Synthesis, characterization, and antibacterial activity of two zinc(II) complexes with Schiff bases from halogenated salicylaldehyde and amantadine

Article abstract of DOI:10.1134/S1070328414080132

By a condensation reaction of halogenated salicylaldehyde and amantadine, two new Schiff base ligands (HL¹ and HL²) were synthesized, respectively. A followed mixture of the ligands and zinc(II) chloride in the presence of NaOH in an alcoholic medium brought out two novel complexes (ZnL₂ ¹) (I) and (ZnL₂ ² (II). These two complexes were characterized by the means of melting point, elemental analysis, IR, UV-Vis, ¹H NMR, molar conductance and single-crystal X-ray diffraction analysis. X-ray diffraction analysis reveals that I crystallizes in monoclinic system, P2₁/c space group, a = 9.7812(5), b = 25.6198(12), c = 27.7381(18) A, β = 105.881(4), F(000) = 1416, R₁ = 0.0731, wR₂ = 0.1147; II crystallizes in orthorhombic system, Pbca space group, a = 11.1717(10), b = 20.5888(15), c = 27.7381(18) A, F(000) = 2976, R₁ = 0.1341, wR₂ = 0.1410. Both in I and II, the central zinc(II) atom is four-coordinated via two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry.

Full text of DOI:10.1134/S1070328414080132

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2014, Vol. 40, No. 9, pp. 634–642. © Pleiades Publishing, Ltd., 2014.
Synthesis, Characterization, and Antibacterial Activity of Two
Zinc(II) Complexes with Schiff Bases from Halogenated
1
Salicylaldehyde and Amantadine
a
a
a
a
a,
a
a
b
Q. Yang , C. Xu , G. C. Han , X. C. Liu , X. D. Jin *, B. X. Wang , D. L. Liu , and H. H. Hu
a
College of Chemistry, Liaoning University, Shenyang, 110036 P.R. China
b
Liaoning Shangyu Bidding Ltd., Shenyang, 110031 P.R. China
*
eꢀmail: jinxudong@lnu.edu.cn
Received January 17, 2014
Abstract
—By a condensation reaction of halogenated salicylaldehyde and amantadine, two new Schiff base
1
2
ligands (HL and HL ) were synthesized, respectively. A followed mixture of the ligands and zinc(II) chloride
(I) and (ZnL )
in the presence of NaOH in an alcoholic medium brought out two novel complexes (ZnL1 )
2
2
2
(
II). These two complexes were characterized by the means of melting point, elemental analysis, IR, UVꢀVis,
1
H NMR, molar conductance and singleꢀcrystal Xꢀray diffraction analysis. Xꢀray diffraction analysis reveals
that crystallizes in monoclinic system, 2 / space group, = 9.7812(5), = 25.6198(12),
7.7381(18) = 105.881(4), (000) = 1416, R1 = 0.0731, wR2 = 0.1147; II crystallizes in orthorhombic
system, Pbca space group, = 11.1717(10), = 20.5888(15), = 27.7381(18) (000) = 2976, R1 = 0.1341,
wR2 = 0.1410. Both in and II, the central zinc(II) atom is fourꢀcoordinated via two nitrogen atoms and two
I
P
c
a
b
c =
1
2
Å,
β
F
a
b
c
Å, F
I
oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry.
DOI: l10.1134/S1070328414080132
1
INTRODUCTION
vestigated and their absolute structures were determined
by a singleꢀcrystal Xꢀray diffraction analysis. The antiꢀ
bacterial activities of complexes against two bacteria Esꢀ
cherichia coli and Bacillus subtilis were simultaneously inꢀ
vestigated.
