Postfunctionalization of luminescent bipyridine PtII bisacetylides by click chemistry

Article abstract of DOI:10.1002/ejic.201200061

The synthesis of a family of differently substituted 5- and 4,4′-ethynyl-bpy Pt^II bisacetylide complexes (bpy = 2,2′-bipyridine) and their postfunctionalization using click chemistry is described. Cu^I-catalyzed azide-alkyne [3+2] cyc

Full text of DOI:10.1002/ejic.201200061

FULL PAPER
DOI: 10.1002/ejic.201200061
Postfunctionalization of Luminescent Bipyridine PtII Bisacetylides by Click
Chemistry
Ilona Stengel,[a,b] Cristian A. Strassert,[b,c] Edward A. Plummer,[b,c] Chen-Han Chien,[c]
Luisa De Cola,*[b,c] and Peter Bäuerle*[a,b]
Keywords: Platinum / Click chemistry / Luminescence
The synthesis of a family of differently substituted 5- and
4,4Ј-ethynyl-bpy PtII bisacetylide complexes (bpy = 2,2Ј-bi-
pyridine) and their postfunctionalization using click chemis-
try is described. CuI-catalyzed azide–alkyne [3+2] cycload-
dition was an efficient method to decorate the PtII complexes
with a manifold of moieties in high yields. The absorption
and emission properties and the electrochemical behaviour
of all of the complexes have been investigated. The studied
compounds emit at room temperature between 598 and
660 nm, reaching photoluminescence quantum yields of 0.33
in solution. The bright luminescent properties of the unsub-
stituted bpy PtII bisacetylide complex remained unaffected
upon click-functionalization as the resulting triazole substitu-
ent has no significant influence on the nonradiative decay
rate constant. This route opens new possibilities for to control
the bulk of the complexes, their solubility, and their further
extension or immobilization on macromolecules, polymers
and surfaces without affecting their intrinsic properties. Two
derivatives were selected as triplet emitter molecules in solu-
tion-processed polymer-based organic light-emitting de-
vices.
tions in these compounds can be used as a tool in supra-
molecular chemistry, self-assembled materials and vapolu-
minescent sensors.[4,5]
Introduction
Luminescent square-planar PtII complexes have attracted
great attention in different research fields over the past 10–
20 years. Different series of compounds with aromatic li-
gands have been synthesized and show strong emission
from intraligand (IL) or metal-to-ligand charge transfer
(MLCT) excited states, which makes them potential candi-
dates for electroluminescent devices.[1] Substitution of the
coordinated ligands with suitable donor or acceptor groups
allows the nature of the excited states to be tuned, thus,
enabling the synthesis of complexes with a pronounced
MLCT character, which can find application as materials
for sensors[2] or nonlinear optics.[3] In contrast to octa-
hedral IrIII complexes, which have been successfully applied
and commercialized as luminescent materials in organic
light-emitting diodes (OLEDs), square-planar PtII com-
plexes have not yet reached the required performance
mainly due to their tendency to aggregate and lower sta-
bility. On the other hand, Pt–Pt and π–π stacking interac-
Organometallic synthesis has provided a huge variety of
differently substituted PtII complexes, such as cyclometall-
ated compounds,[6] derivatives with chelating ligands such
as terpyridine,[7] bipyridine (bpy)[8,9] and their analogous N-
chelates.[10] The most brightly luminescent PtII complexes
are those with strong donor ligands on one side and aro-
matic π-accepting ligands on the other side. Strong donors
such as acetylides push the unoccupied dx2–y2 orbital up in
energy and inhibit the population of d–d excited states,
which would otherwise facilitate nonradiative decay.[11]
Aromatic ligands provide lowest unoccupied molecular or-
bitals (LUMOs) for low-energy emissive states, mostly of
ligand centred or MLCT nature. Furthermore, the planarity
of the complex is an important issue, as a higher rigidity
diminishes the tendency for nonradiative decay, thus, en-
hancing
the
photoluminescence
quantum
yield
(PLQY).[9c–9d,12]
Bpy PtII bisacetylides and their photophysical properties
have been previously investigated by several groups. The
first derivatives of this kind were 1,10-phenanthroline PtII
bis(phenylacetylide), synthesized and characterized in 1994
by Che and coworkers,[8f] followed by (4,4Ј-dimethyl-bpy)
PtII bis(phenylacetylide) in 1997.[8g] In general, the com-
plexes showed characteristic MLCT absorption and un-
structured emission bands in solution at room temperature,
which reached PLQYs of up to 0.75.[9d] Furthermore, the
emission colour is tunable over a wide range depending on
[a] Institute of Organic Chemistry II and Advanced Materials,
University of Ulm,
Albert-Einstein-Allee 11, 89081 Ulm, Germany
E-mail: peter.baeuerle@uni-ulm.de
[b] Dutch Polymer Institute (DPI),
P.O. Box 902, 5600 AX Eindhoven, The Netherlands
[c] Center for Nanotechnology, University of Münster,
Heisenbergstrasse 11, 48149 Münster, Germany
E-mail: decola@uni-muenster.de
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200061.
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FULL PAPER
the electron-donating or -withdrawing character of the sub- pyridine[16] and 4,4Ј-bis(trimethylsilylethynyl)-2,2Ј-bipyr-
stituents attached to the coordinated ligands. Two interest- idine,[17] were introduced in a ligand exchange reaction with
[18]
ing series of compounds have been synthesized by the cis-(DMSO)2PtIICl2
(DMSO = dimethyl sulfoxide) in
groups of Eisenberg,[8h] who varied the substituents at the acetonitrile at room temperature. The corresponding bpy
phenylacetylide, and Schanze,[8j] who introduced different PtII dichlorides 1[19] and 5 were obtained in high yield. The
functionalities at the bpy ligand in order to understand acetylide ligands were attached using a method initially de-
their effect on the photophysical properties. It was observed scribed by Sonogashira,[20] which has been previously ap-
that the absorption and the emission were redshifted as the plied for similar derivatives.[8g,8k–8l] During our synthetic
electron-donating character of the substituents at the phen- work, we noticed that the final click products showed lower
ylacetylide increased, but the effect is much more pro- solubility in organic solvents than their precursors. Hence,
nounced on the emission than on the absorption. Likewise, we introduced not only phenyl acetylides, but also 4-hex-
a redshift was observed if the electron-donating ability of ylphenyl acetylides with solubilizing alkyl chains. In this re-
the substituents at the bpy decreased. Significant work re- spect, trimethylsilyl (TMS)-protected compounds 2 and 6
garding the nature of the lowest energy excited state of these were obtained under mild reaction conditions in good
compounds has been carried out by Castellano and co- yields from 73–97% (Scheme 1). The corresponding depro-
workers.[9] By comparing phenyl-, tert-butyl- and trimethyl- tected ethynyl-functionalized complexes 3 and 7 were iso-
silylacetylide ligands and their influence on the photophys- lated by stirring 2 and 6 with potassium fluoride in dichlo-
ics of bpy PtII complexes, they systematically investigated romethane and methanol at room temperature for several
their molecular orbital landscape.[9a–9b] All of their observa- hours. The formation of bimetallic PtIICuI complexes was
tions are consistent with a metal- and partly acetylide-local- observed by mass spectrometry of the crude products and
ized highest occupied molecular orbital (HOMO), which in- has been described in the literature before.[21] The CuI cat-
creased in energy with increased electron density, and with ions are able to be coordinated by the two triple bonds in
a bpy-centred LUMO, which decreased in energy with de- the PtII bisacetylide complexes and can be removed by
creased electron density.
A disadvantage of the high rigidity of such compounds cies and by column chromatography.
aqueous workup with ammonia by oxidizing the CuI spe-
is their poor solubility in organic solvents. However, high
The click reaction with phenyl[22] or benzyl[23] azides was
solubilities are required for solution processing, e.g. inkjet either performed using the deprotected ethynyl complexes 3
printing or spin coating of phosphorescent materials. In this and 7, or directly after the in situ deprotection of TMS-
respect, PtII complexes have been covalently bound to solu- protected 2 and 6 with potassium fluoride. The more conve-
ble polymers, either in the backbone or as pendant nient in situ deprotection was therefore chosen as a stan-
groups.[13]
dard protocol, although both methods proceeded in high
In this work, we discuss click chemistry as a method to yields. Cu(CH3CN)4PF6 was used as the catalyst, and ele-
postfunctionalize PtII complexes, e.g. with solubilizing mental copper was added to reduce any oxidized CuII. The
groups. The term click chemistry was coined in 2001 by addition of ethyldiisopropylamine (DIPEA) as a base re-
Sharpless et al.,[14] and CuI-catalyzed azide–alkyne [3+2] cy- sulted in faster reactions because it supports the deproton-
cloaddition (CuAAC) has become a versatile method to ation of the CuI-complexed acetylene.[15c] The reaction pro-
link azides to ethynyl-substituted precursors since then.[15] gress was monitored by TLC. Typically, reaction times
We intended to find out if (a) the method is adaptable to ranged from 24 h to three days. The clicked PtII complexes
PtII coordination compounds, even in the presence of coor- 4 and 8 were obtained in 73–97% yield. Complex 8e, which
dinated acetylide units, and (b) how the resulting triazolyl bears n-hexyl chains at the phenyl triazole unit was synthe-
subsitutents influence the photophysical properties. There- sized by using 4-hexylphenyl azide[24] in the click reaction.
fore, we synthesized a series of different ethynyl- and triazo- It can be directly compared to 8d, which is an isomer that
lyl-substituted bpy PtII bisacetylides and investigated their bears the hexyl chains at the phenyl acetylide units, and to
absorption, emission and electrochemical properties. 8c, a closely related derivative without alkyl chains. In gene-
Furthermore, we successfully used two representative deriv- ral, the 5-substituted bpy compounds were slightly more
atives as dopants in solution-processed polymer-based soluble than their 4,4Ј-disubstituted analogues.
1
light-emitting devices (PLEDs). The performance of the
All complexes were fully characterized by H and, if the
simple devices, using polyvinylcarbzole (PVK) as a host ma- solubility was sufficient, 13C NMR spectroscopy as well as
trix and the PtII complexes as dopants, proved that the com- MALDI-TOF MS, FTIR spectroscopy and elemental
pounds are also suitable for electroluminescence.
analysis. The compounds do not show defined melting
points, but decomposed above 150 °C. Doublets at around
1
9.7 ppm (3J = 6 Hz) are characteristic H NMR signals for
6-H of the bpy ligand in 4,4Ј-substituted bpy PtII com-
plexes. For the 5-substituted derivatives, two doublets were
observed at around 9.6 (3J = 6 Hz) and 10.0 (4J = 2 Hz)
Results and Discussion
Synthesis
The complexes can be categorized into two series, ppm for the protons in the 6Ј- and 6-positions, respectively.
namely, 5-substituted and 4,4Ј-disubstituted bpy PtII bisace- Singlets were observed for the triazole protons at 7.9–
tylides. The bpy ligands, 5-(trimethylsilylethynyl)-2,2Ј-bi- 8.4 ppm for the 5-substituted derivatives in CD2Cl2 at
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Postfunctionalization of Pt Complexes by Click Chemistry
Scheme 1. Synthesis of (a) 2 and 6: CuI, iPr2NH, CH2Cl2, phenylacetylide/4-hexylphenylacetylide, room temp., 12 h, (b) 3 and 7: KF,
MeOH, DCM, room temp., 12 h, (c) 4 and 8: KF, phenyl-/benzyl-/4-hexylphenyl azide, Cu(CH3CN)4PF6, Cu0, DIPEA, CH2Cl2/methanol
(4:1), room temp., 3 d.
25 °C, which shifted to 8.7–9.2 ppm in [D6]DMSO at The absorption bands of the complexes appear redshifted
100 °C. For the 4,4Ј-substituted derivatives, the singlets due and broadened in both the IL and MLCT regions com-
to the triazole protons typically appeared downfield-shifted pared with the unsubstituted reference compound 2,2Ј-bi-
at 8.4–9.0 ppm in CD2Cl2 at 25 °C and 9.0–9.7 ppm in [D6]- pyridinebis(phenylethynyl)platinum(II) (9).[21]
DMSO at 100 °C. MALDI-TOF MS were recorded using
dithranol as the matrix. The molecular mass peak was ob-
tained for all compounds, as well as peaks from the frag-
mentation products, mostly corresponding to the loss of
one or two phenylacetylides. In most cases, a peak corre-
sponding to the dimer was also observed.
Representative absorption spectra are depicted in Fig-
ure 1, which show shifts that originate from the different
substitution patterns. The introduction of conjugated alk-
ynyl groups at the bipyridine ligand causes a redshift and
broadening of the absorption bands, as illustrated by 5-
(TMS-ethynyl)bpyPtII (2a) compared with 9 (Figure 1a).
