Solid-Solid Phase Transitions in [ trans-Pt(PMe3)2(C=CC6H4R)2]-Containing Materials (R = O(CH2)nH; N = 6, 9, 12, and 15)

Article abstract of DOI:10.1021/acs.organomet.8b00304

The title complexes were prepared in Hagihara conditions and were investigated by single crystal X-ray crystallography (n = 6, [Pt]C₆; n = 12, [Pt]C₁₂), X-ray powder diffraction (powder XRD), differential scanning calorimetry (DSC),

Full text of DOI:10.1021/acs.organomet.8b00304

Article
Cite This: Organometallics XXXX, XXX, XXX−XXX
Solid−Solid Phase Transitions in [trans-
Pt(PMe ) (CCC H R) ]‑Containing Materials (R = O(CH ) H; n = 6, 9,
3
2
6 4
2
2 n
12, and 15)
Gabriel Marineau Plante, Daniel Fortin, Armand Soldera,* and Pierre D. Harvey*
Departement de Chimie, Universite de Sherbrooke, Sherbrooke, Quebec J1N 2X8, Canada
́ ́
*
S Supporting Information
ABSTRACT: The title complexes were prepared in Hagihara conditions
and were investigated by single crystal X-ray crystallography (n = 6, [Pt]C6;
n = 12, [Pt]C ), X-ray powder diffraction (powder XRD), differential
1
2
scanning calorimetry (DSC), thermal gravimetric analysis (TGA, [Pt]C ),
12
and steady-state and time-resolved solid state UV−vis and emission
spectroscopy at 298 and 77 K. [Pt]C complex exhibits no phase change
6
with the temperature. Concurrently, [Pt]C (n = 9) and [Pt]C complexes
9
12
exhibit an irreversible Tendo values of 104 and 119 °C, respectively,
associated with a thermal annealing. Finally, [Pt]C15 (n = 15) complex
exhibit a reversible thermal processes with a large hysteresis (Tendo = 126 °C,
Texo = 140 °C) followed by a glass transition (Tendo = 146 °C, Texo = 69 °C)
as depicted by DSC. These phase changes are accompanied by a decrease in
triplet excited state lifetimes upon cycling the sample temperature over and
under the transition temperatures. These various thermal processes induce a
significant decrease in emission lifetimes, strongly suggesting the presence of a reorganization of the complexes in the solid state
favoring more chain-chromophore contacts, thus promoting nonradiative “knocking” processes.
INTRODUCTION
Chart 1. Structures of Complexes (n = 6, 9, 12, and 15)
■
The trans-bis(ethynylbenzene)bis(trialkylphosphine)platinum-
II) species ([Pt]; alkyl = Me, Et, Bu) are chromophores
exhibiting nonlinear optic properties and photonic devices
(
1
2
3
such as light-emitting diodes and solar cells have also been
reported. Concurrently in the field of metallo-mesogens, Pt(II)4
complexes exhibiting liquid crystal properties are numerous,
and can be divided into three distinct categories; ortho-
latter measurements allowed for monitoring of the change in
Pt···Pt separations and the relative density of the materials
exceeding and returning to the transition temperature. The
possible presence of Pt···Pt interactions may generate new
5
6
7,8
metalated, diimines, and [Pt]. In the last category of
metallo-mesogens, only one report indicated the presence of
luminescence. Indeed, Cooper et al. prepared two emissive
complexes with P(n-C H ) (instead of PMe ) and R = H and
1,3
excited states of the [dσ*pσ]* type when the Pt···Pt
separation is short enough (typically below the sum of the
8
17 3
3
10
van der Waals radii). These emissive states generally exhibit
CCC H (referring to the title complex [trans-Pt-
6
5
red-shifted and unstructured emission bands.
