Dalton Transactions
Paper
The filtrate was acidified with concentrated HCl in an ice-water
ZJNU-48. A mixture of H
4
L3 (5.0 mg, 12.2 μmol), and
bath. The precipitation formed was collected by filtration and Cu(NO ) ·3H O (15.0 mg, 62.1 μmol) was dissolved in a mixed
3
2
2
dried under vacuum at 343 K, affording 5,5′-(pyrazine-2,5-diyl)- solvent of DMF (1.5 mL), CH
3 2
CN (0.5 mL), and H O (0.08 mL)
diisophthalate as an off-white solid in a quantitative yield in a 20 mL glass vial. After the addition of 6 M HCl (30 μL), the
1
(
0.75 g, 1.8 mmol). H NMR (DMSO-d , 400.1 MHz) δ (ppm): vial was sealed and heated to 353 K for 72 h and then cooled
6
1
3.523 (s, br, 4H), 9.529 (s, 2H), 8.958 (d, J = 1.2 Hz, 4H), 8.586 to room temperature. The block-shaped crystals formed were
1
3
(d, J = 1.2 Hz, 2H); C NMR (DMSO-d
6
, 150.9 MHz) δ (ppm): collected by filtration in 56% yield. Based on the single-crystal
1
66.840, 149.212, 142.120, 137.021, 132.923, 131.620, 131.502; X-ray structural determination, TGA and elemental ana-
−1
selected FTIR (KBr, cm ): 1716, 1605, 1498, 1456, 1435, 1327, lyses, ZJNU-48 can be the best formulated as [Cu
2
2 2
L3(H O) ]·
1
279, 1248, 1161, 1039, 910, 758, 712, 677.
3DMF·4CH
3
CN·3H O. Elemental analysis calcd for
2
5
,5′-(Pyrimidine-2,5-diyl)diisophthalate (H L3). To a mixture C H N O Cu : C, 44.22%, H, 5.12%, N, 12.54%; found:
4
37 51
9
16
2
−
1
of 5-bromo-2-iodopyrimidine (1.19 g, 4.2 mmol), dimethyl C, 44.11%, H, 5.06%, N, 12.57%; selected FTIR (KBr, cm ):
(5-pinacolboryl)isophthalate (2.96 g, 9.2 mmol), Pd(PPh
3
)
4
1660, 1635, 1593, 1452, 1394, 1365, 1323, 1254, 1095, 775,
(
0.24 g, 0.2 mmol) and Cs CO (4.11 g, 12.6 mmol) was added 760, 729.
2
3
degassed dioxane (100 mL). The resulting suspension was
stirred under reflux under a nitrogen atmosphere for 72 h.
2.4. Crystal structure determination
After that, the precipitate was collected by filtration, washed The intensity data for ZJNU-46 and ZJNU-48 were collected
with 1,4-dioxane and then recrystallized with toluene to obtain at 296(2) K on a Bruker SMART APEX II CCD area-detector
a pure tetramethyl ester intermediate as a white solid in 58% diffractometer using graphite monochromated Mo-K radiation
α
1
yield (1.13 g, 2.4 mmol). H NMR (CDCl , 400.1 MHz) δ (ppm): (λ = 0.71073 Å). The structures were solved by direct methods
3
9.386 (d, J = 1.6 Hz, 2H), 9.158 (s, 2H), 8.863 (t, J = 1.6 Hz, 1H), using the program SHELXS-97. All non-hydrogen atoms were
8.804 (t, J = 1.6 Hz, 1H), 8.538 (d, J = 1.6 Hz, 2H), 4.041 (s, 6H), refined anisotropically by full matrix least-squares methods
4.038 (s, 6H). To the tetramethyl ester intermediate (0.23 g, using SHELXL-97. The unit cell includes a large region of dis-
0.5 mmol) in THF (30 mL) and methanol (30 mL) was added ordered solvent molecules which could not be modelled as dis-
6
M NaOH aqueous solution (30 mL, 180 mmol). The mixture crete atomic sites. We employed PLATON/SQUEEZE15 to
was stirred under reflux overnight. After the solution was calculate the diffraction contribution of solvent molecules and
cooled to room temperature, the solvent was rota-evaporated, thereby to produce a set of solvent-free diffraction intensities.