The absorption is further redshifted upon introduction of n-
hexyl chains (e.g. 2b), which enhance the electron-donating
character of the coordinated phenylacetylides, thus, raising
Photophysical Characterization
The photophysical data of the compounds is summarized the HOMO. However, the molar extinction coefficient is
in Table 1. Absorption spectra were recorded in dicholoro- not affected by the hexyl chains. As expected, no remark-
methane (DCM) at room temperature and display charac- able difference was observed between 5-substituted com-
teristic IL π–π* transitions between 250 and 350 nm from plexes bearing TMS-protected or unprotected ethynyl
the coordinated bipyridine, as well as MLCT bands span- groups at the bpy ligand (cf. 2a and 3a). Noticeably, how-
ning from 350 to 550 nm. The molar extinction coefficients ever, a blueshift of the MLCT absorption and an additional
of the MLCT absorption maxima range from 5900– broadening of the IL absorption are observed, for instance,
6400 m–1 cm–1 for the 5-substituted derivatives, and from by comparison of the 5-ethynyl-bpy PtII complex 3a and
8500–12700 m–1 cm–1 for the 4,4Ј-substituted compounds. its clicked derivative 4a (Figure 1b). It is known that click
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Table 1. Photophysical parameters of the investigated complexes.[a]
[b]
λabs [nm][b]
λem
λem 77 K[c] Φ[b,d]
[nm]
τ[b]
[ns]
kr
knr
τ 77 K[e]
[μs]
(ε [m–1 cm–1])
[nm]
[105 s–1]
[105 s–1]
2a
2b
3a
3b
4a
4b
4c
4d
6a
6b
7a
7b
8a
8b
8c
8d
8e
9
425 (6300)
432 (6300)
424 (6100)
429 (6200)
412 (5900)
418 (6400)
413 (6000)
416 (5900)
430 (11000)
435 (10800)
432 (9100)
435 (8500)
418 (10800)
422 (10800)
421 (11200)
426 (11500)
420 (12700)
405 (7100)
610
638
612
645
598
623
605
628
626
653
631
660
603
608
619
626
604
577
533
552
539
546
535
543
532
540
536
560
554
581
536
531
0.09
0.02
0.08
0.03
0.24
0.08
0.19
0.05
0.18
0.05
0.10
0.02
0.33
0.08
321
85
251
66
2.8
2.4
3.2
4.5
3.4
3.6
3.1
2.7
3.7
3.6
3.0
2.2
4.2
2.9
2.6
4.6
3.5
3.7
28
120
37
150
11
41
13
51
17
69
1.5 (27%), 3.8 (73%)
2.1 (17%), 3.9 (83%)
1.3 (28%), 3.6 (72%)
1.7 (17%), 3.9 (83%)
1.4 (10%), 4.0 (90%)
3.1 (55%), 5.1 (45%)
1.6 (7%), 4.2 (93%)
2.4 (33%), 4.9 (67%)
0.5 (28%), 2.1 (72%)
1.4 (29%), 3.6 (71%)
0.4 (10%), 3.6 (90%)
1.1 (13%), 3.6 (87%)
3.5 (100%)
696
222
613
186
483
138
330
90
777
273
688
218
709
749
27
110
8.6
34
12
41
11
9.6
1.9 (41%), 4.0 (59%)
2.6 (38%), 4.8 (62%)
2.5 (65%), 8.6 (35%)
3.6 (100%)
[528][f] 555 0.18
508
556
509
0.10
0.25
0.28
3.1 (100%)
[a] Φ = Photoluminescence quantum yield, exciting at the MLCT absorption maximum. τ = Emission decay lifetime, monitored at the
maximum of the emission spectrum, λEx = 431 nm. Radiative decay rate constant, kr = Φ/τ. Nonradiative decay rate constant, knr = (1 –
Φ)/τ. [b] All measurements were carried out in spectroscopic grade DCM at c ≈ 10–5 molL–1. Measured at room temp. (298 K). [c]
Measured at 77 K in DCM glassy matrix. [d] Measured with an integrating sphere. Quantum yields and lifetimes correspond to deaerated
solutions. [e] Lifetimes at 77 K in a DCM glassy matrix, monitoring the most energetic emission maximum; relative amplitudes of the
components are given in brackets. [f] The maximum of the additional shoulder is given in brackets.
chemistry is not a suitable method for the synthesis of ex- chromophoric units of 8a, 8c and 8e can be considered
tended π-conjugated systems, and it has been shown that if equivalent because of to the lack of interaction through the
conjugated building blocks are directly connected through triazole unit.
the resulting 1,2,3-triazol-4-yl moiety, the elongated systems
Further effects can be observed in the luminescence spec-
hardly display any redshift in the absorption spectra.[25] Ste- tra in deaerated DCM at room temperature and 77 K. At
ric effects that induce a twist of the triazole ring and room temperature, all compounds except 9, which is blue-
weaken the mesomeric interactions through the nitrogen shifted and has a maximum at 577 nm, display broad, un-
atoms involved are considered to be responsible for the po- structured emission bands with maxima ranging from 598–
orly mediated conjugation. As a result, the triazole substitu- 660 nm. In addition, the large Stokes shifts (7136–
ent constitutes a σ donor rather than a π* acceptor. Indeed, 8115 cm–1) and the excited state liftetimes (66–777 ns) are
almost no difference is observed in the absorption bands indicative of 3MLCT excited states. In general, the emission
if, for instance, the conjugated phenyl click product 4c is shifts caused by different substitution patterns follow the
compared to the benzyl derivative 4a, which further proves same trends observed for the MLCT absorption bands (vide
that the triazole constitutes an insulating bridging unit be- supra). However, generally, the emission maxima of the
tween the π-conjugated systems.
substituted complexes display larger redshifts (609–
Within the 4,4Ј-substituted series, similar trends can be 2180 cm–1) than the corresponding MLCT absorption
observed. However, the 4,4Ј-substituted complexes showed bands (420–1703 cm–1) compared to 9.
slightly redshifted absorption spectra and higher extinction
Figure 2a depicts the emission spectra of 9 and examples
coefficients compared with their 5-substituted analogues. of the 5-substituted series, 2a, 4a and 4b, which demonstrate
Hexyl chains at the phenylacetylide units again cause a red- the general trends observed. If an ethynyl-substituted com-
shift of the MLCT absorption (e.g. 6a and 6b). A blue- plex (e.g. 2a) is compared with its click product (e.g. 4a), a
shifted absorption is observed after the ethynyl group is distinct blueshift is observed, whereas the insertion of hexyl
clicked with benzyl azide (e.g. 7a and 8a). However, the mo- chains (e.g. 4b) causes a redshift. Vibrational progressions
lar extinction coefficient of the MLCT band is marginally and blueshifts are apparent at 77 K (Figure 2b) and the
increased with the triazolyl substituents, as opposed to the emission profiles become structured. However, the trends
5-substituted series. Figure 1c exemplifies the general state- mentioned above are still observed. The shifts and vi-
ment that there is no significant change in the absorption brational progressions can be explained by the lack of stabi-
3
spectra if the benzyl (e.g. 8a) and phenyl (e.g. 8c/8e) click lization of the excited MLCT states by the frozen solvent,
3
products are compared, which is because of the insulating which results in a shift of the MLCT state to higher ener-
nature of the triazole linker (vide supra). Furthermore, gies compared to fluid solutions. Greater mixing with the
there is no noticeable shift if the alkyl chains are attached close-lying 3IL states can therefore occur, which leads to
to the clicked phenyl moiety on the bpy ligand (8e). Indeed, more structured emissions and longer excited-state life-
the absorption spectra of the complexes are identical as the times.
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Postfunctionalization of Pt Complexes by Click Chemistry
uct (e.g. 8a) is compared with the corresponding conjugated
phenyl click product (e.g. 8c), only a slight redshift of the
MLCT emission band is observed. Thus, the direct linkage
of an aromatic moiety to the triazole ring has no significant
influence on the lumophoric unit. Nonetheless, although
the MLCT absorption maximum of 8c is shifted by only
170 cm–1 to lower energies compared with 8a, the emission
maximum is shifted by about 429 cm–1. Even though the
triazole spacer hinders the delocalization of the bipyridine
ligand to the clicked moiety, its effect is more pronounced
on the emissive state than on the vertical absorption state.
This is confirmed by the blueshifted emission spectrum of
8e (Figure 3) compared with 8c, and can be explained by
the electron-donor ability of the hexyl chains. As already
discussed for the 5-substituted complexes, for the 4,4Ј-sub-
3
stituted compounds we also see a larger IL character of
the emission at 77 K. The effect is more pronounced with
3
substituents that favour a larger IL character of the emis-
sive state (e.g. clicked phenyl groups) and by those that de-
stabilize the HOMO (e.g. hexyl groups at the phenylacet-
ylides). Therefore, blueshifted excitation and emission spec-
tra are observed for 8c and 8d at 77 K compared to 8a and
8b.
Within the 5-substituted series, the 77 K emission spectra
of 2a and 4a look nearly identical between 500 and 650 nm
(Figure 2b). However, an additional emission band at
around 750 nm appears in the spectrum of 2a, which is not
apparent for 4a and 4b, and vanishes at lower concentra-
tions (Figure S1, Supporting Information). Furthermore,
excitation spectra monitored at 77 K at 530 and 740 nm
showed nearly identical profiles (Figure S2). Thus, the red-
shifted band is assigned to an aggregate emission with weak
ground-state coupling (excimer emission), which has been
previously reported.[26] In general, the tendency for aggre-
gation seems to be lower for hexyl-substituted phenylacet-
ylide complexes and 5-substituted click products. For the
4,4Ј-substituted bpy PtII acetylide series, the propensity for
aggregation seems to be higher. Indeed, in some cases, the
intensity of the aggregate luminescence at 77 K is even
higher than the corresponding monomer emission (Fig-
ure 2d). All the compounds were measured at concentra-
tions of 10–5 m and the aggregate emissions at 77 K (if ob-
served) are depicted in the Supporting Information along
with their excited state lifetimes, which are generally shorter
(Ͻ 1 μs). No aggregate emission was observed at room tem-
perature, even at concentrations up to 5ϫ10–4 m in DCM
(e.g. Figure S3).
Figure 1. Absorption spectra of representative PtII complexes in
DCM (c ≈ 10–5 molL–1) at room temp. (a) Influence of n-hexyl
chains at the phenylacetylides on the 5-substituted series and com-
parison with 9, (b) 5-triazolyl- vs. 5-ethynyl-substituted bpy PtII
complexes, (c) different 4,4Ј-triazolyl-substituted bpy PtII deriva-
tives.
The photoluminescence quantum yields (Φ), the lifetimes
(τ) at room temperature and the derived radiative (kr) and
nonradiative (knr) decay rate constants are listed in Table 1.
At room temperature, the 4,4Ј-substituted series (Fig- A Φ of 0.28 was measured for 9, which decreases upon in-
ure 2c) also displays blueshifts upon click functionalization sertion of triple bonds in the 5- or 4,4Ј-postition. The in-
(cf. 6a and 8a), whereas hexyl chains at the phenylacetlyide creased knr value is most likely due to the extended conjuga-
unit (e.g. 8b) give a redshift, as previously observed for the tion and additional vibrational states. A further drop is ob-
5-substituted analogues.
served after attaching hexyl chains to the phenylacetylide
The influence on the emission spectra of different substi- ligands due to a larger density of vibrational states. As a
tuents clicked in the 4,4Ј-position of the bpy PtII complexes result, knr is enhanced and Φ is lowered. For the click-func-
is depicted in Figure 3. For instance, if a benzyl click prod- tionalized complexes, Φ increases again, ranging from 0.18–
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Figure 2. Normalized emission spectra in DCM (c ≈ 10–5 molL–1, λEx = 400 nm) of 5-substituted bpy PtII complexes measured (a) at
room temp. and (b) in a DCM glassy matrix at 77 K. 4,4Ј-Substituted bpy PtII complexes measured (c) at room temp. and (d) in a DCM
glassy matrix measured at 77 K.
hexyl chains at the phenyltriazolyl moiety, has good solubil-
ity and a relatively high Φ of 0.25. The alkyl chains attached
by the triazole linker do not seem to have an influence on
the nonradiative decay rate constant. If the knr values of 8a/
8c/8e and 4a/4c are compared, it is clear that they are rela-
tively low, 9ϫ105–13ϫ105 s–1, and they do not change with
different substituents at the triazolyl moiety.
Conclusively, click chemistry has been shown to be a
suitable method to attach a variety of functional groups to
PtII complexes, such as solubilizing alkyl chains, or to deco-
rate the backbone of target molecules, while precisely con-
trolling the photophysical properties of the lumiphore.
Figure 3. Normalized emission spectra of different 4,4Ј-triazolyl-
Electrochemistry
substituted bpy PtII compounds in DCM (c ≈ 10–5 molL–1) at room
temp., λEx = 430 nm.
