Chiral Amplification by Self-Assembly of Neutral Luminescent Platinum(II) Complexes

Article abstract of DOI:10.1002/chem.201605103

Two novel enantiomerically pure chiral ligands and the corresponding neutral Pt^II complexes have been synthetized and characterized. The self-assembly properties of the complexes have been investigated using different morphological and photophysical techniques. The two enantiomeric complexes, 4 a and 4 b, show high tendency to self-assemble into chiral supramolecular aggregates with right (P) and left-handed (M) helical configurations, respectively, as proven by SEM and absorption circular dichroism. The formation of such organized structures is driven by the formation of metallophilic and π–π interactions between spatially close Pt complexes with an enhancement of the chiro-optical properties in the solid state.

Full text of DOI:10.1002/chem.201605103

DOI: 10.1002/chem.201605103
Communication
&
Supramolecular Chemistry
Chiral Amplification by Self-Assembly of Neutral Luminescent
Platinum(II) Complexes
[
a]
Alessandro Aliprandi, Christelle M. Croisetu, Matteo Mauro, and Luisa De Cola*
eventually yield self-assembled structures with enhanced prop-
erties.
Abstract: Two novel enantiomerically pure chiral ligands
and the corresponding neutral Pt complexes have been
II
II
During the last decades, luminescent Pt complexes bearing
synthetized and characterized. The self-assembly proper-
ties of the complexes have been investigated using differ-
ent morphological and photophysical techniques. The two
enantiomeric complexes, 4a and 4b, show high tendency
to self-assemble into chiral supramolecular aggregates
with right (P) and left-handed (M) helical configurations,
respectively, as proven by SEM and absorption circular di-
chroism. The formation of such organized structures is
driven by the formation of metallophilic and p–p interac-
tions between spatially close Pt complexes with an en-
hancement of the chiro-optical properties in the solid
state.
large p-conjugated C- and N-based chelating ligands have
drawn a lot of attention due to their fascinating photophysical
[3]
and electrochemical properties. Some of these complexes
have been investigated for their high tendency towards stack-
ing through weak noncovalent metal–metal and/or p–p ligand
[
4]
II
interactions. It has been shown that luminescent Pt com-
plexes are capable to form supramolecular architectures as
[5]
[6]
[7]
liquid crystals, nanowires, and metallogelators with (elec-
[8]
[9]
tro)optical and sensing properties.
To date, some examples of platinum complexes showing
chiro-optical properties in solution have already been reported
[10]
using cyclometallated platinum(II) complexes, alkynylplatinu-
[
11]
[12]
m(II) bipyridyl complexes, and cycloplatinated helicenes.
[13a]
Our group has recently reported
on self-assembled long-
The synthesis of long-range-ordered chiral structures with sizes
spanning from the molecular level to nano- and microscale
and up to the macroscopic world are still a great challenge.
Indeed, chirality extended to tenth of units is synthetically not
easily accessible because the structures are too small to be
range-ordered fibers by using platinum complexes bearing
N^N^N azole-based ligands that showed linearly polarized
light emission with a very high photoluminescence quantum
yield (PLQY) of up to 75%. We have also shown that it is possi-
ble to follow complex self-assembly processes in real time by
taking advantage of different emission colors of the assem-
[
1]
made individually by top-down methods. Supramolecular
chemistry and self-assembly are powerful tools for the creation
of large architectures and they can be an alternative strategy
to overcome such a problem. Nature makes large use of non-
covalently bound systems possessing specific functions, and
DNA helices and a-helical proteins represent significant exam-
ples. Furthermore, the helical morphology of such biomole-
cules expresses the chiral information encoded in their chemi-
[13b]
blies.
Herein, we report the synthesis of two enantiomeric pure Pt
II
complexes containing an ancillary pyridine functionalized with
an asymmetric carbon atom to introduce chirality. The com-
plexes do not display any sizeable spectroscopic chiral feature
in solution, but upon self-assembly chiral fiber-type structures
are formed. The fibers have been characterized using different
spectroscopic techniques, such as electronic absorption,
steady-state and time-resolved luminescence, absorption circu-
lar dichroism (CD), and fluorescent microscopy. Additionally
the morphology of the assemblies was investigated by elec-
tron scanning microscopy (SEM).