(
PMe ) (CCC H R) ]) as viscous liquids at 298 K but
3
2
6
4
2
9
could transform into a glass phase upon cooling. Taking into
account the rich photophysical properties of the [Pt] species
and the paucity of metalogen properties, it became appropriate
to further explore this category of materials. The obvious
structural modification is anchoring of long carbon chains on
the ethynylbenzene groups. We now report the preparation
and characterization of four luminescent X−[Pt]−X complexes
where X = O(CH ) H (n = 6 ([Pt]C ), 9 ([Pt]C ), 12
RESULTS AND DISCUSSION
Synthesis and X-ray Structures. The complexes were
■
synthesized according to well-established procedures under
11
Hagihara conditions (Scheme 1; see Scheme S1 for the
chemical intermediates). The trans-geometry was confirmed
1
31
195
12
from the J( P− Pt) coupling constants (Experimental
Section), and the X-ray structures for [Pt]C and [Pt]C
6
12
2
n
6
9
(
Figures 1 and 2; see crystallographic data in Table S1). The
(
[Pt]C ), and 15 ([Pt]C ); Chart 1), but no glass transition
12 15
1
31
H and P NMR, and IR spectra and mass spectrograms of the
nor the presence of liquid crystals were observed. However,
Pt]C , [Pt]C , and [Pt]C complexes exhibit irreversible
complexes and intermediates are placed in Figures S1−S36.
[
9
12
15
solid−solid phase transitions above room temperature, which
are accompanied by changes in X-ray powder diffraction
patterns and photophysical properties. Concurrently, these
Received: May 10, 2018
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00304
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. Synthesis Route for [Pt]C , [Pt]C , [Pt]C , and [Pt]C (n = 6, 9, 12, and 15)
6
9
12
15
Table 1. Interplanar C H ···C H Distances (d), ∠C−CC,
6
4
6
4
and θ angles for trans-Pt(PMe ) (CCC H R)
3
2
6
4
2
d (Å) ∠C−CC (deg) θ (deg)
R
temp.
0.5
0.3
0.2
0.4
0.3
0.9
0.5
177.0
179.3
177.9
177.8
178.7
176.1
175.3
7.9
28.5
26.9
28.4
29.0
30.2
33.7
O(CH ) H
172 K
173 K
173 K
296 K
296 K
2
6
O(CH ) H (mol. 1)
2
12
O(CH ) H (mol. 2)
2
12
O(CH ) H (mol. 1)
2
12
O(CH ) H (mol. 2)
2
12
1
3
SCH3
CH3
173 K
120 K
1
4
quasi-planar complex but differs significantly from other related
13,14
complexes reported in this work and from the literature
Table 1). This comparison has a direct consequence on the
resulting photophysical properties (described below) as
(
Figure 1. Top: crystal packing of [Pt]C at 172 K. Bottom: space
6
filling model of two neighboring [Pt]C complexes in the crystal.
6
demonstrated in a recent detailed study on related [Pt]
15
complexes. Indeed, the resulting emission lifetimes for this
type of complex is found to be a function of its structural
parameters and its environment. The n-(CH ) H chains adopt
2
6
‑
‑‑
the classic zigzag geometry and the HC C−O−CH skeleton
2
sits on the same plane. The angle formed by the n-(CH ) H
2
6
chains and C H CC−Pt−CCC H axis is ∼128°, and the
6
4
6
4
three fragments together form a Z-shaped molecule in the
crystal. An examination of the crystal packing indicates the
presence of close PMe ···PMe contacts (Figure 1). The
3
3
adopted Z-shape of [Pt]C complex and the presence of
6
obvious PMe ···PMe contacts promote tight interlocking
3
3
interactions preventing any easy sliding of the molecules upon
heating (see the thermal behavior below). Moreover, this steric
situation may also speculatively correlate with the lower
dihedral angle θ.
Figure 2. Top: crystal packing of [Pt]C12 at 296 K. Bottom: space-
filling model of two neighboring [Pt]C12 complexes in the crystal.
Note the presence of static disorders of the last three carbons of the
C -chains in the bottom complex.
