X. Xu et al. / Polyhedron 95 (2015) 69–74
71
Table 1
J = 8.2 Hz, 2H), 3.94 (q, J = 6.94 Hz, 1H), 1.38 (d, J = 7.03 Hz, 3H);
Anal. Calc. for C9H11NO2: C, 65.48; H, 6.67; N, 8.48. Found: C,
65.50; H, 6.77; N, 8.39%.
Crystal data and structure refinements for complexes 1 and 2.
Crystal parameters
CCDC No.
Formula
Formula weight
Space group
a (Å)
1
2
1034547
C9H7CuN6O2
294.75
1034548
C16H12N10O4Zn
473.73
Pc
5.5263(11)
17.491(4)
9.7331(19)
90
92.05(3)
90
940.2(3)
2
1.673
1.357
480
0.0292
1.069
3. Results and discussion
P21/c
12.2891(5)
10.3566(4)
9.3372(3)
90
105.211(4)
90
1146.74(7)
4
1.707
1.908
592
0.0328
1.109
3.1. Syntheses of the complexes
b (Å)
c (Å)
Caution! Due to the fact that sodium azide is potentially explo-
sive and dangerous, small amount of compounds are prepared in
each experiment and should be handled with extra care.
a
(°)
b (°)
c
(°)
V (Å3)
Both H(4-nptz) and H(4-nbtz) are slightly soluble in water and
are difficult to coordinate with metal atom at room temperature.
Since the crystalline products 1 and 2 cannot be obtained by direct
aqueous reactions at room temperature, the solvo/hydrothermal
technique is applied to cultivate their crystals. Notably, two com-
pletely different synthetic methods were employed to obtain crys-
talline products under solvothermal conditions. Complex 1 was
obtained by direct reaction of 4-nptz and CuCl under solvothermal
condition, whereas complex 2 was synthesized by the in situ [3+2]
cycloaddition reaction of 4-nitrophenylacetonitrile, sodium azide
and Zn(NO3)2, which skipped the synthesis of 4-nbtz.
Noteworthy, we also tried to synthesize the complex 2 by direct
reaction similar to that of complex 1, however, an unknown pow-
der were obtained as the products. In addition, complex 1 was pre-
pared with metal ion and ligand molar ratio of 2:1, the attempt to
change the molar ratio of reactants to 1:2 or other ratios still
results in the same product with slightly lower yields.
Z
Dcalc. (g cmÀ3
)
l
(mmÀ1
)
F(000)
Rint
Goodness-of-fit (GOF) on F2
R1, wR2 (I > 2
R1, wR2 (all data)
r
(I))
0.0494, 0.0969
0.0796, 0.1091
0.0291, 0.0658
0.0314, 0.0702
Table 2
Selected bonds lengths (Å) and angles (°) for complexes 1 and 2.
Bonds (Å)
1
Bonds (Å)
2
Cu(1)–N(1)
Cu(1)–N(6)
Cu(1)–N(2)I
Cu(1)–N(4)II
2.010(3)
2.026(3)
2.027(3)
2.082(3)
Zn(1)–N(1)
Zn(1)–N(4)I
Zn(1)–N(6)
Zn(1)–N(8)II
1.988(3)
2.022(3)
1.989(3)
1.987(3)
Bond angles (°)
1
Bond angles (°)
2
N(1)–Cu(1)–N(6)
N(1)–Cu(1)–N(2)I
N(6)–Cu(1)–N(2)I
N(1)–Cu(1)–N(4)II
N(6)–Cu(1)–N(4)II
N(2)I–Cu(1)–N(4)II
114.3(1)
111.9(1)
112.1(1)
111.1(1)
98.5(1)
N(8)II–Zn(1)–N(1)
N(8)II–Zn(1)–N(6)
N(1)–Zn(1)–N(6)
N(8)II–Zn(1)–N(4)I
N(1)–Zn(1)–N(4)I
N(6)–Zn(1)–N(4)I
114.6(2)
118.5(2)
105.8(2)
107.9(1)
105.5(1)
103.3(1)
3.2. Thermal analysis of complexes 1 and 2
As important property of inorganic–organic hybrid materials,
the thermal stabilities of complexes 1 and 2 were studied by ther-
mogravimetric experiments conducted under air atmosphere.
However, several tests show that explosion would occur to com-
plex 1 and 2 when the temperature is higher than 325 °C for 1,
and 368 °C for 2. Before the explosion, the acetonitrile molecule
in complex 1 is lost during 160–325 °C (calculated: 13.9%; found:
14.3%) (Fig. S1, in Supporting Information).
