → H11/2 transition at 665
nm, with a strong glum of |0.16|. Only a few examples of
dysprosium complexes exhibiting CPL have been reported,
with dissymmetry factors ranging from 0.012 to 0.01323 to
0.4.24 Smaller dissymmetry factors for the 4F9/2 → 6H15/2 (479
4
nm) and F9/2
→
6H13/2 (575 nm) transitions were also
5
4
active D4 → F6 transition. Our observations imply that the
observed (glum = |0.05| and |0.03|, respectively). The CPL
E
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Lifetimes for each complex were determined using an excitation
wavelength of 280 nm on an OLIS CPL Solo utilizing the
Globalworks and Photon Counting Phosphorescence (PCPH)
Lifetime Software. For individual sample conditions for each
wavelength, see pages S12−S22 of the Supporting Information.
Mass Spectrometry. High-resolution mass spectrometry was
conducted for each complex using an Applied Biosystems Sciex Qstar
Elite LC mass spectrometer.
Single-Crystal X-ray Crystallography. Single-crystal X-ray
diffraction studies were performed at Vanderbilt University. A suitable
crystal of each sample was selected for analysis and mounted in a
polyimide loop. All measurements were taken on a Rigaku Oxford
Diffraction Supernova Eos CCD with filtered Mo Kα radiation at a
temperature of 100 K. Using Olex2,25 the structure was determined
with the ShelXL structure solution program using direct methods and
refined with the ShelXL refinement package26 using least-squares
minimization.
magnitudes observed are, this time, consistent with the
expected rotatory strength of the transitions.22
CONCLUSION
■
We have demonstrated that enantiopure N,N,N′,N′-tetrakis(2-
pyridylmethyl)-trans-1,2-diaminocyclohexane (tpdac) is a
competent ligands for lanthanide binding and sensitization,
and that the corresponding complexes emit circularly polarized
luminescence with strong dissymmetry factors. The combina-
tion of 1H NMR, single-crystal X-ray diffraction, and
luminescence studies provided evidence of the existence of a
single C2-symmetrical species in solution. Unusually strong
dissymmetry factors were also observed for some transitions
typically associated with weaker glum values, notably for
europium and terbium, and indicate that these transitions
should not be overlooked in future studies. Derivatives of the
tpdac ligand presented here are synthetically accessible and
open the possibilities for fine-tuning the ligand toward
obtaining higher quantum yields and dissymmetry factors.
CCDC 1970322 [((R,R)-tpdac)Eu(OTf)3] and 1970321 [((S,S)-
tpdac)Eu(OTf)3] contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from the
Cambridge Crystallographic Data Center.
Synthetic Procedures and Characterizations. (R,R)-N,N,N′,N′-
Tetrakis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane, (R,R)-
tpdac. The synthesis for the tpdac ligand was conducted in a manner
similar to that of the tpen analogue previously reported.13 To a 100
mL flame-dried Schlenk flask fit with a stir bar was added 2-
chloromethylpyridine hydrochloride (6.91 g, 0.042 mol, 4.04 equiv),
and the flask was evacuated and placed under nitrogen. The solid was
then dissolved in 5 mL of degassed deionized water, and 10 mL of a 5
M NaOH solution was added until the color changed to dark red-
brown. (R,R)-1,2-Diaminocyclohexane (1.19 g, 0.01 mol, 1 equiv)
was dissolved in 8 mL of dry, degassed dichloromethane (DCM) and
added to the reaction flask. A second 10 mL portion of NaOH
solution was added (0.10 mol, 9.6 equiv total) followed by 0.5 mL of
a 25% cetyltrimethylammonium chloride solution (121 mg, 0.378
mmol, 0.036 equiv). The flask was covered in foil and stirred for 72 h
under nitrogen. The reaction mixture was then extracted three times
with 20 mL of DCM, and the organic layer was washed three times
with deionized water and then dried with sodium sulfate. The solvent
was removed in vacuo, and the solid residue was extracted with
hexanes and left to slowly evaporate. Colorless to slightly yellow
EXPERIMENTAL SECTION
■
General Methods, Materials, and Instrumentation. All
manipulations were carried out air free in a Vigor glovebox or using
Schlenk techniques. The Eu(OTf)3 and Dy(OTf)3 were purchased
from Alfa Aesar. The Tb(OTf)3 was purchased from StremChemicals.
The cetyltrimethylammonium chloride was purchased from Sigma-
Aldrich. Sm(OTf)3, (R,R)-(1,2)-diaminocyclohexane, (S,S)-(1,2)-
diaminocyclohexane, and 2-chloromethylpyridine hydrochloride
were purchased from Oakwood Chemicals.