Complex [Pt]C12 exhibits two crystallographically inde-
pendent molecules per unit cell. The crystal packing also differs
from that of [Pt]C by the obvious (CH ) H chain···chain
6
2 12
12
contacts (Figure 2, top). Some static disorders are also
depicted for the last three carbon atoms of the (CH ) H
2
12
The X-ray powder diffraction patterns present well-defined
chains for one of the two molecules, hence illustrating some
chain mobility. The dihedral angle, θ, and ∠CC−C angles
are in the vicinity of ∼28 ± 1° and ∼178 ± 1°, respectively,
and are both temperature-independent between 173 and 296 K
(Table 1). These X-ray structural parameters (i.e., θ and ∠C
C−C angles) compare well with those reported for other
related trans-Pt(PMe ) (CCC H R) complexes where R =
diffraction peaks in all cases indicating the presence of a
crystalline phase (Figures S37 and 38). The crystal structures
for [Pt]C and [Pt]C (Figures 1 and 2) differ in the packing
6
12
of the long alkyl chains. In the former crystal, one centro-
symmetric independent molecule per unit cell is identified
Table S1; relevant structural parameters are placed in Table 1.
(
3
2
6
4
2
1
3,14
An exhaustive comparison of all [Pt]-complexes from the
literature are also placed in Figure S39 and Table S2.
The dihedral angle made by the C H groups and the central
alkyl chain (Table 1).
The interplanar C H ···C H
6 4 6 4
distance, d, increases slightly by ∼0.1 Å going from 173 to
296 K witnessing a slight thermally induced distortion. These
distortions stem from the C H ···PMe contacts (Figure 2,
6
4
square planar PtP C unit, θ, is 7.9° and the ∠CC−C bond
2
4
6
4
3
angle is 177.0°, indicating that the complex is slightly distorted
bottom). Indeed, as the Pt−P bonds vibrate with higher
from an idealized geometry. The C H planes are parallel to
amplitude upon warming, the PMe collides with the
6
4
3
each other and the resulting interplanar C H ···C H distance,
neighboring C H aromatic, thus inducing a slight displace-
ment of the latter in the lattice. This structural trait is also
6
4
6
4
6
4
d, is 0.5 Å. Note that both parameters are identical for both
halves. These X-ray data suggest that [Pt]C is qualitatively a
apparent for [Pt]C (Figure 1, bottom), but the d value is
6
6
B
DOI: 10.1021/acs.organomet.8b00304
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
more pronounced (d ∼ 0.5 Å) than that of [Pt]C12 (0.2−0.3
Å) at the same temperature (172−173 K).
Thermogravimetric Analysis. The TGA trace was
examined for [Pt]C12 under an argon atmosphere (Figure
S40). The first weight loss associated with a decomposition of
the complex occurs near 200 °C. The weight loss continues
until the next pseudo plateau at ∼300 °C corresponding to a
loss of ∼14%, which can be attributed to the loss of one PMe
3
ligand (theory = 12%). This is convenient since any
decomposition of the samples upon thermal treatment can
readily be detected by 31P NMR. Upon further heating,
another weight loss (of ∼38%) occurs and a plateau at 600 °C
is depicted corresponding to the two (CH ) H chains (theory
2
12
=
37%). Because the PMe ligand is common to all four
3
complexes, the decomposition temperature is assumed to be
about the same (i.e., ∼ 200 °C). In light of the thermal
decomposition evidenced in the DSC traces, X-ray powder
diffraction, and photophysical measurements, the complexes
were never exposed to temperatures exceeding 150 °C (except
Figure 4. Comparison of the powder XRD patterns for [Pt]C and
9
[Pt]C12 at below and above the irreversible solid−solid phase change.
For [Pt]C , the 2θ peak is the 001 plane.
for one case, [Pt]C , 175 °C). The structural integrity of the
9
9
31
compounds was demonstrated by measuring the P NMR
spectra of the complexes in solution before and after the
thermal treatment in the solid state. These spectra are placed
in Figures S14, S15, S17−S20, S22, and S23.
from crystalline phases. Interestingly for [Pt]C , the diffraction
9
peak at 2θ = 4.28° (interplanar distance, d = 20.63 Å) at 25 °C
shifts to 4.14° (d = 21.33 Å) at 120 °C, consistent with a lattice
expansion with the temperature.