Schiffꢀbases are a large class of organic compounds
with imino (–HC= N–) group and simple structures [1–
]. Transition metal complexes of Schiff bases have been
3
amongst the most widely studied coordination comꢀ
pounds in the past few years, since they are found to be of
importance as biochemical, analytical and antimicrobial
reagents [4, 5]. Zinc is a vital element in the life and an
important enzyme active site [6, 7]. The Zn(II) complexꢀ
es of Schiff bases are also biologically active and they exꢀ
hibit enhanced activities as compared to the free Schiff
bases [8]. Tricyclo [3.3.1.1(3,7)] decaneꢀ1ꢀamine
EXPERIMENTAL
Materials and methods. All chemicals and solvents
were of analytical grade and used as received. Elementa1
analysis was carried out on Perkin Elmer Flash EA 1112.
1
Chemical shifts (δ) for H NMR spectra were recorded at
300 MHz on a Varian MercuryꢀVx300 spectrometer in
CDCl solvent containing TMS as an internal standard.
(amantadine) is an antivirotic drug that has been used to
3
treat influenza and Parkinson disease [9–11]. Salicylalꢀ
dehyde derivatives, with one or more haloꢀatoms in the
aromatic ring, showed variety of biological activities such
as antibacterial and antifungal activities [12, 13]. In view
of these points above, in this paper, two zinc(II) complexꢀ
es with Schiff bases from halogenated salicylaldehyde
and amantadine, which are bis(2ꢀ(1ꢀadamantyliminomꢀ
–1
IR spectra were scanned in the range 4000 to 400 cm
with KBr pellets on a Nicolet NEXUS FTꢀIR 5700 specꢀ
trophotometer. UVꢀVis spectrum was measured on a
Perkin Elmer Lambda 25 spectrophotometer. Melting
points were measured on a WRSꢀ1B micro melting point
apparatus which were uncorrected. The molar conducꢀ
tance of the complexes in DMF (1.0 × 10 mol L ) at
room temperature was measured on a DDSꢀ11A conꢀ
ductormeter.
–3
–1
ethyl)ꢀ4ꢀchlorophenolatoꢀN,O)ꢀzinc(II) (
I) and bis(2ꢀ
1ꢀadamantyliminomethyl)ꢀ4ꢀbromophenolatoꢀN,O)ꢀ
(
zinc(II) (II), were designed and synthesized in the presꢀ
ence of NaOH. Their structures were characterized by
Synthesis of ligands. Two Schiff base ligands,
E)ꢀ(ꢀadamantanꢀ1ꢀylimino)methyl)ꢀ4ꢀchloropheꢀ
1
2ꢀ((
the means of IR, UVꢀVIS, H NMR, elemental analysis
and molar conductance. More over, the coordination beꢀ
1
nol (HL ) and 2ꢀ((E)ꢀ(ꢀadamantanꢀ1ꢀylimino)methꢀ
2
haviors of the ligands towards zinc(II) ion were also inꢀ yl)ꢀ4ꢀbromophenol (HL ), were prepared analogousꢀ
ly to the literatures [14–17]. The synthetic route in
1
The article is published in the original.
this work was shown below:
634

SYNTHESIS, CHARACTERIZATION, AND ANTIBACTERIAL ACTIVITY
635
X
OHC
X
NH2 ⋅ HCl
NH2
KOH
C H OH
HO
N
C H OH
2 5
2
5
H O
1
2
HL : X = Cl; HL : X = Br
Amantadine hydrochloride (0.375 g, 2.0 mmol)
and KOH (0.112 g, 2.0 mmol) in 50 mL anhydrous
alcohol were stirred for 1 h. The produced white
precipitates (KCl) were filtered out and the transꢀ
parent liquid was added dropwise to aldehyde
X
N
O
Zn
N
O
(
2.0 mmol) in 30 mL anhydrous alcohol under conꢀ
stant stirring. The resulting solution was refluxed for
1 h, concentrated to about 20 mL through reduced
~
X
pressure distillation and then stood at room temperꢀ
ature. A yellow solid appeared after 2–3 days with
the solvent evaporation. The solid was filtered off
and washed with anhydrous alcohol three times and
airꢀdried.