All materials were used without further purification aside from the
(1,2)-diaminocyclohexanes that were sublimed and then stored under
an inert atmosphere to prevent absorption of water. All solvents used
in syntheses were dried using a solvent purification system from Pure
Process Technology or distilled under nitrogen after being stirred
overnight with calcium hydride.
The chiral tetrakis(2-pyridylmethyl)diaminocyclohexane ligands
(tpdac) were synthesized in a manner similar to that of the tpen
ligand previously reported.13
1
crystals were obtained in two crops: yield 2.52 g, 50.5%; H NMR
NMR Spectroscopy. All NMR spectra were recorded on a Bruker
AVANCE III 400 MHz spectrometer. Chemical shifts are reported in
parts per million relative to the residual nondeuterated solvent peak
(CD3CN, 400 MHz) δ 1.13 (m, 4H, -CH2(CHx)), 1.72 (m, 2H,
-CH2(CHx)), 2.16 (d, J = 11.6 Hz, 2H, -CH2(CHx)), 2.78 (m, 2H,
-CH2(CHx)), 3.60 (d, J = 14.4 Hz, 4H, -NCH2Pyr), 3.72 (d, J = 14.4,
4H, -NCH2Pyr), 7.12 (t, J = 5.6, 6.4 Hz, 4H, CHpyr), 7.49 (dt, J = 1.6,
7.6 Hz, 4H, CHpyr), 7.62 (d, J = 8 Hz, 4H, CHpyr), 8.41 (d, J = 4.4 Hz,
4H, CHpyr); [α]D (c = 0.48 in ACN) +5.48 first crop, (c = 0.63 in
ACN) +6.18 second crop.
(S,S)-N,N,N′,N′-Tetrakis(2-pyridylmethyl)-trans-1,2-diaminocy-
clohexane, (S,S)-tpdac. The synthesis of the enantiomer was the
same as described above: yield 3.28 g, 65.8%; 1H NMR (CD3CN, 400
MHz) δ 1.13 (m, 4H, -CH2(CHx)), 1.72 (m, 2H, -CH2(CHx)), 2.16 (d, J
= 11.6 Hz, 2H, -CH2(CHx)), 2.78 (m, 2H, -CH2(CHx)), 3.60 (d, J = 14.4
Hz, 4H, -NCH2Pyr), 3.72 (d, J = 14.4, 4H, -NCH2Pyr), 7.12 (t, J =
5.6, 6.4 Hz, 4H, CHpyr), 7.49 (dt, J = 1.6, 7.6 Hz, 4H, CHpyr), 7.62 (d,
J = 8 Hz, 4H, CHpyr), 8.41 (d, J = 4.4 Hz, 4H, CHpyr); [α]D (c = 0.52
in ACN) −5.12.
((R,R)-tpdac)Sm(OTf)3. The synthesis of the samarium (R,R)-tpdac
salt was conducted in the same manner as its tpen analogue previously
reported.13 To a 20 mL scintillation vial in the glovebox were added
(R,R)-tpdac (184 mg, 0.38 mmol, 1 equiv) with a stir bar and 3 mL of
dry ACN. Next, samarium(III) trifluoromethanesulfonate was
weighed into a 4 mL vial (230 mg, 0.38 mmol, 1.0 equiv) and
added as a solid to the stirring reaction mixture. The solid dissolved
quickly reacting with the ligand, and the reaction mixture was used to
rinse the 4 mL vial to ensure full transfer of the samarium salt and
stirred overnight. The solution was then filtered and pumped in vacuo
to remove solvent to give a white crystalline solid (380 mg, 92%).
Crystals for photophysical studies were obtained by slow diffusion of
1
for H and relative to BF3(C4H10O) for 19F.
Optical Rotation. Specific rotations for compounds were
measured using a JASCO P-2000 polarimeter with a tungsten-
halogen source reading at 589 nm. For the respective concentrations
of each solution, see this section.
Photophysical Studies. All photophysical studies are performed
in sealed cuvettes under an atmosphere of dry dinitrogen using
anhydrous acetonitrile.
Absorption, excitation, and emission spectra were recorded on a
HORIBA Duetta Spectrophotometer using HORIBA EzSpec
Software. This spectrophotometer is a dual fluorimeter/ultraviolet−
visible instrument equipped with a CCD detector. The measurement
of the absorbance is read 180° from the excitation, and the
fluorescence is taken from a secondary detector 90° offset of the
excitation. Fluorescence values with correction for absorbance were
collected for all samples.
Circularly polarized luminescence was measured on an OLIS CPL
Solo. For more information about the Solo, see page S26 of the
Supporting Information.
