Various coordination architectures constructed from N-[(carboxyphenyl)-sulfonyl]glycine: Structural variation via ligand isomerism effects and metal-directed assembly

Article abstract of DOI:10.1016/j.poly.2009.04.044

Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H₃L₁) and N-[(3-carboxyphenyl)-sulfonyl]glycine (H₃L₂), a series of new coordination polymers, [Mn(phen)(H₂O)₄][HL₁] (1), [Co₃(L₁)₂(bipy)₃(H₂O)₆]_n·8nH₂O (2), [Cu₄(L₁)₂(OH)₂(bipy)₄]_n·12nH₂O (3), [Na(H₂L₁)(H₂O)]_n (4), [Mn₂(HL₂)₂(dpe)₃(H₂O)₂]_n·ndpe (5), (phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene), varying from 0D to 3D, have been synthesized and structurally characterized. Compound 1 has a [Mn(phen)(H₂O)₄]²⁺ cation and a HL₁^2- anion. Compound 2 features a new 1D triple chain, based on octahedral cobalt atoms bridged by bipy molecules and terminally coordinated by two H₃L₁ ligands. Compound 3 has a 2D layered structure, constructed from new alternating chains where H₃L₁, hydroxyl and water molecules simultaneously act as bridging ligands. Compound 4 possesses a bilayer structure in which two adjacent layers are pillared by H₃L₁ ligands into a 2D bilayer network. Compound 5 is a unique 3D coordination polymer in which each Mn center binds two trans-located dpe molecules. The thermal stability as well as magnetic properties of 5 was also studied. This work and our previous work indicate that the positional isomer of the anionic N-[(carboxyphenyl)-sulfonyl]glycine is important in the construction of these network structures, which are also significantly regulated by the metal centers.

Full text of DOI:10.1016/j.poly.2009.04.044

Polyhedron 28 (2009) 2494–2502
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Various coordination architectures constructed
from N-[(carboxyphenyl)-sulfonyl]glycine: Structural variation
via ligand isomerism effects and metal-directed assembly
Lu-Fang Ma a, Li-Ya Wang a, , Shu-Hui Chen a,b, Hong-Wei Hou b, Stuart R. Batten c
*
a College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022, PR China
b Department of Chemistry, Zhengzhou University, Zhengzhou 450001, PR China
c School of Chemistry, Monash University, Victoria 3800, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H3L1)
and N-[(3-carboxyphenyl)-sulfonyl]glycine (H3L2), a series of new coordination polymers, [Mn(phen)-
(H2O)4][HL1] (1), [Co3(L1)2(bipy)3(H2O)6]nꢀ8nH2O (2), [Cu4(L1)2(OH)2(bipy)4]nꢀ12nH2O (3), [Na(H2L1)-
(H2O)]n (4), [Mn2(HL2)2(dpe)3(H2O)2]n ꢀndpe (5), (phen = 1,10-phenanthroline, bipy = 4,40-bipyridine,
dpe = 1,2-di(4-pyridyl)ethylene), varying from 0D to 3D, have been synthesized and structurally charac-
terized. Compound 1 has a [Mn(phen)(H2O)4]2+ cation and a HL12ꢁ anion. Compound 2 features a new 1D
triple chain, based on octahedral cobalt atoms bridged by bipy molecules and terminally coordinated by
two H3L1 ligands. Compound 3 has a 2D layered structure, constructed from new alternating chains
where H3L1, hydroxyl and water molecules simultaneously act as bridging ligands. Compound 4 pos-
sesses a bilayer structure in which two adjacent layers are pillared by H3L1 ligands into a 2D bilayer net-
work. Compound 5 is a unique 3D coordination polymer in which each Mn center binds two trans-located
dpe molecules. The thermal stability as well as magnetic properties of 5 was also studied. This work and
our previous work indicate that the positional isomer of the anionic N-[(carboxyphenyl)-sulfonyl]glycine
is important in the construction of these network structures, which are also significantly regulated by the
metal centers.
Received 14 December 2008
Accepted 30 April 2009
Available online 10 May 2009
Keywords:
N-[(4-carboxyphenyl)-sulfonyl]glycine
N-[(3-carboxyphenyl)-sulfonyl]glycine
Crystal structure
Magnetic properties
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
isomers as the organic component is an effective way to investigate
the effect of the ligand geometry. Usually, ligand isomers having
The rational design and assembly of inorganic coordination
polymers or metal–organic frameworks has received remarkable
attention and has developed rapidly in recent years. Being easily
and efficiently synthesized from relatively simple subunits, these
complexes exhibit fascinating structural topologies and potential
applications as functional materials [1–4]. However, the control
of dimensionality is still a major challenge in the design and syn-
thesis of organic–inorganic frameworks because the final structure
is frequently modulated by various factors such as solvent med-
ium, the geometry of metal ions, coordination character of the or-
ganic ligand, temperature, metal–ligand ratio, template and
counterion [5]. Among these factors, the selection of appropriate
metal ions and organic ligands is often the key in the construction
of complexes. Metal ions, and in particular their radii and coordi-
nation geometry determine the bridging pattern and coordination
modes of the organic ligands, and thus the overall structures of the
complexes. In the crystal engineering, the employment of ligand
similar structures but different coordination modes would lead
to different structural motifs, such as seen for benzenedicarboxy-
lates. Benzenedicarboxylate anions have three structural isomers
(phthalate, isophthalate and terephthalate) with different angles
between the two carboxylato groups, which may exhibit different
geometric effects on the construction of coordination polymers [6].