I
: X = Cl; II: X = Br
Xꢀray structure determination. The crystals of comꢀ
plexes suitable for Xꢀray analysis were obtained after
about one week with a solvent CH Cl /MeOH (1 : 1 v/v)
2
2
slow evaporation. The crystallographic data collections
for complexes and II were conducted on a Bruker
Smart Apex II CCD with graphite monochromated
Mo radiation ( = 0.71073 ) at 296(2) K using the
ꢀscan technique. The data were integrated by using
the SAINT program, which also did the intensities
I
Syntheses of complexes I and II were carried out
in a similar procedure with NaOH, the correspondꢀ
ing Schiff base ligand and zinc(II) chloride in apꢀ
propriate solvents, respectively. 20 mL ethanolic
K
λ
Å
α
ω
NaOH (0.080 g, 2.0 mmol) was added to a solution corrected for Lorentz and polarization effect [19]. An
empirical absorption correction was applied using the
SADABS program [20]. The structures were solved by
direct methods using the program SHELXSꢀ97 and all
of ligand (2.0 mmol) in 20 mL anhydrous ethanol.
After the solution was stirred for ten minutes,
zinc(II) chloride (0.136 g, 1.0 mmol) in 20 mL anꢀ
hydrous ethanol was added and the mixture was reꢀ
nonꢀhydrogen atoms were refined anisotropically on
2
F
by the fullꢀmatrix leastꢀsquares technique using the
fluxed for another 2 h at 60°C. Then the solution SHELXLꢀ97 crystallographic software package [21].
The hydrogen atoms were generated geometrically. All
calculations were performed on a personal computer
with the SHELXLꢀ97 crystallographic software packꢀ
age. The details of the crystal parameters, data collecꢀ
was kept at room temperature overnight and yellowꢀ
ish complex precipitates were filtered off and dried.
The yields were 58% (I) and 61% (II).
tion and refinement for I and II are summarized in Taꢀ
For C H N O Cl Zn · CH OH (I)
3
34
38
2
2
2
ble 1. Selected bond lengths and angles with their estiꢀ
mated standard deviations are given in Table 2. Xꢀray
structures of two complexes are shown in Fig. 1; they
were visualized by Diamond [22].
anal. calcd., %: C, 63.51;
Found, %: C, 63.30;
H, 5.96;
H, 6.00;
N, 4.36.
N, 4.21.
For C H N O Br Zn (II
)
34
38
2
2
2
Supplementary material for structures
been deposited with the Cambridge Crystallographic
Data Centre (no. 893297 ( ), 893298 (II); deposit@
I and II has
anal. calcd., %: C, 55.80;
Found, %: C, 55.75;
H, 5.23;
H, 5.21;
N, 3.83.
N, 4.05.
I
ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
The molar conductance values (λM
2
) are 1.95 and
RESULTS AND DISCUSSION
–1
2
.03 S cm mol for I and II. It was concluded from
In IR spectra of ligands, broad and intensity abꢀ
1
the results that complexes were nonꢀelectrolytic in naꢀ
ture [18].
–1
2
sorptions at 3443 and 3463 cm for HL and HL can be
identified as OH stretching vibration. Free OH stretching
–1
Proposed structures of complexes are the following:
vibration is generally observed at 3500–3600 cm ; the
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 40
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2014

636
YANG et al.
