Hydrogen-bonded supramolecular structures constructed from trinuclear copper units

Article abstract of DOI:10.1007/s11243-011-9515-x

Four copper complexes with similar trinuclear copper units, [Cu ₆(Bmshp)₂(SO₄)₂(H₂O) ₇]?2H₂O (1), [Cu₃(Bmshp)(ClO ₄)₂(H₂O)₄

Full text of DOI:10.1007/s11243-011-9515-x

Transition Met Chem (2011) 36:653–662
DOI 10.1007/s11243-011-9515-x
Hydrogen-bonded supramolecular structures constructed
from trinuclear copper units
•
•
•
Su-Ni Qin Hai-Ming Huang Zi-Lu Chen
Fu-Pei Liang
Received: 29 March 2011 / Accepted: 1 July 2011 / Published online: 16 July 2011
Ó Springer Science+Business Media B.V. 2011
Abstract Four copper complexes with similar trinuclear
copper units, [Cu6(Bmshp)2(SO4)2(H2O)7]ꢀ2H2O (1), [Cu3-
(Bmshp)(ClO4)2(H2O)4]ꢀ5H2O (2), [Cu3(Bmshp)(DMF)4-
(H2O)2]ꢀH2Oꢀ2DMFꢀ2ClO4 (3) and [Cu3(H2Bcshp)(ClO4)2-
(H2O)4]ꢀ3H2O (4) (H4Bmshp = 2,6-bis[(3-methoxysalicy-
lidene)hydrazinocarbonyl]pyridine, H6Bcshp = 2,6-bis[(3-
carboxylsalicylidene)hydrazinocarbonyl]pyridine), were syn-
thesized and characterized by elemental analysis, IR and
single crystal X-ray diffraction analysis. Due to the different
anions, solvents and ligands used in the syntheses, complexes
1–4 exhibit diverse supramolecular structures constructed
from the corresponding trinuclear copper units via H-bonds.
materials and other technologies [2–8]. As an important
part of crystal engineering, the construction of supramo-
lecular structures via self-assembly using individual dis-
crete polynuclear metal complexes as molecular building
blocks has particularly attracted a lot of attention in recent
decades. The process of this self-assembly is based on the
extension among individual molecules by weak covalent or
noncovalent interactions, including Van der Waals, elec-
trostatic and hydrophobic interactions, hydrogen bonds, as
well as p–p and ion-p stacking [9–16]. Among them,
hydrogen bonding interactions provide an important tool in
the formation of ordered supramolecular chains, layers and
three-dimensional frameworks [17]. Examples of the con-
struction of multi-dimensional supramolecular structures
from zero-dimensional discrete polynuclear metal blocks
via hydrogen bonding interactions have been widely
reported [1, 11, 17–21]. From these reported works, we can
see that the building blocks are usually metal carboxylate
clusters and amide-containing complexes due to their
inclination to form H-bonds of COOHꢀꢀꢀN, COOHꢀꢀꢀO and
N–HꢀꢀꢀO, etc. 2,6-Pyridine-diacylhydrazone ligands pos-
sess high flexibility and alterable coordinating sites on the
end groups around the N–N single bonds, which may be
favorable for the construction of discrete polynuclear units
[22–27]. It is reasonable to expect that interesting poly-
dimensional hydrogen-bonded supramolecular architec-
tures constructed from these polynuclear units (as building
blocks) could be obtained by modifying the end groups
around the N–N bonds with functional groups suitable for
the formation of hydrogen bonds.
Introduction
Crystal engineering is a subject devoted to achieving the
assembly of molecules into desirable supramolecular
architectures [1] and studying their potential applications in
the fields of microelectronics, nonlinear optics, porous
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-011-9515-x) contains supplementary
material, which is available to authorized users.
S.-N. Qin ꢀ H.-M. Huang ꢀ Z.-L. Chen ꢀ F.-P. Liang (&)
Key Laboratory for the Chemistry and Molecular Engineering of
Medicinal Resources (Ministry of Education of China), School
of Chemistry and Chemical Engineering, Guangxi Normal
University, Guilin 541004, China
Herein, we present the syntheses and structures of four
copper complexes based on two 2,6-pyridine-diacylhy-
drazone ligands, [Cu6(Bmshp)2(SO4)2(H2O)7]ꢀ2H2O (1),
[Cu3(Bmshp)(ClO4)2(H2O)4]ꢀ5H2O (2), [Cu3(Bmshp)-
(DMF)4(H2O)2]ꢀH2Oꢀ2DMFꢀ2ClO4 (3) and [Cu3(H2Bcshp)-
e-mail: fliangoffice@yahoo.com
S.-N. Qin
State Key Laboratory of Coordination Chemistry, Coordination
Chemistry Institute, School of Chemistry and Chemical
Engineering, Nanjing University, Nanjing 210093, China
123

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Transition Met Chem (2011) 36:653–662
(ClO4)2(H2O)4]ꢀ3H2O (4) (H4Bmshp = 2,6-bis[(3-meth-
oxysalicylidene)hydrazinocarbonyl]pyridine, H6Bcshp =
2,6-bis[(3-carboxylsalicylidene)hydrazinocarbonyl]pyridine).
