Solvent-influenced syntheses and crystal structures of two azido-bridged polynuclear copper(II) complexes derived from 2-[(3-methylaminopropylimino)methyl]phenol with urease inhibitory activities

Article abstract of DOI:10.1007/s11243-009-9289-6

An end-on azido-bridged dinuclear Cu(II) complex, [Cu₂L₂(μ_1,1-N₃)₂]?CH₃OH, and an end-on azido-bridged polynuclear Cu(II) complex, [CuL(μ_1,1-N₃)]_n, derived

Full text of DOI:10.1007/s11243-009-9289-6

Transition Met Chem (2010) 35:13–17
DOI 10.1007/s11243-009-9289-6
Solvent-influenced syntheses and crystal structures of two
azido-bridged polynuclear copper(II) complexes derived
from 2-[(3-methylaminopropylimino)methyl]phenol
with urease inhibitory activities
Li-Li Ni
Che Wang
•
Zhong-Lu You
Kun Li
•
Lin Zhang
•
•
Received: 4 August 2009 / Accepted: 24 September 2009 / Published online: 9 October 2009
Ó Springer Science+Business Media B.V. 2009
Abstract An end-on azido-bridged dinuclear Cu(II)
complex, [Cu L (l –N ) ]ꢀCH OH, and an end-on azido-
ammonia and carbon dioxide [8, 9]. High concentrations of
ammonia arising from this reaction has undesirable conse-
quences in medicine and agriculture [10]. Control of the
activity of urease through the use of inhibitors could decrease
the negative effects. Recently, a few metal complexes show
urease inhibitory activities [11, 12]. In this paper, two azido-
bridged polynuclear complexes, [Cu L (l –N ) ]ꢀCH OH
2
2
1,1
3 2
3
bridged polynuclear Cu(II) complex, [CuL(l –N )] ,
1
,1
3 n
derived from the Schiff base 2-[(3-methylaminopropyli-
mino)methyl]phenol (HL), were synthesized and charac-
terized by physico-chemical and spectroscopic methods.
The two complexes were synthesized and crystallized with
different solvents, methanol for [Cu L (l –N ) ]ꢀCH OH
2
2
1,1
3 2
3
and [CuL(l1,1–N )] , where L denotes an anionic form
2
2
1,1
3 2
3
3 n
and ethanol for [CuL(l1,1–N )] . The Cu atom in each
of 2-[(3-methylaminopropylimino)methyl]phenol (HL,
Scheme 1), have been synthesized and characterized.
The urease inhibitory activities were evaluated.
3
n
complex is five-coordinate in a square pyramidal geometry
with one O and two N atoms of L, and one N atom of an
azide ligand defining the basal plane, and with one N atom
of another azide ligand occupying the apical position. The
urease inhibitory activities of both complexes were
evaluated.
Experimental
Materials and methods
Introduction
Salicylaldehyde and N-methylpropane-1,3-diamine of AR
grade were purchased from Lancaster. Sodium azide and
solvents were purchased from Beijing Chemical Reagent
Company and were used as received. Copper(II) perchlo-
rate was prepared by reaction of Cu (OH) CO with per-
Polynuclear complexes play an important role in coordi-
nation chemistry due to their versatile structures and wide
applications [1–3]. An efficient way to construct such
polynuclear complexes is to use suitable bridging ligands,
2
2
3
chlorate acid in water. Elemental analyses for C, H, and N
were performed on a Perkin–Elmer 240C elemental ana-
lyzer. IR spectra were recorded on a Nicolet AVATAR 360
-
-
-
such as N3 , NCS , and CN [4–6]. Among the bridging
ligands, azide is particularly interesting, which coordinates
to the metal through end-on, end-to-end, and many other
modes. However, we can hardly predict which coordination
mode will be adopted by the azide group [7]. Urease (urea
amidohydrolase; EC 3.5.1.5) is a nickel-containing metal-
loenzyme that catalyzes the hydrolysis of urea to form
-
1
spectrophotometer as KBr pellets in the 4,000–400 cm
region.
