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99.999%) N2 gas was applied in all adsorption measurements. The
experimental temperature was maintained by using liquid nitrogen
(77 K). Prior to measurements, bulk samples of 1 and 2 were
washed with absolute ethanol three times, dried under vacuum,
and then transferred onto a stainless-steel column. After 20 min of
soaking and venting of SC-CO2 by means of a DB-80 simplex
pump, the column pressure regulator was set at 109 bar by soak-
ing with SC-CO2, and the column temperature was raised to 608C.
SC-CO2 in the column was gradually vented after 12 h.
Synthesis of 1
A mixture of ZnSO4·7H2O (0.20 g, 0.70 mmol), H2pytz (0.10 g,
0.47 mmol), H2O (2 mL), CH3CN (5 mL), and DMF (3 mL) was placed
in a 25 mL Teflon-lined stainless-steel container. The mixture was
sealed and heated at 1208C for 3 days. After the mixture was
cooled to ambient temperature at a rate of 58ChÀ1, colorless crys-
tals of 1 were obtained (82%, based on Zn). IR (KBr): n˜ =3357 (m),
3086 (m), 2168 (w), 2042 (vw), 1620 (s), 1585 (s), 1435 (vs), 1185
(vs), 1087 (s), 835 (vs), 794 (s), 759 (w), 738 cmÀ1 (w); elemental
analysis calcd (%) for C7H5ZnN9O: C 28.35, H 1.70, N 42.50; found:
C 28.37, H 1.67, N 42.47.
Figure 3. a) Recycling test for the conversion of aromatic dinitriles into bis-
oxazolines with nanoscale 1. b) A comparison of the powder XRD patterns
of 1 before and after catalysis. c) Recycling test for the conversion of aromat-
ic dinitriles into mono-oxazolines with nanoscale 2. d) A comparison of the
powder XRD patterns of 2 before and after catalysis.
Synthesis of bulk crystals of 1 with PEG 2000
under the same reaction conditions. For the cyclization reac-
tion of aromatic dinitriles and b-aminoalcohols, CPs 1 and 2
could achieve high catalytic selectivity to yield bis- or mono-
oxazolines as a result of bi- or unimolecular activation path-
ways, respectively. The four ZnII centers in 1 could follow coop-
erative bimetallic catalysis in which the two cyano groups of
the aromatic dinitriles were activated simultaneously. Never-
theless, the ZnII centers in 2 were shown to be independently
catalytically active as a result of unimolecular activation path-
ways. We also showed that the CPs maintained their crystallini-
ty after the catalytic reaction. This work illustrated the ability
to synthesize CPs with different sizes from the bulk scale to
the nanoscale and provided important insights into CP-cata-
lyzed cooperative reactions.
A solution of ZnSO4·7H2O (0.10 g, 0.35 mmol) and PEG 2000
(0.20 g) in water (2 mL) was sonicated for 10 min. A mixture of
CH3CN (5 mL), DMF (3 mL), and H2pytz (0.05 g, 0.24 mmol) was
added to the mixture in PEG/H2O and sonicated for another
20 min. Subsequently, the solution was transferred to a 25 mL
Teflon-lined stainless-steel container to allow crystal growth at
1208C for 3 days. After the mixture was cooled to ambient temper-
ature at a rate of 58ChÀ1, colorless bulk crystals of 1 were ob-
tained.
Synthesis of nanocrystals of 1 with PVP
A mixture of ZnSO4·7H2O (0.40 g, 1.40 mmol), PVP (0.050 g), and
H2O (2 mL) was sonicated for 20 min until all PVP was dissolved. A
solution of CH3CN (5 mL), DMF (3 mL), and H2pytz (0.20 g,
0.94 mmol) was added to the mixture in PVP/H2O and sonicated
for another 20 min. Subsequently, the solution was transferred to
a 25 mL Teflon-lined stainless-steel container to allow crystal
growth at 1208C for 3 days. After cooling, the nanocrystals were
isolated by centrifugation at 10000 rpm for 10 min. After removal
of the supernatant, the nanocrystals were washed by sonication
after being redispersed in EtOH (5 mL). The suspension in EtOH
was then centrifuged again for 10 min at 10000 rpm to recover
the nanocrystals.
Experimental Section
Materials and physical measurements
All reagents and solvents were commercially available and used as
received without further purification. FTIR spectra were recorded
on a Bruker-ALPHA spectrophotometer as KBr pellets in the n˜ =
400–4000 cmÀ1 region. Elemental analyses (C and H) were carried
out on a FLASH EA 1112 elemental analyzer. Powder XRD patterns
were recorded by using CuKa1 radiation on a PANalyticalX’Pert PRO
diffractometer. A Hitachi TM-1000 field-emission scanning electron
microscope was used to image the particle sizes and morpholo-
gies. Thermal analyses were performed on a Netzsch STA 449C
thermal analyzer at a heating rate of 108CminÀ1 in air. 1H and
13C NMR spectra were obtained on a Bruker Avance-400 spectrom-
eter. HRMS-ESI was performed on a MicroTM Q-TOF mass spectrom-
eter. AAS was performed on a Z28000 graphite-oven atomic ab-
sorption spectrophotometer. The PSDs of 1 were collected on a Mi-
cromeritics ASAP 2420 accelerated surface area and porosimetry
system under ultrahigh vacuum in a clean system, with a dia-
phragm and turbo pumping system. Ultrahigh-purity grade (>
Synthesis of 2
A mixture of Zn(NO3)2·6H2O (0.059 g, 0.20 mmol), H2pytz (0.022 g,
0.1 mmol), H2O (5 mL), and DMF (3 mL) was placed in a 25 mL
Teflon-lined stainless-steel container. The mixture was sealed and
heated at 1208C for 3 days. After the mixture was cooled to ambi-
ent temperature at a rate of 58ChÀ1, colorless crystals of 2 were
obtained (82%, based on Zn). IR (KBr): n˜ =3593 (m), 3409 (m), 3091
(m), 2168 (w), 2049 (vw), 1617 (s), 1580 (m), 1436 (vs), 1178 (s),
1048 (vw), 827 (s), 789 (s), 757 (s), 663 cmÀ1 (m); elemental analysis
calcd (%) for C14H14Zn2N18O4: C 26.72, H 2.42, N 40.07; found: C
26.75, H 2.39, N 40.06.
Chem. Eur. J. 2016, 22, 6389 – 6396
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