The four complexes exhibit similar trinuclear structural units.
However, different hydrogen-bonded supramolecular struc-
tures constructed from the trinuclear copper units are
obtained due to the differences of anions, solvent molecules
and functional groups on the ligands in the complexes.
in a yield of 60%. IR (cm-1): 3409(s), 1649(m), 1603(s),
1542(s), 1216(s), 1126(m), 1081(w).
Preparation of [Cu3(Bmshp)(ClO4)2(H2O)4]ꢀ5H2O (2)
A solution of Cu(ClO4)2ꢀ6H2O (0.1105 g, 0.3 mmol) in
methanol (8 mL) was slowly added to a solution of
H4Bmshp (0.0463 g, 0.1 mmol) in methanol (5 mL). The
resulting solution was stirred for 3 h and then filtered. The
filtrate was allowed to evaporate at room temperature, giv-
ing dark green crystals of 2 suitable for single crystal X-ray
diffraction after 2 weeks in a yield of 38%. Anal. Calc. for
C23H35Cl2Cu3N5O23 (1011.08): C, 27.3; H, 3.5; N, 6.9.
Found: C, 27.5; H, 3.6; N, 6.8. IR (cm-1): 3429(s), 1620(m),
1603(m), 1546(s), 1219(s), 1116(s), 1102(s), 1085(s).
Experimental
All reagents and solvents were purchased commercially as
reagent grade and used without further purification. 2,6-
Pyridine-dicarboxylic hydrazide was synthesized by litera-
ture methods [28]. IR spectra were recorded in the range
4,000–400 cm-1 on a Perkin-Elmer PE Spectrum One FT/IR
spectrometer using KBr pellets. Elemental analyses were
performed on a Perkin-Elmer PE 2400 II CHN elemental
analyzer.
Preparation of [Cu3(Bmshp)(DMF)4(H2O)2]ꢀH2Oꢀ
2DMFꢀ2ClO4 (3)
A solution of Cu(ClO4)2ꢀ6H2O (0.1105 g, 0.3 mmol) in
ethanol (8 mL) was slowly added to a solution of H4Bmshp
(0.0463 g, 0.1 mmol) in DMF (5 mL). The resulting solu-
tion was stirred for 4 h and then filtered. The filtrate was
allowed to evaporate at room temperature, giving dark
green crystals of 3 suitable for single crystal X-ray diffrac-
tion after 4 weeks in a yield of 40%. Anal. Calc. for
C41H65Cl2Cu3N11O23 (1341.56): C, 36.7; H, 4.9; N, 11.3.
Found: C, 37.0; H, 5.0; N, 11.2. IR (cm-1): 3429(s), 1651(s),
1602(m), 1543(s), 1217(s), 1142(s), 1110(s), 1087(s).
Preparation of 2,6-bis[(3-
methoxysalicylidene)hydrazinocarbonyl]pyridine
(H4Bmshp) [29]
H4Bmshp was prepared by the reaction of 2,6-pyridine-
dicarboxylic hydrazide (1.95 g, 0.01 mol) with 2-hydroxy-
3-methoxybenzaldehyde (3.04 g, 0.02 mol) under reflux in
ethanol for 4 h. A yellow precipitate was isolated by filtra-
tion and washed with ethanol and ether (yield 92%). Anal.
Calc. for C23H21N5O6 (463.45): C, 59.6; H, 4.6; N, 15.0.
Found: C, 59.9; H, 4.8; N, 14.7. IR (cm-1): 3453(s), 3243(s),
1673(s), 1608(m), 1540(s), 1252(s), 1080(s), 732(s).
Preparation of [Cu3(H2Bcshp)(ClO4)2(H2O)4]ꢀ3H2O (4)
A methanol solution (8 mL) of Cu(ClO4)2ꢀ6H2O (0.1105 g,
0.3 mmol) was added to a methanol (5 mL) solution of
H6Bcshp (0.0491 g, 0.1 mmol) with two drops of Et3N (ca.
0.1 mL). The resulting solution was stirred for 3 h and then
filtered. The filtrate was allowed to evaporate at room
temperature, giving dark green crystals suitable for single
crystal X-ray diffraction after 2 weeks in a yield of 41%.
IR (cm-1): 3433(s), 1677(s), 1624(m), 1590(m), 1551(s),
1426(m), 1226(m), 1145(s), 1110(s), 1087(s).
Preparation of 2,6-bis[(3-
carboxylsalicylidene)hydrazinocarbonyl]pyridine
(H6Bcshp)
H6Bcshp was prepared by the reaction of 2,6-pyridine-
dicarboxylic hydrazide (1.95 g, 0.01 mol) with 2-hydroxy-
3-carboxybenzaldehyde (3.32 g, 0.02 mol) under reflux in
ethanol for 4 h. A yellow precipitate was isolated by fil-
tration and washed with ethanol and ether (yield 93%).