To date, a variety of metal organic frameworks have been reported,
however, systematic studies of the isomeric effect on the genera-
tion of such coordination frameworks are surprisingly rare [7].
With this in mind, one crucial aim of this work was to explore
the effect of two isomers on the structural assembly. This may pro-
vide further insights in designing new hybrid crystalline materials.
Furthermore, amino acid is one of the most important biological
ligands. Recently, amino acids with flexible coordination modes
have been utilized to construct metal–organic supramolecular
networks [8]. To date, a number of Ln-amino acid and transition
metal–amino acid complexes with mononuclear, binuclear or
chain structural motifs have been synthesized [9]. Several reports
of polynuclear transition metal clusters or various 3d–4f high-
nuclearity clusters with different structural motifs have also
* Corresponding author. Tel.: +86 0379 65523593; fax: +86 0379 65511205.
E-mail address: wlya@lynu.edu.cn (L.-Y. Wang).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.04.044

L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
2495
TM
reported [10]. However, reports of metal complexes of amino acids
with high dimensional structures are rare [11]. This may be due to
deprotonated amino acids preferring to chelate metal centers
through their amine N and carboxylic O atoms to form five-mem-
bered rings which prevent extension into high dimensional struc-
tures. In order to overcome this problem, our research has
focused on designing a new versatile ligand which contains both
carboxylate and amino acid groups by introduction of an aromatic
carboxylato group at its amino group.
tar 360 E.S.P.IR spectrometer. The crystal structure determination
was performed on a Bruker SMART APEX II CCD diffractometer
equipped with graphite-monochromatized Mo
Ka radiation
(k = 0.71073 Å). Thermogravimetric analyses (TG) were carried
out on a STA449C integration thermal analyzer. The PXRD patterns
were recorded with a Rigaku D/Max 3III diffractometer with a
scanning rate of four degrees per minute. Variable-temperature
magnetic susceptibilities were measured using a MPMS-7 SQUID
magnetometer.
We have recently used such a multifunctional amino acid deriv-
ative, namely N-[(3-carboxyphenyl)-sulfonyl]glycine, to create a
series of unusual metal–organic frameworks [12,13]. In compari-
son to benzenedicarboxylic acids, N-[(3-carboxyphenyl)-sulfo-
nyl]glycine not only contains two bridging carboxylato moieties
but also possesses another two potential coordination sites, i.e.,
the nitrogen atom and oxygen atoms of the sulfonate groups. This
asymmetric geometry may produce beautiful new structural mo-
tifs and useful functional properties. To further probe the influence
of systematic variations of ligand structures and metal ions on the
overall molecular architectures, we extend the building blocks
from the bent N-[(3-carboxyphenyl)-sulfonyl]glycine to its quasi-
linear isomer N-[(4-carboxyphenyl)-sulfonyl]-glycine to explore
the isomeric effect on network assembly. Herein, the synthesis
and X-ray crystal structures of eight coordination networks,
including our previous reported [Mn2(HL2)2(phen)4]nꢀ8nH2O (6),
[Co3(L2)2(bipy)2(H2O)6]nꢀ2nCH3OHꢀ8nH2O (7) and [Ca(H2O)4Cu2(bi-
py)2(L2)2]nꢀ4nH2O (8), formed by Cu2+, Mn2+, Co2+ salts with H3L1
and H3L2 are reported (See Schemes 1 and 2). The influence of li-
gand isomerism and metal ions on the final structures of the
assemblies is discussed.
2.2. Synthesis of N-[(4-carboxyphenyl)-sulfonyl]glycine
To a solution of glycine (2.25 g, 0.03 mol) in NaOH 2 M (30 mL),
4-(chlorosulfonyl)benzoic acid (6.78 g, 0.03 mol) was added. The
mixture was stirred at room temperature for 2 h, and the aqueous
solution was then acidified to pH 4 with 6 M hydrochloric acid,
upon which a white solid derivative began to crystallize at once
with a yield of about 60%. Anal. Calc. for C9H9NO6S: C, 41.70; H,
3.50; N, 5.40. Found: C, 41.79; H, 3.62; N, 5.58%. IR: 3287s,
1718s, 1432s, 1171m, 753m, 1336s, 897m.
