Fluorescent properties of three zinc(II) coordination polymers derived from flexible N-(4/3-carboxyphenyl)iminodiacetic acids

Article abstract of DOI:10.1002/zaac.201100433

Three polymers [Zn₂(p-CPIDA)(OH)]_n (1), [Zn ₂(p-HCPIDA)₂(bipy)(H₂O)₄] ·2H₂O (2), and [Zn(m-HCPIDA)(bipy)]_n (3) [p/m-H₃CPIDA = N-(4/3-carboxyphenyl) iminodiacetic acid, bipy = 4, 4′-bipyridine] were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, X-ray powder diffraction patterns (XPRD), FTIR spectroscopy, and fluorescence analyses. Compound 1 displays an interesting three-dimensional framework consisting of novel paddle wheel Zn ₈O₁₀C₂ units, which are further linked by p-CPIDA^3- ligands with versatile coordination modes. In 2, the structural motifs formed by terminal p-HCPIDA^2- ligands and Zn ^II ions are bridged by ancillary bipy to give a zero-dimensional Z-shaped dimer. Compound 3 has an infinite zigzag chain linked by bipy, in which terminal m-HCPIDA^2- ligands alternately run along the chain like flags. Compounds 2 and 3 are further connected by hydrogen bonding and π...π stacking interactions to result in 3D supramolecular frameworks. Moreover, compounds 1-3 exhibit intense solid state fluorescent emissions at room temperature. Copyright

Full text of DOI:10.1002/zaac.201100433

ARTICLE
DOI: 10.1002/zaac.201100433
Fluorescent Properties of three Zinc(II) Coordination Polymers derived from
Flexible N-(4/3-Carboxyphenyl)iminodiacetic Acids
Xiao-Chuan Chai,*[a] Yan-Fei Zhao,[b] Qiao-Juan Gong,[a] Yong-Ping Liang,[a]
Han-Hui Zhang,[c] and Yi-Ping Chen[c]
Keywords: Multicarboxylate; Coordination modes; Topological analysis; Zinc; Fluorescence
Abstract. Three polymers [Zn2(p-CPIDA)(OH)]n (1), [Zn2(p- motifs formed by terminal p-HCPIDA2– ligands and ZnII ions are
HCPIDA)2(bipy)(H2O)4]·2H2O (2), and [Zn(m-HCPIDA)(bipy)]n (3)
bridged by ancillary bipy to give a zero-dimensional Z-shaped dimer.
[p/m-H3CPIDA = N-(4/3-carboxyphenyl) iminodiacetic acid, bipy = Compound 3 has an infinite zigzag chain linked by bipy, in which
4,4Ј-bipyridine] were hydrothermally synthesized and characterized by terminal m-HCPIDA2– ligands alternately run along the chain like
single-crystal X-ray diffraction, X-ray powder diffraction patterns flags. Compounds 2 and 3 are further connected by hydrogen bonding
(XPRD), FTIR spectroscopy, and fluorescence analyses. Compound 1 and π···π stacking interactions to result in 3D supramolecular frame-
displays an interesting three-dimensional framework consisting of works. Moreover, compounds 1–3 exhibit intense solid state fluores-
novel paddle wheel Zn8O10C2 units, which are further linked by p- cent emissions at room temperature.
CPIDA3– ligands with versatile coordination modes. In 2, the structural
H3CPIDA). As known, few examples have been reported in
Introduction
The coordination polymers constructed from multicarboxyl-
previous work by our group and others.[6,7] The p/m-H3CPIDA
ligands have rigid benzoic acid moieties and flexible iminodia-
ates have received considerable attention for intriguing archi-
cetates, which can exhibit a great variety of coordination
tectures and wide applications in catalysis, gas adsorption, mo-
modes. The nitrogen atoms are also good candidates for the
lecular sensors, electrical conductivity, nonlinear optics, fluo-
rescence, magnetism, and so on.[1] The strong coordinating
ability of carboxylates can adopt versatile modes, from ter-
minal monodentately to various bridging modes, in the forma-
tion of coordination polymers.[2] Furthermore, depending upon
the degree of deprotonation, they can act as hydrogen bonding
acceptors and donors to assemble fascinating supramolecular
frameworks.[3] The rigid aromatic multicarboxylates, for ex-
ample, 1,4-benzenedicarboxylate, 1,3,5-benzenetricarboxylate,
and 1,2,4,5-benzenetetracarboxylate have been investigated
extensively.[4] However, the flexible multicarboxylates are rel-
atively underdeveloped, though the special conformation and
coordination functionality might generate some unprecedented
coordination frameworks.[5]
construction of novel compounds. On the other hand, they hold
flexibility because of the presence of the –CH2– spacers, which
can bend to meet the requirement of the coordination confor-
mation of metal ions. Moreover, the phenyl rings can more
easily provide π···π stacking interactions to generate supra-
molecular frameworks.