Anal. Calc. for C23H17N5O8 (491.42): C, 56.2; H, 3.7; N,
9.4. Found: C, 56.4; H, 3.9; N, 9.5. IR (cm-1): 3436(s),
3274(m), 1670(s), 1606(m), 1542(m), 1237(m).
X-ray crystallography study
Suitable single crystals of 1–4 were selected and mounted
in air onto thin glass fibers. X-ray diffraction studies on 1,
3, 4 were performed at 298(2) K except 2 at 291(2) K,
using a Bruker CCDArea Detector with graphite-mono-
Preparation of [Cu6(Bmshp)2(SO4)2(H2O)7]ꢀ2H2O (1)
˚
chromated Mo-Ka radiation (k = 0.71073 A). The struc-
A
DMF (10 mL) solution of H4Bmshp (0.0926 g,
tures were solved by direct methods using the SHELXS-97
program package and refined against F2 by full-matrix
least-squares methods with SHELXL-97 [30]. All nonhy-
drogen atoms were anisotropic and hydrogen atoms on C
0.2 mmol) was layered on an aqueous solution (10 mL) of
CuSO4ꢀ5H2O (0.1520 g, 0.6 mmol) in a glass tube. Dark
green block crystals were collected after 7 days’ diffusion
123

Transition Met Chem (2011) 36:653–662
655
atoms were included on calculated positions, riding on their
coordinating sites of Cu2 and Cu3 are occupied by an
Opyridyl-acylamide atom (O1 for Cu2 and O2 for Cu3), an
carriers. Complex 1 reveals highly disordered solvents,
2-
SO4 anions and coordinated water molecules within the
O
phenolic atom (O3 for Cu2 and O5 for Cu3) and a Npyridyl-
lattice interstices. The diffraction data of 1 were treated by
the ‘‘SQUEEZE’’ method as implemented in PLATON [31].
For the solution of the structure of complex 4, there are still
some solvent accessible voids indicated by PLATON pro-
gram. However, we could not find any suitable Q peaks for
any solvent molecules in the difference Fourier map by the
program. Thus, this unsolvable solvent was squeezed using
PLATON program. Although the structure refinement is a
little poor, the structure was properly modeled with rea-
sonable refinement parameters for all resolved atoms. This
indicates that the trinuclear skeleton and the resolved guest
water molecules of 4 were determined without any doubt.
The present data of 4 reveal a supramolecular structure
different from those of 1–3, which provides enough
information for us to clarify the diversity of H-bonded
supramolecular structures constructed from similar trinu-
clear copper units. A summary of crystallographic and
structural refinement data for 1–4 is given in Table 1.
Selected bond lengths and bond angles for 1–4 are listed in
Table S1. Hydrogen bonds for 1–4 are listed in Table 2.
CCDC 792038–792041 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via http://www.ccdc.cam.ac.uk/data_request/cif.
hydrazine atom (N3 for Cu2 and N5 for Cu3) from Bmshp4-
.
The remaining two coordinating sites are occupied by one
oxygen atom (O15) from one water molecule and another
oxygen atom (O11/O20) from the disordered SO42-/H2O
ligands for Cu2, and two oxygen atoms (O16 and O17)
from two water molecules for Cu3, respectively. The bond
distances of C1–O1 and C1–N2, C7–O2 and C7–N4 in
pyridyl-acylamide groups of Bmshp4- are 1.306(13) A and
˚
˚
˚
˚
1.333(14) A, 1.320(13) A and 1.263(13) A, respectively,
suggesting the coordination of acylamide groups to Cu(II)
in the enolic form [32].
Complex 1 presents various hydrogen bonds (Table 2;
Fig. 2). The coordinated water ligands on Cu2 form hydrogen
bonds O15–H15AꢀꢀꢀO5b and O15–H15AꢀꢀꢀO6b with the
Ophenolic and Omethoxy atoms on Cu3b from the adjacent
hexanuclear unit. While the coordinated water ligands on Cu3
interact with the Omethoxy, Owater, Ophenolic and Osulfate atoms
on Cu2c from another adjacent hexanuclear unit, forming
hydrogen bonds O16–H16BꢀꢀꢀO4c, O17–H17BꢀꢀꢀO15c, O16–
H16AꢀꢀꢀO20c, O16–H16AꢀꢀꢀO3c, O16–H16AꢀꢀꢀO11c and
O16–H16AꢀꢀꢀO13c. The hexanuclear units of 1 are extended
into a 1D chain via these intermolecular hydrogen bonds.
Furthermore, adjacent 1D chains are connected via interchain
hydrogen bonds O17–H17AꢀꢀꢀO8d (between one coordinated
water ligand on Cu3 and one oxygen atom of SO42- anion)
and O19–H19AꢀꢀꢀO1e (between one guest water molecule and
the Opyridyl-acylamide atom on Cu2), as well as intramolecular
hydrogen bond O15–H15BꢀꢀꢀO19 between one coordinated
water ligand on Cu2 and the guest water molecule, to form a
2D supramolecular network of 1.