Preparation of HL
To a methanol solution (20 mL) of salicylaldehyde
122.1 mg, 1.0 mmol), a methanol solution (20 mL) of
(
L.-L. Ni ꢀ Z.-L. You (&) ꢀ L. Zhang ꢀ C. Wang ꢀ K. Li
Department of Chemistry and Chemical Engineering, Liaoning
Normal University, 116029 Dalian, People’s Republic of China
e-mail: youzhonglu@yahoo.com.cn
N-methylpropane-1,3-diamine (88.1 mg, 1.0 mmol) was
added with stirring. The mixture was stirred for 30 min at
room temperature to give a yellow solution. Then, the
123

1
4
Transition Met Chem (2010) 35:13–17
Table 1 Crystal data for the complexes
N
N
H
Complex
[Cu
CH
2
L
2
(l1,1–N
3
)
2
]ꢀ
3 n
[CuL(l1,1–N )]
3
OH
OH
Chemical formula
Fw
C
23
H
34Cu
2
N
10
O
3
11 5
C H15CuN O
Scheme 1 Ligand HL
625.68
Block/blue
296.82
Crystal shape/color
Crystal size (mm)
T (K)
Block/blue
0.31 9 0.27 9 0.22 0.22 9 0.16 9 0.11
methanol was evaporated to give yellow oil of HL. Yield:
86 mg (97%). Anal. Calcd (%) for C H N O: C, 68.7;
298(2)
298(2)
0.71073
Monoclinic
Cc
1
1
1 16 2
˚
H, 8.4; N, 14.6. Found (%): C, 68.4; H, 8.5; N, 14.8.
-
Characteristic IR data (cm ): 1645 (s).
k (MoKa) (A)
0.71073
Triclinic
P - 1
1
Crystal system
Space group
˚
a (A)
Preparation of [Cu L (l –N ) ]ꢀCH OH
7.901(1)
9.957(2)
18.245(3)
86.966(2)
78.953(2)
74.586(2)
1358.1(4)
2
12.427(2)
17.568(3)
6.876(2)
90
2
2
1,1
3 2
3
˚
b (A)
˚
c (A)
To a methanol solution (5 mL) of HL (19.2 mg, 0.1 mmol)
and sodium azide (6.5 mg, 0.1 mmol), a methanol solution
a (°)
b (°)
c (°)
(
5 mL) of copper(II) perchlorate (37.0 mg, 0.1 mmol) was
122.749(2)
90
added with stirring. The mixture was stirred for 10 min at
room temperature and filtered. Upon keeping the filtrate in
air for a week, blue block-shaped crystals of the complex,
suitable for X-ray diffraction, were formed on slow evap-
oration of the solvent. Yield: 14.1 mg (45%). Anal. Calcd
3
V ( A˚ )
1262.4(4)
4
Z
-1
)
l (MoKa) (cm
T (min)
1.611
1.726
0.635
0.703
(
(
(
%) for C H Cu N O : C, 44.2; H, 5.5; N, 22.4. Found
23 34 2 10 3
T (max)
0.718
0.833
%): C, 44.9; H, 5.2; N, 23.3. Characteristic IR data
-3
)
D
c
(g cm
1.530
1.562
-
cm ): 3427 (b, w), 3218 (m), 2039 (s), 1618 (s).
1
Reflections/parameters 5451/353
2545/167
2229
Unique reflections
3388
Preparation of [CuL(l1,1–N )]
2
3
n
Goodness of fit on F
0.975
0.975
R
int
0.0559
0.0656
0.1563
0.1060
0.1819
0.0297
0.0356
0.0704
0.0416
0.0729
[
CuL(l1,1–N )] was prepared in ethanol solution by a
3
n
R
1
[I C 2r(I)]
[I C 2r(I)]
(all data)
wR (all data)
similar procedure as that described for [Cu L (l –N ) ]ꢀ
2
2
1,1
3 2
wR
2
CH OH. Blue block-shaped crystals of the complex were
3
R
1
obtained after 5 days. Yield: 20.8 mg (70%). Anal. Calcd
2
(
(
(
%) for C H CuN O: C, 44.5; H, 5.1; N, 23.6. Found
11 15 5
%): C, 44.3; H, 5.3; N, 23.9. Characteristic IR data
-
cm ): 3232 (m), 2037 (s), 1617 (s).
1
˚
Caution: Azide salts and perchlorate salts are potentially
0.90(1) A. All other H atoms were placed in calculated
positions and constrained to ride on their parent atoms. The
crystallographic data for the complexes are summarized in
Table 1. Selected bond lengths and angles are given in
Table 2. Hydrogen bonds are listed in Table 3. Crystallo-
graphic data for the complexes have been deposited with
the Cambridge Crystallographic Data Center (CCDC
638055 for [Cu L (l –N ) ]ꢀCH OH, and 731413 for
explosive and should be handled with small quantities with
care.
X-ray crystallography
Diffraction intensities for the two complexes were col-
lected at 298(2) K using a Bruker SMART 1000 CCD area
2
2
1,1
3 2
3
˚
detector with MoKa radiation (k = 0.71073 A). The col-
[CuL(l1,1–N )] ).