In this work, bipy was introduced as ancillary ligand for the
effective hydrogen bonding and π···π stacking interactions in
the formation of supramolecular architectures. ZnII ions were
employed for the good fluorescent characteristics of their com-
pounds.[8] Three coordination polymers [Zn2(p-CPIDA)(OH)]n
(1), [Zn2(p-HCPIDA)2(bipy)(H2O)4]·2H2O (2), and [Zn(m-
HCPIDA)(bipy)]n (2) were prepared by hydrothermal synthe-
sis. Compound 1 adopts a novel 3D framework with trinodal
(3,4,5)-connected topology. Compounds 2 and 3 exhibit a Z-
shaped dimer and a zigzag chain with bipy ligands, respec-
tively. The XPRD patterns, FTIR spectroscopy, and fluorescent
properties were investigated.
Recently, we have focused on the flexible multicarboxylate
ligands of type N-(4/3-carboxyphenyl)iminodiacetic acid (p/m-
* Dr. X. C. Chai
Fax: +86-359-2090394
E-Mail: xiaochuanchai@hotmail.com
[a] Department of Applied Chemistry
Yuncheng University
Yuncheng, 044000, P. R.China
[b] Biochemical Experiments Center
Yuncheng University
Results and Discussion
Crystal Structures
Yuncheng, 044000, P. R.China
[c] Department of Chemistry
Fuzhou University
The coordination modes of p-CPIDA3–, p-HCPIDA2–, and
m-HCPIDA2– in 1–3 are shown in Scheme 1. The coordination
mode for p-CPIDA3– in Scheme 1a is reported for the first
time.
Fuzhou, 350108, P. R.China
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201100433 or from the au-
thor.
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X.-C. Chai et al.
ARTICLE
Scheme 1. Coordination modes of p-CPIDA3– (a), p-HCPIDA2– (b),
and m-HCPIDA2– (c) in 1–3.
[Zn2(p-CPIDA)(OH)]n (1)
Compound 1 has a 3D framework. The asymmetric unit con-
sists of two ZnII ions, one p-CPIDA3– ligand, and one coordi-
nated OH– anion. As shown in Figure 1, the distorted tetrahe-
dron of Zn1 is completed by four oxygen atoms from two
equivalent p-CPIDA3– ligands and one OH– anion. Zn2 adopts
a distorted tetragonal pyramidal arrangement, the basal plane
is formed by four oxygen atoms from three p-CPIDA3– ligands
and the apical position is occupied by the OH– anion. The Zn–
O bond lengths are in the range 1.918(3)–2.482(2) Å.
Figure 2. (a) 2D layer on the bc plane with paddle wheel Zn8O10C2
units. (b) 3D framework of 1 along the b axis. (c) The trinodal (3,4,5)-
connected topology of 1 with (3·72)(3·42·5·6·7)(3·42·5·6·73·8·9).
Figure 1. Coordination of ZnII ions in 1 (40% thermal ellipsoids prob-
ability). Hydrogen atoms are omitted for clarity. Symmetry codes: A, –
x, y+1/2, –z+1/2; B, –x+1, y+1/2, –z+1/2; C, –x, y+1, –z; D, x–1, y, z.
To better understand the structure, the topological analysis
approach is employed. As mentioned, each p-CPIDA3– can be
treated as a 5-connected node. Whereas, considering the link-
age of p-CPIDA3– and OH–, Zn1 and Zn2 are regarded as 3-
and 4-connected nodes, respectively. Finally, the 3D frame-
work exhibits a novel trinodal (3,4,5)-connected topology with
Schläfli symbol (3·72)(3·42·5·6·7)(3·42·5·6·73·8·9), wherein the
notations correspond to the Zn1, Zn2, and p-CPIDA3– nodes,
respectively (Figure 2c).
