ARTICLE
group. The last step is the exchange of Br against N3 group
which was conducted in analogy to the literature.
was removed by distillation, and the brown residue was dis-
solved in chloroform (20 mL) and extracted two times with
water (60 mL). The organic phase was collected, dried with
Na2SO4, filtered over a glass frit, concentrated by evapora-
tion, and the crude product was purified via silica gel
column chromatography (Rf: 0.12, CHCl3).
Yield: 89%. 1H NMR (400 MHz; CDCl3): d (ppm) ¼ 8.06 (s, 1H),
6.94 (s, 1H), 3.67 (t, 2H, J ¼ 7.4 Hz), 3.26 (t, 2H, J ¼ 6.7 Hz), 1.91
(s, 3H), 1.68 (m, 2H), 1.59 (m, 2H), 1.30–1.45 (m, 4H).
Synthesis of Thymine-Functionalized PCL (1)
via Click-Reaction
1
Yield: 55%. H NMR (400 MHz, CDCl3) ppm: 7.84 (d, 4H, J ¼
8.6 Hz), 7.46 (m, 4H), 7.33 (m, 4H) 7.07 (d, 4H, J ¼ 8.6 Hz);
13C NMR (100 MHz, CDCl3) ppm: 197.71, 159.65 156.50,
133.37, 132.37, 130.97, 127.70, 124.01, 122.53, 118.26,
117.85, and 114.01.
The functionalization of PCL with a thymine endgroup (1)
was conducted via azide/alkyne click-reaction, using 2,20-
bipyridyl as base and Cu(I)Br as a catalyst. The reaction was
done in a one-necked flask carefully dried and purged with
argon. Alkyne-functionalized PCL (4a; 200 mg, 4.8 ꢂ 10ꢀ5
mol) and azide-functionalized thymine (5; 36 mg, 1.4 ꢂ
10ꢀ4 mol) were dissolved in 4 mL of dry toluene, then a so-
lution of 2,20-bipyridyl (148 mg, 9.5 ꢂ 10ꢀ4 mol) in toluene
(2 mL) was added via a syringe and the mixture was
degassed with argon to remove the oxygen for 30 min. Sub-
sequently, a catalytic amount of Cu(I)Br (4.7 mg, 3.3 ꢂ 10ꢀ5
mol) was weighed in, the flask was closed by a cap with a
septum, and the mixture was degassed with argon again.
The reaction proceeded for 24 h by stirring at 80 ꢁC. After-
wards, the reaction mixture was cooled down to room tem-
perature and filtered over a short neutral Al2O3 column to
remove the Cu(I)Br. The solvent was removed by distillation;
the crude product was dissolved in 10 mL of DCM, slowly
added in methanol (200 mL) and left overnight for complete
precipitation. The precipitation step was repeated two times
to remove the excess of azide-functionalized thymine (5) and
2,20-bipyridyl, which are well soluble in methanol. The pure
product 1a was filtered off and dried in high vacuum.
Conversion with Dicyandiamide. 4,4-Bis-(3-cyano-phe-
noxy)-benzophenone (0.454 g, 1.09 mmol), dicyandiamide
(0.366 g, 1.09 mmol), and KOH (0.03 g, 1.09 mmol) were sus-
pended in dry isopropanol, degassed with argon, and stirred
for 6 days at 90 ꢁC. Afterwards, the reaction mixture was
cooled down to room temperature, and the crude product (2)
was collected by filtration over a frit, washed with water and
isopropanol three times, and dried in high vacuum.
Yield: 75%.1H NMR (400 MHz, DMSO-d6) ppm: 8.09 (d, 2H,
J ¼ 8.1 Hz), 7.93 (s, 2H), 7.77 (d, 4H, J ¼ 8.8 Hz), 7.53 (t,
2H, J ¼ 8.0 Hz), 7.30 (d, 1H, J ¼ 7.9 Hz), 7.09 (d, 1H, J ¼ 8.9
Hz), 6.72 (s, 8H). 13C NMR (100 MHz, DMSO-d6) d (ppm):
194.00, 169.45, 167.75, 161.86, 154.87, 140.09, 135.72,
130.77, 130.40, 124.85, 123.56, 119.61, and 118.32.