Selected complexes have been investigated electrochemi-
cally to determine their redox properties and to measure
0.33 for products without hexyl chains and from 0.05–0.10 the HOMO/LUMO energy levels of the series. Cyclic vol-
for compounds with hexyl chains on the phenylacetylide tammetry (CV) was measured in N,N-dimethylformamide
ligands. Even though the latter complexes have good solu- (DMF) solution with tetrabutylammonium hexafluoro-
bility, as opposed to their derivatives without alkyl chains, phosphate (TBAPF6) as the supporting electrolyte. Table 2
they are also less emissive. Interestingly, 8e, which bears summarizes the electrochemical data. The cyclic voltammo-
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Postfunctionalization of Pt Complexes by Click Chemistry
grams look alike for all complexes. There are two reversible
reduction waves at around –1.5 and –2.2 V (vs. Fc/Fc+),
which correspond to two one-electron reductions of the bpy
ligand.[8k] An irreversible oxidation wave at around 0.9 V
corresponds to the PtII/PtIII oxidation, which can be seen
in Figure 4a for 8a. The irreversibility is probably due to
the reductive elimination of the phenylacetylide ligands as
a follow-up reaction after the PtII core is oxidized.[27]
Differential pulse voltammograms (DPVs) were recorded to
determine standard potentials (Figure 4b). The reductive
waves were well resolved, but the irreversibility of the oxi-
dation made the acquisition of well-resolved DPVs chal-
lenging. For all complexes, the HOMO levels lie in the
range of –5.74 to –5.92 eV vs. vacuum, and the LUMO
levels between –3.74 and –3.51 eV, except for 9, which
shows a LUMO at –3.46 eV. Hexyl chains at the phenylacet-
ylide ligands seem to have almost no effect on the HOMO/
LUMO levels. After the click reaction (going from ethylene
substituents to triazole substituents) the HOMO and espe-
cially the LUMO energies increase, which is consistent with
the observed blueshifts in the absorption and emission spec-
tra. If the 4,4Ј-substitution pattern is compared to the 5-
substitution pattern, one can see that the changes in
HOMO/LUMO energies are very small.
Table 2. Electrochemical parameters of selected complexes.
[a]
[a]
[a]
[b]
[b]
[c]
E0
[V]
E0
[V]
E0
[V]
EHOMO
[eV]
ELUMO
[eV]
Eg
ox
red1
red2
Figure 4. (a) Representative CVs and (b) DPVs of 8a in DMF
(0.1 m TBAPF6), c = 10–3 molL–1, scan rate 100 mV s–1.
[eV]
2a 0.92
2b 0.87
3a 0.97
4a 0.83
4b 0.86
4c 0.86
4d 0.83
6a 0.94
7a 0.91
7b 1.10
8a 0.81
8c 0.83
8d 0.80
8e 0.87
–1.53
–1.53
–1.53
–1.65
–1.66
–1.62
–1.66
–1.45
–1.48
–1.49
–1.62
–1.63
–1.61
–1.61
–1.72
–2.22
–2.22
–2.21
–2.28
–2.29
–2.23
–2.28
–2.05
–2.08
–2.11
–2.24
–2.24
–2.21
–2.22
–2.38
–5.85
–5.84
–5.92
–5.79
–5.83
–5.81
–5.80
–5.90
–5.85
–5.92
–5.79
–5.77
–5.74
–5.81
–5.88
–3.74
–3.69
–3.67
–3.53
–3.52
–3.56
–3.51
–3.72
–3.63
–3.68
–3.57
–3.55
–3.56
–3.57
–3.46
2.12
2.15
2.25
2.26
2.31
2.26
2.29
2.18
2.22
2.23
2.22
2.22
2.18
2.22
2.43
PLED Fabrication
In order to test the applicability of our clicked PtII acet-
ylides as triplet emitters in PLEDs, the two brightest deriva-
tives, 4a and 8a, were investigated as dopants. The com-
plexes were employed in a solution-processed simple device
structure: ITO/PEDOT (35 nm)/PVK:PBD:x wt.-% Pt
(60 nm)/TPBI (30 nm)/CsF (1.5 nm)/Al (80 nm). [ITO = in-
dium tin oxide, PEDOT
= poly(3,4-ethylenedioxythi-
9
0.91
ophene), PBD = 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-
oxadiazole, TPBI = 1,3,5-tris(1-phenyl-1H-benzo[d]imid-
azol-2-yl)benzene, x = 3, 5]. A schematic representation of
the device architecture is given in Figure 5.
[a] Measured vs. Fc/Fc+ in DMF (0.1 m TBAPF6), c = 10–3 molL–1,
295 K, scan rate = 100 mVs–1. Potentials were determined using
DPV. [b] Vs. vacuum, determined from the onsets of oxidation and
reduction waves, using the equation EHOMO/LUMO = –5.1 eV –
Eoxonset/Ered1
.
[c] Calculated by the difference of the values
onset [28]
of ELUMO and EHOMO
.
The energy gap was calculated by the difference of the
HOMO and LUMO energies to be between 2.1 and 2.3 eV
for all compounds, whereas the gap for 9 is about 0.2 eV
higher (2.43 eV). In general, it can be stated that the actual
HOMO/LUMO gaps differ to some extent from the spec-
troscopic absorptions and emissions, which indicates that
they cannot be simply regarded as HOMO–LUMO transi-
tions. The HOMO/LUMO gaps are consistent with the ob-
served photophysical trends, even though the electrochemi-
cally measured differences are less pronounced.
Figure 5. Schematic representation of the device architecture, EL
= PVK:PBD: x wt.-% Pt (x = 3, 5).
Eur. J. Inorg. Chem. 2012, 1795–1809
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1801

L. De Cola, P. Bäuerle et al.
FULL PAPER
Table 3. PLED performances obtained with 4a and 8a in PVK.
Device
Dopant
Loading [wt.-%] Lmax [cdm–2][a] LE [cdA–1][b]
PE [lmW–1][c]
EQE [%][d] Von [V][e]
CIE [x,y][f]
1
2
3
4a
4a
8a
5
3
3
6648
9052
2408
3.3
3.0
2.0
1.3
1.7
0.7
0.91
0.82
0.55
5.6
4.9
5.6
0.44, 0.55
0.43, 0.56
0.44, 0.55
[a] Maximum luminance. [b] Light-harvesting efficiency. [c] Power conversion efficiency. [d] External quantum efficiency. [e] Turn-on
voltage recorded at 1 cdm–2. [f] Commission International de l’Eclairage coordinates at 11 V.
The films were prepared by spin coating tetrachloroeth- adequate. The maximum brightness of 6648 and 9052
ane solutions, even though the solubility of 8a was relatively cdm–2 for devices with 5 and 3 wt.-% 4a, respectively, was
low. The highest attainable concentration was 3 wt.-% of 8a obtained at voltages of ca. 13 V (Figure 6b). A device with
in a PVK matrix. Complex 4a was processed at the same a comparable structure and a related emitter complex [4,4Ј-
concentration for comparison (Table 3). The better solubil- dimethyl-bpy PtII bis(phenylacetylide)] was described in
ity of 4a allowed the use of higher dopant concentrations 2001 by Che and coworkers, who reported a maximum lu-
in PVK. The best device was obtained using 5 wt.-% of 4a. minance of 945 cdm–2 at 28 V and a maximum power effi-
By using this simple device structure, the performances ciency of 1.33 lmW–1.[8k] A more recent example of spin-
of the spin-coated devices with a maximum power conver- coated OLEDs using PtII phosphors in an optimized device
sion efficiency (PE) of 1.7 lmW–1, light-harvesting effi- structure delivered light-harvesting efficiencies of 15.6
ciency (LE) of 3.3 cdA–1 and external quantum efficiency cdA–1 and a maximum brightness of 11360 cdm–2.[4d] De-
(EQE) of 0.91% cannot compete with state-of-the-art de- spite the fact that the our devices can still be improved,
vices that use PtII complexes as triplet emitter molecules in they also demonstrate the suitability of the click-decorated
vapour-deposited devices.[1d,1e] However, the energy transfer complexes for solution-processed PLEDs.
from the PVK matrix to the PtII dopant occurred quantita-
tively as the electroluminescence spectra did not show emis-
Conclusions
sion from the PVK host (Figure 6a). The turn-on voltage
of the resulting orange emitting devices was measured at 1
cdm–2 and ranged from 4.9 to 5.6 V, which shows that the
charge-transport ability of the PtII complexes employed is
A series of substituted bpy PtII bisacetylides was synthe-
sized and postfunctionalized with different azides by click
chemistry and their photophysical and electrochemical
properties were investigated. They showed 3MLCT emission
at room temperature with maxima ranging from 598–
660 nm and their PLQYs in solution reached 0.33, which
shows that click chemistry is an efficient method to func-
tionalize luminescent bpy PtII complexes without diminish-
ing their emissive properties. Several substituents can be in-
troduced in high yields by employing the corresponding az-
ides without affecting the acetylide ligands. If the complexes
are linked through a triazole ring to different moieties, only
minor influences on knr were observed despite the fact that
slight absorption and emission shifts become apparent.
Furthermore, the PLQYs remain unaffected, which is not
the case if additional groups, such as solubilizing alkyl
chains, are introduced to the phenylacetlyide ligands. There-
fore, the CuAAC click reaction, which results in 1,2,3-tri-
azoles as bridging moieties, constitutes a versatile and ade-
quate method for the postfunctionalization of PtII com-
plexes, both from synthetic and photophysical viewpoints.
This opens the possibility to covalently link PtII emitters to
surfaces, polymers or other molecular scaffolds, which is the
objective of ongoing investigations in our labs.
Experimental Section
Synthesis: 5-(Trimethylsilylethynyl)-2,2Ј-bipyridine,[16] 4,4Ј-bis(tri-
methylsilylethynyl)-2,2Ј-bipyridine,[17] cis-dichloro(dimethyl sulfox-
ide)platinum(II),[18] phenyl azide,[22] benzyl azide,[23] 4-hexylphenyl
azide[24] and 1-ethynyl-4-hexylbenzene[29] were synthesized accord-
Figure 6. (a) Electroluminescence spectra and (b) current density/
voltage/brightness plot for Device 1 using 5 wt.-% 4a.
[30]
ing to literature protocols. CODPt(CϵCPh)2
was synthesized
1802
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 1795–1809

Postfunctionalization of Pt Complexes by Click Chemistry
[31]
from CODPtCl2 by analogy to 2a (COD = cyclooctadiene). Po-
been corrected for wavelength sensitivity. IR spectra was measured
with a Perkin–Elmer FTIR Spectrum 2000. CV experiments were
performed with a computer-controlled Autolab PGSTAT30 po-
tentiostat in a three-electrode single-compartment cell with a plati-
num working electrode, a platinum wire counter electrode and an
Ag/AgCl reference electrode. All potentials were internally refer-
enced to the Fc/Fc+ couple.
tassium tetrachloroplatinate (K2PtCl4) was purchased from ABCR
and
tetrakis(acetonitrile)copper(I)
hexafluorophosphate
[Cu(CH3CN)4PF6] was purchased from Aldrich. 2,2Ј-Bipyridine,
phenylacetylene and all solvents were purchased from Merck
(VWR International) and were used as received for workup pro-
cedures, distilled for purification purposes and dried for use in reac-
tions according to standard protocols.[32] Column chromatography
was performed with flash silica gel, particle size 0.04–0.064 mm,
from Macherey–Nagel and basic aluminium oxide (alumina) “90”
(particle size 0.04–0.064 mm) from Merck, respectively. The alu-
mina was deactivated to “Brockmann” activity II–III by adding
5% distilled water. TLC was carried out on aluminium sheets
coated with silica gel (Merck TLC Silica gel 60 F254) and alumin-
ium oxide (Merck TLC Aluminium oxide 150 F254, neutral).
PLED Fabrication: The light-emitting devices were fabricated using
the structure ITO/PEDOT:PSS (35 nm)/emitting layer (60–80 nm)/
TPBI (30 nm)/CsF (1.5 nm)/Al (80 nm), in which PEDOT:PSS is
poly(styrenesulfonate)-doped
poly(3,4-ethylenedioxythiophene).