Quantum yields were determined using two methods. Absolute
quantum yields were determined using an Edinburgh FLS1000
spectrophotometer equipped with a PMT 980 detector and a barium
sulfate-coated integrating sphere using the Fluoracle software.
External quantum yields were obtained using 9,10-diphenylanthracene
as a standard (see pages S26 and S27 of the Supporting Information).
F
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1
ether into a dilute solution in dimethoxyethane: H NMR (CD3CN,
400 MHz) δ 11.3 (s [br], CHpyr, 2H), 8.35 (t, J = 7.6 Hz, CHpyr, 2H),
8.04 (dd, J = 5.2, 6.8 Hz, CHpyr, 2H), 7.92 (d, J = 8.0 Hz, CHpyr, 2H),
7.48 (s [br], -NCH2Ar, 2H), 7.39 (t, J = 7.6 Hz, CHpyr, 2H), 6.90 (dd,
J = 6.0, 6.4 Hz, CHpyr, 4H), 6.45 (d, J = 7.6 Hz, CHpyr, 2H), 5.43 (s
[br], -CH2(CHx), 2H), 4.48 (d, J = 15.2 Hz, -NCH2Ar, 2H), 3.27 (d, J
= 16.8 Hz, -NCH2Ar, 2H), 2.93 (d, J = 12.0 Hz, -CH2(CHx), 2H), 2.63
(s [br], -CH2(CHx), 2H), 2.17 (d, J = 8.4 Hz, -CH2(CHx), 2H), 1.77 (t, J
= 8.4 Hz, -CH2(CHx), 2H), −0.24 (s [br], -NCH2Ar, 2H); all efforts to
obtain 13C NMR data were unsuccessful; 19F NMR (CD3CN, 376.512
MHz) δ −79.2 (s, 9F, -OSO2CF3); [α]D (c = 0.66 in ACN) +5.91;
HRMS calcd for C32H34F6N6O6S2Sm+ ([M − (-OSO2CF3)]+)
928.1077, found 928.0810. Anal. Calcd for C33H34F9N6O9S3Sm: C,
36.83; H, 3.18; N, 7.81. Found: C, 36.22; H, 3.11; N, 7.77.
NMR data were unsuccessful; 19F NMR (CD3CN, 376.512 MHz) δ
−74.0 (s, 9F, -OSO2CF3); [α]D (c = 0.60 in ACN) +6.78; HRMS
calcd for C32H34F6N6O6S2Dy+ ([M − (-OSO2CF3)]+) 940.117, found
640.1074. Anal. Calcd for C33H34F9N6O9S3Dy: C, 36.42; H, 3.15; N,
7.72. Found: C, 36.55; H, 3.25; N, 7.90.
((S,S)-tpdac)Dy(OTf)3. The synthesis of the dysprosium complex
with the (S,S)-tpdac ligand is identical to that of its (R,R)-tpdac
1
analogue: yield 94%; H NMR (CD3CN, 400 MHz) δ 162.3 (s [br],
2H), 116.52 (s [br], 2H), 92.29 (s [br], 4H), 76.69 (s [br], 2H),
71.38 (s [br], 2H), 53.78 (s [br], 4H), 38.18 (s [br], 4H), 18.47 (s
[br], 4H), −37.85 (s [br], 4H), −41.17 (s [br], 2H), −196.86 (s [br],
4H); all efforts to obtain 13C NMR data were unsuccessful; 19F NMR
(CD3CN, 376.512 MHz) δ −74.0 (s, 9F, -OSO2CF3); [α]D (c = 0.62
in ACN) −7.71; HRMS calcd for C32H34F6N6O6S2Dy+ ([M −
(-OSO2CF3)]+) 940.117, found 640.1074. Anal. Calcd for
C33H34F9N6O9S3Dy: C, 36.42; H, 3.15; N, 7.72. Found: C, 36.58;
H, 3.30; N, 7.88.
((S,S)-tpdac)Sm(OTf)3. The synthesis of the samarium complex
with the (S,S)-tpdac ligand is identical to that of its (R,R)-tpdac
analogue: yield 95%; H NMR (CD3CN, 400 MHz) δ 11.3 (s [br],
1
((R,R)-tpdac)Tb(OTf)3. The synthesis of the terbium complex with
(R,R)-tpdac is identical to that of ((R,R)-tpdac)Sm(OTf)3 above,
substituting a terbium triflate salt: yield 98%; 1H NMR (CD3CN, 400
MHz) δ 241.65 (s [br], 2H), 202.57 (s [br], 2H), 184.84 (s [br],
2H), 109.10 (s [br], 4H), 70.03 (s [br], 2H), 65.22 (s [br], 2H),
57.71 (s [br], 2H), 43.88 (s [br], 4H), 18.35 (s [br], 4H), 0.16 (s
[br], 2H), −27.65 (s [br], 2H), −31.26 (s [br], 2H), −61.61 (s [br],
4H); all efforts to obtain 13C NMR data were unsuccessful; 19F NMR
(CD3CN, 376.512 MHz) δ −73.7 (s, 9F, -OSO2CF3); [α]D (c = 0.52
in ACN) +7.23; HRMS calcd for C32H34F6N6O6S2Tb+ ([M −
(-OSO2CF3)]+) 935.113, found 935.0882. Anal. Calcd for
C33H34F9N6O9S3Tb: C, 36.54; H, 3.16; N, 7.75. Found: C, 37.46;
H, 3.35; N, 8.65. Anal. Found is more consistent with calcd for
C35H37F9N7O9S3Tb (M + ACN): C, 37.63; H, 3.34; N, 8.78.
