Microwave solid phase synthesis, characterization and antimicrobial activities of 2,2'-[(1E,1'E)-{ethane-1,2-diylbis(azanylylidene)}bis(methanylylidene)]bis(4-chlorophenol)manganese(II)

Article abstract of DOI:10.14233/ajchem.2015.18876

One mononuclear complex (1) has been designed and synthesized by 2,2'-[(1E,1'E)-{ethane-1,2-diylbis(azanylylidene)}bis(methanylylidene)]bis(4-chlorophenol) (L) with MnCl₂·4H₂O in microwave radiation assistance. The complex was charac

Full text of DOI:10.14233/ajchem.2015.18876

Asian Journal of Chemistry; Vol. 27, No. 9 (2015), 3404-3406
A
SIAN
J
OURNAL OF HEMISTRY
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http://dx.doi.org/10.14233/ajchem.2015.18876
Microwave Solid Phase Synthesis, Characterization and Antimicrobial Activities of 2,2'-[(1E,1'E)-
{ethane-1,2-diylbis(azanylylidene)}bis(methanylylidene)]bis(4-chlorophenol)manganese(II)
*
SUO-PING XU and DAN-DAN WEI
Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University, Xuzhou 221116, P.R. China
*Corresponding author: Fax: +86 516 83500366; Tel: +86 516 83403165; E-mail: xsp62@jsnu.edu.cn
Received: 24 November 2014;
Accepted: 30 December 2014;
Published online: 26 May 2015;
AJC-17265
One mononuclear complex (1) has been designed and synthesized by 2,2'-[(1E,1'E)-{ethane-1,2-diylbis(azanylylidene)}bis(methanylylidene)]bis(4-
chlorophenol) (L) with MnCl2·4H2O in microwave radiation assistance. The complex was characterized by X-ray crystallo-graphy, confirming
that the central mangances(II) was coordinated by two oxygen atoms, two nitrogen atoms from L and two oxygen atoms from H2O. The
complex was assayed for in vitro antibacterial (B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli and E. cloacae) activities and
showed better antimicrobial activity against Gram positive strains than Gram negative strains.
Keywords: Salicylaldehyde type's schiff base, Mononuclear mangancse(II) complex, Antibacterial activity.
0.4 % of the theoretical values. Melting points were measured
on a Boetius micro melting point apparatus.
INTRODUCTION
Salicylaldehyde containing Schiff bases and their metal
complexes show a wide spectrum of antimicrobial properties1-7.
Lots of researchers studied the synthesis, characterization and
structure-activity relationship (SAR) of Schiff bases8-12.Although
these methods synthesize reliable routes for the preparation
of Schiff base type's complexes, most of them follow lengthy
procedures and time. Therefore, the development of direct and
efficient procedures for these classes of compounds from mate-
rials has been the target of synthetic organic chemistry. In this
paper, one mononuclear complex(1) was synthesized by 2,2'-
[(1E,1'E)-{ethane-1,2-diylbis(azanylyli-dene)}bis(methanyl-
ylidene)]bis(4-chlorophenol) (L) with MnCl2·4H2O in
microwave radiation assistance. The complex were assayed
for antibacterial activities against three Gram positive bacterial
strains (Bacillus subtilis, Staphylococcus aureus and Strepto-
coccus faecalis) and three Gram negative bacterial strains
(Escherichia coli, Pseudomonas aeruginosa and Enterobacter
cloacae ) by the 3-(4,5-dimethyl-2-triazyl)-2,5-diphenyl-2H-
tetrazolium bromide (MTT) method.
Preparation of 5-choro-2-hydroxybenzaldehyde and
ethane-1,2-diamine in ethanol (L) and its mangancse(II)
complex(1): Compound L was designed and synthesized from
5-choro-2-hydroxybenzaldehyde and ethane-1,2-diamine in
ethanol. The ligand and MnCl2·4H2O were mixed together and
microwave radiated 4 min in 200 W. The brown powder was
dissolved in ethanol/DMF(2/1) and afforded 2,2'-[(1E,1'E)-
{ethane-1,2-diylbis(azanylylidene)} bis(methanylylidene)]bis-
(4-chlorophenol)manganese(II) (1) (Scheme-I).
Cl
Cl
Cl
O
N
N
NH2
H2
N
+
OH
OH
HO
L
Cl
Cl
Cl
Cl
N
N
MW 2 00W
4 min
N
N
MnCl .4H
O
2
2
+
Mn
O
O
O
OH
2
OH
HO
H
2
1
Scheme-I: Synthesis of L and its Mn complex (1)
Preparation of L:A mixture of 5-choro-2-hydroxybenzal-
dehyde (20 mmol ) and ethane-1,2-diamine (10 mmol) in 20 mL
ethanol was refluxed for 1 h. After filtration, the yellow solid
was washed with athanol and water, dried and recrystallized
from ethanol.Yield: 76 %, m.p.: 125-128 °C. UV(λ nm): 375;
253. Selected IR (KBr, νmax, cm-1): 2960(m), 1638(s), 1595(m),
1524(s), 1455(s), 1378(s), 1332(m), 1309(s), 1241(m), 1175(s),
1138(m), 1089(s), 1052(m), 970(s), 834(m), 706(m); 1H NMR
(CDCl3) δ ppm: 11.65(s,2H), 8.24(s, 2H), 7.48(d, J = 7.2 Hz,
EXPERIMENTAL
All chemicals were of reagent grade and used as received.
UV spectra were recorded on a U-3000 spectrophotometer.
IR spectra were recorded on a Nexus 870 FT-IR. 1H NMR spectra
were recorded on a Bruker DPX 300 model spectrometer
(Bruker Bioscience, USA) in CDCl3. Elemental analyses were
performed on a CHN-O-Rapid instrument and were within