Differential Scanning Calorimetry and Powder X-ray
Diffraction. The DSC traces of [Pt]C exhibit no phase
6
The monotonic evolution of 2θ (5.80 → 5.51 → 5.36°; 100
plane) and d (15.23 → 16.00 → 16.47 Å) with the temperature
(−100 (temperature at which the structure was determined)
change between 22 and 150 °C. Thus, this material can then
serve as a comparison. Concurrently, [Pt]C and [Pt]C
9
12
exhibit irreversible thermal processes in the 100−120 °C
range (Figure 3). Conversely, [Pt]C15 shows two reversible
→
20 → 120 °C) for [Pt]C , a compound where no phase
6
change was observed, is very similar. However, for [Pt]C , the
9
peak at 2θ = 4.14° (d = 21.33 Å) becomes very small and is
replaced by a much stronger peak at 2θ = 4.94° corresponding
to d = 17.87 Å. In a similar manner, 2θ (3.82 → 3.74 → 3.66°
(
weak shoulder)) and d (23.11 → 23.61 → 24.12 Å; 001
plane) exhibit the expected behavior associated with a thermal
expansion for [Pt]C12 (T = 25 (one temperature at which the
structure was determined), 120, and 130 °C, respectively). At
the phase transition, a strong new scattering appears at 4.04°
(
(
d = 21.85 Å). This decrease in interplanar distance of 3.46
from 21.33 to 17.87 Å) for [Pt]C and 2.27 Å (from 24.12 to
9
2
1.85 Å) for [Pt]C12 for their irreversible endothermic process
is also consistent with an annealing behavior leading to the
formation of a polymorph. The fact that the strongest
scattering of the low-temperature phase is still observed in
the high temperature phase may be indicative of a slow kinetic
conversion. In these cases, this situation provided information
on the change in interplanar distances for these two
compounds.
Figure 3. DSC traces of [Pt]C , [Pt]C , [Pt]C , and [Pt]C , in the
6
9
12
15
Moreover, upon increasing the temperature, the DSC trace
for [Pt]C exhibits two endothermic processes at 126 and 146
2
0−150 °C range. Scan rate = 10 °C/min. The values in parentheses
15
are the area under the peaks.
°
C, appearing as a sharp and a broad peak, respectively, during
the first scan. On the return scan, a sharp exothermic peak is
recorded at 141 °C, and upon the second cycle another broad
one at 69 °C appears. The cycling permits observation of a
shift of the first endothermic signal from 126 to 123 °C,
whereas the second one remained at 146 °C. Multiple
subsequent cyclings do not induce any major progression of
the overall shape of the DSC traces and the peak positions (see
Supporting Information). The powder XRD patterns were
measured before and after these phase transformation (Figure
5).
thermal processes in the 50−150 °C range (Figure 3). None of
these phase changes are due to a melting process, as evidenced
by the powder XRD patterns, which indicate the presence of
crystalline phases below and above the transition temperatures
(
Figure 4). [Pt]C and [Pt]C exhibit irreversible endother-
9 12
mic processes at 104 and 119 °C, respectively, similar to an
annealing process where as for the second scan and the
subsequent scans, no thermal behavior is depicted (endo or
exo).
The powder XRD patterns for [Pt]C and [Pt]C12 below
The patterns at 40, 100, and 135 °C exhibits well-resolved
scattering peaks indicating the presence of crystalline phases.
9
and above this transition indicate a phase change going to and
C
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Organometallics
Article
Figure 6. Left: comparison of the powder XRD patterns of [Pt]C15 at
2
1
5 °C before and after (2θ = 3.36°, d = 26.27 Å) keeping the solid at
20 °C for 2 h. Right: comparison of the powder XRD pattern of
[
Pt]C12 at 25 °C after keeping the solid at 120 °C for 2 h with that of
[
Pt]C15 at 25 °C before thermal annealing. Note that the [Pt]C15
sample exhibits a different pattern from that shown in Figure 5
stressing the presence of multiple phases after synthesis (and quick
precipitation) but is reminiscent of the one recorded at 100 °C at the
early stage of the thermal annealing of this sample.
