Syntheses, crystallization and selective dye adsorption of three Co(II) coordination polymers via one-pot reaction

Article abstract of DOI:10.1016/j.poly.2017.08.004

Three novel Co(II) coordination polymers, namely [Co(HL)(4,4′-bibp)]_n (1), [Co(HL)(4,4′-bibp)]_n (2) and {[Co₂(L)(4,4′-bibp)₂(H₂O)₃(HCOO)]·2H₂O·HCOOH}_n (3) (H₃L = 5-(2′′-carboxylphenoxy)isophthalic, 4,4′-bibp = 4,4′-bis(imidazol-1-yl)biphenyl) were synthesized through one-pot reaction under co-crystallization conditions. These complexes were characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Complexes 1 and 2 were supramolecular isomers with different 2D configurations. Complex 1 shows a sql 2D-network with a [Co(HL^2?)]_n single-strand helix chain and another [Co(4,4′-bibp)]_n single-strand helix chain, which are further assembled into 3D supramolecular architectures through H-bonds and C–H?N bonds. While complex 2 exhibits another 2D-network with two different [Co(HL^2?)]_n helix chains (left and right) and one [Co(4,4′-bibp)]_n zigzag chain, which further constructing a 3D supramolecular structure through H-bonds. Compared with 1 and 2, 3 also shows a sql 2D-network with a bigger channel which influenced by the coordination environment of metal ions. Furthermore, the selective dye adsorption studies indicate that complex 1 can highly and selectively adsorb Methyl Orange (MO) in a short time, and complex 2 shows a highly adsorption activity for Alizarin Red S (ARS) than Methyl Orange, and complex 3 can selectively adsorb Methyl Orange.

Full text of DOI:10.1016/j.poly.2017.08.004

Accepted Manuscript
Syntheses, crystallization and selective dye adsorption of three Co(II) coordi-
nation polymers via one-pot reaction
Xiang-min Meng, Xiao-yin Zhang, Xin-ping Wang, Rui-xue Wu, Xia Zhang,
Fan Jin, Yu-hua Fan
PII:
S0277-5387(17)30524-7
DOI:
http://dx.doi.org/10.1016/j.poly.2017.08.004
POLY 12768
Reference:
Polyhedron
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23 April 2017
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2 August 2017
Please cite this article as: X-m. Meng, X-y. Zhang, X-p. Wang, R-x. Wu, X. Zhang, F. Jin, Y-h. Fan, Syntheses,
crystallization and selective dye adsorption of three Co(II) coordination polymers via one-pot reaction,
Polyhedron (2017), doi: http://dx.doi.org/10.1016/j.poly.2017.08.004
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Syntheses, crystallization and selective dye adsorption of three
Co(II) coordination polymers via one-pot reaction
Xiang-min Meng a,b, Xiao-yin Zhang a, Xin-ping Wang b, Rui-xue Wu a, Xia Zhang a, Fan Jin c,*, Yu-hua Fana,*
aKey Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College
of Chemistry and Chemical Engineering, Ocean University of China,
Qingdao, Shandong 266100, P.R. China
bCollege of Marine Science and Biological Engineering, Qingdao University of Science and
Technology, Qingdao, Shandong 266042, P.R. China
cMax Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic
Microbiology(SYNMIKRO), Marburg, Germany
Abstract
Three novel Co(II) coordination polymers, namely {[Co(HL)(4,4'-bibp)]n (1),
[Co(HL)(4,4'-bibp)]n (2) and {[Co2(L)(4,4'-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n
(3) (H3L = 5-(2′′-carboxylphenoxy)isophthalic, 4,4'-bibp =
4,4'-bis(imidazol-1-yl)biphenyl) were synthesized through one-pot reaction under
co-crystallization conditions. These complexes were characterized by elemental
analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG)
analysis and single-crystal X-ray diffraction. Complexes 1 and 2 were supramolecular
isomers with different 2D configurations. Complex 1 shows a sql 2D-network with a
[Co(HL2-)]n single-strand helix chain and another [Co(4,4'-bibp)]n single-strand helix
chain, which are further assembled into 3D supramolecular architectures through
H-bonds and C-H···N bonds. While complex 2 exhibits another 2D-network with two
different [Co(HL2-)]n helix chains (left and right) and one [Co(4,4'-bibp)]n zigzag
chain, which further constructing a 3D supramolecular structure through H-bonds.
Compared with 1 and 2, 3 also shows a sql 2D-network with a bigger channel which
influenced by the coordination environment of metal ions. Furthermore, the selective
dye adsorption studies indicate that complex 1 can highly and selectively adsorb
Methyl Orange (MO) in a short time, and complex 2 shows a highly adsorption
activity for Alizarin Red S (ARS) than Methyl Orange, and complex 3 can selectively
adsorb Methyl Orange.
Keywords: Coordination polymers; One-pot reaction; Co-crystallization condition;
Supramolecular isomer; Selective dye adsorption.
* Corresponding author. Tel./fax: +86 532 66781932
E-mail address: fanyuhua303@163.com (Y. Fan);
pkujinfan@gmail.com (F. Jin).
1

