DOI: 10.1039/C5TC01703C
Journal of Materials Chemistry C
ARTICLE
Journal Name
coordination networks can be achieved in solution by a self-assembly ethanol (50 mL) was heated to reflux for 5 days and cooled to room
process between Ln(III) ions and ditopic ligands and can result in the temperature afterwards. The precipitate was filtered off and washed
formation of dynamic stimuli-responsive materials.12 Furthermore, it with ethanol to yield the desired product as an off-white solid (0.67 g,
has been found that the concentration, ligand to metal ratio as well as 1.24 mmol, 72 %). The product was further purified by
the ligand flexibility plays an important role on the morphology of the recrystallization from glacial acid which was repeated for five times.
1
3
coordination network in solution, whereby changes from a branched
H NMR (500 MHz, CDCl
3
): δ (ppm) = 7.38 (dd, 4H, JHH = 8.79,
1
9
3
network to polymeric rings can be achieved. However, compared to 4.75 Hz, N-CH=CH-CH=CH-C), 7.90 (dd, 4H, JHH = 8.49, 7.92 Hz,
studies of morphology controllable self-assembled supramolecular N-CH=CH-CH=CH-C), 8.07 (s, 4H, PhH), 8.69 (d, 4H, JHH = 7.97
Ln(III) coordination networks in solution, their properties have been Hz, N-CH=CH-CH=CH-C), 8.76 (d, 4H, JHH = 4.69 Hz, N-CH=CH-
3
3
rarely studied in the solid state. To further extend the knowledge in CH=CH-C), 8.81 (s, 4H, Ph-PyH). ES+ TOF HRMS (CHCl
3
): m/z
541.2136), 271.0865 [M +
271.1104). Elemental Analysis (540.62
+
+
25 6
this area, we herein report the formation of emissive Eu(III) based 541.1641 [M + H] (calc. for C36H N
2
+
2+
26 6
metallo-supramolecular polymers with a solid state controllable 2H] (calc. for C28H N
morphology.
g/mol) found: C 79.82, H 4.25, N 15.38, expected: C 79.98, H 4.47,
N 15.55
Experimental
Preparation of metallo-supramolecular polymers
Materials
For the preparation of the metallo-supramolecular polymers in a
ligand to metal ratio of 1:1, Eu(NO
3
)
3
·5H
2
O (0.1 mmol) was dissolved
All commercially obtained chemicals were used as received
3 2
without any further purification. Eu(NO )·5H
O was stored in a in a mixture of acetonitrile and chloroform (v:v / 1:1, 200 mL in total).
glovebox under controlled atmosphere. All solvents were of Ligand 1 (0.1 mmol) in chloroform (100 mL) was sonicated until
HPLC grade. If not otherwise stated, all synthetic procedures and complete dissolution. The resulting solution was added dropwise
measurements were carried out at room temperature.
3 3
under vigorous stirring to the solution of Eu(NO ) at room
temperature. After complete addition the resulting solution was
allowed to evaporate slowly under an atmosphere of nitrogen. After
several hours an off-white precipitate appeared which was filtered off
and washed several times with chloroform and acetonitrile. The
resulting powder was dried under vacuum overnight. For the metallo-
supramolecular polymers in a ligand to metal ratio of 2:1 and 3:1, the
amount of ligand added was adjusted to 0.2 mmol and 0.3 mmol
respectively while the other parameters remained constant. The
obtained yields were 92% (ligand to metal ratio 1:1), 81% (ligand to
metal ratio 2:1), and 63% (ligand to metal ratio 3:1).
Synthesis of ligand 1
The terpyridine-based ditopic ligand was prepared according to a
modified reported literature three step synthetic procedure.
2
0,21
(2E,2'E)-3,3'-(1,4-phenylene)bis(1-(pyridin-2-yl)prop-2-en-1-one)
(1a) Terephthalaldehyde (1.8 g, 13.42 mmol, 1 eq) was added to a
mixture of potassium hydroxide (1.5 g, 26.84 mmol, 2 eq) in water
10 mL) and methanol (250 mL). After complete dissolution, 2-
(
acetylpyridine (3 mL, 26.84 mmol, 2 eq) was added and a yellow
precipitate occurred. The resulting suspension was left stirring for two
days at room temperature. Afterwards the precipitate was filtered off,
Instrumentation and methods
washed with methanol, and dried in air overnight. The desired product
1
was obtained as a yellow solid (3.44 g, 10.11 mmol, 75%). H NMR NMR spectra were recorded on a Bruker 400 MHz and on a JEOL
3
): δ (ppm) = 7.50 (dd, 2H, JHH = 7.84, 4.58 Hz, N- 500 MHz spectrometer. High resolution mass spectra were
CH=CH-CH=CH-C), 7.77 (s, 4H, PyH), 7.89 (dd, 2H, JHH = 7.90, recorded on a Shimdazu LCMS-IT-TOF Liquid Chromatograph
3
(
400 MHz, CDCl
3
3
7
.80 Hz, N-CH=CH-CH=CH-C), 7.93 (d, 2H, JHH = 16.05 Hz, OC- Mass Spectrometer. Samples for mass spectra had a concentration
3
-4
CH=CH), 8.20 (d, 2H, JHH = 7.86 Hz, N-CH=CH-CH=CH-C), 8.35 of about 1 x 10 M and were filtered through a 0.2 µm syringe
3
3
(
d, 2H, JHH = 16.11 Hz, OC-CH=CH), 8.75 (d, 2H, JHH = 4.77 Hz, filter prior to injecting into the spectrometer. Elemental analysis
1
3
N-CH=CH-CH=CH-C). C NMR (100 MHz, CDCl
3
): δ (ppm) = was performed on a Thermo Scientific Elemental Analyzer (Flash
1
1
(
22.0, 123.12, 127.14, 129.41, 137.21, 137.32, 143.72, 149.04, 1112 Series) with a typical sample amount of around 2 mg.