Synthesis of Initiator, Polymerization and
Functionalization of PIB
2-Chloro-2,4,4-trimethyl-pentane was used as initiator for
the living cationic polymerization and was synthesized
according to the literature.43
Yield: 72% .1H NMR (400 MHz (CD3)2SO): d (ppm) ¼ 11.14
(s, 1H), 7.82 (s, 1H), 7.49 (s, 1H) 4.31 (t, 2H, J ¼ 5.3 Hz),
4.27 (t, 2H, J ¼ 7.2 Hz), 3.98 (t, 72H, J ¼ 6.4 Hz), 3.58 (t, 2H,
J ¼ 7.2 Hz), 2.61 (t, 2H, J ¼ 6.6 Hz), 2.27 (t, 72H, J ¼ 7.2
Hz), 1.74 (s, 3H), 1.55 (m, 152 H), 1.29 (m, 76H).
Yield: 90% 1H NMR (400 MHz; CDCl3): d (ppm) ¼ 1.86 (s,
2H), 1.65 (s, 6H), 1.04 (s, 9H).
Polymerization of isobutylene was conducted in analogy to
the literature44 using 2-chlor-2,4,4-trimethyl-pentane/TiCl4 as
initiating system to achieve allyl-telechelic polyisobutylene.
The synthesis of the PCL-polymer 1b was conducted in anal-
ogy to 1a.
Yield: 90%. 1H NMR (400 MHz; CDCl3): d (ppm) ¼ 5.85 (m,
1H), 5.00 (m, 2H), 2.01 (d, 1H, J ¼ 7.4 Hz), 1.42 (s, 146 H),
1.11 (s, 438 H), 0.99 (s, 15 H). The synthesis of the azide-tel-
echelic polyisobutylen (6) was achieved in analogy to the lit-
erature45 starting from allyl-telechelic polyisobutylen and
includes three steps. The first step was the reaction between
allyl-telechelic polyisobutylen and 9-borabicyclo[3.3.1.]no-
nane/3-chloroperbenzoicc acid to introduce OH endgroup.46
The second step was the formation of Br-telechelic PIB via
the Appel reaction whereby hydroxy telechelic PIB reacts
with triphenylphosphine/carbon tetrabromide. The last step
was the exchange of Br against N3 group using trimethylsilyl
azide/tetrabutylammonium fluoride.45
Synthesis of 4,4-Bis-[3-(2,4-Diamino-[1,3,5]triazin-6-yl)-
phenoxy]benzophenone (2)
Compound (2) was synthesised in analogy to the strategy
reported by Beijer et al.42 The synthetic approach includes
two steps: (a) synthesis of 4,4-bis-(3-cyano-phenoxy)-benzo-
phenone and (b) the conversion with dicyandiamide.
Synthesis of 4,4-Bis-(3-Cyano-phenoxy)benzophenone. 4,4-
Difluorobenzophenone (0.450 g, 0.002 mol), 3-cyanophenole
(0.476 g, 0.002 mol), K2CO3 (0.830 g, 0.002 mol), dry tolu-
ene (20 mL), and dry DMA (20 mL) were placed into a
50 mL round-bottom flask equipped with a Dean-Stark trap
and a condenser and purged with argon. The reaction mix-
Yield: 90% 1H NMR (400 MHz; CDCl3): d (ppm) ¼ 3.23 (t, 2H,
ꢁ
ture was heated to 110 C via an oil bath for the period of 6
J ¼ 6.9 Hz), 1.42 (s, 146H), 1.11 (s, 438 H), 0.99 (s, 15H)
h while liberated water was condensed and separated using
a Dean-Stark apparatus. Afterward, the toluene was removed
by distillation, and the reaction mixture was stirred to reflux
for 72 h at 170 ꢁC. Finally, the mixture was cooled down
to 100 ꢁC and filtered over filter paper. In addition, DMF
Synthesis of 6-(4-Ethynylbenzyl)-1,3,5-triazine-
2,4-diamine (7)
The synthesis was conducted in analogy to the strategy
reported by Herbst et al.47 In a two-neck round-bottom flask,
SUPRAMOLECULAR POLY(e-CAPROLACTONE)–POLY(ISOBUTYLENE), OSTAS ET AL.
3407
Ostas, Elena