Table 1. Crystal data and structure refinement information for compounds
I
and II
Value
Parameter
I
II
Formula weight
Crystal size, mm
Crystal system
Space group
674.98
0.34
Monoclinic
2 /
731.85
0.43
×
×
0.28
0.41
×
0.31 × 0.23
Orthorhombic
Pbca
P
c
1
a
, Å
, Å
, Å
9.7812(5)
25.6198(12)
13.5526(6)
105.881(4)
11.1717(10)
20.5888(15)
27.7381(18)
90
b
c
β
, deg
, Å3
3
266.6(3)
6380.1(8)
V
Z
4
8
1
.372
1416
.953
2.56–28.13
1.524
ρ
, g cm–3
calcd
F
(000)
, mm–1
2976
0
3.308
μ
θ
Range, deg
2.46–25.00
Index ranges
–11
≤
h
≤
8, –30
≤
k
≤
22,
–13
≤
h
≤
8, –24
≤
k ≤ 15,
–11
≤
l
≤
16
–32
≤
l
≤
21
Reflections collected/unique
12102/5746
0.0250
14936/5619
0.0625
Rint
Data/restraints/parameters
GOOF
5746/0/472
1.028
5619/0/452
1.033
R1
/
/
wR2
(
I
> 2
σ
(
I
))*
0.0458/0.0982
0.0731/0.1147
0.0585/0.1077
0.1341/0.1410
R1
wR2 (all data)
Absorption correction
Refinement method
Empirical
Fullꢀmatrix leastꢀsquares on F2
.586/–0.324 0.922/–0.594
Δρmax/Δρmin, e
Å–3
0
*
R1
=
Σ
||Fo| – |Fc||/|Fo|; wR2 = [ w – /
Σ
(Fo2
F ) Σw(F ) ] .
2 2
2 2 1 2
c o
observed lower value is due to intramolecular hydroꢀ
gen bonding. This band is absent in
ing deprotonation of phenolic OH group occurs prior
to the coordination. A band assigned to C=N stretchꢀ
The main UVꢀVis data for two complexes are
and II, illustratꢀ showed in Table 3. These two complexes exhibited
I
similar pattern in the ultraviolet spectra but significant
changes in the visible spectra compared to their ligands.
There exist obvious absorption bands at 382 nm in the
complexes, which are not found in the ligands. This
change indicates that these zinc(II) chloride interact
strongly with the Schiff base ligands. The zinc(II) ion
–
1
1
–1
ing vibration 1629 cm in HL and 1626 cm in
2
–1
HL moves to lower wavenumber 1612 cm in
–
I
and
1
1
611 cm in II, implying a coordination of the Schiff
bases through azomethine nitrogen to Zn(II) in I and is coordinated by oxygen atom and nitrogen atom. The
1
2
II. The spectra of HL and HL displays similar strong maximal absorption bands at about 230 nm for ligands
–1
and complexes are due to the benzenoid conjugate
structure.
bands exactly at 1279 cm , which are fairly certain to
C–O stretching vibration; these bands occur in and II
at lower frequency 1162 cm . In the low frequency reꢀ
I
–1
1
H NMR data for complexes in CDCl was given in
3
Table 4, in which all data for ligands are also provided
–
1
gions, the presence of absorptions at 500 and 495 cm
for
I
and II reveals that there exists Zn–O vibration, for comparison. Single peaks at 14.51 and 14.55 ppm
1
2
indicating that oxygen of the Schiff bases is coordinatꢀ for HL and HL are assigned to the phenolic hydroxyl
ed to Zn(II). protons. Because of the intramolecular hydrogen bond
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SYNTHESIS, CHARACTERIZATION, AND ANTIBACTERIAL ACTIVITY
637
Table 2. Selected bond length (Å) and angles (deg) in
Bond , Å
I
and II
d
Bond
d, Å
I
Zn(1)–O(2)
1.909(2)
2.009(3)
4.483(2)
1.284(4)
1.285(4)
Zn(1)–O(1)
1.933(2)
2.011(3)
1.512(6)
1.499(4)
1.493(4)
Zn(1)–N(2)
C(13)–C(28)
N(1)–C(7)
Zn(1)–N(1)
C(12)–C(16)
N(1)–C(8)
N(2)–C(24)
N(2)–C(25)
II
N(1)–Zn(1)
N(2)–Zn(1)
C(9)–C(26)
N(1)–C(7)
N(2)–C(24)
1.993(5)
1.998(5)
4.422(6)
1.285(6)
1.280(7)
O(1)–Zn(1)
O(2)–Zn(1)
C(12)–C(17)
N(1)–C(8)
N(2)–C(25)
1.919(4)