and the residue was re-dissolved in water, and filtered. The The resulting new files were used to further refine the struc-
filtrate was acidified with concentrated HCl in an ice-water tures. The H atoms on C atoms were generated geometrically.
bath. The precipitation formed was collected by filtration and The crystal data and structure refinement parameters for the
dried under vacuum at 343 K, affording 5,5′-(pyrimidine-2,5- two compounds are presented in Table S1 in the ESI.†
diyl)diisophthalate as an off-white solid in a quantitative yield
1
2.5. Calculation of the isosteric heat of C H adsorption
2 2
(
0.20 g, 0.5 mmol). H NMR (DMSO-d
6
, 600.1 MHz) δ (ppm):
9
8
1
1
.394 (s, 2H), 9.219 (d, J = 1.2 Hz, 2H), 8.620 (t, J = 1.2 Hz, 1H), The isosteric heat of C H adsorption, Q , was calculated
2
2
st
1
3
.566 (s, 3H); C NMR (DMSO-d , 150.9 Hz) δ (ppm): 166.832, using the Clausius–Clapeyron equation, expressed as
6
66.814, 161.507, 156.343, 137.999, 135.216, 133.084, 132.622,
ꢀ
ꢁ
@
ln P
32.567, 132.409, 131.948, 130.936, 130.505; selected FTIR
Qst ¼ ꢀR
ð1Þ
KBr, cm− ): 1713, 1605, 1551, 1454, 1406, 1385, 1271, 1255,
1
@ð1=TÞ
q
(
1
234, 1157, 1105, 912, 756, 677, 661.
where P is the pressure, T is the temperature, R is the gas con-
stant, and q is the adsorption amount. Linear fitting of ln
P versus 1/T for the C H adsorption is provided in Fig. S5 in
the ESI.† The slope of ln P ∼ 1/T was derived from the fitted
line, and Qst was calculated from the above equation.
2
2
2
.3. Synthesis and characterization of the MOFs
ZJNU-46. A mixture of H
4
L1 (5.0 mg, 12.2 μmol), and
Cu(NO ) ·3H O (15.0 mg, 62.1 μmol) was dissolved in a mixed
3
2
2
solvent of N,N-dimethyl formamide (DMF, 1.5 mL), ethanol
EtOH, 0.5 mL), and H O (0.08 mL) in a 20 mL glass vial. After
the addition of 6 M HCl (50 μL), the vial was sealed and heated
(
2
3
3
. Results and discussion
.1. Synthesis and characterization
L1 and H L3 were readily synthesized by
2% yield. Based on the single-crystal X-ray structural determi- palladium-catalyzed Suzuki cross-coupling between dimethyl
nation, TGA and elemental analysis, ZJNU-46 can be the best 5-(pinacolboryl)isophthalate and the corresponding dihalo
formulated as [Cu L1(H O) ]·3DMF·4EtOH·3H O. Elemental compounds, 2,5-dibromopyrazine and 5-bromo-2-iodopyrimi-
analysis calcd for C H N O Cu : C, 43.64%, H, 6.20%, dine, followed by hydrolysis and acidification. The detailed
to 353 K for 24 h and then cooled to room temperature. The
block-shaped crystals formed were collected by filtration in The organic linkers H
4
4
6
2
2
2
2
3
7
63
5
20
2
N, 6.83%; found: C, 43.49%, H, 6.21%, N, 6.74%; selected synthesis procedures are shown in the Experimental section.
FTIR (KBr, cm− ): 1657, 1637, 1495, 1448, 1414, 1379, 1254, The chemical structures of the organic linkers and their
1
1
159, 1095, 775, 760, 729.
intermediates were characterized by NMR spectroscopy. The
This journal is © The Royal Society of Chemistry 2016
Dalton Trans.