2.3. Preparation of 1–5
2.3.1. [Mn(phen)(H2O)4][HL1] (1)
A mixture of Mn(ClO4)2 ꢀ 6H2O (0.16 g, 0.5 mmol) and H3L1
(0.26 g, 1 mmol) was stirred into 15 mL of water. The pH was then
adjusted to ca. 5 with 1 M NaOH. A solution of phen (0.21 g,
1 mmol) in ethanol (3 mL) was then added. The reaction mixture
was heated on a water bath for 10 h at 70 °C, and then filtered.
The yellow crystals were separated from the mother liquor by slow
evaporation at room temperature after 4 weeks. Anal. Calc. for
C21H23MnN3O10S: C, 44.69; H, 4.11; N, 7.44. Found: C, 44.51; H,
4.19; N, 7.50%. IR: 3413s, 1676s, 1411s, 1167m, 729m, 1345s,
851m.
2. Experimental
2.1. Materials and instruments
2.3.2. [Co3(L1)2(bipy)3(H2O)6]nꢀ8nH2O (2)
All reagents used in the syntheses were of analytical grade. Ele-
mental analyses for carbon, hydrogen and nitrogen atoms were
performed on a Vario EL III elemental analyzer. The infrared spec-
tra (4000–600 cmꢁ1) were recorded by using KBr pellet on an Ava-
A mixture of Co(OAc)2ꢀ4H2O (0.13 g, 0.5 mmol) and H3L1 (0.13 g,
0.5 mmol) was stirred into 15 mL of water, and then refluxed for
ca. 1 h. The pH was then adjusted to ca. 6 with 1 M NaOH. A solu-
tion of bipy (0.04 g, 0.25 mmol) in methanol (3 mL) was then
Scheme 1. Summary of the products obtained from the reactions of metal ions and H3L1.
Scheme 2. Summary of the products obtained from the reactions of metal ions and H3L2.

2496
L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
added. The reaction mixture was heated on a water bath for 10 h at
70 °C, and then filtered. The red crystals were separated from the
mother liquor by slow evaporation at room temperature after
2 weeks. Anal. Calc. for C48H64Co3N8O26S2: C, 40.89; H, 4.58; N,
7.94. Found: C, 40.76; H, 4.67; N, 7.81%. IR: 3412s, 1684s, 1567s
1427s, 1127s, 1160m, 725m, 1396s, 864m.
2.3.3. [Cu4(L1)2(OH)2(bipy)4]nꢀ12nH2O (3)
Complex 3 was synthesized using a procedure analogous to that
of 2 except that Cu(OAc)2ꢀH2O was used instead of Co(OAc)2ꢀ4H2O
and 1.2 mmol Ca(OH)2 was added. Blue crystals were produced
after 3 weeks. Anal. Calc. for C29H35Cu2N5O13S: C, 42.44; H, 4.30;
N, 8.53. Found: C, 42.56; H, 4.26; N, 8.68%. IR: 3415s, 1695s,
1427s, 1159m, 706m, 1332 s, 864m.
2.3.4. [Na(H2L1)(H2O)]n (4)
An aqueous methanol solution of Mn(OAc)2 ꢀ 4H2O (0.12 g,
0.5 mmol), H3L (0.13 g, 0.5 mmol) and bipy (0.04 g, 0.25 mmol)
was stirred for 6 h at room temperature and then filtered. The
pH was then adjusted ca. 6 with 1 M NaOH. The filtrate was al-
lowed to stand for 1 week. The colorless crystals obtained were
suitable for X-ray analysis. Yield: 26%. Anal. Calc. for C9H10NNaO7S:
C, 36.13; H, 3.37; N, 4.68. Found: C, 36.21; H, 3.52; N, 4.61%. IR:
3423s, 1714s, 1417s, 1109s, 1157m, 721m, 1362s, 814m.
2.3.5. [Mn2(HL2)2(dpe)3(H2O)2]nꢀndpe (5)
Complex 5 was synthesized in a procedure analogous to that of
4 except that dpe and H3L1 were used instead of bipy and H3L2.
Yield: 35%. Anal. Calc. for C66H56Mn2N10O14S2: C, 57.13; H, 4.07;
N, 10.10. Found: C, 57.01; H, 3.93; N, 9.98%. IR: 3423s, 1597s,
1420s, 1161m, 731m, 1389s, 857m.
Fig. 1. (a) Molecular structure of 1. (b) View of the 2D supramolecular system of 1
showing the cyclic intramolecular hydrogen bonding interactions.