Results and discussion
Structure description of complex 1
The single crystal X-ray diffraction analysis reveals that
complex 1 crystallizes in the triclinic space group P¯ı. It
presents a centrosymmetric hexanuclear structure formed
by the connection of two trinuclear units [Cu3(Bmsh-
p)(H2O)3.5] via two SO42- anions. The SO42- ligand in 1 is
disordered over two positions. One part of the disordered
Structure description of complex 2
Complex 2 crystallizes in the triclinic space group P¯ı and
presents a trinuclear structure [Cu3(Bmshp)(ClO4)2(H2O)4],
which is similar to the trinuclear secondary building unit
[Cu3(Bmshp)(H2O)3.5] of 1. As shown in Fig. 3, Cu1 is five-
coordinated in a distorted trigonal bipyramidal geometry by
a Npyridyl atom (N3), two Npyridyl-acylamide atoms (N2 and N4)
from Bmshp4- and two oxygen atoms (O2 and O3) from two
water ligands. Cu2 and Cu3 show the same coordination
environment of distorted square pyramidal geometries. The
coordination atoms are an Opyridyl-acylamide atom (O13 for
Cu2 and O14 for Cu3), an Ophenolic atom (O11 for Cu2 and
O15 for Cu3), a Npyridyl-hydrazine atom (N1 for Cu2 and N5 for
Cu3) from Bmshp4-, an oxygen atom (O1 for Cu2 and O4 for
Cu3) from water and a disordered oxygen atom (O18/O180
for Cu2 and O24/O240 for Cu3) of ClO4- anion. The bond
distances of C–O and C–N in pyridyl-acylamide groups of
2-
SO4 ligand coordinates to Cu1 in a monodentate mode,
while the other part, which is further disordered with a
water molecule over the same position of Cu2, behaves as a
l2-bridge linking Cu2 and Cu1a. As shown in Fig. 1, the
H4Bmshp ligand in each trinuclear unit loses its four pro-
tons to coordinate to three Cu(II) atoms (Cu1, Cu2 and
Cu3) as a nonadentate ligand with its two –OCH3 groups
free from coordination. Cu1 is four-coordinated in a dis-
torted square planar geometry by a Npyridyl atom (N1) and
two Npyridyl-acylamide atoms (N2 and N4) from one Bmshp4-
ligand and one oxygen atom (O7 or O14a) from the dis-
ordered SO42- anion. Cu2 and Cu3 are five-coordinated in
distorted square pyramidal geometries. Three of the
Bmshp4- are about 1.27 and 1.33 A, respectively,
˚
123

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Transition Met Chem (2011) 36:653–662
Table 1 Crystallographic data and refinement summary for 1–4
1
2
3
4
Empirical formula
Formula weight
Crystal system
Space group
C46H52Cu6N10O29S2
1654.34
C23H35Cl2Cu3N5O23
1011.08
C41H65Cl2Cu3N11O23
1341.56
C23H27Cl2Cu3N5O23
1003.02
Triclinic
Triclinic
Triclinic
Triclinic
P¯ı
P¯ı
P¯ı
P¯ı
˚
a (A)
10.1795(8)
13.9093(14)
14.5460(17)
64.008(2)
75.989(3)
74.774(3)
1767.0(3)
1
10.5593(13)
11.1133(14)
17.129(2)
74.789(2)
87.596(2)
76.209(2)
1883.2(4)
2
14.6377(13)
14.7695(14)
16.1666(18)
69.7630(10)
66.6160(10)
74.066(2)
9.8385(10)
11.4596(13)
18.790(2)
76.614(2)
78.212(2)
66.0380(10)
1868.8(4)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V(A )
2971.5(5)
Z
2
DCalc (g cm-3
)
1.555
1.783
1.499
1.783
l (Mo-Ka) (mm-1
)
1.915
1.915
1.236
1.929
F(000)
836
1026
1386
1010
h (°)
1.57–25.01
8531/5867 (0.0522)
1.086
2.31–25.01
13025/6478 (0.0291)
1.013
1.49–25.01
15591/10331 (0.0348)
1.021
2.10–25.01
8794/6289 (0.0852)
0.941
Reflections collected/unique (Rint
Goodness-of-fit on F2
)
R indices [I [ 2r (I)]
R1 = 0.0939,
wR2 = 0.2423
R1 = 0.1603,
wR2 = 0.2684
1.012, -0.884
R1 = 0.0431,
wR2 = 0.1063
R1 = 0.0658,
wR2 = 0.1193
0.678, -0.618
R1 = 0.0514,
wR2 = 0.1126
R1 = 0.1098,
wR2 = 0.1490
0.699, -0.499
R1 = 0.1354,
wR2 = 0.2973
R1 = 0.2255,
wR2 = 0.3482
0.896, -0.948
R indices (all data)
Largest diff. peak and hole (e A-3
)
suggesting that the acylamide groups are coordinated to
Cu(II) in the enolic form [32].