Figure 5. Comparison of the powder XRD patterns for [Pt]C15 at
selected temperatures between the phase change temperatures.
phosphorescence. If the phosphorescence is present, then τ <
P
1
μs (i.e., within the pulse width of the flash lamp). The
However, at 155 °C, a large hollow under the sharp signals
appears and indicates the presence of an amorphous phase.
These measurements allow for an interpretation of the thermal
behaviors. The sharp signals with a small hysteresis at T = 123
fluorescence turns out to be either absent or too weak to be
investigated in the solid state (i.e., at 298 and 77 K) and in
2MeTHF solution at 77 K, so only the phosphorescence is
studied. During the course of this investigation, the intensity of
the excitation light was varied (using neutral density filters),
and the observed emission intensity was linear with that of the
excitation. In parallel, the emission lifetimes and their relative
contributions (described below) remained constant. These
tests indicate that under the irradiation conditions used no
triplet−triplet annihilation nor photoinduced decomposition
takes place. Interestingly, these emissions exhibit multiple
(
endo) and 140 °C (exo) is a first-order solid−solid phase
transition between two ordered lattices. The broad signal at
46 °C is an order−disorder phase change with a
recrystallization at 69 °C (exo). At 40 °C, two scatterings at
θ = 3.28 and 3.70° are evident (d = 26.91 and 23.86 Å,
respectively), but the former becomes dominant at 100 °C (2θ
3.30° and 3.68°; d = 26.75 and 23.99 Å), and unique at 135
C (2θ = 3.60°; d = 24.52 Å). At 155 °C, only the peak at
.50° (d = 25.22 Å) is observable. Conclusively, upon the
1
2
=
°
3
phosphorescence lifetimes, τ (Tables 2 and 3). The presence
of multiple components in the emission decays (i.e., mostly
two or three in these cases) is not unprecedented.
origins of these multiple emissive “species” have been
P
15,17
synthesis of [Pt]C15 (after purification by column chromatog-
raphy and solvent evaporation) two crystal lattices are
generated. However, upon thermal treatment, one of them
Various
17a
15,17c
suggested (i.e., O -quenching, two conformers)
but is
2
(
2θ = 3.70° at 40 °C) disappears, while the other one remains
often not discussed or assessed in detail.
with its characteristic thermal behavior (cycle 2 in Figure 3; see
Figure S41 for the subsequent cycles). The data before and
after thermal annealing of [Pt]C15 for 2 h are very different.
Interestingly, the patterns after thermal annealing exhibit some
striking similarities with those from before [Pt]C12 annealing
In a recent an detailed investigation on related complexes, it
was unambiguously demonstrated that these complexes give
rise to multiexponential decays in the solid state and in glassy
15
matices. The reason for this is that depending on the
structural distortion (i.e., different θ and ∠CC−C angles)
and the crystal sites (i.e., complexes located at the surfaces
versus inside the bulk or unit cells exhibiting two
crystallographycally independent molecules with their own θ
and ∠CC−C bond angles) specific emission lifetime are
prone to appear for each situation. Since the thermal treatment
induces changes in the lattice, then changes in θ and ∠CC−
C angles are expected, and consequently, changes in emission
lifetimes are also anticipated. In Table 2, several thermal cycles
(from 2 to 4) were performed, but for convenience, only the
last one is provided where there are no further changes.
In this work, it became apparent from Table 1 that the
dihedral angle made by the C H groups and the central square
(Figure 6). This comparison is suggestive of isostructurality
with the expected difference that the interplanar distances are
anticipated to be longer for [Pt]C .
