Paper
Soft Matter
Experimental section
Materials
DMF, and stirred at ambient temperature overnight. The mixture
was filtered and the filtrate was evaporated to dryness. The product
was obtained after precipitation in 95% ethanol. After drying in a
0
0
2
,3 -O-Isopropylidene guanosine (G, J&K, 98%) was purified
twice by evaporating from dried pyridine. N-Isopropyl acrylamide
NIPAM, J&K, 99%) was purified by recrystallization from hexane.
vacuum oven overnight at room temperature, it was obtained as a
1
white powder. H-NMR (400 MHz, DMSO-d ), d (TMS, ppm): 10.71
6
(
2
0
(
(
1H, NH), 7.84 (1H, H-1), 6.54 (2H, NH
1H, H-2 ), 5.17 (1H, H-3 ), 4.37 (2H, H-4 ), 4.28 (1H, H-5 ),
O), 2.50 (DMSO-d
.32 (3H, H-3).
2
), 6.03 (1H, H-1 ), 5.24
0
,2 -Azobis(isobutyronitrile) (AIBN, TCI, 98%) was purified by
recrystallization from ethanol. Propargyl alcohol (Xiya (Shandong),
9%) and e-caprolactone (e-CL, J&K, 99%) were distilled twice
under reduced pressure, respectively. Besides, all solvents taking
0
0
0
0
0
3
1
.32 (H
2
6
), 1.51 (3H, H-2), 1.37 (6H, H-6 ),
9
part in the reactions were distilled to dewater, i.e. pyridine, Synthesis of alkyne-terminal poly(e-caprolactone) (PCL-alkyne)
dichloromethane (DCM), N,N-dimethylformamide (DMF) and
toluene. Other unmentioned chemicals were used directly without
further treatment, i.e. 4-dimethylaminepyridine (DMAP, KeLong
PCL-alkyne was prepared by the ROP reaction with propargyl
28
alcohol as an initiator. Novozyme 435 was added to a dried
00 mL round-bottom flask, which was previously deoxyge-
1
(Chengdu), AR), Cu(I)Br (J&K, 98%), 1,1,4,7,7-pentamethyldiethylene-
nated by degassing and backfilling with nitrogen three times.
Dry toluene, dry propargyl alcohol and dry e-caprolactone were
then injected under a nitrogen atmosphere. When homo-
genized, the transparent solution was stirred at 70 1C for 24 h
under a N2 atmosphere. After cooling to room temperature,
Novozyme 435 was removed by filtration. The filtrate was
removed under reduced pressure and then dissolved in chloro-
triamine (PMDETA, J&K, 98%), 2-bromoisobutyryl bromide (BiBB,
J&K, 98%), and 2-aminoethanethiol (AETꢀHCl, Alfa Aesar, 98%).
0
0
0
Synthesis of 5 -O-isobromobutyryl-2 ,3 -O-isopropylidene
guanosine (G-Br)
2
0,24
0 0 0
5 -O-isobromobutyryl-2 ,3 -
According to literature procedures,
0
0
O-isopropylidene guanosine was obtained by the reaction of 2 ,3 -
O-isopropylidene guanosine (G) and 2-bromoisobutyryl bromide
form. The product was obtained after precipitation in cold diethyl
1
ether. H-NMR (400 MHz, CDCl
3
), d (TMS, ppm): PCL-alkyne: 1.38
(BiBB) employing DMAP as the catalyst under a nitrogen atmo-
(H-4), 1.65 (H-3, H-5), 2.31 (H-2), 2.47 (HCRC–), 3.65 (H-7), 4.06
sphere at room temperature for 18 h. After quenching with 2 mL
MeOH and removal of the solvent, the product was obtained from
(
H-6), 4.57 (HCRC–CH –).