3
n
lected data were reduced using the SAINT program [13],
and multi-scan absorption corrections were performed
using the SADABS program [14]. Both structures were
solved by direct methods. The complexes were refined
Urease inhibitory test
The measurement of urease inhibitory activities was car-
ried out according to the method reported by Tanaka [16].
Acetohydroxamic acid was used as a reference. Generally,
the assay mixture, containing 25 lL of jack bean urease
(10 kU/l) and 25 lL of the tested compounds of various
2
against F by full-matrix least-squares methods using the
SHELXTL program [15]. All of the non-hydrogen atoms
were refined anisotropically. The amino H atoms in the
complexes were located in difference Fourier maps and
refined isotropically, with N–H distances restrained to
concentrations (dissolved in DMSO/H O = 1:1 (v/v)), was
2
1
23

Transition Met Chem (2010) 35:13–17
15
˚
Table 2 Selected bond lengths (A) and angles (°) for the complexes
Table 4 Inhibitory activities of urease
[
Cu
2
L
2
(l1,1–N
3
)
2
]ꢀCH
3
OH
Tested material
IC50 (lM)
Bond lengths
Cu1–O1
[
Cu
L
2 2
(l1,1–N
3
)
2
]ꢀCH
3
OH
61.3 ± 0.13
63.2 ± 0.15
[100
1.917(4)
2.037(5)
2.018(4)
1.963(5)
2.048(5)
Cu1–N1
Cu1–N5
Cu2–O2
Cu2–N4
Cu2–N8
1.958(4)
2.342(5)
1.910(4)
2.007(5)
2.356(5)
[
CuL(l1,1–N
3
)]
n
Cu1–N2
HL
Cu1–N8
Copper(II) perchlorate
Acetohydroxamic acid
12.80 ± 0.27
42.12 ± 0.08
Cu2–N3
Cu2–N5
Bond angles
O1–Cu1–N1
N1–Cu1–N8
N1–Cu1–N2
O1–Cu1–N5
N8–Cu1–N5
O2–Cu2–N3
N3–Cu2–N4
N3–Cu2–N5
O2–Cu2–N8
N4–Cu2–N8
91.4(2)
176.7(2)
93.0(2)
102.3(2)
81.3(2)
90.8(2)
93.1(2)
173.0(2)
97.4(2)
94.4(2)
O1–Cu1–N8
O1–Cu1–N2
N8–Cu1–N2
N1–Cu1–N5
N2–Cu1–N5
O2–Cu2–N4
O2–Cu2–N5
N4–Cu2–N5
N3–Cu2–N8
N5–Cu2–N8
89.9(2)
161.7(2)
84.9(2)
101.4(2)
94.2(2)
165.9(2)
87.6(2)
86.8(2)
106.6(2)
80.4(2)
the buffer from 6.8 to 7.7, was measured by a micro-plate
reader (570 nm) with the end-point being determined by
the color of phenol red indicator. The results are listed in
Table 4.
Results and discussion
The influence of the hydrogen bonds on the coordination
modes of the azide groups has been discussed in a recent
report [17]. In this paper, the two complexes were syn-
thesized following the same procedures and starting
materials, except for the solvents used in the synthesis and
crystallization. The polarity of methanol is stronger than
that of ethanol, which made the methanol molecules
readily reside in the crystal structures of the complexes
through hydrogen bonds [18, 19]. For [Cu L (l –N ) ]ꢀ
[
CuL(l1,1–N
3
)]
n
Bond lengths
Cu1–O1
1.926(4)
2.048(4)
2.524(4)
Cu1–N1
Cu1–N3
1.982(4)
2.012(4)
Cu1–N2
#1
Cu1–N3
Bond angles
O1–Cu1–N1
N1–Cu1–N3
N1–Cu1–N2
O1–Cu1–N3
N2–Cu1–N3
2
2
1,1
3 2
90.5(2)
158.4(2)
95.5(2)
87.3(2)
91.2(2)
O1–Cu1–N3
O1–Cu1–N2
N3–Cu1–N2
N1–Cu1–N3
N3–Cu1–N3
88.6(2)
173.8(2)
86.3(2)
CH OH, there are three intramolecular N–HꢀꢀꢀO and
3
O–HꢀꢀꢀO hydrogen bonds between the two CuL units, while
for [CuL(l –N )] , there is one N–HꢀꢀꢀO hydrogen bond
#
#
1
1
#1
#1
1,1
3 n
92.0(2)
between the adjacent two CuL units, and one N–HꢀꢀꢀN
hydrogen bond between the ligand L and the azide group.