15
Emission Spectra and Lifetime. trans-Pt(PR ) (C
3
2
CC H ) chromophore, [Pt], is well-known to be emissive
6
4 2
from its lowest-energy triplet state, which is best described as
mostly ππ* excited state, mixed with a metal-to-ligand charge
transfer contribution (see ref 15, its corresponding Supporting
Information, and the references therein). Typical emission
spectra of the complexes, here [Pt]C , under various
6
conditions are presented in Figure 7, whereas the spectra for
the other complexes are placed in Figures S42−S57. The
characteristic phosphorescence band of the trans-Pt-
6
4
planar PtP C unit, θ, can adopt various values from 7 to 33°,
2
4
16
(
PR ) (CCC H ) chromophore is readily observed in
and multiple crystalline and amorphous phases exist, so various
sites can induce such a behavior. Interestingly, a literature
survey on [trans-Pt(PR ) (CCC H X) ] (R = Me, Et, Bu; X
3
2
6
4 2
the 420−600 nm window in four experimental conditions.
At 298 K in 2MeTHF solution, only a weak fluorescence
3
2
6
4
2
band at ∼365 nm is observed with a fluorescence lifetime, τ ,
<
This fluorescence may also be accompanied by a very weak
= various groups) complexes and analogues indicates that θ
can also be highly variable (6° < θ < 89°; 37 entries, see the
Supporting Information for details). We also propose that the
F
90 ps (note that the fwhm of the nanoLED laser is ∼90 ps).
D
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Article
Figure 7. Absorption (black), emission (red), and excitation (blue) spectra of [Pt]C in the solid state or in 2MeTHF. The signals at ∼370 and
6
∼450 nm are fluorescence and phosphorescence, respectively.
Table 2. Emission Lifetimes at 298 K in the Solid State upon
Thermal Treatment
phosphorescence lifetimes decrease globally upon repeated
thermal treatments and may change the number of
components until they do not vary any more (Table 2, Figure
a
[Pt]C6
[Pt]C9
8
). Again, the decrease in τ values is entirely consistent with
P
%
χ2
τP (μs)
%
χ2
τP (μs)
an increase in nonradiative processes induced by the effect of
thermal annealing where the average distances between the
chromophores decrease (as concluded by the powder XRD
experiments). These thermal treatments are accompanied by
changes in the general shape of the emission spectra as well
(Figure 8). This significant change in the spectral fingerprint is
associated with a change in crystal site or the direct
environment of the chromophore upon thermal annealing.
1
7
2
.97
.25
.28
78.8
21.2
62.7
2.95
10.2
0.17
2.30
26.5
73.5
12.8
72.7
14.5
no tr.
1.173
no tr.
1.006
last tr.
0.998
last tr.
1.007
5
.53
37.3
6
.50
[Pt]C15
[Pt]C12
χ2
χ2
τP (μs)
.47
10.5
%
τP (μs)
%
Moreover, the variation of the τ values upon the thermal
e
1
26.6
10.8
62.6
21.0
17.6
5.7
1.79
7.43
34.8
2.28
23.6
17.8
58.5
62.7
treatment is by far the largest for [Pt]C , in comparison with
15
no tr.
1.028
no tr.
1.066
those for [Pt]C , [Pt]C , and [Pt]C and (Figure 8 and Table
6
9
12
3
4.2
2
). This feature suggests that the longest alkyl chains provide
0
2
8
.59
.33
.76
greater degrees of freedom for inducing both molecular
movements (i.e., better packing) and “knocking” processes.
Finally, the absence of Pt···Pt interactions (as obviously
observed in the X-ray structures) precluded the formation of
emissive [dσ*pσ]* excited states and the corresponding
red-shifted and unstructured emission bands. This contrasts
last tr.
1.026
last tr.
0.998
5.53
37.3
3
2.6
55.7
a
Tr = treatment. In 2MeTHF solution, τ (T ) < 1 μs and τ (S ) < 90
1,3
10
e
1
e
1
ps for all cases.
8
8
with the emission characteristics of the related d −d complex
Pt (dppm) (CCC H ) (dppm = bis(diphenylphosphino)-
resulting τP is site-dependent where θ varies with its
surroundings in the crystal lattices, as well as the nature of
the surroundings. Taking this literature into account and the
fact that upon thermal annealing the complex’s environment
changes, often leading to tighter packing, the closer proximity
of the trans-Pt(PR ) (CCC H ) chromophore with its
2
2
6
5 2
methane) where the two Pt(II) metals are held face-to-face by
18
the two bridging dppm ligands. In this work, no unstructured
emission was detected above 600 nm under any experimental
condition used.