Scheme 1a depicts the coordination modes of p-CPIDA3– in
1. The rigid carboxylate attached to phenyl ring exhibits biden-
tate μ2-η1:η1 bridging mode. The flexible iminodiacetate con-
nect three ZnII atoms to generate a big eight-member ring
ZnNC4O2, where two carboxylate groups adopt bidentate
bridging μ2-η1:η1 and chelating/bridging μ2-η1:η1 modes,
respectively. Thus Zn1 and Zn2 are connected by iminodiacet-
ates and OH– to form an infinite 2D corrugated layer on the
bc plane with paddle wheel Zn8O10C2 units (Figure 2a), in
which the shortest Zn···Zn separation is 3.111(4) Å. In Fig-
ure 2b, the adjacent layers are alternately connected by rigid
[Zn2(p-HCPIDA)2(bipy)(H2O)4]·2H2O (2)
Compound 2 features a Z-shaped dimer. In the asymmetric
carboxylate of p-CPIDA3– in head-to-tail mode to construct a unit, there are one ZnII ion, one p-HCPIDA2– ligand, a half
new 3D framework. There are weak hydrogen bonding interac- bipy molecule, two coordinated H2O molecules, and one guest
tions with the O···O separation being 2.924(5) Å and C···O dis- H2O molecule. The ZnII ion is hexacoordinated by two oxygen
tances in the range of 3.228(5)–3.469(1) Å, respectively atoms from the iminodiacetate function of p-HCPIDA2–, two
(Table 1).
nitrogen atoms from p-HCPIDA2– and bipy, and two H2O mo-
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Zinc(II) Coordination Polymers with N-(4/3-Carboxyphenyl)iminodiacetic Acids
Table 1. Parameters of hydrogen bonds for compounds 1–3.
D–H···A
d(D–H) /Å
d(H···A) /Å
d(D···A) /Å
ϽDHA /°
a)
1
2
O7–H7OH···O4A
C2–H2a···O6B
C4–H4b···O4C
C6–H6···O2D
0.84
0.99
0.99
0.95
2.15
2.52
2.40
2.58
2.924(5)
3.399(6)
3.228(5)
3.469(1)
153
147
140
155
b)
O7–H7a···O9A
O7–H7b···O1B
O8–H8a···O4C
O8–H8b···O2A
O9–H9a···O1
O9–H9b···O4D
C5–H5···O3
0.85
0.84
0.85
0.85
0.85
0.85
0.95
0.99
1.92
1.82
1.88
1.87
2.00
1.88
2.55
2.55
2.754(4)
2.666(5)
2.732(7)
2.724(2)
2.857(5)
2.712(2)
3.149(3)
3.522(9)
166
173
177
169
174
164
121
167
C8–H8b···O7A
c)
3
O5–H5···O2A
0.84
0.99
0.99
0.95
0.95
0.95
0.95
1.80
2.55
2.52
2.51
2.58
2.31
2.52
2.612(9)
3.354(3)
3.394(4)
3.186(6)
3.500(9)
3.227(4)
3.127(4)
164
138
147
128
163
162
122
C2–H2a···O6B
C2–H2b···O2C
C11–H11···O4D
C15–H15···O6A
C18–H18···O4E
C21–H21···O6A
Symmetry codes: a) A, x, y + 1, z; B, 1–x, –y, –z; C, –x, –y, –z; D, x, 1/2–y, 1/2 + z. b) A, 3/2–x, –1/2 + y, 1/2–z; B, 1+x, y, z; C, 3/2–x, 1/2 +
y, 1/2–z; D, –1+x, 1+y, z. c) A, 1–x, 1/2 + y, 1/2–z; B, 1 –x, –1/2 + y, 1/2 –z; C, 1–x, –y, –z; D, –x, –y, –z; E, –x, 1–y, –z.