1. Introduction
Recently, construction of two or more coordination polymers with different
structures through co-crystallization has attracted much attention not only for their
intriguing structure and topology, but also for their potential application in selective
molecule adsorption, gas storage, separation, luminescence, catalysis, magnetism, and
so on.[1-12] Especially, based on the pore of the coordination polymers, dyes removal
from contaminated water attracts the attention of the majority of researchers.[13]
However, it is still a challenge to synthesize and modify functional coordination
polymers to quickly remove the dyes from wastewater.
According to the reports, the rigid and flexible mixed ligands system was usually
used to construct coordination polymers, because the flexible ligands could exhibit
more complicated and unusual structures, as functional groups on the ligands offer
variable configurations.[14-18] 5-(2′′-carboxylphenoxy)isophthalic acid (H3L) is an
aromatic multicarboxylate ligand and has a series of advantages: i) the free rotation of
the C-O-C between two benzene rings can promote the flexibility of the ligands to
construct a more complicated structure; ii) the different location of the carboxylic
groups can enhance the probability to coordinate with metal ions; iii) the three
carboxylic group could show more coordination modes while coordinating to metal
ions. 4,4'-bis(imidazol-1-yl)biphenyl (4,4'-bibp) is a rigid N-donor ancillary ligand
which can promote stability of the final structure.(Scheme 1) We expect to obtain
cobalt compounds with special structures and functions through mixed ligands system.
To our surprise, three coordination polymers (complexes 1-3) were obtained through
one-pot reaction under co-crystallization conditions, namely, [Co(HL)(4,4'-bibp)]n (1),
[Co(HL)(4,4'-bibp)]n (2) and {[Co2(L)(4,4'-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n
(3), and two of them (complexes 1 and 2) were supramolecular isomers. Although
research on one-pot synthesis for two or more coordinated polymers has been
conducted in recent years, to best of our knowledge, such a synthesis procedure for
achieving two supramolecular isomers has rarely been reported.[19, 20] Fortunately,
based on the different colors and shapes of these crystals, we can separate the
complexes by hand picking.[15] (Scheme 2) All compounds were characterized by
single crystal X-ray diffraction analysis. Moreover, the selective dye adsorption
activities of three Co(II) compounds were also investigated in detail.
Scheme 1
2