1.915(4)
1.530(4)
1.481(9)
1.493(7)
Angle
ω
, deg
Angle
ω
, deg
I
O(2)Zn(1)O(1)
O(1)Zn(1)N(2)
N(2)Zn(1)N(1)
C(7)N(1)C(8)
C(8)N(1)Zn(1)
C(24)N(2)Zn(1)
C(1)O(1)Zn(1)
111.97(11)
110.16(11)
124.57(11)
117.8(3)
O(2)Zn(1)N(2)
O(1)Zn(1)N(1)
O(2)Zn(1)N(1)
C(7)N(1)Zn(1)
C(24)N(2)C(25)
C(25)N(2)Zn(1)
C(18)O(2)Zn(1)
97.07(11)
97.17(10)
116.35(10)
118.7(2)
123.52(19)
120.0(2)
118.4(3)
121.6(2)
124.9(2)
125.3(2)
II
C(7)N(1)C(8)
C(7)N(1)Zn(1)
C(8)N(1)Zn(1)
C(24)N(2)C(25)
O(2)Zn(1)O(1)
O(2)Zn(1)N(1)
O(1)Zn(1)N(2)
119.8(6)
118.9(4)
121.2(5)
119.1(5)
112.2(2)
111.9(2)
108.26(19)
C(24)N(2)Zn(1)
C(25)N(2)Zn(1)
C(1)O(1)Zn(1)
C(18)O(2)Zn(1)
O(2)Zn(1)N(2)
O(1)Zn(1)N(1)
N(1)Zn(1)N(2)
118.9(4)
121.5(4)
123.8(4)
125.5(4)
97.80(19)
98.45(19)
128.5(2)
formation of CH = N···HO, they are observed in lower lower field regions of 8.17 ppm. Multiplet peaks at
field. While in complexes
I
and II, the phenolic hyꢀ 6.73–7.36 ppm can be assigned to aromatic protons in
1
2
ligands and complexes. The CH and CH groups from adꢀ
droxyl protons of HL and HL are eliminated as the
formation of complexes, resulting in a disappearance
of the single peak to the phenolic hydroxyl proton as
2
amantane are identified in the range of 1.52–2.19 ppm.
The crystallographic analysis reveals that in
asymmetric unit has one zinc(II) mononuclear comꢀ
I each
1
well as the intramolecular hydrogen bond. In HL and
2
HL signals appear in 8.24 and 8.23 ppm can be cerꢀ plex and one solvent methanol molecule. The central
tainly attributed to HC=N proton [23]. However, in zinc(II) atom in
I lies on a twofold rotation axis and is
the spectra of complexes, these signals are observed in bonded to the oxygen and nitrogen donor atoms of the
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638
YANG et al.
Table 3. Main UVꢀVis data for ligands and complexes short C=N bond distance of 1.283
Å
) coordinated to a
metal centre, where the imine form is predominant.
The distinctly shortened Zn(1)–O(1) and elongated
Zn(1)–N(1) bonds in are 1.933 and 2.011 , respecꢀ
tively (the normal bond length of them are about 1.950
(nm)*
Compound
λ
λ
min
I
Å
max
HL1
and 1.970 Å), so the coordination geometry around
228(1.614),
54(0.597),
28(0.239)
244(0.496),
290(0.032)
the Zn2 ion reflects Jahn–Teller effect [26]. The
+
2
3
shortest distance between two adamantane carbons
from two ligands is 4.483
dicating transꢀcoordination of two ligands to zinc
(Fig. 1a) The distances of two neighboring zinc atoms
along the axis are 8.612 in . The bidentate coordiꢀ
nation mode of refrains itself from forming intramoꢀ
Å for C(13)–C(28) in I, inꢀ
I
230(1.432),
244(0.918),
292(0.046),
352(0.118)
248(0.950),
330(0.162),
382(0.171)
x
Å
I
I
lecular hydrogen bonds because of deprotonated
ligands reason, but there also exists two sixꢀmembered
rings through a zinc ion, two oxygen atoms and two niꢀ
HL2
230(1.460),
52(0.522),
28(0.199)
248(0.494),
290(0.036)
2
3
trogen atoms [27]. In addition to complex
methanol molecule is distinctly found in crystal,
which is involved in an intermolecular O–H···O hyꢀ
drogen bond in (Fig. 2a). Geometric parameters of
O(3)–H(3 ···O(1) hydrogen bond in are the followꢀ
ing: D–H 0.84; H A 1.949; D A 2.766(4) ; angle
DHA 164.18
I, one
II
230(1.474),
244(0.948),
294(0.055),
348(0.134)
248(0.973),
330(0.177),
382(0.213)
I
A)
I
…
…
Å
°
.