lecules in a distorted octahedral arrangement (Figure 3a). The
In 2, the rigid carboxylate group at the phenyl ring remains
Zn–O bond lengths vary from 2.016(3) to 2.174(2) Å and the free and p-HCPIDA2– presents the coordination mode shown
Zn–N bond lengths are 2.146(3) and 2.450(3) Å, respectively. in Scheme 1b, linking one ZnII ion to generate two five-mem-
bered ZnNC2O rings through the nitrogen atom and two mono-
dentately connected carboxylate groups in flexible iminodia-
cetate. Based on the connection, the ZnII ion is coordinated by
terminated p-HCPIDA2– ligands to form a [Zn(p-HCPIDA)]
motif. Two neighboring [Zn(p-HCPIDA)] motifs are bridged
by bipy in “Z”-shaped conformations to generate a 0D dimeric
structure (Figure 3a). The dimers are further linked by strong
hydrogen bonding and π···π stacking interactions into a 3D
supramolecular framework (Figure 3b). Besides the O–H···O
hydrogen bonds from carboxylate oxygen atoms, coordinated
and guest H2O molecules [O···O, 2.712(2)–2.857(5) Å], C–
H···O hydrogen bonds are found with C···O distances being
3.149(3) and 3.522(9) Å (Table 1). There are obvious π···π
stacking between phenyl rings of p-HCPIDA2– and pyridine
rings of bipy in the Z-shape dimers. The adjacent dimers are
linked by another type of π···π stacking between phenyl rings
of p-HCPIDA2–, which further stabilize the 3D supramolecular
framework (Table 2).
Table 2. Parameters of aromatic–aromatic interactions for compounds
2 and 3.
Cg(I) Ǟ Cg(J)
dπ–π /Å
dc–c /Å
Dihedral angles /°
a)
b)
2
3
Cg(1) Ǟ Cg(2) 3.458(3)
Cg(2) Ǟ Cg(2) 3.410(4)
3.481(4)
3.995(1)
3.595(4)
3.774(8)
12.26
0.03
9.08
i
Cg(1) Ǟ Cg(2) 3.241(3)
i
Cg(1) Ǟ Cg(3) 3.389(4)
20.43
a) i, –1+x, –y, –z. Definition of rings: Cg(1): N(1), C(4), C(3), C(2),
C(1), C(5); Cg(2): C(10), C(11), C(12), C(13), C(15), C(16). b) i, x,
Figure 3. (a) Coordination of ZnII ions in 2 (40% thermal ellipsoids
probability). Hydrogen atoms are omitted for clarity. Symmetry codes: 1/2–y, –1/2+z. Definition of rings: Cg(1): C(5), C(6), C(7), C(9),
A, –x+2, –y+1, –z. (b) View of the 3D supramolecular framework of C(10), C(11); Cg(2): N(2), C(12), C(13), C(16), C(15), C(14); Cg(3):
2 along the a axis. Dashed lines represent hydrogen bonds.
N(3), C(19), C(18), C(17), C(21), C(20).
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X.-C. Chai et al.
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[Zn(m-HCPIDA)(bipy)]n (3)
Compound 3 has a 1D zigzag chain structure. The asymmet-
ric unit contains one ZnII ion, one m-HCPIDA2–, and one bipy
molecule. Figure 4 shows that the central ZnII ion is located in
a distorted tetragonal pyramid arrangement surrounded by two
oxygen atoms from iminodiacetate groups of m-HCPIDA2– li-
gands, three nitrogen atoms from one m-HCPIDA2– ligand and
two equivalent bipy ligands. The Zn–O bond lengths are
1.942(2) and 1.961(2) Å, and the bond lengths of Zn–N are in
the range of 2.052(2)–2.463(2) Å, respectively.
Figure 4. Coordination environment of ZnII in 3 (40% thermal ellip-
soids probability). Hydrogen atoms on carbon atoms are omitted for
clarity. Symmetry codes: A, x, –y+1/2, z+1/2.
Figure 5. (a) View of the zigzag chains on the bc plane stacked by
π···π interactions into a supramolecular layer. (b) View of the 3D sup-
ramolecular framework of 3. Dashed lines represent hydrogen bonds
between the layers.