((S,S)-tpdac)Tb(OTf)3. The synthesis of the terbium complex with
the (S,S)-tpdac ligand is identical to that of its (R,R)-tpdac analogue:
CHpyr, 2H), 8.35 (t, J = 7.6 Hz, CHpyr, 2H), 8.04 (dd, J = 5.2, 6.8 Hz,
CHpyr, 2H), 7.92 (d, J = 8.0 Hz, CHpyr, 2H), 7.48 (s [br], NCH2Ar,
2H), 7.39 (t, J = 7.6 Hz, CHpyr, 2H), 6.90 (dd, J = 6.0, 6.4 Hz, CHpyr
,
4H), 6.45 (d, J = 7.6 Hz, CHpyr, 2H), 5.43 (s [br], -CH2(CHx), 2H),
4.48 (d, J = 15.2 Hz, -NCH2Ar, 2H), 3.27 (d, J = 16.8 Hz, -NCH2Ar,
2H), 2.93 (d, J = 12.0 Hz, -CH2(CHx), 2H), 2.63 (s [br], -CH2(CHx)
,
2H), 2.17 (d, J = 8.4 Hz, -CH2(CHx), 2H), 1.77 (t, J = 8.4 Hz,
-CH2(CHx), 2H), −0.24 (s [br], -NCH2Ar, 2H); all efforts to obtain
13C NMR data were unsuccessful; 19F NMR (CD3CN, 376.512 MHz)
δ −79.2 (s, 9F, -OSO2CF3); [α]D (c = 0.60 in ACN) −7.46; HRMS
calcd for C32H34F6N6O6S2Sm+ ([M − (-OSO2CF3)]+) 928.1077,
found 928.1048. Anal. Calcd for C33H34F9N6O9S3Sm: C, 36.83; H,
3.18; N, 7.81. Found: C, 36.99; H, 3.23; N, 7.91.
((R,R)-tpdac)Eu(OTf)3. The synthesis of the europium complex with
(R,R)-tpdac is identical to that of ((R,R)-tpdac)Sm(OTf)3 above,
1
substituting a europium triflate salt: yield 96%; H NMR (CD3CN,
1
yield 95%; H NMR (CD3CN, 400 MHz) δ 241.65 (s [br], 2H),
400 MHz) δ 12.19 (s [br], 2H), 10.94 (s [br], 2H), 10.23 (s [br],
2H), 8.98 (s [br], 2H), 5.73 (t, J = 8.0 Hz, 2H), 3.48 (s [br], 2H), 2.4
(s [br], 2H), 2.20 (s [br], 2H), 0.00 (d, J = 8.0 Hz, 2H), −1.55 (s
[br], 2H), −2.35 (s [br], 2H), −2.91 (s [br], 2H), −3.16 (d, J = 12.0
Hz, 2H), −4.98 (s [br], 4H), −7.23 (s [br], 2H), −11.01 (s [br],
2H); all efforts to obtain 13C NMR data were unsuccessful; 19F NMR
(CD3CN, 376.512 MHz) δ −79.3 (s, 9F, -OSO2CF3); [α]D (c = 0.58
in ACN) +6.56; HRMS calcd for C32H34F6N6O6S2Eu+ ([M −
(-OSO2CF3)]+) 929.111, found 929.0637. Anal. Calcd for
C33H34F9N6O9S3Eu: C, 36.78; H, 3.18; N, 7.80. Found: C, 37.01;
H, 3.27; N, 7.91.
