Synthesis, structures and antimicrobial activities of nickel(II) and zinc(II) diaminomaleonitrile-based complexes

Article abstract of DOI:10.1007/s11243-018-0241-5

Three Ni(II) and Zn(II) complexes [Ni(L1)], [Ni(L2)], and [Zn(L3)(DMSO)] (L1?=?2,3-bis(2-hydroxybenzylideneimino)-2,3-butenedinitrile, L2?=?2,3-bis(2-hydroxy-3-methoxybenzylideneimino)-2,3-butenedinitrile, L3?=?2,3-bis(2-hydroxy-1-naphthylideneimino)-2,3-butenedinitrile) were obtained in DMSO by one-pot syntheses. The complexes were characterized by physicochemical and spectroscopic methods. Also, their solid-state structures were determined by single-crystal X-ray diffraction. The geometries of the Ni(II) and Zn(II) complexes were square planar and square pyramidal, respectively. The complexes were screened in vitro against a fungal species and eight species of bacteria, revealing their antimicrobial activity.

Full text of DOI:10.1007/s11243-018-0241-5

Transition Metal Chemistry
https://doi.org/10.1007/s11243-018-0241-5
Synthesis, structures and antimicrobial activities of nickel(II)
and zinc(II) diaminomaleonitrile‑based complexes
1
1
2
2
3
Iran Sheikhshoaie · Najmeh Lotf · Joachim Sieler · Harald Krautscheid · Moj Khaleghi
Received: 23 January 2018 / Accepted: 25 April 2018
©
The Author(s) 2018
Abstract
Three Ni(II) and Zn(II) complexes [Ni(L1)], [Ni(L2)], and [Zn(L3)(DMSO)] (L1 = 2,3-bis(2-hydroxybenzylideneimino)-
2
,3-butenedinitrile, L2 = 2,3-bis(2-hydroxy-3-methoxybenzylideneimino)-2,3-butenedinitrile, L3 = 2,3-bis(2-hydroxy-
-naphthylideneimino)-2,3-butenedinitrile) were obtained in DMSO by one-pot syntheses. The complexes were characterized
1
by physicochemical and spectroscopic methods. Also, their solid-state structures were determined by single-crystal X-ray
difraction. The geometries oꢀ the Ni(II) and Zn(II) complexes were square planar and square pyramidal, respectively. The
complexes were screened in vitro against a ꢀungal species and eight species oꢀ bacteria, revealing their antimicrobial activity.
Introduction
DAMN with diferent aromatic aldehydes can ꢀorm 1:1 and/
or 1:2 Schif base ligands [14]. In recent studies, we have
reported the synthesis and characterization oꢀ complexes
incorporating tridentate NNO-Schif base ligands based on
diaminomaleonitrile [15, 16]. In this project, our eforts were
directed to the synthesis and characterization oꢀ nickel(II)
and zinc(II) complexes with tetradentate N O -Schif base
The synthesis and characterization oꢀ Schif bases and their
transition metal complexes has attracted considerable atten-
tion in recent decades [1–3]. Schif base ligands with a vari-
ety oꢀ donor atoms including nitrogen, oxygen and sulꢀur
can be coordinated with transition metal atoms. Depending
on the type and oxidation state oꢀ the central metal atom
and the ligand structure, they can be bidentate, tridentate,
tetradentate or polydentate, and depending on the nature
oꢀ the possible counter ion, transition metal Schif’s base
complexes show various coordination modes with varying
degree oꢀ distortion [4, 5]. Among these, the tetradentate
Schif bases with N O coordination sites belong to ligands
2
2
ligands based on diaminomaleonitrile and various aldehydes
such as 2-hydroxybenzaldehyde, 3-methoxy-2-hydroxyben-
zaldehyde and 2-hydroxy-1-naphthaldehyde.
Experimental
2
2
investigated most oꢀten in coordination chemistry [6–8].