The ITO glass substrate was treated for 10 min with UV/O3 (UVO
Cleaner 144AX, Jelight Company) before further processing. The
PEDOT:PSS was spin-coated directly onto ITO substrate, using a
spincoater P6700 (Specialty Coating Systems) and then dried at
100 °C for 10 min. The emitting layer, containing a PVK host poly-
mer blended with 30 wt.-% of PBD and 3–5 wt.-% of platinum(II)
complex, was spin-coated on top of the PEDOT:PSS layer using
tetrachloroethane as solvent. The sample was then dried for 90 min
at 50 °C. Prior to film casting, the polymer solution was filtered
through a Teflon filter (0.45 μm). The TPBI layer was grown
through thermal sublimation in a vacuum of 3ϫ10–6 mbar using
an MBraun evaporation chamber. The cathode was completed
through thermal deposition of CsF (1.5 nm)/Al (80 nm). All mea-
surements were conducted inside a glove box under an inert atmo-
sphere. The electroluminescent device was characterized by at-
taching a computer-controlled low-noise single-channel direct-cur-
rent power source that can act as both voltage source and current
source, and a voltage meter or current meter (Keithley 2600, Ke-
ithley Instruments). Light from the diode was coupled to a photo-
diode and read by an electrometer/high-resistance meter (Keithley
6517, Keithley Instruments). The data output was managed by a
Labview-based program (National Instruments). Calibration of the
photodiode was performed at a fixed current with a luminance me-
ter (LS-100 Minolta). For every diode with a different spectral dis-
tribution of light, the photocurrent as measured by the photodiode
was correlated to the light output in candles per square meter by
this calibration. When recording an electroluminscence spectrum,
a fibreoptic-coupled spectrometer (USB2000, Ocean Optics) was
used. The emission was corrected for the wavelength dependence
of the spectrometer.
Physicochemical, Electrochemical and Photophysical Measurements:
NMR spectra were recorded with a Bruker 400 spectrometer at
25 °C, unless noted otherwise. 500 MHz spectra were recorded with
a Bruker 500 spectrometer. Chemical shifts (δ) are expressed in ppm
1
13C
using residual solvent protons (CDCl3: δ H = 7.26 and δ
=
1
13C
77.36 ppm; CD2Cl2: δ H = 5.33 and δ = 54.24 ppm; [D6]DMSO:
13C
1
δ H = 2.54 and δ = 40.45 ppm)[33] as internal standards. Occa-
sionally, attached proton test (APT) spectra were measured for the
specific evaluation of the 13C NMR spectra. The numbering of
atoms for the assignment of NMR signals was chosen for practical
considerations and does not conform to IUPAC nomenclature.
MALDI-TOF MS were measured with a Bruker Daltonics Reflex
III and HRMS were measured with a micrOTOF-Q43 apparatus
and ESI source at the University of Stuttgart and with a Bruker
solariX spectrometer and MALDI or ESI source at Ulm Univer-
sity. Melting points were determined with a Büchi B-545 apparatus.
Elemental analyses were performed with an Elementar Vario EL.
Optical measurements were carried out in 1-cm cuvettes with
Merck spectroscopic grade solvents. Absorption spectra were re-
corded with a Perkin–Elmer Lambda 19 spectrometer. Steady-state
luminescence experiments were performed with a Spex FluoroLog-
3 spectrofluorometer (Horiba–Jobin–Yvon Inc.) equipped with a
TBX detector and double excitation and emission monochroma-
tors. The emission spectra were corrected for monochromator and
detector efficiency and for the source intensity (450 W xenon
lamp). Time-resolved measurements were performed using the
time-correlated single-photon counting option with the Spex Fluo-
roLog-3 instrument. A NanoLED [431 nm; full width half maxi-
mum (FWHM) Ͻ 200 ps] with repetition rates between 10 kHz and
1 MHz was used to excite the samples. The excitation sources were
mounted directly on the sample chamber at 90° to a double grating
emission monochromator (2.1 nm/mm dispersion; 1200 grooves/
mm) and collected by a TBX-4-X single-photon-counting detector.
The photons collected at the detector were correlated by a time-to-
amplitude converter to the S3 excitation pulse. Signals were col-
lected using an IBH DataStation Hub photon counting module
and data analysis was performed using the commercially available
DAS6 software (Horiba–Jobin–Yvon Inc.). The quality of fit was
assessed by minimizing the reduced chi squared function (χ2) and
visual inspection of the weighted residuals. Luminescence quantum
yields were measured with a Hamamatsu Photonics absolute PL
quantum yield measurement system (C9920-02) equipped with a
L9799-01 CW Xenon light source (150 W), monochromator (exci-
tation wavelengths: 250–700 nm; bandwidth: FWHM 10 nm),
C7473 photonic multichannel analyzer, integrating sphere and em-
ploying U6039-05 PLQY measurement software (Hamamatsu Pho-
tonics, Ltd., Shizuoka). The detector was a PMA multichannel cap-
able of simultaneously measuring multiple wavelengths that have
Dichloro[5-(trimethylsilylethynyl)-2,2Ј-bipyridine]platinum(II) (1):[19]
(DMSO)2PtCl2 (0.242 g, 0.573 mmol) and 5-(trimethylsilylethynyl)-
2,2Ј-bipyridine (0.145 g, 0.573 mmol) were dissolved in acetonitrile
(25 mL) and stirring was continued at room temp. overnight. The
solvent was removed in vacuo, and the residue was suspended in
diethyl ether, filtered and washed with diethyl ether. The solid was
dried in vacuo, and 1 (0.249 g, 0.48 mmol, 84%) remained as an
1
orange powder. Rf = 0.29 (alumina, DCM). H NMR (400 MHz,
CD2Cl2): δ = 0.31 (s, 9 H, 3ϫCH3), 7.60–7.64 (m, 1 H, H-5Ј), 7.98
3
3
(d, J = 8.4 Hz, 1 H, H-3), 8.02 (d, J = 7.8 Hz, 1 H, H-3Ј), 8.19
4
3
4
(dd, J = 1.8 Hz, J = 8.4 Hz, 1 H, H-4), 8.21 (td, J = 1.4 Hz, 1
H, 3J = 7.9 Hz, H-4Ј), 9.65 (d, J = 1.8 Hz, 1 H, H-6), 9.66 (dd, J
= 1.1 Hz, 3J = 5.9 Hz, 1 H, H-6Ј) ppm. 13C NMR (100 MHz,
CD2Cl2): δ = 0.0 (3ϫCH3), 99.0 (CϵC-TMS), 105.8 (CϵC-bpy),
123.3 (C-3), 124.1 (C-3Ј), 124.8 (C-5), 128.1 (C-5Ј), 140.3 (C-4),
142.4 (C-4Ј), 150.2 (C-6), 152.4 (C-6Ј), 156.3 (C-2), 157.1 (C-2Ј)
4
4
ppm. IR (KBr): ν = 3048 (m), 2959 (w), 2162 (w), 1604 (w), 1468
˜
(s), 1442 (m), 1376 (m), 1249 (m), 1235 (m), 882 (s), 845 (s) cm–1.
MS (MALDI-TOF, dithranol): m/z = 481 [M – Cl]+, 962 [2 M – 2
Cl]+, 998 [2 M – Cl]+.
Bis(phenylethynyl)[5-(trimethylsilylethynyl)-2,2Ј-bipyridine]plati-
num(II) (2a):[8l] Compound 1 (0.10 g, 0.193 mmol) was dissolved in
Eur. J. Inorg. Chem. 2012, 1795–1809
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1803

L. De Cola, P. Bäuerle et al.
FULL PAPER
DCM (10 mL) and diisopropylamine (0.5 mL) under argon. The
solution was degassed, and CuI (4 mg, 0.021 mmol) and phenyl-
1 H, H-6) ppm. 13C NMR (100 MHz, CD2Cl2): δ = 78.9 (CϵC-
bpy), 85.8 (C-2ЈЈ), 100.8 (CϵC-H), 102.6 + 102.7 (C-1ЈЈ), 123.4 (C-
acetylene (0.085 mL, 0.772 mmol, 0.079 g) were added. Stirring at 3Ј), 123.8 (C-5), 124.2 (C-3), 126.5 (C-3ЈЈ), 128.5 (C-5Ј), 128.7 +
room temp. was continued overnight. The solvent was removed in
vacuo, and the crude product was purified by column chromatog-
raphy using alumina and petroleum ether (PE)/DCM (1:5). Product
2a (122 mg, 0.188 mmol, 97%) was obtained as an orange powder.
Rf = 0.50 (alumina, PE/DCM, 1:5). 1H NMR (400 MHz, CD2Cl2):
δ = 0.32 (s, 9 H, 3ϫCH3), 7.19–7.23 (m, 2 H, H-6ЈЈ), 7.29–7.33
(m, 4 H, H-5ЈЈ), 7.50–7.52 (m, 4 H, H-4ЈЈ), 7.59–7.63 (m, 1 H, H-
128.8 (C-5ЈЈ, C-6ЈЈ), 132.5 (C-4ЈЈ), 139.8 (C-4Ј), 142.4 (C-4), 151.9
(C-6Ј), 154.5 (C-6), 156.2 (C-2,2Ј) ppm. IR (KBr): ν = 3215 (s),
˜
2124 (m), 2112 (s), 1592 (m), 1485 (s), 1466 (m), 1440 (m), 784 (m),
758 (s), 694 (m) cm–1. MS (MALDI-TOF, dithranol): m/z = 577
[M]+, 1154 [2 M]+. C28H18N2Pt (577.55): calcd. C 58.23, H 3.14, N
4.85; found C 57.97, H 3.26, N 4.78.
(5-Ethynyl-2,2Ј-bipyridine)bis(4-hexylphenylethynyl)platinum(II)
(3b): Complex 2b (74.7 mg, 0.091 mmol) was dissolved in DCM
(15 mL) and methanol (2 mL). KF (8 mg, 0.137 mmol) was added,
and stirring was continued at room temp. overnight. The solvent
was removed in vacuo, and the residue was purified by column
chromatography with alumina and PE/DCM (1:2). Product 3b
(67 mg, 0.090 mmol, 99%) was obtained as an orange powder. Rf
3
5Ј), 8.09–8.18 (m, 4 H, H-3,3Ј, 4,4Ј), 9.68 (d, J = 5.5 Hz, 1 H, H-
6Ј), 9.77 (d, 4J = 1.7 Hz, 1 H, H-6) ppm. 13C NMR (100 MHz,
CD2Cl2): δ = 0.2 (3ϫCH3), 87.8 + 88.6 (C-2ЈЈ), 100.1 (2ϫCϵC-
TMS), 102.6 (C-1ЈЈ), 104.5 (2ϫCϵC-bpy), 123.9 (C-3Ј), 124.5 (C-
3), 124.6 (C-5), 126.5 + 126.6 (C-3ЈЈ), 128.2 (C-5Ј), 128.8 + 128.9
(C-5ЈЈ, C-6ЈЈ), 132.5 + 132.6 (C-4ЈЈ), 139.6 (C-4Ј), 141.8 (C-4), 151.7
(C-6Ј), 154.1 (C-6), 155.6 (C-2Ј), 156.4 (C-2) ppm. IR (KBr): ν =
˜
1
= 0.38 (alumina, DCM/PE, 2:1). H NMR (400 MHz, CD2Cl2): δ
3073 (w), 3049 (m), 3023 (w), 2958 (m), 2166 (w), 2126 (s), 2115
(s), 1635 (w), 1592 (m), 1485 (s), 1468 (m), 1249 (m), 1237 (m),
1217 (m), 1067 (m), 1025 (m), 878 (s), 844 (s), 754 (s), 692 (s) cm–1.
MS (MALDI-TOF, dithranol): m/z = 649 [M]+, 1298 [2 M]+.
C31H26N2PtSi (649.74): calcd. C 57.31, H 4.03, N 4.31; found C
56.93, H 4.17, N 4.16.
3
= 0.91 (t, J = 6.8 Hz, 6 H, H-12ЈЈ), 1.31–1.39 (m, 12 H, H-11ЈЈ,
H-10ЈЈ, H-9ЈЈ), 1.60–1.68 (m, 4 H, H-8ЈЈ), 2.62 (t, 3J = 7.7 Hz, 4
H, H-7ЈЈ), 3.58 (s, 1 H, CϵCH), 7.14 (dd, 4J = 3.1 Hz, 3J = 8.1 Hz,
4
3
4 H, H-5ЈЈ), 7.40 (dd, J = 3.1 Hz, J = 8.1 Hz, 4 H, H-4ЈЈ), 7.56–
4
7.60 (m, 1 H, H-5Ј), 8.10–8.16 (m, 3 H, H-4,4Ј H-3), 8.20 (dd, J
3
3
= 1.9 Hz, J = 8.4 Hz, 1 H, H-3Ј) 9.64 (d, J = 5.7 Hz, 1 H, H-6Ј),
9.72 (d, 4J = 1.7 Hz, 1 H, H-6) ppm. 13C NMR (100 MHz,
CD2Cl2): δ = 14.7 (C-12ЈЈ), 23.5 (C-11ЈЈ), 29.9 (C-10ЈЈ), 32.3 (C-
9ЈЈ), 32.6 (C-8ЈЈ), 36.6 (C-7ЈЈ), 79.1 (CϵC-bpy), 85.7 (CϵC-H),
86.0 + 86.7 (C-2ЈЈ), 102.6 + 102.7 (C-1ЈЈ), 123.6 (C-3Ј), 123.7 (C-
Bis(4-hexylphenylethynyl)[5-(trimethylsilylethynyl)-2,2Ј-bipyridine]-
platinum(II) (2b): Compound 1 (0.30 g, 0.579 mmol) was dissolved
in DCM (60 mL), and diisopropylamine (4 mL) was added. The
solution was degassed, and CuI (10 mg, 0.060 mmol) and 1-eth-
ynyl-4-hexylbenzene (0.324 g, 1.736 mmol) were added. Stirring 5), 124.4 (C-3), 126.0 (C-3ЈЈ), 128.4 (C-5Ј), 128.9 (C-5ЈЈ), 132.4 (C-
was continued at room temp. overnight. The solvent was removed
in vacuo, and the residue was purified by column chromatography
4ЈЈ), 139.7 (C-4Ј), 141.6 (C-6ЈЈ), 142.4 (C-4), 151.9 (C-6Ј), 154.4 (C-
6), 156.3 (C-2,2Ј) ppm. IR (KBr): ν = 2955 (m), 2926 (s), 2854 (m),
˜
with alumina and DCM/PE (5:4). Product 2b (0.426 g, 0.521 mmol, 2113 (m), 1636 (s, br), 1504 (m), 1467 (m), 825 (m), 781 (m) cm–1.