Besides four coordinated water ligands, there exist five
guest water molecules in 2. Four of them (O6, O9, O10 and
O5) are hydrogen bonded with each other to form a four-
membered water aggregate, exhibiting O6–H11WꢀꢀꢀO9m,
O9m–H17WmꢀꢀꢀO10m and O10m–H19WmꢀꢀꢀO5 H-bonds
with angles in the range of 126°–179°. At the same time,
two terminal water molecules of this four-membered
aggregate form hydrogen bonds with the coordinated
waters on central Cu1 and terminal Cu3 in two trinuclear
units from two adjacent 1D chains (O2–H3WꢀꢀꢀO6 and O5–
H9WꢀꢀꢀO4l H-bonds), respectively. These interactions
extend the four-membered water aggregate into a six-
membered one. Two adjacent six-membered aggregates are
further connected by the O10m–H20WmꢀꢀꢀO10s and
O4l–H7WlꢀꢀꢀO9s H-bonds to form an interesting centro-
symmetric twelve-membered water aggregate (Fig. 4).
Each 1D chain is linked to adjacent ones via the twelve-
membered water aggregates, forming a 2D network of 2
as shown in Fig. 4. Furthermore, adjacent 2D sheets of 2
are extended into a 3D framework via the further inter-
molecular hydrogen bonds between the fifth guest water
The Bmshp4- ligand in 2 behaves a nonadentate ligand to
coordinate to three Cu(II) centers. Its two –OCH3 groups are
free from coordination. All nonhydrogen atoms of Bmshp4-
ligand and three Cu(II) atoms in 2 are nearly coplanar, with
the ClO4- anions on Cu2 and Cu3 lying on different sides of
this plane. Such planarity and similar coordination were also
observed in those reported trinuclear copper complexes
[Cu3(L1)(DMSO)5(H2O)][ClO4]2ꢀH2O (L1 = 2,6-bis[(sali-
cylidene)hydrazinocarbonyl]pyridine) [32], [Cu3(L2-4H)
(H2O)3(CH3OH)](NO3)2 (L2 = 2,6-bis[(3-hydroxylsalicy-
lidene)hydrazinocarbonyl]pyridine) [33] and [Cu3(2poap-
2H)(H2O)(DMF)3(CH3OH)2](BF4)4 [34].
There are two coordinated water ligands on the central
Cu(II) (Cu1) in 2. One is hydrogen bonded to the Ophenolic
atom on Cu3 from one adjacent trinuclear unit (O3–H5Wꢀꢀꢀ
h
˚
O15 H-bond at OꢀꢀꢀO = 2.752(5) A). While the other water
is hydrogen bonded to the Omethoxy and Ophenolic atoms on Cu2
from another adjacent trinuclear unit (O2–H4WꢀꢀꢀO11f and
O2–H4WꢀꢀꢀO12f H-bonds at OꢀꢀꢀO = 2.846(5) and
-
˚
3.073(5) A). These O–HꢀꢀꢀO hydrogen bonds help to build 1D
molecules, ClO4 anions and coordinated water ligands
supramolecular chains of 2 (Table 2; Fig. 4).
(Fig. S1).
123

Transition Met Chem (2011) 36:653–662
657
˚
Table 2 Hydrogen bonds (A and °) for 1–4
Table 2 continued
D–HꢀꢀꢀA
D–HꢀꢀꢀA
d (HꢀꢀꢀA)
d (DꢀꢀꢀA)
\DHA
d (HꢀꢀꢀA)
d (DꢀꢀꢀA)
\DHA
O8–H8BꢀꢀꢀO6h
O23–H23DꢀꢀꢀO10t
O23–H23EꢀꢀꢀO21m
4
2.5
2.972(5)
2.961(6)
2.716(7)
116
1
O15–H15AꢀꢀꢀO6b
O15–H15AꢀꢀꢀO5b
O15–H15BꢀꢀꢀO19
O16–H16AꢀꢀꢀO20c
O16–H16AꢀꢀꢀO11c
O16–H16AꢀꢀꢀO3c
O16–H16AꢀꢀꢀO13c
O16–H16BꢀꢀꢀO4c
O17–H17AꢀꢀꢀO8d
O17–H17BꢀꢀꢀO15c
O19–H19AꢀꢀꢀO1e
O20–H20AꢀꢀꢀO7a
2
2.23
2.24
1.89
1.98
2.2
3.053(13)
2.811(12)
2.717(15)
2.83(2)
162.3
125
2.11
1.87
174.1
173.9
165.6
178.9
161.3
112.5
125.3
134
O4–H4ꢀꢀꢀO3
O7–H7ꢀꢀꢀO6
1.78
1.8
2.521(14)
2.529(14)
2.74(3)
149.1