2.4. Crystallographic data collection and structures determination
Single-crystals of 1–5 were put on a Bruker SMART APEX II CCD
diffractometer equipped with a graphite monochromated Mo K
a
3. Results and discussion
radiation (k = 0.71073 Å) at room temperature. The structures were
solved by direct methods with SHELXS-97. A full-matrix least-
squares refinement on F2 was carried out using SHELXL-97. The crys-
tallographic data and selected bond lengths and angles for 1–5 are
listed in Table 1 and Table S1, Supplementary data. Hydrogen
bonds parameters in 1–5 are listed in Table S2.
3.1. Description of the structures
3.1.1. [Mn(phen)(H2O)4][HL1] (1)
As shown in Fig. 1a, the unit of 1 contains a [Mn(phen)(H2O)4]2+
2ꢁ
cation and a HL1
anion. The Mn(II) ion is six-coordinated
Table 1
Crystallographic data for complexes 1–5.
Compounds
1
2
3
4
5
Formula
Mr
T (K)
C21H23MnN3O10
564.42
291(2)
S
C48H64Co3N8O26S2
1409.98
291(2)
C29H35Cu2N5O13
820.76
291(2)
S
C9H10N Na O7
299.23
291(2)
S
C66H56Mn2N10O14S2
1387.21
293(2)
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
monoclinic
C2/c
monoclinic
C2/c
monoclinic
P2/n
triclinic
P1
monoclinic
C2/c
23.228(5)
13.909(3)
15.045(3)
24.906(2)
14.9985(12)
17.3262(14)
16.948(3)
11.144(2)
17.273(3)
5.5061(11)
7.6378(16)
14.332(3)
79.301(2)
88.416(2)
75.341(2)
572.8(2)
2
37.011(3)
8.5952(7)
26.729(2)
a
(°)
b (°)
100.134(2)
117.199(10)
99.373(3)
129.231(10)
c
(°)
V (Å3)
4784.7(17)
8
1.567
2328
5756.5(8)
4
1.627
3218.9(11)
4
1.694
1688
6586.5(10)
4
1.399
Z
q
(g cmꢁ3
)
1.735
308
F(0 0 0)
2916
2864
Goodness-of-fit
1.043
1.023
1.028
1.040
1.052
Crystal size (mm3)
0.33 ꢂ 0.29 ꢂ 0.22
0.0292, 0.0725
0.0361, 0.0773
0.246, ꢁ0.304
0.27 ꢂ 0.17 ꢂ 0.15
0.0330, 0.0795
0.0435, 0.0861
0.523, ꢁ0.506
0.18 ꢂ 0.07 ꢂ 0.07
0.0559, 0.1273
0.1029, 0.1521
0.774, ꢁ0.907
0.26 ꢂ 0.24 ꢂ 0.13
0.0326, 0.0856
0.0394, 0.0903
0.289, ꢁ0.428
0.33 ꢂ 0.26 ꢂ 0.25
0.0667, 0.1854
0.0857, 0.2039
1.734, ꢁ0.464
R1, wR2 [I > 2r(I)]
R1, wR2 (all data)
Largest difference in peak and hole (e Åꢁ3
)

L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
2497
(MnN2O4) and the coordination polyhedron is a distorted octahe-
dral geometry. The bond lengths of Mn1–O are in the range of
2.1451(13)–2.2070(13) Å. The phen molecule chelating to the
Mn(II) ion with Mn1–N1 and Mn1–N2 bond distances of
2.3010(16) and 2.2738(15) Å, respectively. It is notable that even
rounded by one carboxylato oxygen atom, one nitrogen atom from
a L13ꢁ ligand and two water molecules in the equatorial plane and
two nitrogen atoms of bipy in the axial position. The Co–OL1 and
Co–Nbipy bond lengths are in agreement with those reported for car-
boxylate and bipy-containing Co(II) complexes. One inner Co1 atom
and two outer Co2 atoms are bridged by single carboxylato group in
a syn–anti mode to form a linear trinuclear cluster with an adjacent
Coꢀ ꢀ ꢀCo distance of 5.736 Å. The similar carboxylato bridged linear
trinuclear Co(II) complexes [Co3(O2CMe)6(bpy)2], [Co3(O2CPh)6-
(base)2], [Co3(O2C(C6H4NO2)6(base)2)] and [Co3(O2CMe)8] have also
been reported in the literatures [14–16]. The trinuclear clusters in 2
are connected to each other through bipy bridges to give rise to a
new 1D triple infinite chain extending along the b-axis (Fig. 2b),
which is different from those of the known 1D polymers with linear
chain [17], zigzag chain [18], helical chain [19], ladder chain [20],
double-stranded chain [21] and 1D double chain motifs [22]. To
the best of our knowledge, this is the first example of a 1D triple
chain complex containing amino acid-type and linear trinuclear
metal arrangements.