3
2
6
4 2
CONCLUSION
neighbors promotes enhanced nonradiative deactivation of the
triplet excited states via collisions. Note again that the flash
lamp employed in this work (100 W lamp; fwhm ≈ 1.5 μs)
does not generate enough power to induce triplet−triplet
annihilation.
■
Prior to this work, only two other reports of phase changes
were known. These concern the push−pull organometallic
polymer ([trans-Pt(PEt ) (CCC H ) ](NC (OMe) 
3
2
6
4
2
6
4
N)) (where NC (OMe) N = quinone diimine; M =
n
6
4
n
Upon subjecting the samples (placed inside a melting point
tube) to a higher temperature, just above the first phase
transition for [Pt]C , and [Pt]C and at 120 °C for [Pt]C15
32400; M = 68400; polydispersity PD = 2.1; degree of
w
19
polymerization DP = 38) and the liquid complexes at room
9
temperature reported by Cooper et al., for which a glass
9
12
and [Pt]C (this sample does not exhibit any phase transition
transition was observed in both cases. To the best of our
6
between 20 °C and decomposition temperature), the
knowledge, this study reports the first solid−solid phase
E
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Article
a
Table 3. Emission Lifetimes at 77 K in the Solid State and 2MeTHF Glass
[
Pt]C6
[Pt]C9
τP (μs)
τP (μs)
%
χ2
%
χ2
2
4
1
6.0
1.8
.84
32.0
68.0
19.9
51.5
28.6
15.5
38.0
2.37
10.3
47.8
6.8
93.2
16.5
42.4
41.1
2
MeTHF 77 K
1.000
2MeTHF 77 K
powder 77 K
1.001
powder 77 K
7.57
9.5
1.010
1.020
1
[
Pt]C12
τP (μs)
.7
7.8
2
6
[Pt]C15
%
χ2
τP (μs)
%
χ2
6
3
11.1
88.9
2.6
14.2
37.9
2.16
8.58
6.5
4.2
6.5
93.5
1.5
2
MeTHF 77 K
1.066
2MeTHF 77 K
powder 77 K
1.004
.06
.94
1.9
4.6
72.8
21.2
powder 77 K
1.010
1.030
4
8
5
1.6
95.4
a
No thermal treatment was applied.
lifetimes and powder XRD scattering peaks upon thermal
treatments. Both led to the expected conclusion that the
closeness of the packing increases upon promoting more
efficient excited states deactivation through intermolecular
knockings.
EXPERIMENTAL SECTION
■
Materials. 4-Iodiophenol (Aldrich), 2-butanone (Anachemia),
K CO (Anachemia), tetrabutylammonium fluoride (TBAF; Aldrich),
2
3
MgSO4 (Fisher), THF (Fisher), DCM (Fisher), n-bromohexane
Aldrich), n-bromononane (Aldrich), n-bromododecane (Aldrich),
(
and n-bromopentadecane (Aldrich) were used as received. Diethyl-
amine (Aldrich) was degassed by reflux under argon atmosphere. Cis-
20
Pd(PPh ) Cl was prepared from PdCl and PPh in benzonitrile.
3
2
2
2
3
cis-Pt(PMe ) Cl was prepared from K PtCl , SEt , and PMe in
3
2
2
2
4
2
3
21
water. The description of the synthesis intermediates starting from
commercial compounds is placed in the Supporting Information.
These compounds are trivial and are obtained from standard
procedures. Only the last step is included in this section, along with
their characterization data.
Synthesis of [Pt]C , [Pt]C , [Pt]C , and [Pt]C . Under argon,
6
9
12
15
cis-Pt(PMe ) Cl (1 equiv), CuI (0.01 equiv), and the corresponding
3
2
2
[((4-(alkyloxy)phenyl)ethynyl)trimethylsilane] (2 equiv; see the
Supporting Information for their syntheses) were added to degassed
diethylamine (18 equiv). The mixture was stirred for 24 h at room
temperature. The solvent was removed under reduced pressure. The
resulting product was purified by column chromatography using
hexanes and progressively going to DCM to remove most of the
impurities. The product was removed from the column using hexanes
mixed with methanol.