((S,S)-tpdac)Eu(OTf)3. The synthesis of the europium complex with
the (S,S)-tpdac ligand is identical to that of its (R,R)-tpdac analogue:
yield 93%; 1H NMR (CD3CN, 400 MHz) δ 12.19 (s [br], 2H), 10.94
(s [br], 2H), 10.23 (s [br], 2H), 8.98 (s [br], 2H), 5.73 (t, J = 8.0 Hz,
2H), 3.48 (s [br], 2H), 2.4 (s [br], 2H), 2.20 (s [br], 2H), 0.00 (d, J
= 8.0 Hz, 2H), −1.55 (s [br], 2H), −2.35 (s [br], 2H), −2.91 (s [br],
2H), −3.16 (d, J = 12.0 Hz, 2H), −4.98 (s [br], 4H), −7.23 (s [br],
2H), −11.01 (s [br], 2H); all efforts to obtain 13C NMR data were
unsuccessful; 19F NMR (CD3CN, 376.512 MHz) δ −79.3 (s, 9F,
-OSO2CF3); [α]D (c = 0.60 in ACN) −8.37; HRMS calcd for
C32H34F6N6O6S2Eu+ ([M − (-OSO2CF3)]+) 929.111, found
929.1107. Anal. Calcd for C33H34F9N6O9S3Eu: C, 36.78; H, 3.18;
N, 7.80. Found: C, 36.82; H, 3.17; N, 7.88.
202.57 (s [br], 2H), 184.84 (s [br], 2H), 109.10 (s [br], 4H), 70.03
(s [br], 2H), 65.22 (s [br], 2H), 57.71 (s [br], 2H), 43.88 (s [br],
4H), 18.35 (s [br], 4H), 0.16 (s [br], 2H), −27.65 (s [br], 2H),
−31.26 (s [br], 2H), −61.61 (s [br], 4H); all efforts to obtain 13C
NMR data were unsuccessful; 19F NMR (CD3CN, 376.512 MHz) δ
−73.7 (s, 9F, -OSO2CF3); [α]D (c = 0.60 in ACN) −6.93; HRMS
calcd for C32H34F6N6O6S2Tb+ ([M − (-OSO2CF3)]+) 935.113, found
935.0098. Anal. Calcd for C33H34F9N6O9S3Tb: C, 36.54; H, 3.16; N,
7.75. Found: C, 37.01; H, 3.21; N, 7.91.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c00628.
■
sı
NMR spectra, crystallographic parameters and refine-
ment data, and additional spectroscopic data (PDF)
Accession Codes
CCDC 1970321−1970322 and 1995232 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
((S,S)-tpdac)Gd(OTf)3. The synthesis of the gadolinium complex
with (S,S)-tpdac is identical to that of ((S,S)-tpdac)Sm(OTf)3 above,
1
substituting a gadolinium triflate salt: yield 95%; H NMR (CD3CN,
400 MHz) δ 13.21 (s [br], 2H), 8.22 (s [br], 4H), 7.94 (s [br], 6H),
7.44 (s [br], 12H), 3.40 (s [br], 4H), 2.30 (s [br], 4H), 0.92 (s [br],
2H).
AUTHOR INFORMATION
Corresponding Author
■
̈
Gael Ung − Department of Chemistry, University of Connecticut,
((R,R)-tpdac)Dy(OTf)3. The synthesis of the dysprosium complex
with (R,R)-tpdac is identical to that of ((R,R)-tpdac)Sm(OTf)3
Storrs, Connecticut 06269, United States; orcid.org/0000-
1
0002-6313-3658; Email: gael.ung@uconn.edu
above, substituting a dysprosium triflate salt: yield 97%; H NMR
(CD3CN, 400 MHz) δ 162.3 (s [br], 2H), 116.52 (s [br], 2H), 92.29
(s [br], 4H), 76.69 (s [br], 2H), 71.38 (s [br], 2H), 53.78 (s [br],
4H), 38.18 (s [br], 4H), 18.47 (s [br], 4H), −37.85 (s [br], 4H),
−41.17 (s [br], 2H), −196.86 (s [br], 4H); all efforts to obtain 13C
Authors
Kaitlynn M. Ayers − Department of Chemistry, University of
Connecticut, Storrs, Connecticut 06269, United States
G
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Article
Stalke, D.; Sakuda, E.; Umakoshi, K.; Longhi, G.; Abbate, S.; Clever,
G. H. Chiral-at-Metal Phosphorescent Square-Planar Pt(II)-Com-
plexes from an Achiral Organometallic Ligand. J. Am. Chem. Soc.
2017, 139, 6863−6866. (c) Song, J.; Wang, M.; Zhou, X.; Xiang, H.