Scheme 2
2. Experimental section
2.1 Materials and physical measurements
All reagents and solvents were obtained from Jinan Henghua Sci. & Tec. Co. Ltd.
and were used without further purification. The infrared spectrum was recorded as
KBr pellets on a Nicolet 170SX spectrometer in the 4000-400 cm-1 region. Elemental
analysis (C, H, and N) was performed on a 2400 model Perkin-Elmer analyzer.
Thermogravimetric analysis (TGA) was conducted on a Perkin-Elmer TGA-7
thermogravimetric analyzer under N2 conditions from room temperature to 800 °C
with a heating rate of 10 °C min-1. The X-ray powder diffraction patterns (XRPD)
were collected on a Panalytical X-Pert pro diffractometer with Cu-Kα radiation.
Topological analysis was performed and confirmed by the Topos program and the
Systre software.[21]
2.2 Synthesis of complexes [Co(HL)(4,4'-bibp)]n (1), [Co(HL)(4,4'-bibp)]n (2) and
{[Co2(L)(4,4'-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n (3)
A mixture of H3L (0.032 g, 0.1 mmol), Co(NO3)2·6H2O (0.058 g, 0.2 mmol) and
4,4'-bibp (0.058 g, 0.2 mmol) were dissolved in 8 mL of DMAC/H2O (1:1, v/v). The
final mixture was placed in a Teflon-lined stainless steel vessel, heated to 130 °C for
72 h, and then cooled (a descent rate of 5 °C h-1) to room temperature. Three different
crystals 1 (pink, block-shaped), 2 (crimson, rice-shaped) and 3 (purple, strip-shaped)
were obtained.(Scheme 2) The crystals were separated by hand picking and yield of
the reaction were ca. 15% in 1, 10% in 2, 25% in 3 based on H3L. Elemental analysis
calcd. for C33H22CoN4O7 (1): C, 61.40; H 3.43; N 8.68, Found: C, 61.35; H 3.41; N
8.61; calcd. for C33H22CoN4O7 (2): C, 61.40; H 3.43; N 8.68, Found: C, 61.42; H 3.40;
N 8.65; calcd. for C53H48Co2N8O16 (3): C, 54.37; H 4.13; N 9.57, Found: C, 54.31; H
4.11; N 9.52. IR (KBr pellet, cm-1 ), for 1: 3152 (w), 3033 (m), 1721 (m), 1562 (s),
1508 (m), 1432 (m), 1416 (m), 1386 (m), 1309 (w), 1277 (m), 1212 (w), 1126 (w),
1101 (m), 1066 (m), 1009 (w), 972 (m), 855 (m), 819 (w), 787 (m), 727 (w), 666 (w);
for 2: 3133 (w), 3026 (w), 1710 (m), 1571 (s), 1511 (s), 1441 (m), 1412 (w), 1375 (m),
1302 (w), 1265 (m), 1222 (w), 1135 (w), 1111 (w), 1056 (m), 1003 (w), 974 (m), 862
(w), 809 (w), 781 (w), 736 (w), 686 (w), 633 (w); for 3: 3387 (m), 3128 (w), 3051 (w),
3

1609 (w), 1577 (s), 1515 (s), 1444 (w), 1383 (m), 1344 (w), 1306 (m), 1247 (m), 1121
(w), 1065 (m), 1003 (w), 962 (m), 817 (m), 773 (w), 729 (w), 653 (w).
2.3 X-ray crystallography
X-ray crystallography data of complexes 1-3 were collected on a Bruker Apex
Smart CCD diffractometer at 293(2) K with graphite-monochromatized Mo-Kα
radiation (λ = 0.71073 Å) by using the ω-2ө scan mode. The structure was solved by
direct methods using SHELXS-97.[22] The non-hydrogen atoms were defined by the
Fourier synthesis method. Positional and thermal parameters were refined by the full
matrix least-squares method (on F2) to convergence.[23] Crystallographic data for
complexes 1-3 are given in Table 1. Selected bond lengths and angles for 1-3 are
listed in Table S1†. CCDC numbers for complexes of 1-3 are 1535706 for 1, 1535707
for 2 and 1536098 for 3.
3. Results and discussion
3.1 Structure description of [Co(HL)(4,4'-bibp)]n (1)
Complexes 1-3 were synthesized by Co(NO3)2·6H2O, H3L and 4,4'-bibp in one-pot
reaction under solvothermal condition at 130 °C. The result of single crystal X-ray
diffraction analysis showed that complexes 1 and 2 are isomers. The two isomers (1
and 2) crystallize in the monoclinic system with space group P21/c. As shown in Fig.
1a and Fig. 2a, the asymmetric units of the two isomers (1 and 2) consist of one Co(II)
ion, one HL2- carboxylate ligand and one 4,4'-bibp N-donor ligands. Each Co(II) is
four-coordinated by two O atoms from two independent HL2- ligands and two N
atoms from two different 4,4'-bibp bridging linkers, which adopts a distorted
tetrahedral {CoN2O2} coordination geometry. The bond lengths of Co-O and Co-N
are in the range of Co-O = 1.985(3)-2.012(3) Å and Co-N = 2.066(3)-2.072(3) Å,
respectively, in 1; and Co-O= 2.016(3)-2.105(3) Å and Co-N= 2.033(4)-2.062(4) Å,
respectively, in 2.
In compound 1, the partially deprotonated HL2- ligand connects two adjacent Co(II)
ions to construct a single-strand helix chain ([Co(HL2-)]n) along the a axis. Meanwhile,
two adjacent Co(II) ions are also connect by 4,4'-bibp ligands, which further show
another single-strand helix chain ([Co(4,4'-bibp)]n) along the c axis. Two types of 1D
helix chains are alternatively connected with each other and constructed a 2D network
4