The transition metal complexes ꢀormed ꢀrom tetradentate
Schif bases exhibit a wide range oꢀ biological properties
Materials and methods
All reagents ꢀor synthesis and analysis were purchased ꢀrom
Merck and used without ꢀurther puriꢁcation. Elemental anal-
yses were recorded on a Thermo Finnigan Flash Elemental
Analyzer 1112EA. Melting points were measured on an
Electrothermal-9100 apparatus. The IR measurements were
taken on a FTIR Tensor 27 inꢀrared spectrophotometer as
[
9–12]. 2,3-Diamino-cis-2-butenedinitrile (diaminomaleoni-
trile: DAMN) is an attractive precursors to nucleotides and
is considered as an intermediate in the synthesis oꢀ a wide
variety oꢀ heterocyclic compounds [13]. The condensation oꢀ
−
1 1
KBr disks in the range oꢀ 400–4000 cm . H NMR spectra
were measured on a Bruker AVANCE BRX 250 MHz spec-
*
Iran Sheikhshoaie
i_shoaie@yahoo.com; shoaie@uk.ac.ir
trometer using d -DMSO as solvent ꢀor the complexes. The
6
1
2
3
Department oꢀ Chemistry, Faculty oꢀ Science, Shahid
Bahonar University oꢀ Kerman, Kerman, Iran
chemical shiꢀt values (δ) are given in ppm. The electronic
absorption spectra in DMSO solution were recorded by a
Cary 50 UV–Vis spectrophotometer. Bacteria were isolated
Fakultät ꢀür Chemie und Mineralogie, Universität Leipzig,
0
4103 Leipzig, Germany
ꢀ
rom clinical samples or purchased ꢀrom Merck Company.
Department oꢀ Biology, Faculty oꢀ Science, Shahid Bahonar
University oꢀ Kerman, Kerman, Iran
Vol.:(0
1
123456789)
3

Transition Metal Chemistry
Preparation of [Ni(L1)] and [Ni(L2)]
–CH=N), 7.20–6.45 (m, 6H, ArH), 3.74 (s, 6H, –OCH ).
3
−
1
−1
UV–Vis spectra [λ , nm (log ε, L mol cm ); DMSO
max
A solution oꢀ 2-hydroxybenzaldehyde (2.0 mmol, 0.21 ml)
solution]: 270 (4.29), 355 (4.16), 375 (4.13), 395 (4.14),
ꢀ
or H L1 and 3-methoxy-2-hydroxybenzaldehyde (0.304 g,
520 (3.97), 600 (4.13). Anal. Calcd. ꢀor C H N NiO : C,
2
20 18
4
6
2
.0 mmol) ꢀor H L2 and 2,3-diamino-cis-2-butenedini-
51.2; H, 3.8; N, 11.9%. Found: C, 51.0; H, 3.7; N, 11.7%.
2
trile (0.108 g, 1.0 mmol) in DMSO (5 ml) was heated ꢀor
3
0 min. Aꢀterward, triethylamine (0.200 g, 2.0 mmol) and
Preparation of [Zn(L3)(DMSO)]
NiCl ·6H O (0.238 g, 1.0 mmol) in DMSO (5 ml) were
2
2
added dropwise and the resulting reaction mixture was
reꢂuxed ꢀor 4 h while stirring constantly. The clear green
solution was allowed to stand several days at room tem-
perature, providing blue single crystals suitable ꢀor X-ray
crystallography (Scheme 1).
This complex was synthesized similar to [Ni(L1)] and
[Ni(L2)] complexes. To a solution oꢀ 2-hydroxy-1-naph-
thaldehyde (0.344 g, 2.0 mmol) in DMSO (10 ml),
2,3-diamino-cis-2-butenedinitrile (0.108 g, 1.0 mmol) was
added and reꢂuxed ꢀor 30 min. A deep brown solution was
obtained. Aꢀter adding triethylamine (0.200 g, 2.0 mmol)
and Zn(CH CO ) ·2H O (0.219 g, 1.0 mmol) to the solution,
[
Ni(L1)]: Yield: 0.242 g (65%); m.p. > 300 °C IR (KBr,
−
1
cm ): 2218 (C≡N), 1611 (C=N), 1576 (C=C)
,
aliphatic
3
2 2
2
1
517 (C=C)
, 1195 (C–O), 754 (Ni–N), 418 (Ni–O).
the color oꢀ the solution changed to black. Dark red single
crystals suitable ꢀor crystallography appeared aꢀter 2 weeks
standing (Scheme 2). Yield 0.407 g (73%); m.p. > 300 °C.
aromatic
1
H NMR (250 MHz, d -DMSO, ppm): δ = 8.57 (s, 2H,
6
–
CH=N), 7.45–6.24 (m, 8H, ArH). UV–Vis spectra [λ
,
max
−
1
−1
−1
nm (log ε, L mol cm ); DMSO solution]: 265 (4.46),
05 (4.30), 380 (4.25), 440 (4.08), 530 (4.09), 595 (4.08).