[
2]
cal components. Currently, there is a growing interest to-
wards the preparation of synthetic chiral functional structures
for application in asymmetric catalysis, molecular recognition,
chiro-optical switches, optoelectronics, and sensing, amongst
all.
Several planar, aromatic systems undergo self-assembly
thanks to their favorable electronic and geometrical features.
The synthetic strategy employed for the preparation of two
chiral pyridine derivatives and their respective platinum com-
plexes is shown in Scheme 1.
II
Amongst them, Pt complexes are a special class of molecules
that can combine the physico–chemical properties of a heavy
metal center together with the square–planar geometry that
Mandelic acid has been selected to introduce a single asym-
metric carbon on the ancillary ligands, while the insertion of
moieties able to engage in hydrogen bonds (amide and hy-
droxyl groups) and p–p stacking (benzyl ring) promotes self-
assembly. We expect that the establishment of the weak inter-
actions provides a driving force to induce chiral supramolec-
ular self-assembly of the platinum complexes. Also, platinum
complexes bearing the chromophoric terdendate ligand, 2,6-
bis(3-(trifluoromethyl)-1H-1,2,4-triazol-5-yl)pyridine (pyC -CF -
[
a] Dr. A. Aliprandi, C. M. Croisetu, Dr. M. Mauro, Prof. Dr. L. D. Cola
Laboratoire de Chimie et des Biomatꢀriaux Supramolꢀculaires
Institut de Science et d’Ingꢀnierie Supramoleculaire (I.S.I.S.)
Universitꢀ de Strasbourg & CNRS UMR 7006
8
alleꢀ Gaspard Monge, 67083 Strasbourg (France)
Fax: (+33)3-68-85-52-42
E-mail: decola@unistra.fr
5
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Communication
Figure 1. Absorption and emission spectra (lexc =300 nm) of 4a (black line)
and 4b (red line) in THF at a concentration of 5.1ꢁ10 m.
Scheme 1. Synthesis of the chiral pyridine derivatives. a) NHS, DCC, 1,4-diox-
ane, room temperature, N , overnight. b) 4-Picolylamine, 1,4-dioxane, 508C,
, overnight. c) PtCl DMSO , TEA, MeOH, N2, 8 hours, reflux.
ꢀ5
2
N
2
2
2
ꢀ
1
ꢀ1
(
e=3725m cm ), attributed to singlet-manifold intraligand
1
tzH ) have been already proven to possess a high tendency to
( IL) p!p* transitions of the tridentate ligand and metal-per-
2
[
13]
form highly emissive assemblies,
and the occurrence of
turbed charge transfer transitions. A broad, featureless and
ꢀ
1
ꢀ1
Pt···Pt and p–p interactions can be assessed using emission
spectroscopy.
weaker band (e=784m cm ) is observed in the region be-
tween 340–440 nm that can be attributed to the HOMO!
LUMO transitions described as the admixture of spin-allowed
The synthetic procedure starts form the selective activation
of the carboxylic group of commercially available 1a,b by
using N-hydroxysuccinimide (NHS) and N,N’-dicyclohexylcarbo-
diimide (DCC) as the coupling agent in 1,4-dioxane under mild
conditions. Subsequently, the amide coupling is carried out by
adding 4-picolylamine to the activated NHS ester, yielding the
pure enantiomer of the ancillary ligand 3a,b as a white
powder upon filtration and washing. Finally, the target Pt com-
plexes 4a,b have been obtained as enantiomerically pure de-
rivatives in fairly good yields (60–77%) following the complex-
1
1
metal-to-ligand charge transfer ( MLCT) and intraligand ( IL)
transitions. Such attributions have been made on the basis of
[
13–14]
closely-related achiral complexes previously reported.