*
The values in brackets being absorption intensities.
The crystallographic analysis reveals that in II each
asymmetric unit has only one independent zinc(II)
two bidentate ligand molecules in a transꢀarrangeꢀ mononuclear complex. The central zinc(II) atom in
ment. The geometry around Zn(II) in is intermediate lies on a twofold rotation axis and is bonded to the oxꢀ
between square planar and tetrahedral, where the diꢀ ygen and nitrogen donor atoms of the two bidentate
hedral angle between the two coordination planes deꢀ ligand molecules in a transꢀarrangement. The geomeꢀ
fined by O(2)Zn(1)N(2) and O(1)Zn(1)N(1) is 86.55
try around Zn(II) in II is intermediate between square
24]. Bond angles also show that the coordination geꢀ planar and tetrahedral, where the dihedral angle beꢀ
ometry about the zinc atom in is distorted tetrahedral tween the two coordination planes defined by
= [360 – ( )]/141 = 0.84) [25] with O(2)Zn(1)N(2) and O(1)Zn(1)N(1) is 83.09
N(1)Zn(1)N(2) ( ) and O(2)Zn(1)N(1) (
) angles of Bond angles also show that the coordination geꢀ
24.57(11) and 116.35(10)
, respectively, which is ometry about the zinc atom in II is distorted tetraꢀ
expected for a typical Schiff base ligand (containing a hedral ( = [360 – ( )]/141 = 0.85) with
I
I
°
[
I
(τ
°
α
+
β
°
°.
4
α
β
1
°
°
τ
°
α
+
β
°
4
Table 4. 1H NMR data for ligands and complexes (
δ
in ppm,
Ar–H
14.51 (s., 1H) 8.24 (s., 1H) 7.27–7.15 (m., 2H); 6.87 (d., 3
J in Hz)
Comꢀ
pound
Ar–OH
CH=N
Adamantane ring–H
HL1
J
= 9.6, 1H) 2.19 (s., 3H, CH); 1.83 (s., 6H, CH2);
.79–1.67 (m., 6H, CH2)
1
I
8.17 (s., 1H) 7.19 (d.d., 3
.08 (d., 4
= 2.7, 1H); 6.78 (d.,
J
= 9.0, 4
J
= 2.7, 1H);
2.09 (s., 3H, CH); 1.94 (d., 3J = 11.7,
3
3
7
J
J
= 9.0, 1H) 3H, CH ); 1.68 (t
ꢀ
like,
J
= 11.4/13.8,
H, CH ); 1.52 (d., J = 12.3, 3H, CH2)
2
2
3
6
HL2
II
14.55 (s., 1H) 8.23 (s., 1H) 7.36 (s., 1H); 7.34 (d.d., 3J = 8.7, 4J = 2.4, 2.19 (s., 3H, CH); 1.83–1.67
3
4
1
H, Ar–H); 6.83 (d.d.,
J
= 8.1,
J
= 1.2,
(m., 12H, CH2)
1H, Ar–H)
8.17 (s., 1H) 7.30 (d.d., 3
.22 (d., 4
= 2.7, 1H); 6.73 (d.,
J
= 9.3, 4
J
= 2.7, 1H);
2.10 (s., 3H, CH); 1.93 (d., 3J = 11.7,
3
3
7
J
J
= 9.3, 1H) 3H, CH ); 1.68 (t
ꢀ
like,
J
= 11.1/12.6,
2
3
6
H, CH ); 1.52 (d., J = 12.3, 3H, CH2)
2
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SYNTHESIS, CHARACTERIZATION, AND ANTIBACTERIAL ACTIVITY
a)
639
(
C(10)
C(17)
C(11)
C(16)
C(15)
C(9)
C(12)
C(19) C(20)
C(14)
C(18)
C(21)
C(22)
C(8)
N(1)
O(2)
C(13)
Cl(2)
C(7)
C(6)
C(23)
C(24)
C(5)
C(4)
Zn(1)
O(1)
C(28) C(25)
N(2)
C(1)
Cl(1)
C(2)
C(26)
C(3)
C(27)
C(33)
C(29)