with the 8.312(4) × 17.136(5) Å2 window.(Fig. 1b) These adjacent 2D layers are
further connected through H-bonds and C-H···N bonds to form a stable 3D
supramolecular with a -A-B-A- fashion.(Fig. 1c) From the viewpoint of structural
topology, the whole structure exhibits a sql uninodal 4-connected 3D supramolecular
network with a (44·62) symbol point.(Fig. 1d)
Fig. 1. (a-d)
3.2 Structure description of [Co(HL)(4,4'-bibp)]n (2)
The space group and asymmetric unit of complex 2 are same with the complex
1.(Fig. 2a) In complex 2, two adjacent Co(II) ions are also connected by the partially
deprotonated HL- ligands and formed two different single-strand [Co(HL2-)]n helix
chains along the b axis. Compared with 1, two neighbouring Co(II) ions are bridged
by 4,4'-bibp bridging linkers to generate a zigzag chain ([Co(4,4'-bibp)]n) along the a
axis in 2. Two different [Co(HL2-)]n helix chains are connected by [Co(4,4'-bibp)]n
zigzag chain and constructed a 2D network with the 9.841(2) × 16.959(2) Å2
window.(Fig. 2b) These 2D networks are connected through H-bonds to complete the
3D supramolecular with a -A-B-A- fashion (Fig. 2c). Through simplification, this
supramolecular network could be regarded as a uninodal 4-connected sql with the
point symbol of (44·62).(Fig. 2d)
Fig. 2. (a-d)
3.3 Structure description of {[Co2(L)(4,4'-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n (3)
Single-crystal X-ray diffraction analysis exhibits that 3 crystallizes in the Triclinic
system with space group Pī. In contrast to complexes 1 and 2, the independent unit of
3 is composed by two types of Co(II) ions (Co1 and Co2), one L3- carboxylate ligand,
two 4,4'-bibp N-donor ligands, three coordination water and one COO-. As depicted in
Fig. 3a, Co2 is six-coordinated by three O atoms from three coordination water
molecules, and one O atom from one coordination COO- molecule and two N atoms
from two independent 4,4'-bibp ligands, which formed a slightly distorted
octahedral geometry. However, Co1 is four-coordinated by two O atoms from two
independent L3- ligands and two N atoms from two different 4,4'-bibp N-donor
5

ligands, and it adopts a slightly distorted tetrahedral geometry. The bond lengths of
Co-O and Co-N are in the range of Co-O = 1.947(3)-2.163(3) Å and Co-N=
2.036(3)-2.125(3) Å, respectively.
In complex 3, only Co1 is connected by the completely deprotonated L3- ligands
forming a single-strand helix chain ([Co(L3-)]n) along the c axis. While two adjacent
Co1 and Co2 are connected by 4,4'-bibp N-donor ligands to construct a 1D
[Co2(4,4'-bibp)2]n linear chain. Two types of 1D chains are alternatively connected
with each other, constructing a 2D network with the bigger window 8.263(2) ×
33.774(5) Å2.(Fig. 3b) The two adjacent 2D networks are further catenated with each
other through O-H···O hydrogen bonds and C-H···C bonds.(Fig. 3c) From the
viewpoint of structural topology, the whole structure also exhibits a sql uninodal
4-connected 3D supramolecular framework with the point symbol (44·62).(Fig. 3d)
Fig. 3. (a-d)
3.4 Structural comparison and discussion
In our work, complexes 1-3 were synthesized by one-pot reaction, while these
complexes afford diverse structures which were influenced by the flexibility of H3L.
The dihedral angles between the two phenyl rings of H3L ligands are shown in
scheme 3. In isomers 1 and 2, the H3L ligand exhibits two different dihedral angles
and constructions. In 1, the HL2- ligand connects two adjacent Co(II) ions forming a
[Co(HL2-)]n single-strand helix chain. However, in 2, there are two types of
carboxylate helix chains (left and right) which were influenced by the flexibility of
H3L. Meanwhile, the completely deprotonated L3- ligand connects two adjacent Co(II)
ions to construct a single-strand [Co(L3-)]n helix chain with similar dihedral angles
with 1 [83.098(3)º in 1 and 74.874(4)º in 3]. Affected by the metal coordination
environment, there are three different channels in 1-3 [8.312(4) × 17.136(5) Å2 in 1,
9.841(2) × 16.959(2) Å2 in 2 and 8.263(2) × 33.774(5) Å2 in 3]. Moreover, the
4,4'-bibp ligand exhibits three different configurations 1D chains (single-strand helix,
zigzag and linear) through coordinating with metal ions.
Scheme 3
6