1
[
Pt]C : Yield = 28%. H NMR (300 MHz, CD Cl ) δ 7.23 (d, J =
6
2
2
8
1
6
.7 Hz, 4H), 6.78 (d, J = 8.8 Hz, 4H), 3.95 (t, J = 6.6 Hz, 4H), 1.88−
.67 (m, 22H), 1.54−1.42 (m, 4H), 1.42−1.28 (m, 8H), 0.94 (t, J =
3
1
1
31
195
P− Pt
.9 Hz, 6H). P NMR (300 Hz; CD Cl ) δ −20.70 ( J
= 2308
2
2
−
1
Hz). IR (ν(CC)) 2107 cm . Elem. Anal. (theory): C, 54.46; H,
6
6
.99; O, 4.27; (found) C, 53.93; H, 6.91; O, 4.26. [Pt]C : Yield =
9
1
0%. H NMR (300 MHz, CD Cl ) δ 7.19 (d, J = 8.7 Hz, 4H), 6.74
2
2
(
1
d, J = 8.8 Hz, 4H), 3.91 (t, 4H), 1.86−1.64 (m, 22H), 1.44 (m, 5H),
Figure 8. Comparison of the emission decays of [Pt]C , [Pt]C ,
31
6
9
.29 (m, 19H), 0.89 (m, 6H). P NMR (300 Hz; CD Cl ) δ −20.70
2
2
[
Pt]C , and [Pt]C upon thermal treatments.
1
−1
12
15
31 195
P− Pt
(
(
J
= 2308 Hz). IR (ν(CC)) 2108 cm . Elem. Anal.
theory): C, 57.61; H, 7.74; O, 3.84; (found): C, 57.65; H, 7.68; O,
1
4
4
.05. [Pt]C : Yield = 45%. H NMR (300 MHz, CDCl ) δ 7.25 (s,
1
2
3
transition between two ordered phases for luminescent
H), 6.77 (d, J = 8.8 Hz, 4H), 3.93 (t, J = 6.6 Hz, 4H), 1.92−1.64 (m,
materials built upon the [trans-Pt(PR ) (CCC H ) ]
31
3
2
6
4
2
22H), 1.37 (d, J = 50.7 Hz, 36H), 0.90 (t, J = 6.7 Hz, 6H). P NMR
(
2111 cm . Elem. Anal. (theory): C, 60.18; H, 8.34; O, 3.49; (found):
C, 60.19; H, 8.34; O, 3.67. [Pt]C : Yield 69%. H NMR (300 MHz,
chromophore. This luminescence feature was used to obtain
information on the molecular behavior upon the thermal
annealing, as demonstrated by both variation of the emission
1
31
195
P− Pt
300 Hz; CDCl ) δ −20.60 ( J
= 2314 Hz). IR (ν(CC))
3
−
1
1
1
5
F
DOI: 10.1021/acs.organomet.8b00304
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
CDCl ) δ 7.25 (d, 4H), 6.77 (d, J = 8.8 Hz, 4H), 3.93 (t, J = 6.6 Hz,
3
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AUTHOR INFORMATION
Corresponding Authors
E-mail: Armand.Soldera@USherbrooke.ca.
E-mail: Pierre.Harvey@USherbrooke.ca.
■
*
*
ORCID
Daniel Fortin: 0000-0002-0223-6362
Armand Soldera: 0000-0001-5467-5714
Pierre D. Harvey: 0000-0002-6809-1629
modeling of push−pull diacetylide platinum complexes in TiO
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Notes
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The authors declare no competing financial interest.
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ACKNOWLEDGMENTS
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The NSERC, Natural Sciences and Engineering Research
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the Centre d’Etudes des Mater
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iaux Avances de l’Universite de
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