Pho-
toexcitation in any of the absorption band of samples of 4a,b
in THF at room temperature gave a structured blue emission
with maxima at 462, 490, and 527 nm that display a low inten-
sity with a PLQY of only 0.2%. The low emission intensities
were also accompanied by very short excited state lifetimes
(t=2.8 ns) for both complexes.
[
13]
ation procedure reported elsewhere.
The absorption spectra of both complexes 4a and 4b in
Information about the chirality of the investigated systems
was gathered by recording circular dichroic (CD) absorption
spectra. As expected, samples of the chiral ligands 3a,b in
ꢀ5
THF at 5.1ꢁ10 m are displayed in Figure 1.
ꢀ
3
As expected, upon irradiation with unpolarized light, sam-
ples of the two enantiomers show identical spectroscopic
properties due to the fact that their different chirality has no
effect on the absorption and the emission spectra.
MeOH at 1.03ꢁ10 m gave a clear signal with a small either
negative or positive Cotton effect at l=235 nm, with resulting
spectra that are mirror images of each other (Figure 2a).
These findings demonstrate that the two ligands are pre-
pared as enantiomeric derivatives, confirming that the chirality
that was present in the starting compound mandelic acid has
been preserved during the synthetic pathway to obtain the
pyridine derivative. We can thus expect that the chirality is
The two complexes 4a,b in THF at low concentration and
room temperature display intense bands in the UV region
of the absorption spectrum with lmax,abs =254 nm (e=
ꢀ
1
ꢀ1
ꢀ1
ꢀ1
2
8451m cm ), 300 nm (e=18706m cm ), and 332 nm
Figure 2. Ellipticity spectra recorded for the investigated ligands and complexes in solution. a) CD spectra obtained for the ligands 3a (black trace) and 3b
ꢀ
3
ꢀ6ꢀ
(
4
red trace) in MeOH at a concentration of 1.03ꢁ10 m at room temperature. b) CD spectra for the complex 4a in THF (concentration range: 2.78ꢁ10
–
ꢀ
4
.00ꢁ10 m) showing absence of differential absorption between left and right circularly polarized light.
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also preserved during the formation of complex 4a,b. The CD
spectra of 4a and 4b have been recorded in THF and no sizea-
ble CD signal was detected at any concentration in the range
of the noninteracting complexes (Figure 1), suggesting that
the formation of the assemblies is not quantitative. The batho-
chromic shift in the emission profile and the higher emission
quantum yields are strong indications that the nature of the
emitting excited state of the assemblies is different from the
luminescent excited state of the complexes in solution. The
square planar geometry leads, indeed, to the formation of
ꢀ
6
ꢀ4
2.78ꢁ10 –4.00ꢁ10 m (Figure 2b). The absence of a CD
signal in solution can be explained if one takes into account
the origin of the transitions observed in the unpolarized ab-
sorption spectra of the two enantiomeric complexes (Figure 1).
In the same spectral region of the recorded CD spectra, the
2
Pt···Pt interactions through the dz orbitals of the metals that
1
UV/Vis transitions are mainly due to the LC bands of the tri-
raise the energy of the HOMO orbitals. Upon assembly, the
nature of the lowest electronic transitions is changed to a trip-
1
1
dentate ligand, as well as the MLCT and ILCT bands involving
both tridentate ligands and also the heavy metal center. On
such moieties chiral information is indeed not present, while
only little contribution of the ancillary ligand to the absorption
spectra can be expected in the spectral region. As a result, the
intensity of the CD signal, which can be only caused by the
single asymmetric carbon of the mandelic acid moiety, is too
weak if compared to the overall light absorption of the com-
plex. The increase of the concentration is expected to increase
the CD signal, however the saturation of the detector occurs
before detecting any CD signal.
3
let metal–metal-to-ligand charge transfer ( MMLCT). The forma-
tion of the new excited state is also clearly evident in the exci-
tation spectra recorded at lem =560 nm, which shows a strong
bathochromic shift with respect to the absorption spectra in
solution. This shift is due to the formation of a new band with
1
a MMLCT character upon establishment of Pt···Pt interactions.