4. Obtainment of complexes 1-3 at different conditions
For the purpose of purifying these complexes, we have optimized the reaction
conditions of crystallization for three different crystals. As shown in Table S2†, the
detailed studies were conducted and observed: (1) Reaction temperature was 130 °C,
heating time is 72h and cooling time is 20h (a descent rate of 5 °C h-1). When
DMF/H2O (VDMF:VH O = 1:1),(Fig. S1) CH3CN/H2O (VCH CN:VH O = 1:1) or
2
3
2
DMF/CH3CN/H2O (VDMF:VCH CN:VH O = 1:1:1) were used as the solvent system, the
3
2
complex 2 was obtained under these solvothermal reactions. While the ratio of these
mixed solvent were reduced to 1:2 respectively, fewer 2 was obtained; When
DMF/CH3OH (VDMF:VCH3OH = 1:1) (Fig. S2) or DMF/CH3OH/H2O (VDMF:VCH3OH:VH2O
1:1:1) were used as the solvent system, the complex 1 was obtained. While CH3OH
was replaced by CH3CH2OH, a lot of powder appeared. (2) Reaction temperature was
90 °C, heating time is 72h and cooling time is 12h (a descent rate of 5 °C h-1), the
=
DMF/H2O (VDMF:VH O = 1:1) or CH3CN/H2O (VCH3CN:VH2O = 1:1) were used as the
2
solvent system, two-component complexes of 1 and 2 were obtained under these
solvothermal reactions. (3) Reaction temperature was 150 °C, heating time is 72h and
cooling time is 24h (a descent rate of 5 °C h-1), H2O was used as the solvent, the
amount of 1 and 2 gradually generated with the addition of NaOH, then the white
powder was obtained under this hydrothermal reaction. To determine whether the
ratio of H3L/4,4'-bibp/Co(NO3)2·6H2O influenced the formation of these complexes
or not, the ratio of 1:2:2 was replaced by 1:1:1. Consequently, the complex 3 was
obtained under DMF/H2O (VDMF:VH2O = 1:1) (Fig. S3) or CH3CN/H2O (VCH3CN:VH2O
=
1:1) solvent system at 130 °C after 72h, complex 2 and 3 were obtained under
DMA/H2O solvothermal reaction system with a solvent ratio of 1:1 at 130 °C.(Table
S2†) Moreover, the purities of complexes 1-3 were confirmed by powder X-ray
diffraction (PXRD) measurements, respectively. The results reveal that the
experimental PXRD patterns well match the simulated patterns based on the
single-crystal X-ray data (Fig. S4).
5. Thermal analyses
For investigating the thermal stabilities of compounds 1-3, their thermal behaviors
were performed by TGA.(Fig. S5) The experiments were investigated in an N2
atmosphere with a heating rate of 10 °C min-1. For complex 1, the destruction of the
7