90%) remained as a red-brown solid. Rf = 0.36 (alumina, DCM/
MS (MALDI-TOF, dithranol): m/z = 745 [M]+, 1490 [2 M]+.
40H42N2Pt (745.88): calcd. C 64.41, H 5.68, N 3.76; found C
PE, 5:4). 1H NMR (400 MHz, CD2Cl2): δ = 0.34 (s, 9 H, 3ϫCH3),
C
0.90–0.94 (m, 6 H, H-12ЈЈ), 1.36–1.42 (m, 12 H, H-11ЈЈ, H-10ЈЈ, H- 64.32, H 5.74, N 3.73.
9ЈЈ), 1.61–1.69 (m, 4 H, H-8ЈЈ), 2.62–2.66 (m, 4 H, H-7ЈЈ), 7.14 (d,
[5-(1-Benzyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bipyridine]bis(phenyleth-
3
3J = 8.1 Hz, 4 H, H-5ЈЈ), 7.37 + 7.40 (2ϫd, J = 8.1 Hz, 2ϫ2 H,
ynyl)platinum(II) (4a): Complex 2a (30 mg, 0.046 mmol) was dis-
solved in DCM (8 mL) and methanol (2 mL), and KF (4 mg,
0.069 mmol) was added under argon. The solution was degassed,
and Cu(CH3CN)4PF6 (3.4 mg, 0.009 mmol), DIPEA (0.02 mL,
0.092 mmol, 11.9 mg), elemental copper (1 mg, 0.009 mmol) and
benzyl azide (9.3 mg, 0.069 mmol) were added. Stirring at room
temp. was continued for 4 d. 25 % ammonia (5 mL) in water
(15 mL) and DCM (50 mL) were added. After stirring the solution
vigorously for some minutes, the layers were separated, and the
aqueous layer was extracted with DCM (30 mL). The organic layer
was washed with 0.1 m Na2/ethylenediaminetetraacetic acid
(EDTA) solution and dried with Na2SO4. The solvent was removed
in vacuo, and the residue was purified by column chromatography
with silica and DCM/diethyl ether (10:1). The product was dis-
solved in DCM and PE was added to precipitate the solid, which
was collected by filtration, washed with PE and dried in vacuo.
Product 2a (30 mg, 0.042 mmol, 91%) remained as an orange pow-
der. Rf = 0.21 (silica, DCM/diethyl ether, 10:1). 1H NMR
(500 MHz, [D6]DMSO, 375 K): δ = 5.75 (s, 2 H, H-benzyl), 7.20–
7.23 (m, 2 H, H-6ЈЈ), 7.30–7.34 (m, 4 H, H-5ЈЈ), 7.40–7.44 (m, 7 H,
H-m,p-Ph, H-4ЈЈ), 7.50–7.51 (m, 2 H, H-o-Ph), 7.86–7.89 (m, 1 H,
H-4ЈЈ), 7.43–7.47 (m, 1 H, H-5Ј), 7.97 (td, 4J = 1.5 Hz, 3J = 7.8 Hz,
1 H, H-4Ј), 8.08 (dd, J = 1.9 Hz, J = 8.3 Hz, 1 H, H-3Ј), 8.13–
4
3
4
8.18 (m, 2 H, H-3, H-4), 9.37 (d, J = 1.6 Hz, 1 H, H-6), 9.43 (dd,
4J = 1.0 Hz, J = 5.5 Hz, 1 H, H-6Ј) ppm. 13C NMR (100 MHz,
3
CD2Cl2): δ = 0.2 (3ϫCH3), 14.7 (C-12ЈЈ), 23.6 (C-11ЈЈ), 29.8 (C-
10ЈЈ), 32.2 (C-9ЈЈ), 32.5 (C-8ЈЈ), 36.5 (C-7ЈЈ), 87.0 + 87.9 (C-2ЈЈ),
100.2 (CϵC-TMS), 102.4 (C-1ЈЈ), 104.0 (CϵC-bpy), 124.1 (C-5),
124.4 (C-3Ј), 125.0 (C-3), 126.0 (C-3ЈЈ), 127.9 (C-5Ј), 128.9 (C-5ЈЈ),
132.3 + 132.3 (C-4ЈЈ), 139.4 (C-4Ј), 141.4 + 141.5 (C-6ЈЈ), 141.8 (C-
4), 151.2 (C-6Ј), 153.5 (C-6), 155.5 (C-2Ј), 156.1 (C-2) ppm. IR
(KBr): ν = 2956 (m), 2926 (s), 2854 (m), 2167 (w), 2113 (m), 1637
˜
(w), 1604 (m), 1504 (m), 1467 (m), 1440 (w), 1376 (w), 1249 (m),
1236 (w), 878 (m), 844 (s) cm–1. MS (MALDI-TOF, dithranol): m/z
= 818 [M]+, 1634 [2 M]+. C43H50N2PtSi (818.06): calcd. C 63.13,
H 6.16, N 3.42; found C 63.11, H 6.15, N 3.37.
(5-Ethynyl-2,2Ј-bipyridine)bis(phenylethynyl)platinum(II) (3a):
Complex 2a (90 mg, 0.139 mmol) was dissolved in DCM (15 mL),
and KF (12 mg, 0.208 mmol) and methanol (2 mL) were added.
Stirring was continued at room temp. The solvent was removed in
vacuo, and the residue was purified by column chromatography
4
3
3
with alumina and PE/DCM (1:5) and 100 % DCM. Product 3a H-5Ј), 8.39 (td, J = 1.5 Hz, J = 7.9 Hz, 1 H, H-4Ј), 8.62 (d, J =
3
(75 mg, 0.13 mmol, 94%) remained as a red-brown powder. Rf =
0.16 (alumina, PE/DCM, 1:5). H NMR (400 MHz, CD2Cl2): δ =
3.59 (s, 1 H, CϵCH), 7.19–7.24 (m, 2 H, H-6ЈЈ), 7.29–7.24 (m, 4
8.1 Hz, 1 H, H-3Ј), 8.66 (d, J = 8.4 Hz, 1 H, H-3), 8.71 (s, 1 H,
H-5ЈЈЈ), 8.72 (dd, J = 2.0 Hz, J = 8.3 Hz, 1 H, H-4), 9.65 (dd, J
1
4
3
4
3
4
= 0.9 Hz, J = 5.5 Hz, 1 H, H-6Ј), 10.32 (d, J = 1.7 Hz, 1 H, H-
H, H-5ЈЈ), 7.48–7.51 (m, 4 H, H-4ЈЈ), 7.58–7.64 (m, 1 H, H-5Ј), 6) ppm. 13C NMR (125 MHz, [D6]DMSO, 375 K): δ = 54.0 (C-
4
3
8.12–8.16 (m, 3 H, H-4,4Ј, 3), 8.22 (dd, J = 1.9 Hz, J = 8.4 Hz, benzyl), 89.3 (C-2ЈЈ), 101.6 (C-1ЈЈ), 124.0 (C-5ЈЈЈ), 124.2 (C-3),
1 H, H-3Ј), 9.66 (d, J = 5.5 Hz, 1 H, H-6Ј), 9.74 (d, J = 1.5 Hz, 124.5 (C-3Ј), 125.6 (C-4), 128.2 (C-5Ј), 128.3 + 128.4 (C-5ЈЈ), 128.4
3
4
1804 Eur. J. Inorg. Chem. 2012, 1795–1809
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Postfunctionalization of Pt Complexes by Click Chemistry
(C-o-Ph), 128.7 (C-p-Ph), 128.8 (C-3ЈЈ), 129.2 (C-m-Ph), 130.0 (C- Bis(4-hexylphenylethynyl)[5-(1-phenyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bi-
q-Ph), 131.7 + 131.9 (C-4ЈЈ), 135.8 (C-5), 136.0 (C-4Ј), 140.1 (C- pyridine]platinum(II) (4d): Complex 2b (63 mg, 0.077 mmol) was
6ЈЈ), 142.7 (C-4ЈЈЈ), 147.3 (C-6Ј), 150.5 (C-6), 155.2 (C-2Ј), 156.3 dissolved in DCM (24 mL) and methanol (6 mL) under argon. KF
(C-2) ppm. IR (KBr): ν = 3070 (m), 3047 (m), 2927 (w), 2111 (s),
(7 mg, 0.116 mmol), Cu(CH3CN)4PF6 (6 mg, 0.015 mmol), phenyl
˜
1633 (m), 1605 (m), 1592 (m), 1486 (s), 1468 (m), 1456 (m), 1440 azide (14 mg, 0.116 mmol), elemental copper (1 mg, 0.015 mmol)
(m), 1043 (m), 784 (m), 756 (s), 726 (m), 694 (s) cm–1. MS
and DIPEA (0.03 mL, 0.154 mmol, 20 mg) were added. The syn-
thesis and purification were carried out as described above for 4a.
(MALDI-TOF, dithranol): m/z = 710 [M]+, 1420 [2 M]+.
C
35H25N5Pt (710.71): calcd. C 59.15, H 3.55, N 9.85; found C Product 4d (58 mg, 0.067 mmol, 87%) was obtained as a red-brown
58.93, H 3.60, N 9.42.
solid. Rf = 0.41 (silica, DCM/diethyl ether, 20:1). 1H NMR
(400 MHz, CD2Cl2): δ = 0.92–0.95 (m, 6 H, H-12ЈЈ), 1.36–1.43 (m,
12 H, H-9ЈЈ, H-10ЈЈ, H-11ЈЈ), 1.61–1.70 (m, 4 H, H-8ЈЈ), 2.61–2.67
(m, 4 H, H-7ЈЈ), 7.14–7.16 (m, 4 H, H-5ЈЈ), 7.24–7.28 (m, 1 H, H-
[5-(1-Benzyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bipyridine]bis(4-hexylphen-
ylethynyl)platinum(II) (4b): Complex 2b (84.7 mg, 0.104 mmol) was
dissolved in DCM (24 mL) and methanol (6 mL) under argon. KF
(9 mg, 0.155 mmol), Cu(CH3CN)4PF6 (8 mg, 0.021 mmol), benzyl
azide (21 mg, 0.155 mmol), elemental copper (1 mg, 0.021 mmol)
and DIPEA (0.04 mL, 0.207 mmol, 27 mg) were added. The syn-
thesis was carried out as described above for compound 4a. The
product was purified by column chromatography with basic alu-
mina and DCM. Product 4b (86.3 mg, 0.10 mmol, 95%) was ob-
tained as a red-brown solid. Rf = 0.27 (alumina, DCM/PE, 2:1).