Anal. Calcd. ꢀor C H N NiO : C, 57.9; H, 2.7; N, 15.0%.
IR (KBr, cm ): 3007 (C–H), 2209 (C≡N), 1601 (C=N),
3
1571 (C=C)
, 1536 (C=C)
, 1267 (C–O), 1183
aliphatic
aromatic
1
(S=O), 747 (Zn–N), 412 (Zn–O). H NMR (250 MHz,
1
8
10
4
2
Found: C, 57.7; H, 2.6; N, 14.9%.
d -DMSO, ppm): δ = 9.25 (s, 2H, –CH=N), 8.06- 6.94
6
[
Ni(L2)]: Yield 0.259 g (60%); m.p. > 300 °C. IR (KBr,
(m, 12H, ArH), 3.30 (s, 6H, CH ). UV–Vis spectra [λ
,
max
3
−
1
−1
−1
cm ): 2225 (C≡N), 1612 (C=N), 1580 (C=C)
,
nm (log ε, L mol cm ); DMSO solution]: 265 (4.65),
355 (4.31), 400 (4.40), 425 (4.38), 465 (4.23), 600 (4.71).
Anal. Calcd. ꢀor C H N O SZn: C, 60.2; H, 3.6; N, 10.0%.
aliphatic
1
538 (C=C)
, 1253 (C–O), 735 (Ni–N), 414 (Ni–O).
aromatic
1
H NMR (250 MHz, d -DMSO, ppm): δ = 8.49 (s, 2H,
6
28 20
4
3
Found: C, 60.0; H, 3.3; N, 9.8%.
NC
CN
N
O
C
C
H
H
C
H
N
O
NC
CN
NiCl ·6H O
Ni
2
2
OH
+
C
C
O
H N
2
NH2
DMSO
R
R
R
1
mmol
2
mmol
R= H
[Ni(L1)]
R= OCH3 [Ni(L2)]
Scheme 1 A schematic representation oꢀ synthesis oꢀ [Ni(L1)] and [Ni(L2)] complexes
NC
CN
N
O
C
C
H
H
C
H
N
O
NC
CN
Zn(CH CO ) ·2H O
3
2 2
2
Zn
OH
+
C
C
O
H N
2
NH2
DMSO
O
S
2
mmol
1 mmol
H C
3
CH3
Scheme 2 A schematic representation oꢀ synthesis oꢀ [Zn(L3)(DMSO)] complex
1
3

Transition Metal Chemistry
X‑ray structure determination
ATCC 27853, Staphylococcus aureus PTCC 1112, Escher-
ichia coli PTCC 1330, Bacillus cereus PTCC 1015 and
Micrococcus luteus PTCC 1110) and three bacteria isolated
ꢀrom clinical samples (Klebsiella pneumoniae, Enterococcus
faecalis and Listeria monocytogenes). Brain Heart Inꢀusion
medium (BHI-Merck) was used ꢀor L. monocytogenes and E.
faecalis, whereas the other bacteria were cultured on Muel-
ler–Hinton medium (Merck). Also, YGC medium (Merck)
was used as the test medium ꢀor the yeast strain.
Suitable crystals ꢀor single-crystal X-ray structure analysis
were selected in mineral oil and mounted on glass ꢁbers.
Difraction data ꢀor [Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)]
were collected on an IPDS-1 diꢀꢀractometer (Stoe&Cie
GmbH, Darmstadt, Germany) using graphite-monochroma-
tized Mo-Kα radiation, (λ = 0.71073 Å). The structures were
solved by direct methods using SHELXS and reꢁned using
SHELXL [17]. All non-hydrogen atoms with the exception
oꢀ the disordered S atom oꢀ the DMSO ligand in [Zn(L3)
Determination of antimicrobial activity
(
DMSO)] were reꢁned anisotropically. Hydrogen atoms
were included in idealized positions. The molecular graph-
ics were drawn with DIAMOND [18]. Crystallographic data
and details oꢀ the data collection and structure reꢁnement
are listed in Table 1, selected bond lengths and angles are
presented in Table 2, and Scheme 3 shows packing views oꢀ
the three complexes.