Compound 3 exhibits the similar [Zn(m-HCPIDA)] motif as
2, the similar coordination modes of m-HCPIDA2– are shown
in Scheme 1c. The rigid carboxylate does not participate in the
coordination. ZnII ions are connected by iminodiacetates to
give [Zn(m-HCPIDA)] motifs with two ZnNC2O five-mem-
bered rings. However, the adjacent motifs are further bridged
by a bipy molecule with the dihedral angle between two pyr-
idine rings being 24.05(2)° to yield a 1D zigzag chain along
the c axis, along which m-HCPIDA2– ligands are alternately
fixed like flags (Figure 5a). Thus, intramolecular π···π stacking
between phenyl rings of m-HCPIDA2– and pyridine rings of
bipy further stabilizes the zigzag chains. The chains are cross-
linked by strong π···π stacking interactions between phenyl
rings and pyridine rings to generate 2D supramolecular layers
on the bc plane (Figure 5a and Table 2), which are further ex-
tended into a 3D supramolecular framework in a –ABAB– se-
quence by hydrogen bonding interactions O/C–H···O (Fig-
ure 5b). The O···O distance is 2.612(9) Å and C···O distances
vary from 3.127(4) to 3.500(9) Å (Table 1).
rigid carboxylate groups do not participate in coordination in
complexes 2 and 3. [Zn(p-HCPIDA)] and [Zn(m-HCPIDA)]
motifs are bridged by bipy ligands to generate a Z-shaped di-
mer and a zigzag chain, respectively. It is only hardly feasible
for the rigid ligand bipy to adjust the configuration like other
flexible ancillary ligands. Hence, the lengths of bipy between
building motifs do not match the lengths of remaining car-
boxyphenyl rings, which influence the coordination of rigid
carboxylates with metal ions. So, it is more difficult for com-
pounds 2 and 3 to generate higher dimensional frameworks as
1. The results indicate that the length and configuration of the
ancillary ligand plays an important role in the assembly pro-
cess of coordination polymers.
XPRD Patterns and FTIR Spectroscopy
The XPRD patterns reveal that all compounds are pure sin-
gle phase and are also of completely identical molecular struc-
tures, corresponding to the simulated results of single-crystal
X-ray diffraction data (Figure S1, Supporting Information).
In Figure S2, the IR spectrum of 1 shows characteristic band
Comparison of Structures
The flexible ligand p-H3CPIDA coordinates with ZnII ions
forming a novel 3D framework of 1. The p-CPIDA3– unit at ca. 3560 cm–1, due to the absorption of stretching vibration
adopts intriguing coordination modes (bidentate chelating/ ν(O–H) of coordinated OH– ions. However, in the IR spectra
bridging μ2-η1:η2 and bridging μ2-η1:η1). In order to modulate of 2 and 3, the broad absorptions at 3400–2900 cm–1 indicate
the structure, the ancillary ligand bipy is introduced. But the the presence of ν(O–H) and ν(C–H), and hydrogen bonding
iminodiacetate groups exhibit simple terminal modes and the interactions O/C–H···O, which are stronger than that in 1.[9]
644
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Zinc(II) Coordination Polymers with N-(4/3-Carboxyphenyl)iminodiacetic Acids
No band in the region 1730–1680 cm–1 in 1 suggests complete frameworks, which decreases the n–π* or π–π* gaps of the
deprotonation of the carboxylates of p-H3CPIDA.[10] As a con- organic ligands. Compound 1 exhibits a quenching of the fluo-
sequence, the bands are shown at 1599, 1575 cm–1 for νas(- rescence with τ1 = 8.887 ns (28.64%) and τ2 = 2.665 ns
COO) and 1526, 1421 cm–1 for νs(COO). Furthermore, the (71.36%). Due to the π···π interactions between p-HCPIDA2–
separations Δ = νas–νs (73 and 154 cm–1) reflect the different and ancillary bipy, compound 2 shows longer lifetime τ1
=
bidentate modes of carboxylates of p-CPIDA3– in 1.[9] The 37.43 ns (98.96%) and τ2 = 5.129 ns (1.04%). The strong
presence of characteristic bands at about 1705 cm–1 in 2 and 3 emission illuminates 2 can be a good candidate for potential
indicate that the partial deprotonation of p-H3CPIDA and m- photoactive materials.
H3CPIDA. The bands of νas(COO) and νs(COO) appear at ca.
1595 and 1400 cm–1, respectively. The separations Δ are
190 cm–1 (for 2) and 201 cm–1 (for 3), corresponding to the
monodentate mode of carboxylates, which are consistent with
the results of the X-ray diffraction analysis.
Conclusions
In this work, the flexible multicarboxylates p-H3CPIDA and
m-H3CPIDA were employed to construct coordination poly-
mers with ZnII in the absence or presence of bipy ligands.
Different coordination modes of carboxylate ligands have sig-
nificant influence on the structures. Compound 1 presents a 3D
framework for the various coordination modes of p-CPIDA3–.