Noteworthy, when the absorption CD spectra were recorded
on samples of the self-assembled fibers made by either 4a or
4b, a strong signal was detected as shown in Figure 3c. For
the two enantiomers, the signals appear to be mirror images
of each other, even though the intensity was not the same
due to the fact that the amount of deposited fibers might be
different. Hence, unlike the THF solutions of 4a and 4b, in the
aggregates, CD signals can be clearly observed with a mirror
effect between the two enantiomer spectra and maxima at
260, 290, 322, 337, 370, and 472 nm. While the CD signal of
the ancillary chiral ligands (Figure 2a) display a single peak
and an onset at around 270 nm, the CD signal of the assem-
bled fibers possess several bands with an onset at 580 nm cor-
ꢀ
1
Upon drop-casting of a 1 mgmL THF solution of either 4a
or 4b onto a quartz substrate, the compounds tend to self-ag-
gregate into highly luminescent fibers by a solvent-assisted
self-assembly processes (Figure 3a).
Photoexcitation of such fibers yields an intense broad fea-
tureless emission that is strongly bathochromically shifted
when compared with the complex in solution (THF). For both
complexes and as shown in Figure 3b, the luminescence spec-
tra display a maximum centered at 560 nm with a PLQY as
high as 57% and 37% for 4a and 4b, respectively. Also, differ-
ent from the THF solution, samples of the self-organized fibers
showed much longer excited-state lifetime with multi-expo-
nential decays, in which the longest components are 582 and
3
responding to the MMLCT band. Such findings suggest that
the asymmetric carbon located on the ancillary pyridine indu-
ces the formation of a long-range-ordered chiral supramolec-
ular architecture supported by the establishment of Pt···Pt and
p–p interactions.
631 ns for 4a and 4b, respectively. The multi-exponential
decay can be attributed to the different environment experi-
enced by the emitting complexes in the aggregated samples.
Such a finding is typically observed for solid-state samples. We
attribute the different PLQY to the absence of morphological
homogeneity of the drop-casted samples. Indeed, a small peak
at 462 nm can be observed in both the emission spectra of the
complexes 4a and 4b, which is characteristic of the emission
Unfortunately, we were not able to obtain single crystals of
the assemblies to have a full structural characterization. To ex-
plore the morphological features of these fibers, SEM analysis
was performed on the self-assembled structures and the
images are depicted in Figure 4.
The SEM analyses were recorded on samples prepared from
the same solution used for the photophysical characterizations,
Figure 3. a) Fluorescence microscopy images of the fibers obtained from 4b upon irradiation at the excitation band of 400–440 nm and imaged with a long-
pass emission filter (filter onset 455 nm). Scale bar=20 mm. b) Emission and excitation spectra obtained for the self-organized fibers of 4a (black trace) and
ꢀ
1
4
b (red trace) prepared by drop-casting onto a quartz substrate using a 1 mgmL THF solution; lexc and lem were 560 and 400 nm for emission and excita-
tion spectra, respectively. c) CD spectra obtained for samples of fibers prepared by using complex 4a (black trace) and 4b (red trace).
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Figure 4. a,b) SEM images of fibers prepared using complex 4a showing P configuration. Scale bar is 4 and 1 mm for (a) and (b), respectively. c,d) SEM images
of fibers prepared using complex 4b showing M configuration. Scale bar is 4 mm and 500 nm for (c) and (d), respectively. All samples were prepared by drop-
ꢀ
1
casting of a THF solution at 1 mgmL onto a glass slide that was subsequently sputtered with Au/Ag.
ꢀ
1
that is a 1 mgmL solution in THF (using a glass substrate). As
show on the images of the fibers for both complexes 4a (Fig-
ure 4a,b) and 4b (Figure 4c,d), the samples gave intercon-
nected fibers with a well-defined helicity as consequence of
the supramolecular chiral organization of the complexes in the
assemblies.
an Olympus BX51 microscope using a 20x objective and an Olym-
pus U-MWBV BP 400–440 nm with dichroic 455 nm and LP 475 nm
as excitation and emission filter cubes, respectively; images were
recorded with a Olympus XC-10 color camera. SEM characterization
was performed employing a FEI scanning electron microscope
Quanta FEG 250 at an acceleration voltage of 10 kV. Samples were
prepared by drop-casting of a THF solution onto a glass slide, and
subsequent plasma-induced deposition of a 5 nm thick layer of
Au/Ag.