2ꢁ
though HL1 does not coordinate to the metal atoms, it plays an
important templation role in the crystallization process of com-
pound 1. Each HL12ꢁ group is involved in significant intermolecular
hydrogen bonding interactions with coordinated water molecules
through its two carboxylato groups. Finally, these cation–anion spe-
cies are organized into a two-dimensional supramolecular architec-
ture (Fig. 1b). The bond lengths and angles of the hydrogen bonding
are in the range of 2.658(2)–2.8088(19) Å and 157.8–175.2°, respec-
tively. By comparison, the previously reported [Mn2(HL2)2
(phen)4]nꢀ8nH2O (6) which displays a binuclear unit and further
forms the 2D supramolecular structure through unique p–p stack-
ing and hydrogen bonding interactions [13]. This structural discrep-
ancy may arise from the different coordination modes displayed by
the HL12ꢁ and HL22ꢁ ligands. The HL12ꢁ acts as a bridging ligand in 6
(Scheme 3c) while HL22ꢁ does not coordinate at all in 1.
In addition, there exist aromatic ring stacking interactions in
the trinuclear unit between benzene rings of L13ꢁ ligands and pyr-
idine rings of bipy, with the centroid to centroid distance being
3.1.2. [Co3(L1)2(bipy)3(H2O)6]nꢀ8nH2O (2)
Complex 2 crystallizes in the space group C2/c. As illustrated in
Fig. 2a, the asymmetric unit contains three Co(II) ions, two L13ꢁ an-
ions, three bipy, six coordinated water and eight lattice water mol-
ecules. The L13ꢁ ligands use the nitrogen atom and one carboxylato
oxygen atom from the glycinato group to chelate one Co atom,
while the remaining carboxylato oxygen atom from the glycinato
group coordinates to another Co atom. The two carboxylato oxygen
atoms of the C6H5COOꢁ group are free, as shown in Scheme 3a.
There are two crystallographically independent cobalt atoms, one
of which (Co2) lies on a center of symmetry, while the other
(Co1) lies on a general position. The geometries around the Co(II)
ions are both distorted octahedra, giving rise to a [4+2] type of con-
figuration. Co1 is coordinated by two carboxylato oxygen atoms
3.77 Å and a dihedral angle of 4.16°. These
p
–
p
stacking interac-
3ꢁ
tions encourage the L1 ligands to alternately decorate two sides
of the 1D triple chain. Extensive hydrogen bonds between coordi-
nated water molecules and lattice water molecules are also
formed, which reinforce the intra- and inter-chain linkages, and re-
sult in the formation of a 3D extended framework. In 2, the two
types of weak interactions, namely hydrogen bonds and aromatic
ring stacking interactions, play an important role in the self-assem-
bly and stabilization of the supramolecular structure. Notably, a re-
lated compound [Co3(L2)2(bipy)2(H2O)6]nꢀ2nCH3OHꢀ8nH2O (7) is
obtained by using H3L2 under similar conditions, however, this
2ꢁ
structure shows a 1D alternating chain with [CoL(H2O)]2 binu-
clear and [Co(bipy)2(H2O)4]2+ mononuclear units along the a-direc-
3ꢁ
from two L1 ligands and two water molecules in the equatorial
tion [12]. Furthermore, the coordination mode of L23ꢁ in 7 (Scheme
3ꢁ
plane and two nitrogen atoms of bipy at the axial sites. Co2 is sur-
3d) is different from that of L1 in 2.
Scheme 3.

2498
L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
Fig. 2. (a) A perspective view of the discrete Co3 cluster, hydrogen atoms and lattice water molecules are omitted for clarity. (b) The 1D triple polymeric chain architecture in
3ꢁ
2, the L1 ligands are omitted for clarity.
3.1.3. [Cu4(L1)2(OH)2(bipy)4]nꢀ12nH2O (3)
was ca. 12.13°) with a close intramolecular separation of ca.
