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interactions as driving force to form other well-defined aggre-
gates. On the other hand, hollow spherical structures can be
found in the 50% hexane–dioxane solution of 3 (Figure 4b).
This formation can be contributed by the sterically bulky tert-
butyl groups on 3 which hinder close packing of the platinu-
m(II) terpyridine moieties. Further increase in hexane content
of the solution of 3 only results in the formation of similar
hollow spherical structures, and no morphological transforma-
tion, as in the study of 1, can be found. This may arise from
the absence of Pt···Pt, p–p and hydrophobic–hydrophobic in-
teractions among the complex 3 molecules, and hence com-
pact superstructures cannot be formed. Together with the UV/
Vis absorption and emission studies of 3 (Figures S19–S21), it is
believed that the bulky tert-butyl groups would hinder the
close packing of the platinum(II) units, which in the absence of
other non-covalent interactions, results in no MMLCT emission
or excimer emission upon increasing the hexane content.
Therefore, 3 would remain weakly emissive at high hexane
content (Figure S21).
of analytical grade and were used without further purification. The
reactions were performed under N2 atmosphere using standard
Schlenk techniques unless specified otherwise.
1
Physical Measurements and Instrumentation. H NMR spectra
were recorded with a Bruker AVANCE 400 (400 MHz) or DPX-300
(300 MHz) Fourier transform NMR spectrometer at room tempera-
ture with tetramethylsilane (Me Si) as the internal reference. Posi-
4
tive-ion FAB mass spectra were recorded on a Thermo Scientific
DFS high-resolution magnetic sector mass spectrometer. MALDI-
TOF-MS were recorded by using an Autoflex Bruker MALDI-TOF MS
system using trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenyli-
dene]malononitrile (DCTB) as the matrix. IR spectra were obtained
as KBr disks by using a Bio-Rad FTS-7 FTIR spectrometer (4000-
ꢀ1
4
00 cm ). Elemental analyses of the platinum(II) complexes were
performed on a Flash EA 1112 elemental analyzer at the Institute
of Chemistry, Chinese Academy of Sciences. Measurements of mo-
lecular mass and molecular mass distribution of a-alkyne-PS were
performed at 308C on Waters 1500 Series gel permeation chroma-
tography (GPC) system equipped with two Waters 515 HPLC
pumps, a Waters 2414 refractive index detector, a 2998 photodiode
array detector and a Styragel HR 3 THF column. Polystyrenes with
narrow molecular weight distribution were used as calibration
standards. THF was used as an eluent at
a flow rate of
ꢀ1
Conclusions
1.0 mLmin . Steady-state excitation and emission spectra were re-
corded on a SPEX Fluorolog-3 model FL3-211 fluorescence spectro-
fluorometer equipped with an R2658P PMT detector. The UV-visible
spectra were obtained by using a Cary 50 (Varian) spectrophotom-
eter equipped with a Xenon flash lamp. Dynamic light scattering
(DLS) measurements were performed at ambient temperature
In conclusion, through simple and versatile functionalization of
the terpyridine ligand and promising alkyne coordination,
a new class of luminescent amphiphilic alkynylplatinum(II) ter-
pyridine–polystyrene complexes has been designed and syn-
thesized. With systematic tuning of the balance of hydrophilici-
ty and hydrophobicity, the complexes are shown to undergo
self-assembly into different superstructures by the systematic
variation of the solvent composition, similar to that of amphi-
philic block copolymers. In addition to hydrophobic–hydropho-
bic interactions which are the main driving forces for the self-
assembly of amphiphilic block copolymers, the Pt···Pt and/or
p–p interactions among the platinum(II) terpyridine moieties
have allowed the complexes to form transformable superstruc-
tures with unique luminescence turn-on and spectroscopic
changes. The present work should provide insights into the
design of new classes of luminescent amphiphilic materials
which can be applicable in the area of nanotechnology and
biomedical diagnostics. Moreover, it should open up a new
strategy to prepare block copolymer mimetics by the introduc-
tion of promising metal-ligand coordination for the develop-
ment of new functional materials.
using a Zetasizer 3000HSA with internal HeNe laser (l =632.8 nm)
0
from Malvern (UK). Transmission electron microscopy (TEM) and
the energy-dispersive X-ray (EDX) experiments were performed on
a Philips CM100 transmission electron microscope with an acceler-
ating voltage of 200 kV or a Philips Tecnai G2 20 S-TWIN transmis-
sion electron microscope with an accelerating voltage of 200 kV at
the Electron Microscope Unit of The University of Hong Kong. The
TEM samples were prepared by drop-casting dilute solutions onto
a carbon-coated copper grid which was then allowed to undergo
slow evaporation of the solvents in air for about 15 minutes.