147.5
152.8
142.5
153.1
154.9
153.7
153.2
160.1
117.2
168.4
167.7
177
3.01(2)
O9–H9AꢀꢀꢀO13i
O9–H9BꢀꢀꢀO21i
O10–H10AꢀꢀꢀO22m
O10–H10BꢀꢀꢀO5u
O15–H15AꢀꢀꢀO21
O15–H15BꢀꢀꢀO8v
O20–H20AꢀꢀꢀO15u
O20–H20BꢀꢀꢀO23u
O21–H21AꢀꢀꢀO18m
O21–H21BꢀꢀꢀO19n
O22–H22AꢀꢀꢀO5w
O22–H22BꢀꢀꢀO14t
O23–H23BꢀꢀꢀO17m
O23–H23AꢀꢀꢀO15
1.96
1.83
1.96
2
2.58
2.65
2.37
1.95
1.88
2.25
2.6
3.006(11)
3.22(3)
2.56(3)
3.021(13)
2.71(2)
2.75(2)
148.4
146.7
157.7
154.9
2.796(15)
2.92(2)
2.629(12)
3.055(14)
3.39(3)
2.13
1.82
2.45
2.19
2.28
1.95
1.94
2.06
1.94
2.58
2.610(15)
3.26(2)
2.69(3)
O1–H1WꢀꢀꢀO6f
2.47
2.63
1.92
2.01
1.82
2
3.235(8)
3.357(5)
2.763(14)
2.829(15)
2.663(6)
2.846(5)
3.073(5)
2.752(5)
2.756(5)
2.860(9)
3.190(7)
2.699(6)
3.142(8)
3.150(6)
2.595(10)
2.929(14)
2.940(13)
2.834(8)
3.063(18)
3.114(18)
3.002(6)
2.968(5)
3.023(7)
2.632(18)
2.956(10)
3.078(10)
3.037(16)
2.53(4)
151
3.12(4)
O1–H1WꢀꢀꢀO2f
144.6
176.4
162.1
172.8
177.7
113.4
174
2.79(3)
g
O1–H2WꢀꢀꢀO180
2.788(19)
2.91(4)
O1–H2WꢀꢀꢀO18g
O2–H3WꢀꢀꢀO6
177.9
179.9
179.9
2.79(3)
O2–H4WꢀꢀꢀO11f
O2–H4WꢀꢀꢀO12f
O3–H5WꢀꢀꢀO15h
O3–H6WꢀꢀꢀO7i
O4–H7WꢀꢀꢀO9j
O4–H8WꢀꢀꢀO5k
O5–H9WꢀꢀꢀO4l
O5–H10WꢀꢀꢀO21k
O5–H10WꢀꢀꢀO15k
O6–H11WꢀꢀꢀO9m
O6–H12WꢀꢀꢀO17n
3.43(3)
2.64
1.9
Symmetry codes: bx, y ? 1, z; cx, y - 1, z; d-x ? 2, -y ? 1,
-z ? 1; e-x ? 2, -y ? 2, -z ? 1; f-x ? 2, -y, -z ? 1; g-x ? 3,
-y, -z ? 1; h-x ? 2, -y, -z; x ? 1, y, z; x ? 1, y - 1, z - 1;
k-x ? 1, -y, -z; lx - 1, y ? 1, z; m-x ? 1, -y ? 1, -z ? 1;
nx - 1, y, z; o-x ? 1, -y, -z ? 1; p-x ? 1, -y ? 1, -z ? 2;
i
j
1.92
2.06
2.34
1.86
2.41
2.65
2
168.5
156.9
177.5
169.2
145.3
118.7
126.1
145
r
s
t
qx ? 1, y, z - 1; -x ? 1, -y ? 1, -z; x, y, z - 1; x, y, z ? 1;
v
ux ? 1, y - 1, z; x - 2, y ? 1, z; wx, y - 1, z ? 1
Structure description of complex 3
2.2
n
O6–H12WꢀꢀꢀO170
2.28
2.01
2.24
2.3
134.8
163.1
164.4
160.7
139
Similar to 2, complex 3 crystallizes in the triclinic space
group P¯ı and presents the similar trinuclear copper unit
[Cu3(Bmshp)(DMF)4(H2O)2]2?. The structural difference
of 3 from 2 is that the apical site and one of the basal
positions of Cu2 and Cu3 are occupied by two DMF
molecules in 3, but by ClO4- anion and one H2O molecule
in 2 (Fig. 5). This might be due to the strong coordinating
ability of DMF solvent used in the synthesis of 3. The C–O
and C–N bond distances in pyridyl-acylamide groups of
O7–H13WꢀꢀꢀO20n
O7–H14WꢀꢀꢀO24l
l
O7–H14WꢀꢀꢀO240
O8–H15WꢀꢀꢀO12n
O8–H15WꢀꢀꢀO11n
O8–H16WꢀꢀꢀO23o
O9–H17WꢀꢀꢀO10
O9–H18WꢀꢀꢀO22o
O9–H18WꢀꢀꢀO21o
O10–H19WꢀꢀꢀO5m
O10–H20WꢀꢀꢀO10p
3
2.31
2.19
2.23
1.83
2.11
2.52
2.18
1.7
151.7
155.7
156.2
174.3
123.8
178.4
163.5
Bmshp4- are about 1.26 and 1.32 A, respectively, which
˚
suggests that the acylamide groups coordinate to Cu(II) the
enolic form [32]. The two –OCH3 groups of the Bmshp4-
ligand in 3 are still free from coordination, which is similar
to the cases in 1 and 2. All nonhydrogen atoms of the
Bmshp4- ligand and three Cu(II) centers are nearly
coplanar, with the two coordinated DMF ligands on the
apical positions of Cu2 and Cu3 lying on different sides of
this plane.