The antimicrobial activities oꢀ [Ni(L1)], [Ni(L2)]
and [Zn(L3)(DMSO)] complexes, NiCl ·6H O and
2
2
Zn(CH CO ) ·2H O against some Gram positive bacteria
3
2 2
2
strains (L. monocytogenes, E. faecalis, S. aureus PTCC
1112, M. luteus PTCC 1110 and B. cereus PTCC 1015),
some Gram negative bacterial strains (E. coli PTCC
1
330, K. pneumoniae, P. aeruginosa ATCC 27853) and
Microorganism strains and culture
a ꢀungal species (C. albicans PTCC 5027) were investi-
gated using agar well difusion plate methods [19]. The
agar media were inoculated with 100 µl oꢀ the inoculums
which were prepared using an overnight culture oꢀ each
In this research, we used one yeast (Candida albicans PTCC
5
027), ꢁve standard bacteria (Pseudomonas aeruginosa
Table 1 Crystallographic
Complex
[Ni(L1)]
[Ni(L2)]
[Zn(L3)(DMSO)]
C H N O SZn
557.91
data collection parameters ꢀor
[
(
Ni(L1)], [Ni(L2)] and [Zn(L3)
DMSO)]
Formula
Formula weight, g mol
Crystal size, mm
C H N NiO
C H N NiO
1
8
10
4
2
20 18
4
6
28 20
4
3
−1
373.01
0.30 × 0.10 × 0.05
469.09
0.10 × 0.10 × 0.08
3
0.20 × 0.20 × 0.10
Crystal color
Temperature, K
Crystal system
Space group
Blue
213
Orthorhombic
Pbcn
Blue
213
Monoclinic
I2/a
Red
213
Triclinic
P 1̄
Unit cell dimensions (Å, °)
a
b
c
α
β
γ
17.133 (2)
6.9752 (4)
26.088 (2)
90
90
90
3117.6 (4)
8
1.589
13.291 (1)
13.0637 (6)
22.605 (2)
90.00
102.322 (7)
90.00
3834.5 (5)
8
1.625
1.061
2.2– 25.0
12,828
3335 (0.165)
1617
280
10.4479 (5)
11.1601 (5)
11.8326 (6)
102.406 (6)
100.556 (6)
111.140 (5)
1204.22 (11)
2
1.539
1.146
2.1–25.9
11,951
4372 (0.0273)
3683
3
Volume, Å
Z
−3
Calculated density, g cm
Absorption coeꢃcient, mm−
θ range ꢀor data collection, °
Reꢂections collected
1
1.264
2.0–25.0
18,304
2681 (0.146)
1003
Independent reꢂections (Rint)
Observed reꢂections [I ≥ 2σ(I)]
Parameters
226
344
R1 (observed reꢂections)
wR2 (all data)
0.0445
0.1028
0.47/− 0.84
0.0786
0.1825
0.74/− 0.72
0.031
0.078
0.49/− 0.30
Largest dif. peak/hole, eÅ−
3
1
3

Transition Metal Chemistry
Table 2 Selected bond lengths
[
[
[
Ni(L1)]
Ni1–N1
Ni1–N2
Ni1–O1
N1–Ni1–N2
N1–Ni1–O1
N1–Ni1–O2
Ni(L2)]
Ni1–N1
Ni1–N2
(
[
Å) and angles (°) oꢀ [Ni(L1)],
Ni(L2)] and [Zn(L3)(DMSO)]
1.854 (6)
1.862 (6)
1.836 (5)
86.2 (3)
94.71 (15)
178.4 (2)
N1–C5
N2–C2
C5–C6
O2–Ni1–N2
Ni1–N1–C1
Ni1–N1–C5
1.320 (9)
1.406 (8)
1.400 (11)
94.19 (16)
112.0 (5)
127.5 (5)
Ni1–O2
N1–C1
C1–C2
O1–Ni1–O2
O1–Ni1–N2
N1–C5–C6
1.834 (5)
1.387 (7)
1.349 (7)
85.0 (2)
177.9 (2)
124.2 (7)
1.838 (6)
1.860 (6)
1.846 (4)
86.0 (3)
94.0 (2)
179.9 (3)
N1–C5
C5–C6
C1–C2
O2–Ni1–N2
Ni1–N1–C1
Ni1–N1–C5
1.327 (9)
1.382 (9)
1.341 (10)
94.1 (2)
112.5 (5)
127.5 (5)
Ni1–O2
N1–C1
1.849 (5)
1.366 (9)
Ni1–O1
N1–Ni1–N2
N1–Ni1–O1
N1–Ni1–O2
Zn(L3)(DMSO)]
Zn1–N1
O1–Ni1–O2
O1–Ni1–N2
N1–C5–C6
85.9 (2)
178.8 (3)
124.1 (8)
2.0813 (14)
2.0992 (17)
1.9530 (16)
1.9742 (13)
87.43 (6)
146.31 (7)
108.81 (7)
79.12 (6)
Zn1–O3
N1–C1
N1–C5
N2–C2
O1–Zn1–O3
O1–Zn1–N2
O2–Zn1–O3
O2–Zn1–N2
O3–Zn1–N2