108.0(1)
Symmetry code: 1, I: Àx + 2, Ày + 1, Àz; II: Àx + 2, y + 1/2, Àz + 1/2. 2, I: x, Ày + 2,
z À 1/2; II: x + 1, y, z.
(0.32 mmol). Under N2 atmosphere, DMA (4 mL) was added by syr-
inge. The tube was sealed and heated at 90 °C for 48 h. After cooled
to room temperature, the reaction mixture was diluted with 10 mL
of ethyl acetate and 5 mL of water. Concentrated HCl was then
added to adjust the pH to 3. The organic layer was separated and
the aqueous layer extracted with ethyl acetate (5 Â 20 mL). The
combined organic layers were washed with brine, dried over
Na2SO4 and concentrated by rotavapor. The residual oil was loaded
on a silica gel column and eluted with ethyl acetate/petroleum
ether (1/5 to 1/1) to afford the final coupling product.
3.3. Structural description of complexes 1 and 2
Complex 1 crystallized in a monoclinic system with P21/c space
group. The asymmetric unit of 1 consists of one CuI center, one 4-
nptz ligand and one CH3CN molecule. The CuI center is surrounded
by four nitrogen atoms with slightly distorted tetrahedral geome-
try, in which three nitrogen atoms (N1, N2I, N4II) are from three 4-
nptz ligands and one nitrogen atom (N6) from one acetonitrile
molecule (Fig. 1a). The lengths of CuÀN bonds are in the range of
2.010(3)À2.082(3) Å with an average of 2.036 Å, and the
NÀCuÀN angles range from 98.5(1)° to 114.3(1)°.
N-phenyl-
-valine (1): 83% yield; 1H NMR (400 MHz, DMSO) d
L
ppm: 7.07 (t, J = 7.78 Hz, 2H), 6.49–6.70 (m, 1H), 5.66 (br. s, 2H),
3.64 (d, J = 6.78 Hz, 1H), 1.94–2.15 (m, 1H), 0.79–1.21 (m, 6H);
Anal. Calc. for C11H15NO2: C, 68.37; H, 7.82; N, 7.24. Found: C,
68.35; H, 7.75, N, 7.12%.
In complex 1, each 4-nptz acts as a tridentate linker (type e in
Scheme 1) connecting three CuI centers to form a 2D planar net-
work paralleling to bc plane. This network containing two types
of cavity, one is a six-membered ring with the closest CuÁ Á ÁCu dis-
tance of 3.589(1) Å, another one is a sixteen-membered ring cov-
ered by nitrophenyl groups (Fig. 1b). Furthermore, TOPOS
program [33] indicates that this 2D plane can be reduced to a 3-
connected fes type topology with a point symbol of (4Á82). These
fes type network are pillared by nitrophenyl groups and linked
by CÀHÁ Á ÁO hydrogen bonding interactions between the methyl
groups of the acetonitrile and the nitro groups of the adjacent
planes, leading to a 3D supramolecular framework. Furthermore,
when the acetonitrile molecule serves as a bridging linker and both
of the 4-nptz molecule and the CuI cation be seen as the four-
N-phenyl-
-phenylalanine (2): 91% yield; 1H NMR (400 MHz,
L
DMSO) d ppm: 7.17–7.37 (m, 2H), 7.06 (t, J = 7.65 Hz, 1H), 6.59
(d, J = 8.03 Hz, 2H), 5.92 (br. s, 1H), 4.13 (t, J = 6.78 Hz, 2H), 2.91–
3.16 (m, 4H); Anal. Calc. for C15H15NO2: C,74.70; H, 6.22; N, 5.81.
Found: C, 74.49; H, 6.32, N, 5.73%.
N-phenyl-
-tyrosine (3): 65% yield; 1H NMR (400 MHz, DMSO) d
L
ppm: 7.00–7.13 (m, 4H), 6.66 (d, J = 8.53 Hz, 2H), 6.67 (d,
J = 7.15 Hz, 2H), 6.56 (m, 1H), 5.82 (t, J = 7.6 Hz, 1H), 3.97–4.10
(m, 1H), 2.81–3.01 (m, 1H); Anal. Calc. for C15H15NO3: C, 70.03;
H, 5.88; N, 5.44. Found: C, 70.06; H, 5.82; N, 5.36%.
N-phenyl-
L
-alanine (4): 72% yield; 1H NMR (400 MHz, DMSO) d
ppm: 7.07 (t, J = 7.78 Hz, 2H), 6.62 (t, J = 7.4 Hz, 1H), 6.55 (d,