O7–H7AꢀꢀꢀO22q
1.78
1.99
2.49
1.88
2.07
2.606(7)
2.825(5)
2.975(5)
2.732(5)
2.911(5)
162.1
168.5
116.8
175.3
172.2
O7–H7BꢀꢀꢀO3r
O7–H7BꢀꢀꢀO4r
O8–H8AꢀꢀꢀO23s
O8–H8BꢀꢀꢀO5h
123

658
Transition Met Chem (2011) 36:653–662
Fig. 1 The perspective view of
the structure of 1, showing the
connection of two trinuclear
2-
units by SO4 anions. H atoms
and guest water molecules are
omitted for clarity. Symmetry
a
code: -x ? 1, -y ? 2, -
z ? 1
Fig. 2 1D H-bonded chain and
2D H-bonded network of 1
Structure description of complex 4
In complex 3, two coordinated water ligands on Cu1 form
hydrogen bonds O7–H7BꢀꢀꢀO3r, O7–H7BꢀꢀꢀO4r, O8–
H8BꢀꢀꢀO5h and O8–H8BꢀꢀꢀO6h with the Omethoxy and Ophe-
nolic atoms on terminal Cu2 and Cu3 from two adjacent tri-
nuclear units. With the aid of these hydrogen bonding
interactions, complex 3 is extended into a 1D chain similar to
that of complex 2 (Table 2; Fig. 6). Each 1D chain is further
extended into a 2D network and 3D framework via electro-
static interactions between [Cu3(Bmshp)(DMF)4(H2O)2]2?
cations and ClO4- anions (Fig. S2).
Similar to 2 and 3, complex 4 also crystallizes in the tri-
clinic space group P¯ı and presents a similar trinuclear
copper unit [Cu3(H2Bcshp)(ClO4)2(H2O)4] as shown in
Fig. 7. However, the main ligand in 4 is H6Bcshp, instead
of H4Bmshp for 1–3. The difference of H6Bcshp from
H4Bmshp is that the –OCH3 group of H4Bmshp is substi-
tuted by the –COOH group in H6Bcshp. The H2Bcshp4-
ligand in 4 coordinates to three Cu(II) centers as a
123

Transition Met Chem (2011) 36:653–662
659
Fig. 3 The perspective view of the trinuclear structure of 2. H atoms
and guest water molecules are omitted for clarity
Fig. 5 The perspective view of the trinuclear structure of 3. H atoms,
-
guest ClO4 anions and solvent molecules are omitted for clarity
nonadentate ligand with its two –COOH groups free from
coordination. The C–O and C–N bond distances in pyridyl-
acylamide groups of H2Bcshp4- are ca. 1.28 and 1.34 A,
˚
respectively, which suggests that the acylamide groups
coordinate to Cu(II) in the enolic form [32]. As for 1–3, all
nonhydrogen atoms of the main ligand (H2Bcshp4-) and
three Cu(II) atoms in 4 are nearly coplanar, with the two
-
coordinated ClO4 anions on Cu2 and Cu3 lying on dif-
ferent sides of this plane.
Fig. 6 1D chain of 3 formed by intermolecular H-bonds
The adjacent trinuclear units of 4 form hydrogen bonds
O15–H15BꢀꢀꢀO8v (OꢀꢀꢀO = 2.610(15) A) between the
˚
further connected to form a 2D network via another two
types of H-bonds, type A and type B, as shown in Fig. 8.
One guest water molecule in 4 forms hydrogen bonds
coordinated water ligand on Cu2 from one trinuclear unit
and the Ocarboxylate atom from the adjacent trinuclear unit,
which extend 4 into a 1D chain (Fig. S3). Each chain is
Fig. 4 1D H-bonded chain and
2D network formed by the
twelve-membered H-bonded
water aggregates of 2.
l
Symmetry code: -x ? 1, -
n
y ? 1, -z ? 1; x - 1, y ? 1,
s
z; x, y, z - 1
123

660
Transition Met Chem (2011) 36:653–662
Fig. 9 2D network of 4 formed by the interlacing type A and type B
hydrogen bonds
Fig. 7 The perspective view of the trinuclear structure of 4. H atoms
and guest water molecules are omitted for clarity
the formation of similar trinuclear units with one diacy-
lhydrazone ligand and three metal atoms in 1–4. However,
hydrogen bonds in the four complexes are extremely dif-
ferent due to the differences of anions, solvent molecules and
functional groups on the ligands in the complexes, which
lead to the formation of a variety of supramolecular struc-
tures constructed by trinuclear copper units via H-bonds.