2.0430 (16)
1.378 (3)
1.319 (2)
1.386 (2)
100.55 (8)
159.77 (7)
102.96 (6)
85.71 (6)
98.08 (8)
N3–C3
C1–C2
C1–C3
C5–C6
C1–N1–C5
Zn1–N1–C1
Zn1–N1–C5
N1–C5–C6
1.135 (3)
1.371 (3)
1.450 (3)
1.404 (3)
121.68 (16)
111.94 (12)
126.06 (13)
126.17 (17)
Zn1–N2
Zn1–O1
Zn1–O2
N1–Zn1–O1
N1–Zn1–O2
N1–Zn1–O3
N1–Zn1–N2
O1–Zn1–O2
97.67 (6)
Scheme 3 The packing view oꢀ
[
[
Ni(L1)] (a), [Ni(L2)] (b) and
Zn(L3)(DMSO)] (c)
microorganism (18–24 h) adjusted to a turbidity equivalent
to a 0.5-McFarland standard. Wells were cut and 50 µl oꢀ
the compounds (10 mg/ml; DMSO was used as solvent)
were added. Each compound was tested in triplicate along
with standard ciproꢂoxacin ꢀor bacteria and ꢂuconazole
was used as a negative control. The minimum inhibitory
concentration (MIC) and minimal bactericidal concen-
tration (MBC) were determined by microdilution assay
(NCCLS, 2008). The cultures were prepared in 24 and
72 h broth cultures oꢀ microorganisms, respectively. The
MIC was deꢁned as the lowest concentration oꢀ compound
to inhibit the growth oꢀ microorganisms, and the MBC was
deꢁned as the lowest concentration oꢀ compound to kill the
microorganisms. Serial dilutions ranging ꢀrom 10 mg/ml
to 39 µg/ml were prepared in medium.
ꢀ
or yeast. The plates were incubated at 37 °C ꢀor 24 h.
The antimicrobial activity was assayed by measuring the
diameter oꢀ the inhibition zone ꢀormed around the well.
The diameter oꢀ the zone oꢀ inhibition was measured by
measuring scale in millimeters (mm). DMSO as solvent
1
3

Transition Metal Chemistry
Results and discussion
Structure description of [Ni(L1)] and [Ni(L2)]
Syntheses and spectroscopic characterization
The molecular structure oꢀ [Ni(L1)] in solid state is shown in
Fig. 1. This complex crystallizes in the orthorhombic space
group Pbcn. The Schif base ligand coordinates to one nickel
atom in a tetradentate manner via phenolate O and imine
N atoms. The geometry around the nickel atom is square
planar, and the angle sum in the nickel plane is 360.1°.
The bond distances between Ni(1) and O are 1.836(5) and
1.834(5) Å, and the Ni(1)–N bond lengths are 1.854(6) and
1.862(6) Å [27].
In general, metal complexes [Ni(L1)], [Ni(L2)] and
[
Zn(L3)(DMSO)] were obtained ꢀrom the condensation
oꢀ DAMN with various aldehydes in the presence oꢀ metal
atoms. The IR spectra oꢀ the complexes exhibit absorption
−
1
bands at 1612, 1611 and 1601 cm respectively, which
are assigned to the (C=N) stretching vibration [20]. The
absence oꢀ an OH stretching vibration suggests that the
O phenolic atoms oꢀ the ligands are deprotonated and
participate in coordination to the nickel and zinc atoms
The molecular structure oꢀ [Ni(L2)] in solid state is shown
in Fig. 2. [Ni(L2)] crystallizes in the monoclinic space group
I2/a. The nickel atom is also ꢀour-coordinated with a square
planar geometry. The coordination environment oꢀ the nickel
atom is very similar to that oꢀ the [Ni(L1)].