3.83 Å. The stacking interactions encourage the L1 ligands to lie
3ꢁ
It can be seen from Fig. 3a that 3 contains tetranuclear Cu(II)
units. Each tetranuclear unit is composed of four Cu(II) ions, two
alternatively above and below the 2D planes, and further extensive
hydrogen bonds exist between coordinated water and lattice water
molecules between the adjacent 2D layers, generating an overall
3D network. The structure of 3 is different from that of [Ca(H2O)4-
Cu2(bipy)2(L2)2]nꢀ4nH2O (8), which has a 2-fold 3D interpenetrat-
ing network where Cu atoms are joined by bipy to generate a 1D
zigzag chain [12]. Every L23ꢁ ligand adopts a tetradentate bridging
3ꢁ
L1 ligands, and two OHꢁ groups. There are also twelve interca-
lated water molecules per tetramer. Within the tetramer, there
are three kinds of crystallographically independent Cu(II) ions with
different coordination environments in the unit. Cu1 and Cu2 are
3ꢁ
bridged by one L1 ligand and Cu2 and Cu3 are bridged by a hy-
droxyl group with distances of 5.374 and 3.369 Å between Cu1/
Cu2 and Cu2/Cu3, respectively. The geometry of Cu1 can be consid-
ered as a distorted octahedral geometry with a [N4O2] coordination
sphere. The four equatorial coordination sites are occupied by N1,
N2, N7 and N7A. Two oxygen atoms (O2, O2A) from two different
glycinato groups occupy the axial coordination sites. The axial
bond lengths (Cu1–O2, 2.354(4) Å) are considerably longer than
the equatorial bond lengths (Cu(1)–N(7) = 2.013(4), Cu(1)–
N(1) = 2.031(6), Cu(1)–N(2) = 2.079(6) Å) leading to the distortion
from regular octahedral geometry. Cu2 is four-coordinated by
one bridging carboxylato oxygen atom, two nitrogen atoms from
different bipy ligands and one bridging hydroxyl group with a
[N2O2] coordination sphere. The Cu2–O7OH (1.917(4) Å) distance
is shorter than that of Cu2–O1L1 (1.969(4) Å), but the Cu2–N dis-
tances (Cu2–N3 = 2.045(4), Cu2–N4 = 2.042(4) Å) are the same
within error. The Cu3 ion is coordinated by two bridged hydroxyl
groups (O7, O7A) and two bipy nitrogen atoms (N5, N6) to form
a square planar geometry. The Cu–O and Cu–N bond distances
are 1.932(4), 2.039(6) and 2.050(6) Å, respectively.
3ꢁ
mode to link one Ca and two Cu atoms in 8 (Scheme 3e) while L1
acts as a tridentate bridging mode to link two Cu atoms forming a
uniform chain in 3.
3.1.4. [Na(H2L1)(H2O)]n (4)
Single-crystal X-ray structural analysis shows that 4 is a bilayer
structure in which two single layers are linked by H2L1 ligands to
generate a 2D bilayer framework. Each sodium is primarily coordi-
nated by two oxygen atoms [Na(1)–O(5), 2.4514(18); Na(1)–O(6),
2.4290(17) Å] from two different glycinato groups, two oxygen
atoms [Na(1)–O(3), 2.4996(17); Na(1)–O(4), 2.4818(17) Å] from
sulfonate groups, one oxygen atom from a carboxylato group of
H2L1 [Na(1)–O(2), 2.4137(17) Å] and one oxygen atom from a
water molecule [Na(1)–O(7), 2.491(2) Å] to furnish a distorted
octahedral geometry (Fig. 4a). Unlike compounds 1–3, oxygen
atoms from both sulfonate groups and C6H5COOꢁ groups coordi-
nate to metal ions. The H2L1ꢁ ligand in 4 acts as a pentadentate li-
gand, as shown in Scheme 3b, where two carboxylato oxygen
atoms from the glycinato group adopt a syn–anti bridging mode,
while the other two oxygen atoms from the sulfonate group exhibit
a syn–syn bridging mode, and the carboxylate from the C6H5COOꢁꢁ
group adopts a monodentate coordination mode. Thus, each H2L1
ligand links five sodium atoms and each sodium center interacts
The asymmetric unit in 3 forms uniform tetranuclear cycles
(Cu1Cu2Cu3Cu2). The tetranuclear units are then connected to-
gether by the coordination bonds between oxygen atoms from
the glycinato groups and Cu(II) ions to form
a
new
ꢀ ꢀ ꢀCu1Cu2Cu3Cu2Cu1Cu2Cu3Cu2ꢀ ꢀ ꢀ 1D chain. These 1D chains are
further interconnected by bipy ligands to generate a 2D wave-like
rectangular grid layer along the a-axis, as shown in Fig. 3b and c.
It is interesting that the aromatic ring containing C(4) atom is
almost parallel to the related pyridine ring containing N(1) atom
in a tetranuclear unit. (the dihedral angle between two planes
ꢁ
with five H2L1 ligands.
On the basis of these connection modes, pairs of Na(1) centers
are doubly bridged by oxygen atoms from glycinato and sulfonate
groups to form an eight-membered ring with a Naꢀ ꢀ ꢀNa separation
of 5.506 Å. These dinuclear units are arranged uniformly to form a

L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
2499
Fig. 4. (a) The local coordination environment of Na ion with atomic numbering
scheme in 4. (b) Perspective view of the single Na–H3L sheet; (c) Side view along the
a-axis showing bilayer motif in 4.
the final 3D supramolecular architecture. This is, to our knowledge,
the first example of bilayer architecture assembled by alkali metal
with amino acid derivatives.