In complex 1, the SO42- anions are involved both in the
coordination and in the hydrogen bonding interactions. The
(O20–H20BꢀꢀꢀO23u and O23–H23AꢀꢀꢀO17m) with the
coordinated water on Cu3 from a trinuclear unit I and the
ꢁ
OClO4 atom on Cu3 from the adjacent trinuclear unit II,
composing type A hydrogen bonds with the OꢀꢀꢀO distances
˚
and O–HꢀꢀꢀO angles in the ranges of 2.69–2.79 A and
117°–180°, respectively. Another guest water molecule in
4 forms hydrogen bonds (O10–H10AꢀꢀꢀO22m and O22–
H22AꢀꢀꢀO5w) with one of the coordinated water ligand on
Cu1 from trinuclear unit I and the Ocarboxylate atom from the
other adjacent trinuclear unit III, composing type B
hydrogen bonds (Table 2). The neighboring H-bonded 1D
chains are linked alternatively by type A and type B
hydrogen bonds to form a 2D network of 4 exhibiting two
kinds of grid networks, with grid dimensions of
2-
l2-bridging coordination of SO4 anions links two trinu-
clear copper units into a hexanuclear complex unit. The
hexanuclear units, which act as basic building blocks of the
supramolecular structure of 1, are linked into 2D supra-
molecular networks by hydrogen bonds between coordi-
nated waters and the Omethoxy, Ophenolic atoms of Bmshp4-
ligand, hydrogen bonds between coordinated water and
coordinated water, hydrogen bonds between guest water
˚
˚
18.3126 9 11.2546 A and 18.3125 9 15.0119 A, respec-
tively, as shown in Fig. 9. Adjacent 2D sheets of 4 are
further extended into a 3D framework via the intermolec-
ular hydrogen bonds between the third guest water mole-
cules, –COOH groups, coordinated water ligands and
2-
molecules and the oxygen atom of SO4 or the Opyridyl-
atom of the ligand, as well as those between
acylamide
coordinated water and guest water molecules. In complex
2, the use of hydrated copper perchlorate as a starting
material and methanol as solvent in the synthesis leads to
-
ClO4 anions (Fig. S4).
-
Structural discussion
the formation of a trinuclear complex with one ClO4
anion and one water molecule for every terminal Cu(II),
and two water ligands on the central Cu(II). The trinuclear
complex units are the basic building blocks of the supra-
molecular structure of 2. The hydrogen bonds between
coordinated water ligands on the central Cu(II) and
The 2,6-pyridine-diacylhydrazone ligands of Bmshp4- and
H2Bcshp4- adopt the same nonadentate binding mode
coordinating to three copper atoms with their two –OCH3
and –COOH groups free from coordination, which result in
Fig. 8 Type A and type B
hydrogen bonds in 4 (I, II and
III are symbols of trinuclear
units)
123

Transition Met Chem (2011) 36:653–662
661
Omethoxy or Ophenolic atoms of Bmshp4- ligands link the
trinuclear units into a 1D supramolecular chain and those
between coordinated water ligands and guest water mole-
cules, which feature a twelve-membered water aggregate,
connect the supramolecular chains into 2D supramolecular
networks. Based on the 2D networks, the 3D supramolec-
ular framework of 2 is built. The use of DMF in the syn-
thesis of 3 results in the isolation of the trinuclear complex
with two DMF ligands coordinating to terminal Cu(II)
atoms and two water ligands binding to the central Cu(II).
1D supramolecular chain due to the presence of coordi-
nated DMF solvent ligands. Complex 4 displays a 3D
supramolecular framework, in which the hydrogen bonds
are different from those in 2 because of the existence of
–COOH groups in the H2Bcshp4- ligand.
Acknowledgments This work was supported by the National Nat-
ural Science Foundation of China (No. 20971029), Guangxi Natural
Science Foundation (No. 2010GXNSFD013018 and 2010G
XNSFF013001).
-
The ClO4 anions are not involved in coordination. The
presence of the coordinating DMF ligands on the terminal
Cu(II) atoms, rather than the water ligand and ClO4- anion
as in the case of 2, blocks the propagation of hydrogen
bonds from the sites of the terminal Cu(II) atoms. As a
result, hydrogen bonds in complex 3 are formed mainly
between the coordinated water ligands of the central Cu(II)
and the Omethoxy, Ophenolic atoms of the Bmshp4- ligands,
which gives only a 1D chain as the supramolecular struc-
ture of complex 3. In the case of complex 4, the trinuclear
complex unit is similar to that of 2 in terms of the com-
positions and their binding fashions. However, the use of
H6Bcshp ligand which bears a –COOH substituent group
leads to a connection fashion of the trinuclear complex
units via hydrogen bonds different from that of 2. It can be
seen that the trinuclear complex units are linked into 1D
chains via the hydrogen bonds between the coordinated
water ligands on Cu2 and the Ocarboxylate atom of the
H2Bcshp4- ligand, and the 1D chains are connected into a
2D grid network by two types of hydrogen bonds involving
guest water molecules, coordinated water ligands, –COOH
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