Synthesis
a-Alkyne-PS. The polymer was synthesized according to a reported
[67]
1
method. Yield: 5.5 g (52%). H NMR (400 MHz, CDCl , 298 K, rela-
3
tive to Me Si): d=0.95–0.97 (br, ꢀC(CH ) ꢀ), 1.43–2.00 (br, backbone
4
3 2
ꢀCH
ꢀ and ꢀCHꢀ), 4.00–4.40 (br, ꢀCꢂCꢀCH ꢀ, ꢀCꢂCꢀH), 6.20–
2
2
ꢀ1
7
.20 ppm (br, phenyl). IR (KBr disk): n˜ =2130 cm (w; v(CꢂC)). GPC
(versus polystyrene in THF): M =2686 Da, M =2873 Da, PDI=
n
w
1
.07.
’-{[Tri(ethylene glycol) monomethyl ether]phenyl}-2,2’:6’,2’’-ter-
pyridine (tpy-C -TEG). It was synthesized according to a litera-
ture procedure for a related terpyridine.
4
Experimental Section
H
6 4
[68]
Yield: 3.6 g (35%).
H NMR (400 MHz, CDCl , 298 K, relative to Me Si): d=3.38 (s, 3H, ꢀ
Materials and Reagents. Propargyl alcohol, 2-bromo-2-methylpro-
pionyl bromide, styrene, N,N,N’,N’’,N’’-pentamethyldiethylenetria-
mine (PMDETA), 1,4-dioxane (spectrophotometric grade, ꢁ99%)
were purchased from Sigma–Aldrich Co. Ltd. Triethylamine was
purchased from Acros Organic Company. Copper(I) bromide (CuBr)
was purchased from AK Scientific. 2-Acetylpyridine was purchased
from Alfa Aesar. Styrene was purified by passing through basic alu-
minum oxide to remove any stabilizers before use. Triethylamine
1
3
4
CH ), 3.50–3.76 (m, 8H, ꢀOCH ꢀ), 3.91 (t, J=4.7 Hz, 2H, ꢀOCH ꢀ),
3
2
2
4
7
6
.20 (t, J=4.7 Hz, 2H, ꢀOCH ꢀ), 7.05 (d, J=8.8 Hz, 2H, ꢀC H ꢀ),
2
6
4
.34 (m, 2H, ꢀC H ꢀ), 7.84–7.90 (m, 4H, tpy), 8.65–8.74 ppm (m,
6
4
+
H, tpy). Positive FAB-MS: m/z=472.0 [M+H] .
4’-[3,5-Bis(dodecyloxy)phenyl]-2,2’:6’,2’’-terpyridine
(tpy-C H -
6 3
(
OC H ) –3,5). It was synthesized according to a literature proce-
12 25 2
[4]
1
dure for a related terpyridine. Yield: 3.1 g (56%). H NMR
400 MHz, CDCl 298 K, relative to Me Si): d=0.88 (t, J=6.3 Hz, 6H,
was distilled under N atmosphere before use. Propargyl 2-bromoi-
2
(
[64]
[65]
3,
4
sobutyrate, tri(ethylene glycol) monomethyl ether tosylate, 4-
tri(ethylene glycol) monomethyl ether]benzaldehyde were syn-
ꢀ
CH ), 1.20–1.40 (m, 40H, ꢀCH ꢀ), 4.04 (t, J=6.3 Hz, 4H, ꢀOCH ꢀ),
[66]
3
2
2
[
6
.55 (s, 1H, ꢀC H ꢀ), 7.00 (s, 2H, ꢀC H ꢀ), 7.35 (t, J=8.0 Hz, 2H,
6
3
6
3
thesized according to reported procedures. All other reagents were
&
&
Chem. Asian J. 2017, 00, 0 – 0
6
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