In particular, complexes 4a and 4b seems to aggregate in
a clockwise and counterclockwise arrangement, respectively,
yielding self-assembled aggregates with right-handed (P) and
left-handed (M) helical configurations, respectively. Further-
more, in both cases, the fibrous nanostructures seem to be the
results of a self-assembly of thinner nanostructures such as
nanofibrils. This observation supports the formation of chiral
supramolecular self-assembled structures onto a substrate
based on the enantiomerically pure complexes prepared.
In conclusion, the synthesis and the characterizations of two
S-hydroxy-N-(4-pyridinylmethyl)-benzeneacetamide (3a): S(+)-
mandelic acid (1 equiv, 1.011 g, 6.64 mmol) and NHS (1 equiv.,
7
57 mg, 6.58 mmol) were dissolved in 1,4-dioxane (20 mL) under
nitrogen. DCC (1.358 g, 6.58 mmol) was added to the mixture at
room temperature and the mixture was stirred for 22 hours and
then filtered. The filtrate was added to a two-neck round-bottom
flask, then 4-(aminomethyl)-pyridine (1 equiv, 714 mg, 6.60 mmol)
was added and the solution was stirred for 1.5 hours under nitro-
gen at 508C. Afterwards, the solvent was evaporated and the
crude product was purified by column chromatography over silica
II
enantiomerically pure blue emitting Pt complexes, 4a and 4b,
has been presented. The compounds show a high tendency
towards self-assembly into chiral supramolecular aggregates
with right- (P) and left-handed (M) helical configurations, re-
spectively, as proven by SEM and CD. While both complexes
gel (SiO , ethyl acetate/methanol: 97/3 then 95/5) to give the S-hy-
2
droxy-N-(4-pyridinylmethyl)-benzeneacetamide as a white solid
1
(704 mg, 2.90 mmol) in 44% yield. H NMR (400 MHz, [D ]MeOD):
4
d=8.41 (d, J(H,H)=6.2 Hz, 2H), 7.50 (d, J(H,H)=6.8 Hz, 2H), 7.35
(m, 3H), 7.27 (d, J(H,H)=6.2 Hz, 2H), 5.11 (s, 1H), 4.47 ppm (s, 2H).
4
a and 4b did not show any detectable CD signals in solution
13
C NMR (100 MHz, [D ]MeOD) d=149.98, 129.42, 129.17, 127.63,
at any concentration investigated, a large enhancement of the
CD signal was observed upon formation of self-assembled
long-range-organized fibers in the solid state.
4
1
23.75, 75.59, 42.51 ppm. HRMS (ESI-TOF): m/z calcd: 243.1128
+
[M+H] ; found: 243.1121.
R-hydroxy-N-(4-pyridinylmethyl)-benzeneacetamide (3b): R(ꢀ)-
mandelic acid (1 equiv, 1.003 g, 6.59 mmol) and NHS (1 equiv,
7
57 mg, 6.58 mmol) were dissolved in 1,4-dioxane (50 mL) under
Experimental Section
nitrogen. DCC (1.359 g, 6.59 mmol) was added to the mixture at
room temperature. The mixture was stirred for overnight and then
filtered. The filtrate was added to a two-neck round-bottom flask,
then 4-(aminomethyl)-pyridine (1 equiv, 722 mg, 6.68 mmol) was
added and the solution was stirred overnight under nitrogen at
All chemicals were obtained from Sigma–Aldrich except for pyC5-
[13]
CF -tzH , which was synthesized as described previously. Electro-
3
2
spray ionization mass spectrometry (ESI-MS) was recorded on a Mi-
croTOF (Bruker) mass spectrometer equipped with an electrospray
source by the mass spectrometry service of the Institut de Chemie
at the University of Strasbourg. Elemental analyses were recorded
by the analytical service of physical measurements and optical
spectroscopy at the University of Strasbourg. Absorption spectra
5
08C. The solution was dried and the crude solid was recrystallized
from ethyl acetate to give R-hydroxy-N-(4-pyridinylmethyl)-benze-
neacetamide as a white solid (450 mg, 1.86 mmol) in 28% yield.