With bipy molecules, compounds 2 and 3 feature a Z-shaped
dimer and a 1D zigzag chain based on terminated p-HCPIDA2–
and m-HCPIDA2–, respectively, which are further linked by
strong hydrogen bonding and π···π stacking interactions into
3D supramolecular frameworks. All compounds have intense
fluorescent emissions in the solid state.
Fluorescent Properties
The solid-state fluorescent properties for 1–3 and free li-
gands were investigated at room temperature and their emis-
sion spectra are given in Figure 6. The ligand p-H3CPIDA ex-
hibits an intense emission at 426 nm upon 334 nm excitation.
The emissions of m-H3CPIDA and bipy are at 420 nm (λex
=
360 nm) and 423 nm (λex = 345 nm), respectively. Compound
1 displays a strong band at 383 nm upon 345 nm excitation.
Compounds 2 and 3 show similar intense emission bands at
500 and 540 nm, when excited at 350 and 370 nm, respec-
tively. The emissions of compounds are similar to those of the
free organic ligands. Since ZnII ions are difficult to oxidize
or to reduce due to their d10 configuration, the emissions of
compounds 1–3 are neither ligand-to-metal charge transfer
(LMCT) nor metal-to-ligand charge transfer (MLCT).[11] As a
result, the emissions can be assigned to intraligand n–π* and
π–π* transitions.
Experimental Section
Materials and Physical Measurements: The ligands p-H3CPIDA and
m-H3CPIDA were prepared according to the reported procedures.[6,7]
Other reagents and solvents were obtained from commercial sources.
The analyses of C, H, and N were performed with an Elementar Vario
EL III elemental analyzer. The XPRD patterns were recorded with a
PANalytical X’pert Pro diffractometer equipped with Cu-Kα radiation
(λ = 1.5406 Å) at room temperature. FTIR spectra were obtained with
a Perkin–Elmer Spectrum 2000 FTIR spectrometer in the range of
400–4000 cm–1 from KBr pellets. UV/Vis DRIS were measured with
a Perkin–Elmer Lambda 900 UV/Vis spectrometer with BaSO4 as the
reference sample. The solid-state fluorescent spectra were carried out
with an Edinburgh Instrument FL/FS-920 fluorescent spectrometer
using xenon lamp for steady fluorescence and H2 nanosecond flash
lamp for transient fluorescence.
[Zn2(p-CPIDA)(OH)]n (1): A mixture of Zn(NO3)2·6H2O (0.059 g,
0.2 mmol) and p-H3CPIDA (0.05 g, 0.2 mmol) was dissolved in H2O
and acetonitrile (8.0 mL, v/v:1/1). The pH value was adjusted to 3.0
with HNO3 (1.0 mol·L–1) and KOH (1.0 mol·L–1). The mixture was
sealed in a 15 mL Teflon-lined stainless autoclave and heated at 120 °C
for 5 days. After cooling to room temperature, light yellow crystals
were obtained in 55% yield (based on Zn). Anal. for C11H9NO7Zn2:
calcd. C 33.19; H 2.28; N 3.52%; found C 33.22; H 2.25; N 3.49%.
IR (KBr): ν˜ = 3562 m, 3092 w, 3047 w, 2980 w, 2914 w, 1599 s, 1575
s, 1526 s, 1475 m, 1421 s, 1306 m, 1268 w, 1227 s, 1162 w, 1047 w,
946 w, 929 s, 853 m, 785 s, 736 s, 703 m, 651 m, 436 w cm–1.
Figure 6. Solid-state emission fluorescent spectra for free p-H3CPIDA,
m-H3CPIDA, 1, 2, and 3 at room temperature.
However, compound 1 shows blue shift relative to the p-
H3CPIDA. It may derive from the coordination effects of p-
CPIDA3– to ZnII ions, which increases the ligand conforma-
tional rigidity and reduces the nonradiative decay of the intrali-
gand.[11] As for 2 and 3, the emission bands are red-shifted
with respect to the free corresponding ligands because of the
[Zn2(p-HCPIDA)2(bipy)(H2O)4]·2H2O (2): A mixture of Zn(NO3)
2·6H2O (0.059 g, 0.2 mmol), p-H3CPIDA (0.05 g, 0.2 mmol), and bipy
(0.04 g, 0.25 mmol) was dissolved in H2O and acetonitrile (8.0 mL, v/
v:1/1). The pH value was adjusted to 2.5 with HNO3 (1.0 mol·L–1) and
KOH (1.0 mol·L–1). The mixture was sealed in a 15 mL Teflon-lined
stainless autoclave and heated at 90 °C for 4 days. After cooling to
abundant π···π stacking interactions in their supramolecular room temperature, colorless crystals were obtained in 64% yield
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X.-C. Chai et al.