framework occurs at ca. 240 °C, finally leading to the formation of the stoichiometric
amount of CoO as a residue (obsd: 31.6%, calcd: 11.6%). For complex 2, the
decomposition of the compound occurs at ca. 235 °C, and the remaining weight
corresponds to the formation of CoO (obsd: 40.4%, calcd: 11.6%). However, for
complex 3, it has two-step of weight losses. The first weight loss of 11.2% in the
temperature range of 70-120 °C is consistent with the removal of the coordinated
water molecules and the lattice H2O and HCOOH molecular (calcd: 11.6%). The
second weight loss corresponds to the loss of the organic ligands at ca. 260 °C, and
the remaining weight corresponds to the formation of CoO (obsd: 36.8%, calcd:
12.6%).
6. Selective dye adsorption studies
Dyes are generally difficult to degrade, because they are highly stable to light and
oxidation.[24] Therefore, how to quickly and economically remove the dyes from
industrial wastewater has drawn a great deal of attention for chemical researchers.[25]
As we know, the size of dye molecular and appropriate voids of materials are main
factors for the adsorption process.[26-31] Therefore, based on the appropriate
channels of complexes 1-3, four organic dyes (Fig. S6, Alizarin Red S (ARS),
Malachite Green Oxalate (MGO), Rhodamine B (RhB) and Methyl Orange (MO))
were selected to investigate the influence of titled complexes on dyes selective
adsorption.[32, 33] 10 mg of 1, 2 and 3 complexes were dispersed in 6 mL aqueous
solution of ARS, MGO, RhB or MO at a concentration of 30 ppm, respectively.
Afterward, four dye aqueous solutions were tested under UV-spectrometry
measurement at different time intervals.
After 48 h, for RhB and MGO solutions, all complexes 1-3 exhibit no obvious
adsorption capacity.(Fig. S7) For MO solution, the titled 1-3 show better adsorption
activity contrasted with RhB and MGO (Fig. 4), the complex 1 shows high and
selective adsorption capacity in MO ( 91.4% after 70 min), while complexes 2 and 3
show lower absorption rate compared with 1 [96.3% (2) and 98.5% (3) after 24 h], the
adsorption activity order is 1 >3 > 2. For ARS solution, as shown in Fig. 5, complexes
1 and 3 did not show obvious absorption capacity (8.1% in 1 and 5.3% in 3 after 48h),
however, complex 2 exhibits high and selective adsorption capacity in ARS (84.4%
after 45 min). Moreover, complex 1 shows higher MO adsorption activities than other
8

reported CPs (e.g. {[(CH3)2NH2][Co2NaL2(CH3COO)2]·xS}n,
{[Cd(tib)2]·2NO3·4DMF} and {[Zn(L)(PDA)]·DMF·3H2O}n),[1, 3, 34] complex 2
shows higher ARS adsorption activities than other reported CPs (e.g.
{[(CH3)2NH2][Co2NaL2(CH3COO)2]·xS}n, {[Cd1.5(cpbda)(bpa)(H2O)2]·1.5H2O}n and
[Cd(H2cpbda)2(bpa)0.5(H2O)]n).[2, 34] The result indicates that 1 may be a good
candidate for high and selective adsorption for MO, and 2 show a better adsorption
activity for ARS than MO, and 3 may be a good candidate for selectively adsorbing
MO. Complexes 1-3 show different adsorption capacities in RhB, MGO, MO and
ARS solutions, which may be caused by the different configurations and steric
hindrance of the dye molecular.(Fig. S6) Meanwhile, the possible reason for that only
2 can adsorb the ARS may be due to the appropriate layer gap between 2D
structures.[35] (Fig. S8) In order to investigate the stability of complexes 1-3, the
PXRD patterns of the recycled powders were obtained, as shown in Fig. S9. The
PXRD result reveals that the three Co(II) complexes were stable in the dye adsorption
process.
Fig. 4
Fig. 5
7. Conclusions
In summary, three Co(II) coordination polymers (complexes 1-3) were obtained
through one-pot reaction under co-crystallization conditions. Among these complexes,
complexes 1 and 2 were supramolecular isomers. Although complexes 1-3 exhibit the
similar sql topological structure, the steric configuration of three complexes were
different. In complex 1, the 2D networks connected each other through H-bonds and
C-H···N bonds, forming a stable 3D supramolecular framework. Compared with 1,
the isomer 2 show another 2D network with two different [Co(HL2-)]n helix chains
(left and right), which construct a 3D supramolecular framework through H-bonds.
Compared with 1 and 2, complex 3 exhibits a different 2D network with bigger
channel which were influenced by the coordination environment of Co(II) ions.
Moreover, the dye adsorption studies indicate that complex 1 may be a good
candidate for high and selective adsorption for MO, and complex 2 shows a better
adsorption activity for ARS than MO, and 3 may be a good candidate for selectively
9