1
H NMR (400 MHz, [D ]MeOD) d=8.41 (d, J(H,H)=6.2 Hz, 2H), 7.50
4
(
4
d, J(H,H)=6.7 Hz, 2H), 7.35 (m, 3H), 7.27 (2H), 5.11 (s, 1H),
.47 ppm (s, 2H). HRMS (ESI-TOF): m/z calcd: 243.1128 [M+H] ;
were measured on
a Shimadzu UV-3600 spectrophotometer
+
double-beam UV-VIS-NIR spectrometer and baseline corrected.
Steady-state emission spectra were recorded on a Horiba Jobin–
Yvon IBH FL-322 Fluorolog 3 spectrometer. Time-resolved measure-
ments were performed on a PicoQuant FluoTime 300 (PicoQuant
GmbH, Germany). Circular dichroic experiments were performed
on Jasco J-810. Photoluminescence quantum yield measurements
found: 243.1105.
Preparation of platinum complex 4a: pyC -CF -tzH (205 mg,
5
3
2
587 mmol), PtCl (DMSO) (244 mg, 578 mmol), and 20 mL methanol
2
2
were added to a 50 mL two-neck round-bottom flask under nitro-
gen. Upon addition of 160 mL triethylamine with a syringe, the re-
sulting mixture became bright yellow. Then S-hydroxy-N-(4-pyridi-
nylmethyl)-benzeneacetamide 3a (141 mg, 582 mmol) was added
and the mixture was heated to 668C. All the products were solubi-
(
4
PLQY) were recorded at a fixed excitation wavelength (lexc
00 nm) using a Hamamatsu Photonics absolute PLQY measure-
ment Quantaurus. Fluorescence microscopy was performed with
=
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Communication
lized in methanol after which a yellow solid precipitated at the
bottom of the flask. The mixture was heated for 6 hours and the
reaction monitored by TLC (silica, ethyl acetate/cyclohexane: 3/1).
The mixture was filtrated at 08C, the light-yellow emissive solid
washed in boiling methanol, then again filtrated, and finally
19, 495–513; d) M. Cavallini, C. Albonetti, F. Biscarini, Adv. Mater. 2009,
2
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1, 1043–1053; e) Z. Luo, S. Zhang, Chem. Soc. Rev. 2012, 41, 4736–
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0, 483–492; j) M. Yang, N. A. Kotov, J. Mater. Chem. 2011, 21, 6775–
washed several times with methanol. The yellow solid complex
6792.
1
was synthetized with a yield of 60%. H NMR (400 MHz, [D ]THF)
8
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d=9.56 (br d, J(H,H)=6.7 Hz, 2H), 8.28 (m, 1H), 8.20 (t, J(H,H)=
8
3
4
.12 Hz, 1H), 7.89 (d, J(H,H)=7.9 Hz, 2H), 7.53 (m, 4H), 7.31 (m,
H), 5.53 (d, J(H,H)=3.9 Hz, 1H), 5.13 (d, J(H,H)=3.8 Hz, H),
1
9
[
.54 ppm (m, 2H). F NMR (376 MHz, [D ]THF) d=ꢀ67.00 ppm.
8
+
HRMS (ESI-TOF) m/z calcd: 785.110 [M+H] ; found: 785.113. Ele-
2
015, 44, 1152–1169.
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mental analysis calcd (%) for C H O N F Pt: C 38.27, H 2.18, N
25
17
2
9 6
[
1
6.07; found: C 38.17, H 2.18, N 15.84.