+
54.24, 189.47. ES+ TOF HRMS (CHCl
3
): m/z 341.1303 [M + H]
Thermogravimetic analysis was carried out on a TGA Q500 (TA
Instruments) using an alumina sample pan. The quantity per
sample for a typical experiment was around 10 mg. The
+
calc. for C22
H N
17 2
O
2
341.1285).
1
,4-Bis[1,5-dioxo-1,5-bis(2-pyridyl)pentan-3-yl]benzene (1b)
A
mixture of (2E,2'E)-3,3'-(1,4-phenylene)bis(1-(pyridin-2-yl)prop-2- experiments were performed under nitrogen gas with a flow rate
en-1-one) (3 g, 8.81 mmol, 1 eq), 2-acetylpyridine (2.16 g, 9.39 mmol, of 60 ml/min. Samples were heated up from room temperature to
o
o
2
(
.2 eq) and potassium hydroxide (1.09 g, 19.39 mmol, 2.2 eq) in water 800 C with a ramp rate of 10 C/min. Elemental analysis was
10 mL) and ethanol (250 mL) was set to reflux overnight and allowed performed by X-ray photoelectron spectroscopy on a Thermo
to cool to room temperature afterwards. The resulting dark red Fischer Scientific Theta Probe XPs with an Al K alpha
solution was filtered and the obtained solid was washed several times monochromatic X-ray source with survey scan pass energy of 200
with ethanol to give the desired product as a white solid (3.39 g, 5.81 eV and high resolution scan pass energy of 40 eV. Microscope
1
mmol, 66 %). H NMR (500 MHz, CDCl
3
): δ (ppm) = 3.61 (d, 8H, slides (Sail Brand Cat. No. 7101) were cut to an approximate size
), 4.09 (q, 2H, JHH = 7.01 Hz, Ph-CH-(CH
), of 1x1 inch and were sonicated in soap (Hellmanex II), DI water,
3
3
J
7
HH = 6.94 Hz, CH
2
2 2
)
3
o
.29 (s, 4H, PhH), 7.43 (dd, 4H, JHH = 7.41, 4.80 Hz, N-CH=CH- acetone, methanol, iso-propanol (20 min each) and dried at 100 C
CH=CH-C), 7.79 (dd, 4H, JHH = 7.23, 8.09 Hz, N-CH=CH-CH=CH- overnight. Prior to spin-coating the glass slides were further treated
C), 7.94 (d, 4H, JHH = 8.01 Hz, N-CH=CH-CH=CH-C), 8.63 (d, 4H, under a Novascan PSD-UVT UV Ozone cleaner for 15 min at
HH = 4.79 Hz, N-CH=CH-CH=CH-C). ES+ TOF HRMS (CHCl
3
): room temperature. Spin-coated samples were prepared using a
3
3
3
J
+
+
m/z 583.2353 [M + H] (calc. for C36
H
31
N
4
O
4
583.2340), 605.2164 Headway Research Inc. spin coater (model PWM32). Typical spin
4
605.2159).
coating parameters were set to a speed of 4000 rpm, speed ramp of
+
+
[
M + Na] (calc. for C36
H
30
N
4
NaO
,4-Bis(2,2':6',2''-terpyridine-4'-yl)benzene (ligand 1)
suspension of 1,4-bis[1,5-dioxo-1,5-bis(2-pyridyl)pentan-3- JEOL FESEM JSM6700F instrument with an accelerating voltage
1
A
1000 rpm/sec and time of 50 sec. SEM images were obtained on a
yl]benzene (1 g, 1.72 mmol) and ammonium acetate (5 g) in abs. of 15 kV using an in-lens detector at a working distance of 7 mm.
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012