C(34)
C(32)
C(30)
C(31)
(b)
C(32)
C(33)
C(3)
C(34)
C(2)
C(31)
C(28)
C(4)
C(27) C(1)
Br(2)
C(29)
C(30)
O(1)
C(25)
N(2)
C(26)
C(5)
C(6)
C(7)
C(24)
C(23)
C(22)
Zn(1)
N(1)
O(2)
C(18)
C(8)
C(21)
C(9)
Br(1)
C(19)
C(16)
C(20)
C(10)
C(17)
C(13)
C(15)
C(11)
C(12)
C(14)
Fig. 1. Xꢀray structure of
I
(a) and II (b). Hydrogen atoms and methanol are omitted for clarity.
No. 9 2014
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 40

640
YANG et al.
(a)
x
y
z
(b)
x
y
z
Fig. 2. The packing diagram of
I
(a) and II (b) viewing along the
z
axis for I and along the
x
axis for II
.
N(1)Zn(1)N(2) (
28.5(2) and 112.2(2)
pected for a typical Schiff base ligand (containing a
short C=N bond distance of 1.286 ) coordinated to a mode of complexes II does not involve intramolecular
α
) and O(2)Zn(1)O(1) (
, respectively, which is exꢀ The distances of two neighboring zinc atoms along the
axis are 7.371 in II. The bidentate coordination
β
) angles of transꢀcoordination of two ligands to zinc (Fig. 1b).
1
°
°
x
Å
Å
metal centre, where the imine form is predominant. hydrogen bonds because the ligands have been deproꢀ
The distinctly shortened Zn(1)–O(1) and elongated tonated, but there also exists two sixꢀmembered rings
Zn(1)–N(1) bonds in II are 1.919 and 1.993
Å
, reꢀ through a zinc ion, two oxygen atoms and two nitrogen
spectively, so the coordination geometry around the atoms. The complex II is found neither to possess inꢀ
2+
Zn ion reflects Jahn–Teller effect. The shortest disꢀ termolecular hydrogen bonding nor interaction
π π
–
tance between two adamantane carbons from two existence in stacking. The complex molecule is regularly
ligands is 4.422 for C(9)–C(26) in II, indicating arranged by weak vander Waals forces to construct a net
Å
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 40
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2014

SYNTHESIS, CHARACTERIZATION, AND ANTIBACTERIAL ACTIVITY
641
Table 5. Inhibitory of compounds against bacteria growth (inhibition zone, mm*)
Bacteria
Escherichia coli
10–2 1.0 10–3 1.0
Bacillus subtilis
10–2 1.0 10–3 1.0
Concentraꢀ
1.0
×
10–1 1.0
×
×
×
10–4 1.0
×
10–5 1.0
×
10–1 1.0
×
×
×
10–4 1.0
×
10–5
–
1
tion (mol L )
HL1
I
6.0
6.0
6.0
6.0
6.0
14.0
13.0
6.0
7.0
6.0
6.0
9.0
6.0
7.0
6.0
8.0
6.0
6.0
12.0
7.0
8.0
7.0
8.0
7.0
9.0
8.0
6.0
8.0
7.0
6.0
6.0
12.0
6.0
10.0
6.0
HL2
II
23.0
10.0
14.0
12.0
9.0
*
Filter paper diameter being 6.0 mm.
structure containing adamantine cages (Fig. 2b). There
are no any solvent molecules in crystal of II
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