4
Preparation of platinum complex 4b: pyC -CF -tzH (201 mg,
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5
3
2
5
76 mmol), PtCl (DMSO) (246 mg, 583 mmol), and 20 mL methanol
2 2
were added to a 50 mL two-neck round-bottom flask under nitro-
gen. Upon addition of 160 mL triethylamine with a syringe, the re-
sulting mixture became bright yellow Then R-hydroxy-N-(4-pyridi-
nylmethyl)-benzeneacetamide 3b (142 mg, 586 mmol) was added
and the mixture heated to 668C for 6 hours. The mixture was fil-
trated and washed several times with methanol to give a yellow
[
8] a) C. A. Strassert, C. H. Chien, M. D. Galvez Lopez, D. Kourkoulos, D.
Hertel, K. Meerholz, L. De Cola, Angew. Chem. Int. Ed. 2011, 50, 946–
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[
solid (347 mg, 442 mmol, yield 77%). 1H NMR (400 MHz, [D ]THF)
8
d=9.58 (br d, J(H,H)=6.7 Hz, 2H), 8.23 (t, J(H,H)=8.12 Hz, 2H),
7
.93 (d, J(H,H)=7.9 Hz, 2H), 7.54 (t, J(H,H)=7.4 Hz, 4H), 7.34–7.24
[10] X.-P. Zhang, J.-F. Mei, J.-C. Lai, C.-H. Li, X.-Z. You, J. Mater. Chem. C 2015,
3, 2350–2357.
(
m, 3H), 5.51 (d, J(H,H)=3.9 Hz, 1H), 5.12 (d, J(H,H)=3.9 Hz, 1H),
19
[
11] a) Y. Mao, K. Liu, L. Meng, L. Chen, L. Chen, T. Yi, Soft matter 2014, 10,
7615–7622; b) S. Y.-L. Leung, W. H. Lam, V. W.-W. Yam, Proc. Natl. Acad.
Sci. USA 2013, 110, 7986–7991.
4
.62–4.47 ppm (m, 2H).
65.14 ppm. HRMS (ESI-TOF) m/z calcd: 807.0951 [M+Na] ;
found: 807.0855. Elemental analysis: calcd (%) for C H O N F Pt: C
F NMR (376 MHz, [D ]THF) d=
8
+
ꢀ
25
17
2
9 6
[
12] a) C. Shen, E. Anger, M. Srebro, N. Vanthuyne, K. K. Deol, T. D. Jefferson,
G. Muller, J. A. G. Williams, L. Toupet, C. Roussel, J. Autschbach, R. Reau,
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Chem. 2010, 122, 103–106.
3
8.27, H 2.18, N 16.07; found: C 38.20, H 2.29, N 16.10.
Acknowledgements
We wish to thank the University of Strasbourg and LDC thanks
AXA funding for financial support.
[13] a) M. Mauro, A. Aliprandi, C. Cebrian, D. Wang, C. Kubel, L. De Cola,
Chem. Commun. 2014, 50, 7269–7272; b) A. Aliprandi, M. Mauro, L.
De Cola, Nat. Chem. 2016, 8, 10–15.
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14] a) M. Mydlak, M. Mauro, F. Polo, M. Felicetti, J. Leonhardt, G. Diener, L.
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Keywords: chirality · luminescence · platinum · self-assembly ·
supramolecular chemistry
[
1] a) Y. Xia, G. M. Whitesides, Angew. Chem. Int. Ed. 1998, 37, 550–575;
Angew. Chem. 1998, 110, 568–594; b) S.-M. Yang, S. G. Jang, D.-G. Choi,
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Manuscript received: November 1, 2016
Final Article published: && &&, 0000
Chem. Eur. J. 2017, 23, 1 – 6
www.chemeurj.org
5
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Communication
COMMUNICATION
&
Supramolecular Chemistry
A. Aliprandi, C. M. Croisetu, M. Mauro,
L. D. Cola*
&& – &&
Chiral Amplification by Self-Assembly
of Neutral Luminescent Platinum(II)
Complexes
II
United luminescence! Neutral Pt com-
supramolecular fibers, thereby showing
an enhancement in luminescence and
chirality.
plexes with two novel enantiomerically
pure chiral ligands are presented. The
platinum complexes self-assemble into
&
&
Chem. Eur. J. 2017, 23, 1 – 6
www.chemeurj.org
6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!