2
chromatography (silica gel) with 2% MeOH in CH Cl as an eluent. Synthesis of guanosine-functionalized poly(e-caprolactone)
2
2
1
H-NMR (400 MHz, DMSO-d ), d (TMS, ppm): 10.73 (1H, NH), 7.86 (G-PCL)
6
0
0
(1H, H-1), 6.56 (2H, NH
2
), 6.04 (1H, H-1 ), 5.23 (1H, H-2 ), 5.18
29,30
According to a procedure as described,
a mixture of
0
0
0
(1H, H-3 ), 4.38, 4.27 (3H, H-4 , H-5 ), 3.36 (H
2
O), 2.50 (DMSO-d
6
),
0
.3 mmol G-N and 0.1 mmol PCL-alkyne was added into the
3
0
1
.86 (6H, H-6 ), 1.51 (3H, H-2), 1.32 (3H, H-3).
pre-dried Schlenk flask, previously deoxygenated by degassing
and backfilling with argon three times. When homogenized
with DMF (50 mL), catalytic amounts of Cu(I)Br and PMDETA
were added. The mixture was stirred under a nitrogen atmo-
Synthesis of guanosine-terminal poly(N-isopropylacrylamide)
G-PNIPAM)
G-PNIPAM was prepared via an ATRP reaction.
(
2
6,27
A mixture of sphere in a pre-heated oil-bath at 60 1C for 24 h. The reaction
G-Br (0.5 mmol) and NIPAM (45 mmol) was added to the pre- was quenched with 2 mL of MeOH, and the solvent was
dried Schlenk flask, previously deoxygenated by degassing and removed under reduced pressure. The product was obtained
backfilling with argon three times. Dry DMF was then injected, as a white powder after precipitation in cold diethyl ether.
1
and after homogenization, Cu(I)Br (0.75 mmol) was added. The
6
H-NMR (400 MHz, DMSO-d ), d (TMS, ppm): G-PCL: 1.29 (H-3),
mixed solution was degassed by three freeze–pump–thaw cycles, 1.53 (H-2, H-4), 2.27 (H-1), 2.50 (DMSO-d ), 3.33 (H O), 3.98
6
2
0
0
0
0
0
and when it maintained at room temperature, PMDETA was (H-5), 4.34 (H-4 ), 4.54 (H-5 ), 5.21 (H-3 ), 5.30 (H-2 ), 5.91 (H-1 ).
added. Then the reaction mixture was degassed repeatedly and
As a control, guanosine-free poly(N-isopropylacrylamide)
stirred under an argon atmosphere in a pre-heated oil-bath at was also synthesized. The free-radical polymerization was con-
0 1C for 24 h. The reaction solution diluted with THF was ducted in DMF with AIBN and AETꢀHCl as the initiator and the
7
3
1 1
induced through a neutral Al O column to remove the catalyst. chain transfer reagent, respectively. H-NMR (400 MHz, D O),
2
3
2
The filtrate was removed under reduced pressure, and the d (TMS, ppm): PNIPAM-NH : 1.04 (–NHCH(CH ) ), 1.47 (–CH–CH –
2
3 2
2
product was recovered as a light yellow solid after precipitating on the main chain), 1.89 (–CH–CH – on the main chain), 3.79
2
1
in diethyl ether three times. H-NMR (400 MHz, DMSO-d ), d (–NHCH(CH ) ), 4.70 (D O).
6
3 2 2
(
(
TMS, ppm): 0.89 (6H, –C(CH
3
)
2
), 1.04 (–NHCH(CH
3 2
) ), 1.47
0
0
0
Synthesis of 5 -O-acetyl-2 ,3 -O-isopropylidene guanosine
G-OAc)
G-OAc was synthesized via a procedure as reported.
–CH–CH – on the main chain), 1.96 (–CH–CH
2
2
– on the main
(
chain), 3.85 (–NHCH(CH ) ), 7.21 (–NHCH(CH ) ), 7.96 (1H, H-1).
3
2
3 2
32,33
A mixture
of 1 mmol 5 -O-isobromobutyryl-2 ,3 -O-isopropylidene guanosine,
mmol acetic anhydride, Et N and DMAP was dissolved in MeCN.
After stirring for 24 h at r.t., the reaction was quenched with
3
were dissolved in 40 mL of MeOH, and a white solid was obtained after filtration and washing
0
0
0
Synthesis of 5 -O-isoazidobutyryl-2 ,3 -O-isopropylidene
guanosine (G-N
A procedure for the preparation of G-N
mmol G-Br and 5 mmol NaN
0
0
0
3
)
2
3
2
4,26
3
was as follows.
1
This journal is ©The Royal Society of Chemistry 2019
Soft Matter, 2019, 15, 102--108 | 103