[
21]. The symmetric diimine nature oꢀ the complexes
is proven by the single band observed in the range oꢀ
−
1
2
209–2225 cm assigned to the (C≡N) stretching vibra-
tion, contrary to two bands observed in monoimine
compounds [22]. The absorption bands in the range oꢀ
Structure description of [Zn(L3)(DMSO)]
−
1
−1
7
35–754 cm and 412–418 cm in the metal complexes
are assigned to stretching modes oꢀ the M–N and M–O
The molecular structure oꢀ [Zn(L3)(DMSO)] in the solid
state is shown in Fig. 3. This complex crystallizes in the
1
bonds, respectively [23]. In the H NMR spectra oꢀ the
̄
complexes, the signal at 9.25, 8.57 and 8.49 ppm respec-
tively is attributed to azomethine protons [15]. The elec-
tronic spectra oꢀ the complexes were recorded in DMSO.
The bands at 265 and 270 nm are attributed to the elec-
tronic transitions π→π* oꢀ the aromatic rings. The bands
between 305 and 400 nm are due to n→π* transitions. The
bands above 400 nm are attributed to the intense charge
transꢀer and intraligand transitions, indicating eꢀꢀicient
conjugation in the metal complexes [24–26].
triclinic space group P1. The zinc atom is surrounded by
two nitrogen atoms and two oxygen atoms ꢀrom the Schif
base ligand and one oxygen atom ꢀrom a DMSO ligand.
The zinc atom is ꢁve-coordinated with a square pyramidal
coordination geometry. The tetradentate ligand occupies
the equatorial plane, and one O-coordinating DMSO ligand
(sulꢀur atom disordered on two positions with 87.8(2) and
12.2(2)%) occupies the apical position. The coordinating
N and O atoms ꢀorm a plane with a maximum deviation oꢀ
0
.1254(9) Å. Zn(1) is positioned 0.4381(9) Å below this
plane (Fig. 3), the angle sum in the zinc plane amounts to
Fig. 1 ORTEP view oꢀ [Ni
(
L1)]; thermal ellipsoids are
drawn at the 50% probability
1
3

Transition Metal Chemistry
Fig. 2 ORTEP view oꢀ [Ni(L2)]
50% ellipsoids)
(
Fig. 3 ORTEP view oꢀ [Zn(L3)
DMSO)] (50% ellipsoids)
(
3
49.9°. The average bond length oꢀ Zn–N is 2.0902 Å. The
in vitro antimicrobial activities (Table 3). Results showed
that all three complexes have potential as antimicrobial
agents. The complex [Ni(L1)] has activity against three
Gram positive bacteria. The rest oꢀ the compounds show
no selectivity between Gram positive and Gram negative
bacterial strains. NiCl ·6H O and complex [Ni(L2)] have an
Zn(1)–O(3) bond distance [2.0430(16) Å] to the DMSO
ligand is slightly longer than those oꢀ Zn(1)–O(1) and
Zn(1)–O(2) to the tetradentate ligand (av, 1.9636 Å) [28–30].