3.1.5. [Mn2(HL2)2(dpe)3(H2O)2]nꢀndpe (5)
The fundamental building unit of 5 is composed of two Mn(II)
cations, two monodentate coordinated dpe, one
l2-dpe, two
2ꢁ
HL2
anions, two coordinated water molecules and one guest
Fig. 3. (a) The coordination environment of a tetranuclear Cu(II) unit in 3, hydrogen
atoms, lattice water molecules and coordinated bipy are omitted for clarity. (b) 2D
layer of 3 constructed from the 1D chain. (c) Schematic representation of a 2D layer
structure.
dpe molecule. The coordinated and uncoordinated dpe molecules
are disordered over two sites. For clarity, only one of these sites
is shown in Fig. 5. The dpe molecules exist in three types of coor-
dination modes (monodentate, bis-monodentate and uncoordi-
nate) in 5, which is unusual in the construction of
polycarboxylate and dpe polymers. Each Mn center exhibits a dis-
torted octahedral geometry with two pyridyl nitrogen atoms from
two dpe ligands in the axial positions, and four oxygen atoms in
1D chain. These chains are linked by –SO2NHCH2COO– groups to
build a ꢁ2D layer (Fig. 4b). Interestingly, the 2D layers are linked
by H2L1 to generate a new 2D bilayer framework with a distance
of 10.899 Å (based on Na. . .Na) between the two single layers (Fig
4c). The adjacent 2D bilayers are further linked to each other by O–
Hꢀ ꢀ ꢀO hydrogen bonds [O(7)–H(2W)ꢀ ꢀ ꢀO(7A), 2.845(6) Å; O(7)–
H(1W)ꢀ ꢀ ꢀO(6), 2.992(3); O(1)–H(1)ꢀ ꢀ ꢀO(5), 2.569(2) Å] to complete
the equatorial plane composed of three oxygen atoms from three
2ꢁ
HL2
ligands and one from coordinated water molecule. The
Mn–O bond distances fall in the range of 2.120(3)–2.189(2) Å,
and the Mn–N bond distances are 2.296(3) and 2.304(3) Å, respec-

2500
L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
to form a 22-membered ring and another four Mn(II) ions and four
2ꢁ
HL2 ligands form a 30-membered ring. Therefore, a [Mn(HL2)
(H2O)] layer is formed through an alternating arrangement of
1
the 22- and 30-membered rings (Fig. 5a). The resulting 2D sheets
are pillared by dpe to generate an overall 3D framework in which
free disordered dpe are encapsulated as guest molecules (Fig. 5b
and c). The adjacent dpe molecules in the channels stack along
the b-axis through p–p stacking interactions through the pyridine
rings to form a 1D supramolecular chain (Fig. 5d). Each Mn center
binds two trans-located dpe molecules. One is a terminal dpe
which lies in the interlayer region and the other is a bridging dpe
which lies alternatively between the 2D planes to link the 2D lay-
ers into a 3D framework.
3.2. Structural diversity of 1–8
It is noteworthy that a variety of framework structures can be
achieved on the basis of the choice of the N-[(carboxyphenyl)-sul-
fonyl]glycine isomers. The slight positional differences of the car-
boxylato groups between these two isomers may lead to
significant geometric diversification of the resulting coordination
polymers. We have successfully isolated and characterized eight
coordination polymers containing Mn, Co, Cu, Na and Ca centers
varying from 0D to 3D. These results illustrate the isomeric effect
of the bridging ligands on coordination polymers. In 1–8, these iso-
mers exhibit several coordination patterns as illustrated in Scheme
3, in which the glycinato and carboxylato groups can adopt the
unidentate, chelating and bridging modes. Thus, the variation of
the N-[(carboxyphenyl)-sulfonyl]glycine isomers used in the
assembled process has a significant role in the structural diversity
shown by 1–8. Secondly, the N-donor auxiliary ligands are good
connectors in mediating and constructing MOFs with specific
structure. In this study, phen, bipy and dpe with different confor-
mations and flexibility were used to investigate their influence
on the structure of the complexes. The steric hindrance of the phen
molecule may contribute to the formation of the discrete units of
complexes 1 and 6, while the introduction of the bipy and dpe
leads to the polymeric structures of complexes 2, 3, 5, 7 and 8.
On the other hand, the choice of metal centers may also have a
significant effect on the binding fashions of the N-[(carboxy-
phenyl)-sulfonyl]glycine isomers as well as the resultant extended
networks of 1–8. For N-[(4-carboxyphenyl)-sulfonyl]glycine/bipy
systems containing 2 and 3, two coordination modes of H3L1 are
observed, and interestingly, two different types of 1D triple chain
or 2D layer frameworks are generated depending on the metal cen-
ters Co or Cu. The structures of 7 and 8 are also metal-controlled,
and notably, Co2+-based complex 7 shows an alternating chain
while a unique 3D interpenetrating architecture is formed in the
case of mixed Ca2+ and Cu2+ in 8. This is consistent with the fact
that the radius of Cu2+ and Ca2+ ions are larger than that of Co2+
ion. This result indicates that the choice of metal ion has a signifi-
cant effect on these polymeric structures as well as the binding
modes of the ligands.