adsorbing MO.
Acknowledgements
This research was supported by the National Natural Science Foundation of China
to C.F. Bi (no. 21371161), the Specialized Research Fund for the Doctoral Program of
Higher Education of China (no. 20120132110015).
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12

Table 1 Summary of crystal data and structure refinement parameters for 1-3a
Compound
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
1
2
3
C33H22CoN4O7
645.48
C33H22CoN4O7
645.48
C51H41Co2N9O12
1089.79
Triclinic
Pī
Monoclinic
P21/c
Monoclinic
P21/c
12.618(6)
8.312(4)
27.572(11)
90
9.8414(13)
11.5635(16)
25.586(4)
90
8.2625(14)
16.427(3)
20.040(3)
105.992(2)
92.815(2)
101.586(2)
2545.6(7)
2
b (Å)
c (Å)
α (°)
100.497(7)
90
98.902(3)
90
β (°)
γ(°)
V (Å3)
2843(2)
4
2876.6(7)
4
Z
Dcalcd(Mg m−3)
µ (mm−1)
Reflections collected
Data/parameters
F(000)
1.508
1.490
1.422
0.662
0.655
0.723
13930
14545
17943
5020 / 407
1324
5087 /407
1324
8982 /691
1120
298(2)
298(2)
298(2)
T (K)
0.0604
0.0693
0.0345
Rint
Final R indices [I > 2σ(I)]
R1 = 0.0461
wR2 = 0.1007
R1 = 0.0947
wR2 = 0.1389
1.072
R1 = 0.0517
wR2 = 0.1228
R1 = 0.1020
wR2 = 0.1621
1.039
R1 = 0.0499
wR2 = 0.1420
R1 = 0.0744
wR2 = 0.1527
1.088
R indices (all data)
Gof
2
2 2
2 2 1/2
a R1 = ΣǁFo| − |Fcǁ/Σ|Fo|, wR2 = [Σw(Fo − Fc ) ]/[Σw(Fo ) ] ·
Scheme 1 Structures of H3L and the 4,4'-bibp N-donor linker.
13

Scheme 2 The optical microscope photographs and topological structures of
complexes 1-3. (complex 1 is pink and block-shaped; complex 2 is crimson and
rice-shaped; complex 3 is purple and strip-shaped)
Scheme 3 The dihedral angles between the two phenyl rings of H3L ligands in
complexes 1-3.
14

Fig. 1. (a) Coordination environment of the Co(II) ion in complex 1. (b) View of the
2D network of 1 (blue spheres: 4,4'-bibp ligands; red spheres: HL2- ligands). (c) The
2D → 3D supramolecular networks through H-bonds and C-H···N interactions. (d)
View of the 4-connected 3D supramolecular frameworks with the point symbol (44·62)
in complex 1.
15

Fig. 2. (a) Coordination environment of the Co(II) ion in complex 2. (b) View of the
2D network of 2 (blue spheres: 4,4'-bibp ligands; red spheres: HL2- ligands). (c) The
→ 3D
2D
supramolecular networks through H-bonds. (d) View of the 4-connected 3D
supramolecular frameworks in complex 2.
16

Fig. 3. (a) Coordination environment of the Co(II) ion in complex 3. (b) View of the
2D network of 3 (blue spheres: 4,4'-bibp ligands; red spheres: L3- ligands). (c) The 2D
→ 3D supramolecular networks through H-bonds C-H···C interactions. (d) View of
the 4-connected 3D supramolecular frameworks in complex 3.
Fig. 4. UV-vis spectra for the uptake of MO from aqueous solutions at various time
intervals for 1-3, respectively.
17

Fig. 5. UV-vis spectra for the uptake of ARS from aqueous solutions at various time
intervals for 1-3, respectively.
18

19