Antimicrobial activities
2
2
antiꢀungal efect against Candida albicans PTCC 5027. As
shown in Table 3, while E. faecalis and L. monocytogenes
isolated ꢀrom clinical samples are resistant to the antibiotics
[
Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)] as well as
NiCl ·6H O and Zn(CH CO ) ·2H O were tested ꢀor their
2
2
3
2 2
2
1
3

Transition Metal Chemistry
Table 3 In vitro antimicrobial activity oꢀ the compounds, 10 mg/ml (IZ)
Microorganism
Inhibition zone (mm)
[
Ni(L1)]
[Ni(L2)]
[Zn(L3)
DMSO)]
NiCl ·6H O
Zn(CH CO ) ·2H O
Ciproꢂoxacin
Fluconazole
2
2
3
2 2
2
(
P. aeruginosa
0
0
8
9
0
0
10
0
0
10
0
11
9
16
10
8
11
0
0
0
0
0
7
0
8
9
11
9
8
9
10
10
11
8
9
11
8
22
0
0
25
27
24
31
0
0
0
0
0
0
0
0
35
0
a
K. pneumonia
a
E. faecalis
S. aureus
E. coli
B. cereus
M. luteus
C. albicans
L. monocytogenes
9
10
18
16
0
9
9
a
10
0
aBacteria isolated ꢀrom clinical samples
ciproꢂoxacin and ꢂuconazole, E. faecalis is sensitive to
Ni(L1)], [Ni(L2)], NiCl ·6H O and Zn(CH CO ) ·2H O
to the metal atoms through both the azomethine N atoms
and phenolic O atoms. The nickel(II) complexes had ꢀour-
coordinate square planar geometries, while the zinc(II)
complex was ꢁve-coordinated with square pyramidal coor-
dination geometry. In the zinc(II) complex, the tetradentate
ligand occupied the equatorial plane and one O-coordinating
DMSO ligand occupied the apical position. The antimicro-
bial activities oꢀ the three complexes and NiCl ·6H O and
[
2
2
3
2 2
2
and L. monocytogenes is sensitive to [Ni(L2)], [Zn(L3)
(
DMSO)], NiCl ·6H O and Zn(CH CO ) ·2H O. The results
2 2 3 2 2 2
oꢀ minimum inhibitory concentration (MIC) and mini-
mum lethal concentration (MBC) experiments are shown
in Table 4. As can be seen, the MIC and MBC values ꢀor
[
Ni(L1)] and [Ni(L2)] are considerably lower than that ꢀor
2
2
NiCl ·6H O and also, ꢀor [Zn(L3)(DMSO)] is lower than
Zn (CH CO ) ·2H O were also studied against diferent
2
2
3 2 2 2
that ꢀor Zn(CH CO ) ·2H O. It means that low concentra-
microorganisms. The results showed that all three complexes
have some potential as antimicrobial agents. Also, accord-
ing to the results oꢀ MIC and MBC, these complexes have
both bacteriostatic and bactericidal efects. Further studies
on the antimicrobial activities oꢀ diaminomaleonitrile-based
complexes are planned ꢀor the ꢀuture.
3
2 2
2
tions oꢀ the complexes not only inhibit the growth oꢀ micro-
organisms, but also kill them. So, they have both bacterio-
static and bactericidal efects.
Conclusion
Acknowledgements The authors grateꢀully acknowledge the ꢁnancial
support provided ꢀor this work by the Shahid Bahonar University oꢀ
Kerman and also by the Universität oꢀ Leipzig, Germany, 04103 Leip-
zig, Germany.
In conclusion, three metal Schif base complexes have been
synthesized and structurally characterized. The results indi-
cated that the ligands were N O -tetradentate coordinated
2
2
Table 4 In vitro antimicrobial
Microorganisms
[Ni(L1)]
MIC
[Ni(L2)]
MBC MIC
[Zn(L3)
DMSO)]
NiCl ·6H O
Zn(CH CO ) ·
3 2 2
2
2
activity oꢀ the compounds,
(
2H O
2
(
MIC and MBC, mg/ml)
MBC MIC MBC MIC MBC MIC
MBC
P. aeruginosa
K. pneumonia
E. faecalis
S. aureus
E. coli
B. cereus
M. luteus
C. albicans
L. monocytogenes
–
–
–
–
5
2.5
–
1.25
2.5
0.625 2.5
2.5
1.25
1.25
2.5
5
–
5
5
1.25
–
–
–
–
–
0.13
–
–
–
–
–
–
–
1.25
–
2.5
2.5
1.25
5
5
2.5
5
1.25
2.5
5
5
0.156 2.5
2.5
10
10
5
10
5
2.5
0.625
2.5
10
5
5
2.5
0.625 2.5
–
–
0.16
–
–
–
5
2.5
–
–
0.625 2.5
0.039 1.25
0.156 2.5
5
2.5
2.5
5
5
10
–
–
0.25
0.625 2.5
1
3

Transition Metal Chemistry
Open Access This article is distributed under the terms oꢀ the Crea-
tive Commons Attribution 4.0 International License (http://creativeco
mmons.org/licenses/by/4.0/), which permits unrestricted use, distribu-
tion, and reproduction in any medium, provided you give appropriate
credit to the original author(s) and the source, provide a link to the
Creative Commons license, and indicate iꢀ changes were made.