Unusual Circularly Polarized and Aggregation-Induced Near-Infrared
Phosphorescence of Helical Platinum(II) Complexes with Tetraden-
tate Salen Ligands. Chem. - Eur. J. 2018, 24, 7128−7132. (d) Tanaka,
S.; Sato, K.; Ichida, K.; Abe, T.; Tsubomura, T.; Suzuki, T.; Shinozaki,
K. Circularly Polarized Luminescence of Chiral Pt(pppb)Cl(pppbH =
1-pyridyl-3-(4,5-pinenopyridyl)benzene) Aggregate in the Excited
State. Chem. - Asian J. 2016, 11, 265−273. (e) Usuki, T.; Uchida, H.;
Omoto, K.; Yamanoi, Y.; Yamada, A.; Iwamura, M.; Nozaki, K.;
Nishihara, H. Enhancement of the Photofunction of Phosphorescent
Pt(II) Cyclometalated Complexes Driven by Substituents: Solid-State
Luminescence and Circularly Polarized Luminescence. J. Org. Chem.
2019, 84, 10749−10756. (f) Zhang, X.-P.; Wang, L.-L.; Qi, X.-W.;
Zhang, D.-S.; Yang, Q.-Y.; Shi, Z.-F.; Lin, Q.; Wu, T. Pt···Pt
Interaction Triggered Tuning of Circularly Polarized Luminescence
Activity in Chiral Dinuclear Platinum(II) Complexes. Dalton Trans.
2018, 47, 10179−10186. (g) Park, G.; Kim, H.; Yang, H.; Park, K. R.;
Song, I.; Oh, J. K.; Kim, C.; You, Y. Amplified Circularly Polarized
Phosphorescence from Co-assemblies of Platinum(II) Complexes.
Chem. Sci. 2019, 10, 1294−1301.
Nathan D. Schley − Department of Chemistry, Vanderbilt
University, Nashville, Tennessee 37235, United States;
orcid.org/0000-0002-1539-6031
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c00628
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the University of Connecticut.
The authors thank Prof. Amy Howell (University of
Connecticut) for use of her polarimeter and Prof. Tomoyasu
Mani (University of Connecticut) for use of his fluorimeter for
quantum yield measurements.
REFERENCES
■
(1) Schadt, M. Liquid Crystal Materials and Liquid Crystal Displays.
Annu. Rev. Mater. Sci. 1997, 27, 305−379.
(2) Farshchi, R.; Ramsteiner, M.; Herfort, J.; Tahraoui, A.; Grahn, H.
T. Optical Communication of Spin Information Between Light
Emitting Diodes. Appl. Phys. Lett. 2011, 98, 162508.
̈
(9) For examples with zinc, see: (a) Aoki, R.; Toyoda, R.; Kogel, J.
(3) Sherson, J. F.; Krauter, H.; Olsson, R. K.; Julsgaard, B.;
Hammerer, K.; Cirac, I.; Polzik, E. S. Quantum Teleportation
Between Light and Matter. Nature 2006, 443, 557−560.
F.; Sakamoto, R.; Kumar, J.; Kitagawa, Y.; Harano, K.; Kawai, T.;
Nishihara, H. Bis(dipyrrinato)zinc(II) Complex Chiroptical Wires:
Exfoliation into Single Strands and Intensification of Circularly
Polarized Luminescence. J. Am. Chem. Soc. 2017, 139, 16024−16027.
(4) Heffern, M. C.; Matosziuk, L. M.; Meade, T. J. Lanthanide
Probes for Bioresponsive Imaging. Chem. Rev. 2014, 114, 4496−4539.
(5) (a) Zinna, F.; Di Bari, L. Lanthanide Circularly Polarized
Luminescence: Bases and Applications. Chirality 2015, 27, 1−13.
(b) Carr, R.; Evans, N. H.; Parker, D. Lanthanide Complexes as
Chiral Probes Exploiting Circularly Polarized Luminescence. Chem.
Soc. Rev. 2012, 41, 7673−7686. (c) Muller, G. Luminescent Chiral
Lanthanide(III) Complexes as Potential Molecular Probes. Dalton
Trans. 2009, 9692−9707.
̈
(b) Kogel, J. F.; Kusaka, S.; Sakamoto, R.; Iwashima, T.; Tsuchiya,
M.; Toyoda, R.; Matsuoka, R.; Tsukamoto, T.; Yuasa, J.; Kitagawa, Y.;
Kawai, T.; Nishihara, H. Heteroleptic [Bis(oxazoline)](dipyrrinato)-
zinc(II) Complexes: Brightand Circularly Polarized Luminescence
from an Originally Achiral Dipyrrinato Ligand. Angew. Chem., Int. Ed.
2016, 55, 1377−1381. (c) Isla, H.; Srebro-Hooper, M.; Jean, M.;
Vanthuyne, N.; Roisnel, T.; Lunkley, J. L.; Muller, G.; Williams, J. A.
G.; Autschbach, J.; Crassous, J. Conformational Changes and
Chiroptical Switching of Enantiopure Bis-helicenic Terpyridine
upon Zn2+ Binding. Chem. Commun. 2016, 52, 5932−5935.