The tighter hydrogen linkage in [Cu L (l –N ) ]ꢀCH OH
109.5(2)
2
2
1,1
3 2
3
than that in [CuL(l1,1–N )] makes the distance of the
3
n
adjacent Cu atoms in [Cu L (l –N ) ]ꢀCH OH shorter
˚
2
2
1,1
3 2
3
Table 3 Hydrogen bond distances (A) and bond angles (°)
D–HꢀꢀꢀA d(D–H) d(HꢀꢀꢀA) d(DꢀꢀꢀA) Angle (D–HꢀꢀꢀA)
Cu (l1,1–N
O3–H3AꢀꢀꢀO1 0.82
N4–H4AꢀꢀꢀO3 0.89(5)
N2–H2ꢀꢀꢀO2 0.90(6)
CuL(l1,1–N
than that in [CuL(l1,1–N )] . Thus, there are two end-on
3
n
azide bridges between the adjacent Cu atoms in
[
L
2 2
3
)
2
]ꢀCH
3
OH
1.93
2.699(7)
156
2.07(5)
2.12(4)
2.958(8) 170(7)
2.905(6) 145(6)
[
3 n
)]
#1
N2–H2ꢀꢀꢀN5
N2–H2ꢀꢀꢀO1
0.899(10) 2.55(3)
0.899(10) 2.42(3)
3.216(6) 132(4)
3.133(5) 137(4)
#1
Symmetry transformation used to generate the equivalent atoms:
1: x, -y, 1/2 ? z
#
preincubated for 1 h at 37 °C in a 96-well assay plate.
Then, 0.2 mL of 100 mM N-(2-hydroxyethyl)piperazine-
0
N -(2-ethanesulfonic acid) buffer at pH 6.8 containing
5
00 mM urea and 0.002% phenol red were added and
incubated at 37 °C. The reaction time, which was required
to produce enough ammonium carbonate to raise the pH of
Fig. 1 Molecular structure of [Cu
probability ellipsoids. Hydrogen bonds are shown as dashed lines
2
L
2
(l1,1–N
3
)
2
]ꢀCH
3
OH at 30%
123

1
6
Transition Met Chem (2010) 35:13–17
solvate, whereas [CuL(l1,1–N )] contains no solvent
3
n
molecules of crystallization. The methanol molecule in
[
Cu L (l –N ) ]ꢀCH OH is linked to the complex mole-
2
2
1,1
3 2
3
cule through N–HꢀꢀꢀO and O–HꢀꢀꢀO hydrogen bonds. With
the exception of the methanol content in the case of
[
Cu L (l –N ) ]ꢀCH OH, the composition of the two
2
2
1,1
3 2
3
compounds is the same, [CuL(N )].
3
Each Cu atom in the complexes has square pyramidal
coordination and is coordinated by one O and two N atoms
of L, and by one N atom of a bridging azide ligand, defining
the base plane, and by one N atom of another bridging azide
ligand, occupying the apical position. The apical coordinate
bond lengths in [Cu L (l –N ) ]ꢀCH OH are much
2
2
1,1
3 2
3
shorter than those in [CuL(l1,1–N )] , which is caused by
3
n
the hydrogen bonds in the complexes. In [Cu L (l –N ) ]ꢀ
2
2
1,1
3 2
3 n
Fig. 2 The unit of [CuL(l1,1–N )] at 30% probability ellipsoids
CH OH, there is one intramolecular O–HꢀꢀꢀO and two
3
N–HꢀꢀꢀO hydrogen bonds between the two CuL units, while
in [CuL(l –N )] , there is only one N–HꢀꢀꢀO hydrogen
[
Cu L (l –N ) ]ꢀCH OH, and one end-on azide bridge
2
2
1,1
3 2
3
1,1
3 n
between those in [CuL(l –N )] .
bond between the two CuL units, and one N–HꢀꢀꢀN hydrogen
bond between the CuL and the adjacent azide ligand. All
other bond lengths are comparable to each other and com-
parable with those observed in other Schiff base copper(II)
complexes [20, 21]. As expected, the coordinate bonds
involving amine N atoms are longer than those involving
imine N atoms. Each bridging azide ligand is nearly linear
and shows bent coordination mode with the metal atoms.
1
,1
3 n
Structures of [Cu L (l –N ) ]ꢀCH OH
2
2
1,1
3 2
3
and [CuL(l1,1–N )]
3
n
Figure 1 gives the perspective view of the complex
Cu L (l –N ) ]ꢀCH OH, and Fig. 2 gives the perspective
[
2
2
1,1
3 2
3
view of the unit of the complex [CuL(l –N )] , respec-
1
,1
3 n
˚
tively, together with the atomic-labeling systems.