1H NMR (400 MHz, CD2Cl2): δ = 0.90–0.94 (m, 6 H, H-12ЈЈ),
1.33–1.42 (m, 12 H, H-9ЈЈ, H-10ЈЈ, H-11ЈЈ), 1.61–1.70 (m, 4 H, H-
8ЈЈ), 2.62–2.65 (m, 4 H, H-7ЈЈ), 5.50 (s, 2 H, H-benzyl), 7.12–7.15
(2ϫd, 3J = 8.2 Hz, 2ϫ2 H, H-5ЈЈ), 7.25–7.27 (m, 2 H, H-o-Ph),
7.35–7.39 (m, 4 H, H-5Ј, H-m,p-Ph), 7.40 + 7.45 (2ϫd, 3J = 8.1 Hz,
2ϫ2 H, H-4ЈЈ), 7.89 (s, 1 H, H-5ЈЈЈ), 7.98 (td, 4J = 1.5 Hz, 3J =
3
5Ј), 7.38 + 7.53 (2ϫd, J = 8.1 Hz, 2ϫ2 H, H-4ЈЈ), 7.44–7.46 (m,
3 H, H-m,p-Ph), 7.69–7.71 (m, 2 H, H-o-Ph), 7.95–8.00 (m, 2 H,
H-3Ј,4Ј), 8.09 (d, 3J = 8.4 Hz, 1 H, H-3), 8.39 (s, 1 H, H-5ЈЈЈ), 8.63
3
(dd, 4J = 2.0 Hz, 1 H, 3J = 8.3 Hz, H-4), 9.28 (d, J = 5.3 Hz, 1 H,
4
H-6Ј), 9.91 (d, J = 1.8 Hz, 1 H, H-6) ppm. 13C NMR (100 MHz,
CD2Cl2): δ = 14.7 (C-12ЈЈ), 23.5 (C-11ЈЈ), 29.9 + 30.0 (C-10ЈЈ), 32.3
(C-9ЈЈ), 32.6 (C-8ЈЈ), 36.6 + 36.7 (C-7ЈЈ), 87.3 + 88.5 (C-2ЈЈ), 102.5
+ 102.6 (C-1ЈЈ), 120.9 (C-3), 121.0 (C-o-Ph), 124.0 (C-5ЈЈ), 124.6
(C-3Ј), 126.2 + 126.3 (C-3ЈЈ), 127.2 (C-5Ј), 128.9 + 129.0 (C-5ЈЈ),
129.6 (C-q-Ph), 130.4 (C-p-Ph), 130.5 (C-m-Ph), 132.3 + 132.7 (C-
4ЈЈ), 136.4 (C-5), 137.2 (C-4), 139.2 (C-4Ј), 141.5 (C-6ЈЈ), 143.7 (C-
4ЈЈЈ), 147.7 (C-6Ј), 150.8 (C-6), 155.1 (C-2Ј), 156.6 (C-2) ppm. IR
(KBr): ν = 2954 (m), 2926 (s), 2854 (m), 2112 (m), 1636 (s), 1602
˜
(m), 1504 (s), 1466 (m), 825 (w), 757 (m) cm–1. MS (MALDI-TOF,
dithranol): m/z = 863 [M]+, 1728 [2 M]+. C46H47N5Pt (865.00):
calcd. C 63.87, H 5.48, N 8.10; found C 63.79, H 5.54, N 8.03.
3
3
7.8 Hz, 1 H, H-4Ј), 8.03 (d, J = 7.8 Hz, 1 H, H-3Ј), 8.10 (d, J =
4
3
8.4 Hz, 1 H, H-3), 8.48 (dd, J = 2.0 Hz, J = 8.4 Hz, 1 H, H-4),
9.50 (dd, 4J = 0.8 Hz, 3J = 5.5 Hz, 1 H, H-6Ј), 9.90 (d, 4J = 1.9 Hz,
1 H, H-6) ppm. 13C NMR (100 MHz, CD2Cl2): δ = 14.7 (C-12ЈЈ), Dichloro[4,4Ј-bis(trimethylsilylethynyl)-2,2Ј-bipyridine]platinum(II)
23.5 (C-11ЈЈ), 29.9 + 30.0 (C-10ЈЈ), 32.3 + 32.4 (C-9ЈЈ), 32.6 (C-
(5): (DMSO)2PtCl2 (0.279 g, 0.66 mmol) and 4,4Ј-bis(trimethylsily-
8ЈЈ), 36.6 + 36.7 (C-7ЈЈ), 55.2 (C-benzyl), 86.9 + 88.0 (C-2ЈЈ), 102.6 lethynyl)-2,2Ј-bipyridine (0.230 g, 0.66 mmol) were dissolved in
(C-1ЈЈ), 122.9 (C-3), 123.8 (C-5ЈЈЈ), 124.4 (C-3Ј), 126.2 (C-3ЈЈ), acetonitrile (25 mL). The yellow solution was stirred at room temp.
127.6 (C-5Ј), 128.9 (C-5ЈЈ), 129.0 (C-o-Ph), 129.6 (C-p-Ph), 130.0
overnight. The solvent was removed in vacuo, and the residue was
(C-m-Ph), 131.2 (C-q-Ph), 132.4 + 132.6 (C-4ЈЈ), 135.5 (C-5), 135.7 suspended in diethyl ether, filtered and washed with diethyl ether.
(C-4), 139.4 (C-4Ј), 141.5 (C-6ЈЈ), 143.5 (C-4ЈЈЈ), 148.3 (C-6Ј), 151.4 The solid was dried in vacuo, and 5 (0.316 g, 0.515 mmol, 78%)
(C-6), 155.2 (C-2), 156.7 (C-2Ј) ppm. IR (KBr): ν = 2955 (m), 2927
remained as a yellow powder. Rf = 0.56 (alumina, DCM). 1H NMR
˜
(s), 2854 (m), 2113 (m), 1635 (m), 1606 (m), 1504 (m), 1466 (m), (400 MHz, CDCl3): δ = 0.31 (s, 18 H, 6ϫCH3), 7.51 (dd, 4J =
826 (w), 725 (m) cm–1. MS (MALDI-TOF, dithranol): m/z = 879
[M]+, 1758 [2 M]+. C47H49N5Pt (879.03): calcd. C 64.22, H 5.62, N
7.97; found C 63.98, H 5.63, N 7.93.
1.5 Hz, 3J = 6.1 Hz, 2 H, H-5,5Ј), 7.93 (d, 4J = 1.5 Hz, 2 H, H-
3,3Ј), 9.66 (d, 3J = 6.1 Hz, 2 H, H-6,6Ј) ppm. 13C NMR (100 MHz,
CDCl3): δ = –0.2 (6 ϫ CH3), 100.3 (2 ϫ CϵC-TMS), 108.1
(2ϫCϵC-bpy), 125.3 (C-5,5Ј), 129.5 (C-3,3Ј), 135.1 (C-4,4Ј), 149.5
Bis(phenylethynyl)[5-(1-phenyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bipyridine]-
platinum(II) (4c): Complex 2a (58 mg, 0.089 mmol) was dissolved
in DCM (24 mL) and methanol (6 mL), and KF (8 mg, 0.13 mmol)
was added under argon. The solution was degassed and
Cu(CH3CN)4PF6 (7 mg, 0.018 mmol), DIPEA (0.03 mL,
0.18 mmol, 23 mg), elemental copper (1 mg, 0.018 mmol) and
phenyl azide (16 mg, 0.13 mmol) were added. Stirring was contin-
ued at room temp. for 3 d. Workup and purification were carried
out by analogy to 4a. Product 4c (60 mg, 0.086 mmol, 97%) was
obtained as a yellow powder. Rf = 0.34 (silica, DCM/diethyl ether,
(C-6,6Ј), 156.7 (C-2,2Ј) ppm. IR (KBr): ν = 3056 (w), 2958 (m),
˜
2897 (w), 2111 (m), 1611 (s), 1531 (m), 1479 (m), 1418 (m), 1250
(m), 1228 (m), 950 (m), 868 (s), 845 (s) cm–1. MS (MALDI-TOF,
d i t h r a n o l ) : m / z = 5 7 7 [ M – C l ] + , 1 1 9 0 [ 2 M – C l ] +
.
C20H24Cl2N2PtSi2 (614.59): calcd. C 39.09, H 3.94, N 4.56; found
C 39.28, H 3.94, N 4.48.
Bis(phenylethynyl)[4,4Ј-bis(trimethylsilylethynyl)-2,2Ј-bipyridine]-
platinum(II) (6a): Compound 5 (0.15 g, 0.244 mmol) was dissolved
in DCM (10 mL) and diisopropylamine (8 mL) under argon. The
solution was degassed, and CuI (5 mg, 0.027 mmol) and phenyl-
acetylene (0.11 mL, 0.976 mmol, 0.100 g) were added. Stirring was
continued at room temp. overnight. The solvent was removed in
1
20:1). H NMR (500 MHz, [D6]DMSO, 375 K): δ = 7.20–7.22 (m,
2 H, H-6ЈЈ), 7.31–7.34 (m, 4 H, H-5ЈЈ), 7.42 + 7.54 (2ϫd, 3J =
7.9 Hz, 2ϫ2 H, H-4ЈЈ), 7.58–7.61 (m, 1 H, H-p-Ph), 7.67–7.70 (m,
2 H, H-m-Ph), 7.86–7.90 (m, 1 H, H-5Ј), 7.92–7.93 (m, 2 H, H-o- vacuo, and the residue was purified by column chromatography
Ph), 8.38–8.40 (m, 1 H, H-4Ј), 8.60–8.61 (m, 1 H, H-3Ј), 8.67–8.69
(m, 1 H, H-3), 8.78–8.80 (m, 1 H, H-4), 9.23 (s, 1 H, H-5ЈЈЈ), 9.62–
using alumina and PE/DCM (2:1 and 1:1). Product 6a (132 mg,
0.177 mmol, 73%) was isolated as a red-brown powder. Rf = 0.38
1
9.65 (m, 1 H, H-6Ј), 10.40–10.42 (m, 1 H, H-6) ppm. IR (KBr): ν (alumina, PE/DCM, 1:1). H NMR (400 MHz, CD2Cl2): δ = 0.33
˜
= 3069 (w), 3052 (w), 3025 (w), 2926 (w), 2112 (s), 1635 (m), 1596
(s), 1505 (m), 1487 (m), 1467 (m), 1441 (w), 1249 (w), 1070 (w), H-5ЈЈ), 7.46–7.49 (m, 4 H, H-4ЈЈ), 7.60 (dd, J = 1.6 Hz, 2 H, J =
1053 (w), 1035 (m), 785 (m), 757 (s), 693 (s) cm–1. MS (MALDI- 5.8 Hz, 5,5Ј-H), 8.07 (d, 4J = 1.2 Hz, 2 H, H-3,3Ј), 9.72 (d, 3J =
TOF, dithranol): m/z = 696 [M]+, 1393 [2 M]+. C34H23N5Pt 5.8 Hz, 2 H, H-6,6Ј) ppm. 13C NMR (100 MHz, CD2Cl2): δ = –0.1
(s, 18 H, 6ϫCH3), 7.17–7.21 (m, 2 H, H-6ЈЈ), 7.27–7.31 (m, 4 H,
4
3
(696.68): calcd. C 58.62, H 3.33, N 10.05; found C 58.53, H 3.35,
N 9.90.
(6ϫCH3), 87.2 (C-2ЈЈ), 101.3 (2ϫCϵC-TMS), 103.1 (C-1ЈЈ), 107.1
(2ϫCϵC-bpy), 125.7 (C-5,5Ј), 126.5 (C-3ЈЈ), 128.7 (C-5ЈЈ,6ЈЈ),
Eur. J. Inorg. Chem. 2012, 1795–1809
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1805

L. De Cola, P. Bäuerle et al.
FULL PAPER
130.4 (C-3,3Ј), 132.6 (C-4ЈЈ), 134.6 (C-4,4Ј), 151.9 (C-6,6Ј), 156.7
H-7ЈЈ), 3.76 (s, 2 H, CϵCH), 7.12 (d, 3J = 8.0 Hz, 4 H, H-5ЈЈ), 7.38
(d, 3J = 8.0 Hz, 4 H, H-4ЈЈ), 7.63 (dd, 4J = 1.1 Hz, 2 H, 3J = 5.7 Hz,
(C-2,2Ј) ppm. IR (KBr): ν = 3074 (w), 3055 (w), 3024 (w), 2960
˜
4
3
(m), 2124 (m), 2115 (m), 1611 (s), 1594 (m), 1485 (m), 1416 (m), H-5,5Ј), 8.10 (d, J = 1.0 Hz, 2 H, H-3,3Ј), 9.75 (d, J = 5.8 Hz, 2
1250 (m), 1230 (m), 1221 (m), 950 (m), 871 (m), 845 (s), 753 (m), H, H-6,6Ј) ppm. 13C NMR (100 MHz, CD2Cl2): δ = 14.7 (C-12ЈЈ),
692 (m) cm–1. MS (MALDI-TOF, dithranol): m/z = 745 [M]+, 1490
[2 M]+. C36H34N2PtSi2 (745.94): calcd. C 57.97, H 4.59, N 3.76;
found C 57.93, H 4.62, N 3.58.
23.5 (C-11ЈЈ), 29.9 (C-10ЈЈ), 32.3 (C-9ЈЈ), 32.6 (C-8ЈЈ), 36.6 (C-7ЈЈ),
86.1 (C-2ЈЈ), 87.4 (CϵC-H), 80.7 (CϵC-bpy), 103.2 (C-1ЈЈ), 125.9
(C-3ЈЈ), 126.3 (C-5,5Ј), 128.8 (C-5ЈЈ), 130.8 (C-3,3Ј), 132.5 (C-4ЈЈ),
134.0 (C-4,4Ј), 141.6 (C-6ЈЈ), 151.9 (C-6,6Ј), 156.7 (C-2,2Ј) ppm. IR
Bis(4-hexylphenylethynyl)[4,4Ј-bis(trimethylsilylethynyl)-2,2Ј-bipyr-
idine]platinum(II) (6b): Compound 5 (0.08 g, 0.130 mmol) was dis-
solved in DCM (30 mL) and diisopropylamine (2 mL) under argon.