Vol. 27, No. 9 (2015) Synthesis of 2,2'-[(1E,1'E)-{ethane-1,2-diylbis(azanylylidene)}bis(methanylylidene)]bis(4-chlorophenol)Mn(II) 3405
2H), 7.20 (d, J = 5.4 Hz, 2H), 6.82 (m, J = 12.6Hz, 2H), 4.06(s,
4H).Anal. Calcd for C16H14N2O2Cl2 (%): C, 56.99; H, 4.18; N,
8.31; found (%): C, 57.06; H, 4.21; N, 8.27.
Antimicrobial activity: The antibacterial activity of L and
1was tested against B. subtilis, S. aureus, S. faecalis, P. aeruginosa,
E. coli and E. cloacae using MTT medium. The MICs of the
test complexes were determined by a colorimetric method using
the dye MTT14. A stock solution of the synthesized complex
(50 µg/mL) in DMSO was prepared and graded quantities of
the test complexes were incorporated in specified quantity of
sterilized liquid medium. A specified quantity of the medium
containing the complex was poured into microtitration plates.
Suspension of the microorganism was prepared to contain
approximately 105 cfu/mL and applied to microtitration plates
with serially diluted complexes in DMSO to be tested and
incubated at 37 °C for 24 h for bacterial. After the MICs were
visually determined on each of the microtitration plates,
50 mL of PBS (Phosphate Buffered Saline 0.01 mol/L, pH
7.4: Na2HPO4·12H2O 2.9 g, KH2PO4 0.2 g, NaCl 8 g, KCl 0.2
g, distilled water 1000 mL) containing 2 mg/mL of MTT was
added to each well. Incubation was continued at room tempe-
rature for 4-5 h. The content of each well was removed and
100 mL of isopropanol containing 5 % 1 mol/L HCl was added
to extract the dye.After 12 h of incubation at room temperature,
the optical density (OD) was measured with a microplate reader
at 570 nm. The observed MICs were presented in Table-2.
Complex 1: Compound L (10 mmol) and MnCl2·4H2O
(10 mmol) were mixed together and microwave radiated 4
min in 200 W. The brown powder was dissolved in ethanol/
DMF(2/1). After standing for 10 days, the single crystals of 1
were obtained, were separated by filtration, washed with ethanol
thrice and dried.Yield: 72 %, m.p.: > 290 °C. UV(λ nm): 378;
250. Selected IR data ( KBr, νmax, cm-1): 3160(m), 1615(s),
1561(m), 1532(s), 1457(s), 1421(m), 1372(m), 1284(s), 1245(m),
1181(m), 1140(s), 1085(m), 1045(s), 974(m), 828(m), 803(m),
712(s). Anal. Calcd for C16H16Cl2MnN2O4 (%): C, 45.09; H,
3.78; N, 6.57; found (%): C, 45.16; H, 3.80; N, 6.55.
Crystal structure determinations and refinements:The
crystallographic date for 1 was collected on a Bruker Smart
1000 CCD area detector diffractometer equipped with MoKα
(λ = 0.71073 Å) radiation using ω-scan mode. Empirical
absorption correction was applied to the data. Unit cell dimen-
sions were obtained with least-squares refinements and all
structures were solved by direct methods with SHELXL-97.
All non-hydrogen atoms were located from the trial structure
and then refined anisotropically.All hydrogens were generated
in idealized positions. All calculations were performed with
SHELXL-97 programs13. Other relevant parameters of the
crystal structure are listed in Table-1.
RESULTS AND DISCUSSION
The complex of the formula C16H16N2O4MnCl2 were
prepared as described in section 2, in moderate yield (72 %).
IR spectra of L show four bands at 2960 and 1638 cm-1,
TABLE-1
CRYSTALLOGRAPHIC AND EXPERIMENTAL DATA FOR 1
Empirical formula
Formula weight
Crystal system
Space group
a(Å)
b(Å)
c(Å)
α(°)
C16H16N2O4MnCl2
426.15
Monoclinic
characteristic of the mixed modes of vibrations arising from
15
normal coordinates having contributions from ν(OH) and ν(C=N)
.
The infrared spectra of complex 1 (KBr pellets) display an
P2(1)/c
intense absorption band at about 1615 cm-1 attributable to the
14.7229(6)
12.0259(5)
14.3257(6)
90
103.9120(10)
90
2462.05(18)
4
296(2)
ν
(C=N) shifted about 23 cm-1 lower wave-number compared with
1638 cm-1 of L. The UV spectra of the complex display an
*
intense absorption peak at 250 nm (π → π ). and 378 nm (n →
π ). The structure of complex 1 were confirmed by a single-
β(°)
*
γ(°)
crystal X-ray diffraction and isshown in Fig. 1 and 2. The
crystal structure consists of mononuclear complex. The mole-
cular structure of complex 1 crystallize in monoclinic with
space group P2(1)/c; bond distances and angles are provided
in Table-3. The complex 1 is electronically neutral mono-
nuclear compound. The central metal (Mn), on an inversion
center, are in octahedral coordination geometry with oxygen
and nitrogen donors from L and two H2O. The general Mn-O
and Mn-N bond lengths are in the range 1.894(9)-2.262(9)
and 1.982(11)-1.985(10) Å, unexceptional and similar to
the corresponding bonds in other manganese Schiff base
V (Å3)
Z
T (K)
Density (g/cm3)
µ(mm-1)
1.610
0.909
1212
F(000)
Data/restrains/parameters
θ Range (°)
Reflections collected/unique
Rint
Final R indices [I > 2σ(I)]
(∆ρ)max, (∆ρ)min (e/Å3)
5787/0/234
1.42 to 27.92
31806/5787
0.0236
R1 = 0.0677, wR2 = 0.1558
1.524 and -0.606
complexes16,17
.
aR = ΣFo-Fc/ΣFo, bwR = [Σ[w(Fo2-Fc2)2]/Σ[w(Fo2)2]]1/2
TABLE-2
MICs (MINIMUM INHIBITORY CONCENTRATIONS) OF THE SYNTHETIC COMPOUNDS
Microorganisms MICs (µg/mL)
Compound
Gram positive
Gram negative
B. subtilis
6.25
S. aureus
6.25
12.5
S. faecalis
6.25
12.5
P. aeruginosa
E. coli
25
25
E. cloacae
12.5
1
L
12.5
25
25
12.5
Penicillin
Kanamycin
1.562
0.39
1.562
1.562
1.562
3.125
6.25
3.125
6.25
3.125
3.125
1.562