ARTICLE
(based on Zn). Anal. for C32H35N4O18Zn2: calcd. C 42.97; H 3.94; N
6.26%; found C 42.89; H 3.92; N 6.31%. IR (KBr): ν˜ = 3227 b, 2937
w, 1706 s, 1595 s, 1535 w, 1404s, 1323m, 1296m, 1278 m, 1222 m,
1194 m, 1160 m, 1116 w, 1064 w, 971 m, 917 m, 843 w, 803 m, 769
m, 728 w, 694 w, 624 w, 470 w, 455 w cm–1.
842921 (Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk).
Supporting Information (see footnote on the first page of this article):
Figure S1 show the experimental and theoretically simulated XPRD
patterns for 1–3. The FTIR and UV/Vis DRIS spectra of 1–3 are shown
in Figure S2 and S3, respectively.
[Zn(m-HCPIDA)(bipy)]n (3): A mixture of Zn(NO3)2·6H2O (0.059 g,
0.2 mmol), m-H3CPIDA (0.05 g, 0.2 mmol) and bipy (0.04 g,
0.25 mmol) was dissolved in H2O and acetonitrile (8.0 mL, v/v:1/1).
The pH value was adjusted to 3.0 with HNO3 (1.0 mol·L–1) and KOH
(1.0 mol·L–1). The mixture was sealed in a 15 mL Teflon-lined stain-
less autoclave and heated at 100 °C for 3 days. After cooling to room
temperature, colorless crystals were obtained in 72% yield (based on
Zn). Anal. for C21H17N3O6Zn: calcd. C 53.35; H 3.62; N 8.89%; found
C 53.49; H 3.72; N 8.63%. IR (KBr): ν˜ = 3435 b, 3065 w, 2925 w,
1703 s, 1655 s, 1595 s, 1453w, 1394 s, 1364 w, 1269 m, 1225 m, 1154
w, 1075 m, 1015 w, 923 w, 868 w, 816 m, 761 m, 749 w, 729 w, 685
w, 641 m, 485 w cm–1.
Acknowledgement
We gratefully acknowledge financial support of this work by the
National Natural Science Foundation of China (No. 20873021) and
Yuncheng University.
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1
2
3
Empirical formula
Formula weight
Crystal system
Space group
a /Å
C11H9NO7Zn2
397.93
monoclinic
P21/c
11.772(2)
7.572(2)
13.663(3)
94.14(3)
1214.8(4)
2.176
C16H19N2O9Zn
448.70
monoclinic
P21/n
7.544(2)
8.812(2)
26.750(5)
95.45(3)
1770.1(6)
1.684
C21H17N3O6Zn
472.75
monoclinic
P21/c
12.730(3)
8.869(3)
17.555(4)
101.37(3)
1943.2(7)
1.616
b /Å
c /Å
β /°
V /Å3
Dc /g·cm–3
Z
4
4
4
F(000)
792
924
968
θ range /deg.
3.08–27.52
3.984
1.071
9600/2788
0.0357
0.0352, 0.1110
0.0367, 0.1124
0.858/–0.391
3.26–27.51
1.443
1.067
13792/4052
0.0311
0.0575, 0.1345
0.0622, 0.1379
1.443/–0.980
3.18–27.56
1.310
1.082
15733/4424
0.0433
0.0415, 0.1164
0.0435, 0.1231
0.609/–0.536
μ /mm–1
Goodness-of-fit on F2
reflns collected /unique
Rint
b)
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R1, wR2 (all data)
Δρmax /Δρmin /e·Å–3
a) R1 = ∑||Fo|–|Fc||/∑|Fo|. b) wR2 = {∑[w(Fo –Fc)2]/∑[w(Fo ) ]}1/2
.
2
2 2
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Received: September 29, 2011
Published Online: January 9, 2012
Z. Anorg. Allg. Chem. 2012, 641–647
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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