CuI (3 mg, 0.014 mmol) and 1-ethynyl-4-hexylbenzene (0.073 g,
0.391 mmol) were added. The reaction mixture was stirred at room
temp. overnight. The solvent was removed in vacuo, and the residue
was purified by column chromatography with alumina and PE/
DCM (1:1). Product 6b (90 mg, 0.098 mmol, 75%) remained as a
dark-brown solid. Rf = 0.78 (alumina, DCM/PE, 1:1). 1H NMR
(400 MHz, CD2Cl2): δ = 0.34 (s, 18 H, 6ϫCH3), 0.89–0.93 (m, 6
H, H-12ЈЈ), 1.31–1.41 (m, 12 H, H-9ЈЈ, H-10ЈЈ, H-11ЈЈ), 1.60–1.67
(m, 4 H, H-8ЈЈ), 2.62 (t, 3J = 7.7 Hz, 4 H, H-7ЈЈ), 7.12 (d, 3J =
(KBr): ν = 2955 (m), 2925 (s), 2854 (m), 2115 (m), 1633 (m), 1611
˜
(s), 1504 (s), 1478 (w), 1411 (m), 1229 (w), 843 (w) cm–1. MS
(MALDI-TOF, dithranol): m/z = 768 [M]+, 1538 [2 M]+.
C
42H42N2Pt (769.90): calcd. C 65.52, H 5.50, N 3.64; found C
65.14, H 5.68, N 3.29.
[4,4Ј-Bis(1-benzyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bipyridine]bis(phenyl-
ethynyl)platinum(II) (8a): Complex 6a (60 mg, 0.080 mmol) was dis-
solved in DCM (24 mL) and methanol (6 mL), and KF (12 mg,
0.201 mmol) was added under argon. Cu(CH3CN)4PF6 (9 mg,
0.024 mmol), DIPEA (0.05 mL, 0.32 mmol, 41 mg), elemental cop-
per (2 mg, 0.024 mmol) and benzyl azide (27 mg, 0.201 mmol) were
added. Stirring was continued at room temp. for 2 d. 25% ammonia
(5 mL) in water (15 mL) and DCM (50 mL) were added. After stir-
ring the solution vigorously for some minutes, the layers were sepa-
rated and the aqueous layer was extracted with DCM (50 mL). The
organic layer was washed with 0.1 m Na2/EDTA solution and dried
with Na2SO4. The solvent was removed in vacuo, and the residue
was purified by column chromatography with silica and DCM/di-
ethyl ether (5:1). The solid was dissolved in DCM and PE was
added to precipitate the yellow powder, which was collected by fil-
tration, washed with PE and dried in vacuo. Product 8a (57 mg,
0.065 mmol, 81%) was obtained as a yellow powder. Rf = 0.53 (sil-
ica, DCM/diethyl ether, 10:1). 1H NMR (500 MHz, [D6]DMSO,
375 K): δ = 5.80 (s, 4 H, H-benzyl), 7.19–7.22 (m, 2 H, H-6ЈЈ),
7.31–7.34 (m, 4 H, H-5ЈЈ), 7.41–7.49 (m, 14 H, H-Ph, H-4ЈЈ), 8.33
3
4
8.0 Hz, 4 H, H-5ЈЈ), 7.38 (d, J = 8.0 Hz, 4 H, H-4ЈЈ), 7.55 (dd, J
3
4
= 1.5 Hz, J = 5.8 Hz, 2 H, H-5,5Ј), 8.01 (d, J = 1.4 Hz, 2 H, H-
4,4Ј), 9.68 (d, 3J = 5.8 Hz, 2 H, H-6,6Ј) ppm. 13C NMR (100 MHz,
CD2Cl2): δ = 0.0 (6ϫCH3), 14.7 (C-12ЈЈ), 23.5 (C-11ЈЈ), 29.9 (C-
10ЈЈ), 32.3 (C-9ЈЈ), 32.6 (C-8ЈЈ), 36.6 (C-7ЈЈ), 86.4 (C-2ЈЈ), 101.4
(CϵC-TMS), 103.0 (C-1ЈЈ), 106.7 (CϵC-bpy), 126.0 (C-5,5Ј), 125.9
(C-3ЈЈ), 128.8 (C-5ЈЈ), 130.3 (C-3,3Ј), 132.5 (C-4ЈЈ), 134.7 (C-4,4Ј),
141.5 (C-6ЈЈ), 151.8 (C-6,6Ј), 156.8 (C-2,2Ј) ppm. IR (KBr): ν =
˜
2958 (m), 2927 (s), 2855 (m), 2115 (m), 1635 (m), 1612 (s), 1504
(s), 1481 (w), 1416 (m), 1250 (s), 1229 (m), 845 (s) cm–1. MS
(MALDI-TOF, dithranol): m/z = 914 [M]+, 1825 [2 M]+.
C48H58N2PtSi2 (914.26): calcd. C 63.06, H 6.39, N 3.06; found C
63.08, H 6.50, N 3.04.
4
3
4
(4,4Ј-Diethynyl-2,2Ј-bipyridine)bis(phenylethynyl)platinum(II) (7a):
Complex 6a (23 mg, 0.031 mmol) was dissolved in DCM (9 mL)
and methanol (1 mL), and KF (4 mg, 0.068 mmol) was added. Stir-
ring at room temp. was continued overnight. The solvent was re-
moved in vacuo, and the residue was purified by column
chromatography with alumina and PE/DCM (1:2) and 100 %
DCM. Product 7a (12 mg, 0.020 mmol, 65%) remained as a brown
powder. Rf = 0.51 (alumina, DCM). 1H NMR (400 MHz, CD2Cl2):
δ = 3.78 (s, 2 H, 2ϫCϵCH), 7.18–7.22 (m, 2 H, H-6ЈЈ), 7.28–7.32
(dd, J = 1.7 Hz, J = 5.9 Hz, 2 H, H-5,5Ј), 9.05 (d, J = 1.4 Hz, 2
H, H-3,3Ј), 9.06 (s, 2 H, H-5ЈЈЈ), 9.68 (d, 3J = 5.9 Hz, 2 H, H-
6,6Ј) ppm. 13C NMR (125 MHz, [D6]DMSO, 375 K): δ = 54.1 (C-
benzyl), 89.8 (C-2ЈЈ), 101.6 (C-1ЈЈ), 120.0 (C-3,3Ј), 123.7 (C-5ЈЈЈ),
125.6 (C-5,5Ј), 125.7 (C-3ЈЈ), 128.3 (C-o-Ph), 128.4 (C-m-Ph), 128.6
(C-q-Ph), 128.8 (C-p-Ph) 129.3 (C-5ЈЈ, C-6ЈЈ), 131.6 (C-4ЈЈ), 135.8
(C-4,4Ј), 143.8 (C-4ЈЈЈ), 150.9 (C-6,6Ј), 157.1 (C-2,2Ј) ppm. IR
(KBr): ν = 3106 (w), 3086 (w), 3049 (w), 3034 (w), 2925 (w), 2123
˜
(m), 2111 (m), 1709 (w), 1626 (s), 1594 (m), 1569 (w), 1487 (m),
1456 (m), 1437 (m), 1359 (w), 1234 (m), 1215 (w), 1093 (w), 1047
(w), 1029 (w), 840 (w), 755 (m), 735 (m), 725 (m), 693 (m) cm–1.
MS (MALDI-TOF, dithranol): m/z = 867 [M]+, 763 [M – PhAc]+.
C44H32N8Pt (867.88): calcd. C 60.89, H 3.72, N 12.91; found C
60.65, H 3.74, N 12.88.
4
(m, 4 H, H-5ЈЈ), 7.46–7.49 (m, 4 H, H-4ЈЈ), 7.67 (dd, J = 1.6 Hz,
4
3J = 5.8 Hz, 2 H, H-5,5), 8.12 (d, J = 1.2 Hz, 2 H, H-3,3Ј), 9.76
(d, 3J = 5.8 Hz, 2 H, H-6,6Ј) ppm. 13C NMR (100 MHz, CD2Cl2):
δ = 80.6 (2ϫCϵC-bpy), 87.5 (C-2ЈЈ), 98.9 (2ϫCϵC-H), 103.2 (C-
1ЈЈ), 126.2 (C-3ЈЈ), 126.6 (C-5,5Ј), 128.7 (C-5ЈЈ, C-6ЈЈ), 131.0 (C-
3,3Ј), 132.6 (C-4ЈЈ), 134.2 (C-4,4Ј), 152.0 (C-6,6Ј), 156.7 (C-2,2Ј)
[4,4Ј-Bis(1-benzyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bipyridine]bis(hexyl-
phenylethynyl)platinum(II) (8b): Complex 6b (64 mg, 0.070 mmol)
was dissolved in DCM (24 mL) and methanol (6 mL), and KF
(10 mg, 0.175 mmol) was added under argon. The solution was de-
gassed, and Cu(CH3CN)4PF6 (7 mg, 0.021 mmol), DIPEA
(0.05 mL, 0.280 mmol, 36 mg), elemental copper (1 mg,
0.021 mmol) and benzyl azide (24 mg, 0.175 mmol) were added.
The synthesis and purification were carried out as described above
ppm. IR (KBr): ν = 3295 (m), 3201 (m), 3055 (w), 2119 (s), 2111
˜
(s), 1614 (m), 1593 (m), 1486 (m), 1412 (w), 839 (w), 754 (m), 693
(m) cm–1. MS (MALDI-TOF, dithranol): m/z = 600 [M – H]+, 1202
[2 M]+. C30H18N2Pt (601.58): calcd. C 59.90, H 3.02, N 4.66; found
C 59.49, H 3.42, N 4.43.
(4,4Ј-Diethynyl-2,2Ј-bipyridine)bis(4-hexylphenylethynyl)platinum-
(II) (7b): Complex 6b (60 mg, 0.066 mmol) was dissolved in DCM
(15 mL) and methanol (2 mL), and KF (11 mg, 0.197 mmol) was for 8a. Product 8b (61 mg, 0.059 mmol, 84%) was obtained as an
added. Stirring was continued overnight. The solvent was removed
in vacuo, and the residue was purified by column chromatography
with alumina and DCM/PE (2:1 and 3:1). After drying in vacuo,
7b (48.4 mg, 0.063 mmol, 95%) remained as a brown solid. Rf =
orange powder. Rf = 0.20 (silica, DCM/diethyl ether, 15:1). 1H
NMR (400 MHz, CD2Cl2): δ = 0.89–0.92 (m, 6 H, H-12ЈЈ), 1.28–
1.39 (m, 12 H, H-9ЈЈ, H-10ЈЈ, H-11ЈЈ), 1.59–1.66 (m, 4 H, H-8ЈЈ),
2.59–2.63 (m, 4 H, H-7ЈЈ), 5.36 (s, 4 H, H-benzyl), 7.09 (d, 3J =
8.1 Hz, 4 H, H-5ЈЈ), 7.24 (d, 3J = 8.1 Hz, 4 H, H-4ЈЈ), 7.27–7.28
1
0.31 (alumina, DCM/PE, 4:1). H NMR (400 MHz, CD2Cl2): δ =
3
0.91 (t, J = 6.7 Hz, 6 H, H-12ЈЈ), 1.31–1.38 (m, 12 H, H-9ЈЈ, H- (m, 4 H, H-o-Ph), 7.34–7.36 (m, 6 H, H-m,p-Ph), 7.77 (dd, 4J =
3
3
4
10ЈЈ, H-11ЈЈ), 1.59–1.66 (m, 4 H, H-8ЈЈ), 2.61 (t, J = 7.7 Hz, 4 H, 1.5 Hz, J = 5.9 Hz, 2 H, H-5,5Ј), 8.40 (s, 2 H, H-5ЈЈЈ), 8.53 (d, J
1806 Eur. J. Inorg. Chem. 2012, 1795–1809
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Postfunctionalization of Pt Complexes by Click Chemistry
= 1.0 Hz, 2 H, H-3,3Ј), 9.36 (d, 3J = 5.9 Hz, 2 H, H-6,6Ј) ppm. 13
C
(0.1 mL, 0.491 mmol, 64 mg), elemental copper (3 mg, 0.049 mmol)
NMR (100 MHz, CD2Cl2): δ = 14.7 (C-12ЈЈ), 23.5 (C-11ЈЈ), 29.9 and 4-hexylphenyl azide (83 mg, 0.401 mmol) were added. The syn-
(C-10ЈЈ), 32.3 (C-9ЈЈ), 32.6 (C-8ЈЈ), 36.6 (C-7ЈЈ), 55.1 (C-benzyl), thesis and purification were carried out as described above for 8a.