3.3. Thermal stability
Thermogravimetric experiments were conducted to study the
thermal stability of 5, which is an important parameter for porous
metal–organic framework materials (Fig. S1, Supplementary data).
The TGA curve for 5 suggests that the first weight loss of 16.37% in
the region of 30–275 °C corresponds to the loss of two coordinated
water and one guest dpe per formula unit (calculated 15.59%),
which is also in agreement with the results of elemental analysis.
The residual framework starts to decompose beyond 300 °C with
a series of complicated weight losses and does not stop until heat-
ing ends at 550 °C. In principle, TGA measurements alone cannot
2ꢁ
Fig. 5. (a) 2D sheets bridged by HL2 molecules. (b) View of the channels formed
by the 3D network. (c) Space-filling model of as viewed down the b-axis
(disordered guest dpe molecules are omitted for clarity). (d) A view of the 1D
5
supramolecular dpe chain constructed by the intermolecular
interactions.
p–p aromatic stacking
tively. The HL22ꢁ ligand displays both monodentate and bis-mono-
dentate bridging coordination modes in the assemblies, as shown
in Scheme 3f. In addition, two HL22ꢁ ligands bridge two Mn(II) ions

L.-F. Ma et al. / Polyhedron 28 (2009) 2494–2502
2501
2ꢁ
be used to determine the stability of an open structure since it may
collapse without a notable change in the weight. As shown in Fig. 6,
the peak positions of the simulated and experimental XRPD pat-
terns for 5 are in agreement with each other, demonstrating the
good phase purity of 5. XPRD measurements at different tempera-
tures (Fig. 6) show that after heating at 275 °C, the spectra are sim-
ilar to the original one, suggesting its crystalline nature is still
maintained after removing the guest dpe molecules.
Mn(II) ions through the HL2 and dpe bridges can be ignored be-
cause of the long length of the HL22ꢁ and dpe ligands. The magnetic
susceptibility data were fitted assuming that the carboxylate
bridges Mn(II) ions to form a uniform chain with an exchange con-
2ꢁ
stant J, and then dpe and HL2 connect the chains to form a 3D
structure with an exchange constant zJ0. The susceptibility data
were thus approximately analyzed by a chain mode of spin S = 5/
2 [23,24]. The least-squares analysis of magnetic susceptibilities
data led to J = ꢁ0.18 cmꢁ1
,
g = 2.04, zJ’ = ꢁ0.04 cmꢁ1 and
3.4. Magnetic properties
R = 1.65 ꢂ 10ꢁ4, The J value indicates a weakly antiferromagnetic
interaction between the nearest Mn(II) ions bridged by H3L1.
The magnetic susceptibilities,
vM, of 5 were measured in the 2–
300 K temperature range, and shown as
v
MT and M versus T plots
v
4. Conclusions
in Fig. 7. The experimental
vMT value of 5 at room temperature is
4.18 cm3 K molꢁ1 per Mn(II) ion, close to the spin value expected
In summary, we have successfully synthesized eight new com-
plexes by using two versatile ligands, N-[(4-carboxyphenyl)-sulfo-
nyl]glycine and its isomer N-[(3-carboxyphenyl)-sulfonyl] glycine.
Their structures range from a 0D cation–anion species to a 3D net-
work with different structural motifs and this result demonstrates
that ligand isomers and metal centers have a tuning effect upon
the motifs of the resultant structures. Subsequent work will be fo-
cused on the construction of new polymers by using these two iso-
mers or other related amino acid derivatives as basic building
units.
for an uncoupled high-spin Mn(II) ion (4.38 cm3 K molꢁ1). The tem-
perature dependence of the reciprocal susceptibilities (1/vM) of 5
obeys the Curie–Weiss law above 5 K with h = ꢁ2.1 K, C = 4.59
cm3ꢀK/mol, R = 4.9 ꢂ 10ꢁ5, which indicates that antiferromagnetic
interactions are operative in 5. According to the structure of 5, it
could be presumed that the main magnetic interactions between
the metal centers might happen between two carboxylate bridged
Mn(II) ions, whereas the superexchange interactions between
Acknowledgements
This work was supported by the Natural Science Foundation of
China (Nos. 20471046 and 20771054) and Henan tackle key prob-
lem of science and technology (Nos. 072102270030 and
072102270034) and the Foundation of Education Committee of
Henan province (Nos. 2006150017 and 2008A150018).
Appendix A. Supplementary data
CCDC 659934–659937, 675251 contain the supplementary
crystallographic data for 1–5. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336 033; or e-mail:
deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.poly.2009.04.044.
Fig. 6. Comparison of XRPD patterns of the simulated pattern from the single-
crystal structure determination, the as-synthesized and the product after heating at
275 °C for 5.
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