(6) (a) Dhbaibi, K.; Favereau, L.; Crassous, J. Enantioenriched
Helicenes and Helicenoids Containing Main-Group Elements (B, Si,
́
N, P). Chem. Rev. 2019, 119, 8846−8953. (b) Sanchez-Carnerero, E.
́
(10) For examples with chromium, see: (a) Jimenez, J.-R.; Doistau,
a, A. G.; Piguet,
M.; Agarrabeitia, A. R.; Moreno, F.; Maroto, B. L.; Muller, G.; Ortiz,
M. J.; de la Moya, S. Circularly Polarized Luminescence from Simple
Organic Molecules. Chem. - Eur. J. 2015, 21, 13488−13500.
B.; Cruz, C. M.; Besnard, C.; Cuerva, J. M.; Campan
̃
C. Chiral Molecular Ruby [Cr(dqp)2]3+ with Long-Lived Circularly
Polarized Luminescence. J. Am. Chem. Soc. 2019, 141, 13244−13252.
(b) Dee, C.; Zinna, F.; Kitzmann, W. R.; Pescitelli, G.; Heinze, K.; Di
Bari, L.; Seitz, M. Strong Circularly Polarized Luminescence of an
Octahedral Chromium(III) Complex. Chem. Commun. 2019, 55,
13078−13081.
(7) For examples with iridium, see: (a) Schaffner-Hamann, C.; von
Zelewsky, A.; Barbieri, A.; Barigelletti, F.; Muller, G.; Riehl, J. P.;
Neels, A. Diastereoselective Formation of Chiral Tris-Cyclometalated
Iridium (III) Complexes: Characterization and Photophysical Proper-
ties. J. Am. Chem. Soc. 2004, 126, 9339−9348. (b) Coughlin, F. J.;
Westrol, M. S.; Oyler, K. D.; Byrne, N.; Kraml, C.; Zysman-Colman,
E.; Lowry, M. S.; Bernhard, S. Synthesis, Separation, and Circularly
Polarized Luminescence Studies of Enantiomers of Iridium(III)
Luminophores. Inorg. Chem. 2008, 47, 2039−2048. (c) Hellou, N.;
Srebro-Hooper, M.; Favereau, L.; Zinna, F.; Caytan, E.; Toupet, L.;
Dorcet, V.; Jean, M.; Vanthuyne, N.; Williams, J. A. G.; Di Bari, L.;
Autschbach, J.; Crassous, J. Enantiopure Cycloiridiated Complexes
Bearing a Pentahelicenic N-Heterocyclic Carbene and Displaying
Long-Lived Circularly Polarized Phosphorescence. Angew. Chem., Int.
Ed. 2017, 56, 8236−8239. (d) Li, T.-Y.; Zheng, Y.-X.; Zhou, Y.-H.
Iridium(III) Phosphorescent Complexes with Dual Stereogenic
Centers: Single Crystal, Electronic Circular Dichroism Evidence and
Circularly Polarized Luminescence Properties. Dalton Trans. 2016,
45, 19234−19237. (e) Yan, Z.-P.; Liao, K.; Han, H.-B.; Su, J.; Zheng,
Y.-X.; Zuo, J.-L. Chiral Iridium(III) Complexes with Four-Membered
Ir−S−P−S Chelating Rings for High-Performance Circularly
Polarized OLEDs. Chem. Commun. 2019, 55, 8215−8218.
(11) Deng, M.; Mukthar, N. F. M.; Schley, N. D.; Ung, G. Yellow
Circularly Polarized Luminescence from C1-Symmetrical Copper(I)
Complexes. Angew. Chem., Int. Ed. 2020, 59, 1228−1231.
(12) (a) Bunzli, J.-C. G.; Eliseeva, S. V. Basics of Lanthanide
̈
̈
̈
̈
Photophysics. In Lanthanide Luminescence; Hanninen, P., Harma, H.,
Eds.; Springer, 2011. (b) Moore, E. G.; Samuel, A. P. S.; Raymond, K.
N. From Antenna to Assay: Lessons Learned in Lanthanide
Luminescence. Acc. Chem. Res. 2009, 42, 542−552.
(13) Ayers, K. M.; Schley, N. D.; Ung, G. Solid State Structures,
Solution Behavior, and Luminescence of Simple Tetrakis(2-
pyridylmethyl)ethylenediamine Lanthanide Complexes. Eur. J. Inorg.
Chem. 2019, 2019, 3769−3775.