3406 Xu et al.
Asian J. Chem.
TABLE-3
SELECTED BOND LENGTHS (Å) AND BOND ANGLES (°) OF COMPLEX 1
Bond
Mn(1)-O(1)
Mn(1)-N(1)
N(1)-C(7)
N(2)-C(9)
Angle
Distance (Å)
1.894(9)
1.985(10)
1.228(17)
1.472(17)
(°)
Bond
Mn(1)-O(2)
Mn(1)-O(6)
N(1)-C(8)
O(2)-C(12)
Angle
Distance (Å)
1.900(8)
2.208(9)
1.521(16)
1.322(14)
(°)
Bond
Mn(1)-N(2)
Mn(1)-O(5)
N(2)-C(10)
O(1)-C(2)
Angle
Distance (Å)
1.982(11)
2.262(9)
1.276(16)
1.293(15)
(°)
O(1)-Mn(1)-O(2)
O(1)-Mn(1)-N(1)
O(1)-Mn(1)-O(6)
N(1)-Mn(1)-O(6)
N(2)-Mn(1)-O(5)
C(12)-O(2)-Mn(1)
C(7)-N(1)-Mn(1)
C(10)-N(2)-Mn(1)
92.8(4)
92.1(4)
91.0(4)
91.8(4)
O(1)-Mn(1)-N(2)
O(2)-Mn(1)-N(1)
O(2)-Mn(1)-O(6)
O(1)-Mn(1)-O(5)
N(1)-Mn(1)-O(5)
C(2)-O(1)-Mn(1)
C(8)-N(1)-Mn(1)
C(9)-N(2)-Mn(1)
174.8(4)
174.9(4)
89.3(4)
92.8(4)
85.7(4)
127.6(8)
111.2(8)
114.5(8)
O(2)-Mn(1)-N(2)
N(2)-Mn(1)-N(1)
N(2)-Mn(1)-O(6)
O(2)-Mn(1)-O(5)
O(6)-Mn(1)-O(5)
C(7)-N(1)-C(8)
C(10)-N(2)-C(9)
92.4(4)
82.7(4)
89.2(4)
92.9(3)
175.5(4)
120.9(11)
120.1(11)
86.7(4)
127.2(8)
127.8(9)
125.4(9)
complex antigenic specificity of Gram negative cells. Anti-
microbial activity of complexes is due to either killing the
microbes or inhibiting their multiplication by blocking their
active sites18. Since the molecular structure is quite similar,
the antibacterial activity of compound 1 is quite similar.
ACKNOWLEDGEMENTS
The work was co-financed by grants from a Project
Funded by the Priority Academic Program Development of
Jiangsu Higher Education Institutions, China.
Fig. 1. Crystal structure of complex 1, showing 30 % probability
displacement ellipsoids (arbitrary spheres for the H atoms)
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Fig. 2. Packing structure of complex 1 the b-axis
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towards Gram positive strains than Gram negative strains when
compared to the positive controls penicillin and kanamycin,
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