The CuꢀꢀꢀCu distances are 3.306(2) A in [Cu L (l –N ) ]ꢀ
2
2
1,1
3 2
˚
[
Cu L (l –N ) ]ꢀCH OH is a double end-on azido-
CH OH and 3.599(2) A in [CuL(l –N )] .
2
2
1,1
3 2
3
3
1,1
3 n
bridged dinuclear copper(II) complex, while [CuL(l –N )]
In the crystal structure of [CuL(l1,1–N )] , the
1
,1
3
n
3 n
is a single end-on azido-bridged polynuclear copper(II)
[CuL(l1,1–N )] units are linked by Cu–N bonds and
3
complex. [Cu L (l –N ) ]ꢀCH OH contains a methanol
intermolecular N–HꢀꢀꢀO and N–HꢀꢀꢀN hydrogen bonds,
2
2
1,1
3 2
3
Fig. 3 The molecular packing
of [CuL(l1,1–N )] viewed
along the b axis. Hydrogen
3
n
bonds are shown as dashed lines
1
23

Transition Met Chem (2010) 35:13–17
17
forming an infinite one-dimensional chain running along
2. Meyer F, Pritzkow H (2001) Inorg Chem Commun 4:305
3
4
5
. Goher MAS, Escuer A, Mautner FA, Al-Salem NA (2002)
Polyhedron 21:1871
. Munno GD, Cipriani F, Armentano D, Julve M, Real JA (2001)
New J Chem 25:1031
. Dey SK, Mondal N, El Fallah MS, Vicente R, Escuer A, Solans
X, Font-Bard ´ı a M, Matsushita T, Gramlich V, Mitra S (2004)
Inorg Chem 43:2427
. Sailaja S, Reddy KR, Rajasekharan MV, Hureau C, Rivi e` re E,
Cano J, Girerd J-J (2003) Inorg Chem 42:180
the c axis (Fig. 3).
Urease inhibitory activities
The urease inhibitory activities of both complexes are
comparable to each other, and slightly weaker than that of
the acetohydroxamic acid co-assayed as a positive refer-
ence against the urease. The Schiff base HL shows no
activity. As a comparison, the urease inhibitory activities of
the two complexes are slightly lower than those we
reported previously [21, 22].
6
7. Ribas J, Escuer A, Montfort M, Vicente R, Corte
Rojo T (1999) Coord Chem Rev 193–195:1027
´
s R, Lezama L,
8
. Karplus PA, Pearson MA, Hausinger RP (1997) Acc Chem Res
0:330
9. Sumner JB (1926) J Biol Chem 69:435
3
1
1
0. Montecucco C, Rappuoli R (2001) Nat Rev Mol Cell Biol 2:457
1. Asato E, Kamamuta K, Akamine Y, Fukami T, Nukada R,
Mikuriya M, Deguchi S, Yokota Y (1997) Bull Chem Soc Jpn
Summary
7
0:639
1
2. Khan MI, Baloch MK, Ashfaq M (2007) J Enzym Inhib Med
Chem 22:343
It is evident from this discussion that the solvents used in
the synthesis and crystallization can influence the compo-
sition and the hydrogen bonding pattern of the complexes.
The urease inhibitory activities show that such complexes
could be potential urease inhibitors.
1
1
3. Bruker (2002) SMART and SAINT. Bruker AXS Inc, Madison
4. Sheldrick GM (1996) SADABS. University of G o¨ ttingen,
Germany
15. Sheldrick GM (1997) SHELXTL V5.1, software reference
manual. Bruker AXS Inc, Madison
1
1
6. Tanaka T, Kawase M, Tani S (2003) Life Sci 73:2985
7. You Z-L, Hou P, Ni L-L, Chen S (2009) Inorg Chem Commun
Acknowledgments This work was financially supported by the
Natural Science Foundation of China (Project No. 20901036) and the
Education Office of Liaoning Province (Project No. 2008T107).
1
2:444
1
1
8. Shi D-H, You Z-L, Xu C, Zhang Q, Zhu H–L (2007) Inorg Chem
Commun 10:404
9. Han X, You Z-L, Xu Y–T, Wang X-M (2006) J Chem Crystallogr
3
6:743
References
2
2
0. You Z-L, Ma X-L, Niu S-Y (2008) J Coord Chem 61:3297
1. Hou P, You Z-L, Zhang L, Ma X-L, Ni L-L (2008) Transition
Met Chem 33:1013
1
. Mukherjee PS, Dalai S, Zangrando E, Lloret F, Chaudhuri NR
2001) Chem Commun 1444
(
22. You Z-L, Zhou P (2008) Transition Met Chem 33:453
123