87.4 (C-2ЈЈ), 102.8 (C-1ЈЈ), 120.1 (C-3,3Ј), 123.7 (C-5ЈЈЈ), 124.9 (C- Product 8e (0.130 g, 0.129 mmol, 79%) remained as an orange
5,5Ј), 126.0 (C-3ЈЈ), 129.0 (C-m-Ph), 129.1 (C-o,q-Ph), 129.6 (C-p-
Ph), 129.9 (C-5ЈЈ), 132.4 (C-4ЈЈ), 135.3 (C-4,4Ј), 141.6 (C-6ЈЈ), 144.5
powder. Rf = 0.57 (silica, DCM/diethyl ether, 25:1). 1H NMR
(400 MHz, CD2Cl2): δ = 0.89–0.93 (m, 6 H, H-15ЈЈЈ), 1.30–1.37 (m,
(C-4ЈЈЈ), 151.4 (C-6,6Ј), 157.1 (C-2,2Ј) ppm. IR (KBr): ν = 2954 12 H, H-12ЈЈЈ, H-13ЈЈЈ, H-14ЈЈЈ), 1.60–1.66 (m, 4 H, H-11ЈЈЈ), 2.65
˜
(w), 2926 (m), 2854 (m), 2113 (m), 1624 (s), 1503 (m), 1556 (m), (t, 3J = 7.7 Hz, 4 H, H-10ЈЈЈ), 7.04–7.13 (m, 6 H, H-5ЈЈ, H-6ЈЈ),
3
1437 (m), 1237 (m), 826 (m), 726 (m) cm–1. MS (MALDI-TOF, 7.19–7.20 (m, 4 H, H-4ЈЈ), 7.24 (d, J = 8.4 Hz, 4 H, H-8ЈЈЈ), 7.71
dithranol): m/z = 1035 [M]+. C56H56N8Pt (1036.20): calcd. C 64.91,
H 5.45, N 10.81; found C 64.81, H 5.54, N 10.94.
(d, 3J = 8.4 Hz, 4 H, H-7ЈЈЈ), 7.92 (d, 3J = 5.8 Hz, 2 H, H-5,5Ј),
8.84 (s, 2 H, H-3,3Ј), 8.92 (s, 2 H, H-5ЈЈЈ), 9.40 (d, J = 5.8 Hz, 2
3
H, H-6,6Ј) ppm. 13C NMR (100 MHz, CD2Cl2): δ = 14.7 (C-15ЈЈЈ),
23.5 (C-14ЈЈЈ), 29.7 (C-13ЈЈЈ), 32.0 (C-12ЈЈЈ), 32.5 (C-11ЈЈЈ), 36.2 (C-
10ЈЈЈ), 88.4 (C-2ЈЈ), 102.7 (C-1ЈЈ), 120.5 (C-3,3Ј), 120.9 (C-8ЈЈЈ),
122.9 (C-5,5Ј), 123.3 (C-5ЈЈЈ), 126.3 (C-3ЈЈ), 128.1 (C-6ЈЈ), 128.5 (C-
5ЈЈ), 130.2 (C-7ЈЈЈ), 132.1 (C-4ЈЈ), 135.0 (C-4,4Ј), 141.3 (C-6ЈЈЈ),
144.4 (C-4ЈЈЈ), 144.9 (C-9ЈЈЈ), 150.6 (C-6,6Ј), 156.6 (C-2,2Ј) ppm.
Bis(phenylethynyl)[4,4Ј-bis(1-phenyl-1H-1,2,3-triazol-4-yl)-2,2Ј-bi-
pyridine]platinum(II) (8c): Complex 6a (60 mg, 0.080 mmol) was
dissolved in DCM (24 mL) and methanol (6 mL), and KF (12 mg,
0.201 mmol) was added under argon. The solution was degassed,
and Cu(CH3CN)4PF6 (9 mg, 0.024 mmol), DIPEA (0.06 mL,
0.322 mmol, 42 mg), elemental copper (2 mg, 0.024 mmol) and
phenyl azide (24 mg, 0.201 mmol) were added. The synthesis and
purification were carried out as described above for 8a. Product 6a
(55 mg, 0.066 mmol, 83%) was obtained as an orange powder. Rf
= 0.19 (silica, DCM/diethyl ether, 10:1). 1H NMR (400 MHz,
CDCl3): δ = 7.14–7.17 (m, 2 H, H-6ЈЈ), 7.22–7.25 (m, 4 H, H-5ЈЈ),
IR (KBr): ν = 3074 (w), 3050 (w), 2954 (m), 2926 (s), 2854 (m),
˜
2122 (m), 2111 (m), 1623 (s), 1593 (m), 1518 (s), 1485 (m), 1443
(m), 1246 (m), 1036 (m), 838 (m), 755 (m) cm–1. HRMS (ESI): m/z
calcd. for C54H52N8Pt [M]+ 1008.4039; found 1008.4003.
(2,2Ј-Bipyridine)bis(phenylethynyl)platinum(II) (9):[21] CODPt-
(CϵCPh)2 (0.05 g, 0.099 mmol) and 2,2Ј-bipyridine (0.016 g,
0.104 mmol) were dissolved in tetrahydrofuran (30 mL) and DCM
(10 mL). The solution was degassed and subsequently heated under
reflux for 3 d. The solvent was removed in vacuo, and the residue
was purified by column chromatography with silica and DCM/di-
ethyl ether (25:1). Product 9 (23 mg, 0.042 mmol, 42%) remained
as a yellow solid. Rf = 0.43 (silica, DCM/diethyl ether, 25:1). 1H
NMR (400 MHz, CD2Cl2): δ = 7.18–7.12 (m, 2 H, H-6ЈЈ), 7.28–
7.32 (m, 4 H, H-5ЈЈ), 7.47–7.49 (m, 4 H, H-4ЈЈ), 7.55–7.58 (m, 2 H,
3
7.39 (d, J = 7.3 Hz, 4 H, H-4ЈЈ), 7.52–7.58 (m, 6 H, H-m,p-Ph),
4
3
7.87–7.89 (m, 4 H, H-o-Ph), 8.05 (dd, J = 1.7 Hz, J = 6.0 Hz, 2
3
H, H-5,5Ј), 8.86 (s, 2 H, H-5ЈЈЈ), 8.96 (s, 2 H, H-3,3Ј), 9.70 (d, J
= 5.7 Hz, 2 H, H-6,6Ј) ppm. 1H NMR (500 MHz, [D6]DMSO,
375 K): δ = 7.20–7.23 (m, 2 H, H-6ЈЈ), 7.31–7.34 (m, 4 H, H-5ЈЈ),
7.43–7.45 (m, 4 H, H-4ЈЈ), 7.61–7.64 (m, 2 H, H-p-Ph), 7.71–7.74
(m, 4 H, H-m-Ph), 8.00–8.02 (m, 4 H, H-o-Ph), 8.42 (dd, 4J =
1.7 Hz, 2 H, 3J = 5.8 Hz, H-5,5Ј), 9.17 (d, 4J = 1.3 Hz, 2 H, H-
3
3,3Ј), 9.69 (s, 2 H, H-5ЈЈЈ), 9.75 (d, J = 5.8 Hz, 2 H, H-6,6Ј) ppm.
3
H-5,5Ј), 8.13–8.19 (m, 4 H, H-3,3Ј, H-4,4Ј), 9.66 (d, J = 4.3 Hz, 2
IR (KBr): ν = 3103 (w), 3072 (m), 2957 (w), 2923 (w), 2111 (m),
˜
H, H-6,6Ј) ppm. 1H NMR (500 MHz, [D6]DMSO, 375 K): δ =
7.18–7.12 (m, 2 H, H-6ЈЈ), 7.29–7.32 (m, 4 H, H-5ЈЈ), 7.38–7.40 (m,
4 H, H-4ЈЈ), 7.86–7.89 (m, 2 H, H-5,5Ј), 8.37–8.40 (m, 2 H, H-4,4Ј),
8.58 (d, 3J = 8.0 Hz, 2 H, H-3,3Ј) 9.64 (d, 3J = 4.6 Hz, 2 H, H-
6,6Ј) ppm. 13C NMR (100 MHz, CD2Cl2): δ = 88.0 (C-2ЈЈ), 102.5
(C-1ЈЈ), 123.9 (C-3,3Ј), 126.4 (C-3ЈЈ), 128.2 (C-5,5Ј), 128.9 (C-5ЈЈ,
C-6ЈЈ), 132.5 (C-4ЈЈ), 139.8 (C-4,4Ј), 151.8 (C-6,6Ј), 157.0 (C-2,2Ј)
ppm. 13C NMR (125 MHz, [D6]DMSO, 375 K): δ = 89.5 (C-2ЈЈ),
101.9 (C-1ЈЈ), 125.5 (C-3,3Ј), 126.1 (C-3ЈЈ), 128.7 (C-5,5Ј), 128.8 (C-
5ЈЈ, C-6ЈЈ), 132.0 (C-4ЈЈ), 140.3 (C-4,4Ј), 150.9 (C-6,6Ј), 156.8 (C-
1623 (s), 1596 (m), 1504 (m), 1486 (m), 1425 (m), 1245 (w), 1034
(m), 755 (m), 689 (m) cm–1. MS (MALDI-TOF, dithranol): m/z =
838 [M]+. C42H28N8Pt (839.83): calcd. C 60.07, H 3.36, N 13.34;
found C 60.07, H 3.40, N 13.07.
Bis(4-hexylphenylethynyl)[4,4Ј-bis(1-phenyl-1H-1,2,3-triazol-4-yl)-
2,2Ј-bipyridine]platinum(II) (8d): Complex 6b (67 mg, 0.073 mmol)
was dissolved in DCM (24 mL) and methanol (6 mL), and KF
(11 mg, 0.183 mmol) was added under argon. The solution was de-
gassed, and Cu(CH3CN)4PF6 (8 mg, 0.022 mmol), DIPEA
(0.05 mL, 0.293 mmol, 38 mg), elemental copper (1 mg,
0.022 mmol) and phenyl azide (22 mg, 0.183 mmol) were added.
The synthesis and purification were carried out as described above
for 8a. Product 8d (54 mg, 0.053 mmol, 73%) was obtained as a
yellow powder. Rf = 0.46 (silica, DCM/diethyl ether, 25:1). 1H
NMR (400 MHz, CD2Cl2): δ = 0.89–0.91 (m, 6 H, H-12ЈЈ), 1.30–
1.36 (m, 12 H, H-9ЈЈ, H-10ЈЈ, H-11ЈЈ), 1.56–1.57 (m, 4 H, H-8ЈЈ),
2,2Ј) ppm. IR (KBr): ν = 3074 (w), 3052 (w), 2122 (m), 2113 (s),
˜
1605 (m), 1593 (m), 1485 (s), 1449 (m), 1160 (m), 1068 (m), 757
(s), 695 (m) cm–1. MS (MALDI-TOF, dithranol): m/z = 553 [M]+,
1107 [2 M]+. C26H18N2Pt (553.53): calcd. C 56.42, H 3.28, N 5.06;
found C 56.33, H 3.28, N 4.92.
Supporting Information (see footnote on the first page of this arti-
cle): Absorption, excitation and emission spectra of all complexes
are provided in the Supporting Information.
3
2.55–2.59 (m, 4 H, H-7ЈЈ), 7.05 (d, J = 8.1 Hz, 4 H, H-5ЈЈ), 7.29
3
(d, J = 8.0 Hz, 4 H, H-4ЈЈ), 7.51–7.58 (m, 6 H, H-m,p-Ph), 7.88–
3
7.90 (m, 4 H, H-o-Ph), 8.06 (dd, 4J = 1.8 Hz, 2 H, J = 5.8 Hz, H-
5,5Ј), 8.91 (s, 2 H, H-5ЈЈЈ), 8.97 (s, 2 H, H-3,3Ј), 9.73 (d, 3J =
Acknowledgments
5.8 Hz, 2 H, H-6,6Ј) ppm. IR (KBr): ν = 2953 (m), 2926 (m), 2853
˜
(m), 2120 (m), 2111 (m), 1624 (s), 1598 (m), 1504 (s), 1247 (m),
1034 (m), 824 (m), 759 (m) cm–1. MS (MALDI-TOF, dithranol):
m/z = 1008 [M]+, 2015 [2 M]+. C54H52N8Pt (1008.15): calcd. C
64.34, H 5.20, N 11.12; found C 64.47, H 5.32, N 10.98.
We thank the Dutch Polymer Institute (DPI) for funding the pro-
ject. This research formed part of the research programme of the
DPI, within project 628.
[4,4Ј-Bis{1-(4-hexylphenyl)-1H-1,2,3-triazol-4-yl}-2,2Ј-bipyridine]bis-
(phenylethynyl)platinum(II) (8e): Complex 6a (0.122 g, 0.164 mmol)
was dissolved in DCM (40 mL) and methanol (10 mL), and KF
(24 mg, 0.410 mmol) was added under argon. The solution was de-
gassed, and Cu(CH3CN)4PF6 (18 mg, 0.049 mmol), DIPEA
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www.eurjic.org
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