(14) (a) Leonzio, M.; Melchior, A.; Faura, G.; Tolazzi, M.; Bettinelli,
M.; Zinna, F.; Arrico, L.; Di Bari, L.; Piccinelli, F. A Chiral Lactate
Reporter Based on Total and Circularly Polarized Tb(III)
Luminescence. New J. Chem. 2018, 42, 7931−7939. (b) Leonzio,
M.; Melchior, A.; Faura, G.; Tolazzi, M.; Zinna, F.; Di Bari, L.;
Piccinelli, F. Strongly Circularly Polarized Emission from Water-
Soluble Eu(III)- and Tb(III)-Based Complexes: A Structural and
Spectroscopic Study. Inorg. Chem. 2017, 56, 4413−4422.
(8) For examples with platinum, see: (a) Zhang, X.-P.; Chang, V. Y.;
Liu, J.; Yang, X.-L.; Huang, W.; Li, Y.; Li, C.-H.; Muller, G.; You, X.-Z.
Potential Switchable Circularly Polarized Luminescence from Chiral
Cyclometalated Platinum(II) Complexes. Inorg. Chem. 2015, 54,
143−152. (b) Schulte, T. R.; Holstein, J. J.; Krause, L.; Michel, R.;
(15) Flack, H. D. On Enantiomorph-Polarity Estimation. Acta
Crystallogr., Sect. A: Found. Crystallogr. 1983, A39, 876−881.
H
https://dx.doi.org/10.1021/acs.inorgchem.0c00628
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
(16) Burdett, J. K.; Hoffmann, R.; Fay, R. C. Eight Coordination.
Inorg. Chem. 1978, 17, 2553−2568.
(17) (a) Binnemans, K. Interpretation of Europium(III) Spectra.
Coord. Chem. Rev. 2015, 295, 1−45. (b) Binnemans, K.; Goerller-
Walrand, C. Application of the Eu3+ Ion for Site Symmetry
Determination. J. Rare Earths 1996, 14, 173−180.
(18) Bischof, C.; Wahsner, J.; Scholten, J.; Trosien, S.; Seitz, M.
Quantification of C-H Quenching in Near-IR Luminescent Ytterbium
and Neodymium Cryptates. J. Am. Chem. Soc. 2010, 132, 14334−
14335.
(19) An, B.-L.; Gong, M.-L.; Li, M.-X.; Zhang, J.-M. Synthesis,
Structure and Luminescence Properties of Samarium (III) and
Dysprosium (III) Complexes with a New Tridentate Organic Ligand.
J. Mol. Struct. 2004, 687, 1−6.
(20) Sastri, V. S.; Bunzli, J.-C.; Rao, V. R.; Rayudu, G. V. S.;
̈
Perumareddi, J. R. Spectroscopy of Lanthanide Complexes. In Modern
Aspects of Rare Earths and Their Complexes; Elsevier Science, 2003.
́
́
(21) Lemanski, K.; Deren, P. J. Luminescent Properties of
Dysprosium (III) Ions in LaAlO3 Nanocrystallites. J. Rare Earths
2011, 29, 1195−1197.
(22) Richardson, F. S. Selection Rules for Lanthanide Optical
Activity. Inorg. Chem. 1980, 19, 2806−2812.
(23) (a) Luck, R. L.; Maupin, C. L.; Parker, D.; Riehl, J. P.; Williams,
J. A. G. Circularly Polarized Luminescence and Structural Studies of a
Dysprosium(III) Complex with an Octadentate Macrocyclic Ligand
Bearing Benzylphosphinate Groups. Inorg. Chim. Acta 2001, 317,
331−337. (b) Petoud, S.; Muller, G.; Moore, E. G.; Xu, J.; Sokolnicki,
J.; Riehl, J. P.; Le, U. N.; Cohen, S. M.; Raymond, K. N. Brilliant Sm,
Eu, Tb, and Dy Chiral Lanthanide Complexes with Strong Circularly
Polarized Luminescence. J. Am. Chem. Soc. 2007, 129, 77−83.
(24) Dickins, R. S.; Howard, J. A. K.; Maupin, C. L.; Moloney, J. M.;
Parker, D.; Riehl, J. P.; Siligardi, G.; Williams, J. A. G. Synthesis,
Time-Resolved Luminescence, NMR Spectroscopy, Circular Dichro-
ism, and Circularly Polarized Luminescence Studies of Enantiopure
Macrocyclic Lanthanide Tetraamide Complexes. Chem. - Eur. J. 1999,
5, 1095−1105.
(25) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A.
K.; Puschmann, H. OLEX2: AComplete Structure Solution, Refine-
ment and Analysis Program. J. Appl. Crystallogr. 2009, 42, 339−341.
(26) Sheldrick, G. A Short History of SHELX. Acta Crystallogr., Sect.
A: Found. Crystallogr. 2008, 64, 112−122.
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