13. Al-Azmi A, Elassar AZA, Booth BL (2003) Tetrahedron
59:2749–2763
14. MacLachlan MJ, Park MK, Thompson LK (1996) Inorg Chem
35:5492–5499
15. Sheikhshoaie I, Ebrahimipour SY, Lotꢁ N, Mague JT, Khaleghi
M (2016) Inorg Chim Acta 442:151–157
1
1
1
6. Lotꢁ N, Sheikhshoaei I, Ebrahimipour SY, Krautscheid H (2017)
J Mol Struct 1149:432–438
7. Sheldrick GM (2008) Acta Crystallogr Sect A Found Crystallogr
References
6
4:112–122
8. Brandenburg K (2010) DIAMOND Version 3.2ꢀ Crystal Impact
GbR Bonn, Germany
1
.
Ray MS, Chattopadhyay Sh, Drew MGB, Figuerola A, Ribas J,
Diaz C, Ghosh A (2005) Eur J Inorg Chem 2005:4562–4571
Costes JP, Dahan F, Laurent JP (1986) Inorg Chem 25:413–416
Bian HD, Xu JY, Gu W, Yan SP, Cheng P, Liao DZ, Jiang ZH
19. Irshad S, Mahmood M, Perveen F (2012) Res J Biol 2:1–8
20. Kumar V, Mishra RK, Shukla S, Mishra R, Singh M, Tiwari I,
Thapliyal K, Upadhyay KK (2013) J Mol Struct 1047:66–72
21. Ebrahimipour SY, Ranjabr ZR, Kermani ET, Amiri BP, Rudbari
HA, Saccá A, Hoseinzade F (2015) Transit Metal Chem 40:39–45
22. Lacroix PG, Di Bella S, Ledoux I (1996) Chem Mater 8:541–545
23. Tolulope MF, Olorunꢀemi O (2014) Der Pharma Chem 6:18–22
24. Gehad G, Abd El-Wahab MZ (2005) Spectrochim Acta
61:1059–1068
2
3
.
.
(
2003) Polyhedron 22:2927–2932
4
5
6
7
8
9
.
.
.
.
.
.
Losada J, Del Peso I, Beyer L (2001) Inorg Chim Acta
3
21:107–115
Santos MLP, Bagatin IA, Pereira EM, Ferreira AMDC (2001) J
Chem Soc Dalton Trans 6:838–844
Reddy PS, Ananthalakshmi PV, Jayatyagaraju V (2011) Eur J
Chem 8:415–420
25. Wang P, Hong Z, Xie Z, Tong Sh, Wong O, Lee CS, Wong N,
Hung L, Lee Sh (2003) Chem Commun 14:1664–1665
26. Ledoux I, Zyss J (1996) Pure Appl Opt 5:603–612
27. Costes JP, Lamère JF, Lepetit Ch, Lacroix PG, Dahan F (2005)
Inorg Chem 44:1973–1982
Ran XG, Wang LY, Lin YC, Hao J, Cao DR (2010) Appl Orga-
nomet Chem 24:741–747
Orio M, Jarjayes O, Kanso H, Philouze C, Neese F, Thomas F
(
2010) Angew Chem Int Ed 49:4989–4992
Fleck M, Layek M, Saha R, Bandyopadhyay D (2013) Transit
Metal Chem 38:715–724
28. Aazam ES, Ng SW, Tiekink ERT (2011) Acta Cryst E
67:m314–m315
1
1
1
0. Raman N, Kulandaisamy A, Thangaraja C, Jeyasubramanian K
29. Wang ZCh, Chu J, Zhan ShZ (2013) Acta Cryst E 69:m419
30. Lin ChW, Chou PT, Liao YH, Lin YCh, Chen ChT, Chen YCh,
Lai ChH, Chen BS, Liu YH, Wang ChCh, Ho ML (2010) Chem
Eur J 16:3770–3782
(
2003) Transit Metal Chem 28:29–36
1. Viswanathamurthi P, Natarajan K (1999) Transit Metal Chem
4:638–641
2. Bendre RS, Tadavi SK, Patil MM (2018) Transit Metal Chem
3:83–89
2
4
1
3