Synthesis, characterization and antibacterial activity of indium(III) complexes with adamantane-ring containing Schiff bases

Article abstract of DOI:10.1080/00958972.2011.575459

Indium(III) chloride tetrahydrate and Schiff-base ligands derived from adamantaneamine and 3-/4-methoxysalicylaldehyde gave two complexes, C ₂₂H₃₂Cl₃InN₂O₃ (1) and C₃₆H₄₄Cl₃

Full text of DOI:10.1080/00958972.2011.575459

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Synthesis, characterization and
antibacterial activity of indium(III)
complexes with adamantane-ring
containing Schiff bases
Xu-Dong Jin a , Yue-Hong Jin b , Zhi-Yuan Zou c , Zhi-Gang Cui a
Hai-Bo Wang a , Ping-Li Kang a , Chun-Hua Ge a & Kai Li a
,
a College of Chemistry, Liaoning University, Shenyang 110036, P. R.
China
b Liaoning Provincial Institute of Measurement, Shenyang 110004,
P. R. China
c Department of Life Science, Liaoning University, Shenyang
110036, P. R. China
Published online: 29 Apr 2011.
To cite this article: Xu-Dong Jin , Yue-Hong Jin , Zhi-Yuan Zou , Zhi-Gang Cui , Hai-Bo Wang ,
Ping-Li Kang , Chun-Hua Ge & Kai Li (2011) Synthesis, characterization and antibacterial activity
of indium(III) complexes with adamantane-ring containing Schiff bases, Journal of Coordination
Chemistry, 64:9, 1533-1543, DOI: 10.1080/00958972.2011.575459
To link to this article: http://dx.doi.org/10.1080/00958972.2011.575459
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Journal of Coordination Chemistry
Vol. 64, No. 9, 10 May 2011, 1533–1543
Synthesis, characterization and antibacterial activity of
indium(III) complexes with adamantane-ring containing
Schiff bases
XU-DONG JIN*y, YUE-HONG JINz, ZHI-YUAN ZOUx, ZHI-GANG CUIy,
HAI-BO WANGy, PING-LI KANGy, CHUN-HUA GEy and KAI LIy
yCollege of Chemistry, Liaoning University, Shenyang 110036, P. R. China
zLiaoning Provincial Institute of Measurement, Shenyang 110004, P. R. China
xDepartment of Life Science, Liaoning University, Shenyang 110036, P. R. China
(Received 8 February 2011; in final form 4 March 2011)
Indium(III) chloride tetrahydrate and Schiff-base ligands derived from adamantaneamine and
3-/4-methoxysalicylaldehyde gave two complexes, C22H32Cl3InN2O3 (1) and C36H44Cl3InN2O4
(2), respectively. The complexes were characterized by IR, 1H NMR, elemental analysis, molar
conductance, thermal analysis, and single-crystal X-ray diffraction. Complex 1 crystallizes in
the monoclinic system, P21/n space group with the asymmetric unit consisting of one
indium(III), one N-(3-methoxysalicylidene)-aminoadamantane (L1), three chlorides and one
N,N-dimethylformamide molecule. The indium is six-coordinate with reversed triangular-prism
ꢀ
geometry via three oxygens and three chlorides. Complex 2 crystallizes in the triclinic system, P1
space group; the asymmetric unit consists of one indium(III), two N-(4methoxysalicylidene)-
aminoadamantane (L2), and three chlorides. The indium is five-coordinate with distorted
trigonal-bipyramidal geometry via two oxygens and three chlorides. Antibacterial activities of
the complexes have been investigated against Escherichia coli and Staphylococcus aureus.
Keywords: Indium(III) complexes; Synthesis; Antibacterial activity; Adamantane; Schiff bases
1. Introduction
A relatively small number of theoretical and practical routes for Schiff base indium
complexes [1–5] have been reported compared with other metal complexes. Schiff base
indium complexes exhibit advantages in antibacterial and anti-cancer activities than
other metal complexes or than the free Schiff bases [6–8]. Adamantaneamine has an
obvious effect on controlling exuviating of the influenza virus, and also restrains virus
going into host cells playing an effective role of preventing influenza A2. In addition it
can alleviate Parkinson symptoms [9]. We designed and synthesized a series of
complexes containing indium and adamantaneamine moiety. We expected the
complexes to demonstrate biological activity by introducing liposoluble adamantane
rings as well as integrating of the biochemical characteristics of Schiff base indium
complexes. In this work, a six-coordinate complex (1) and a five-coordinate complex (2)
*Corresponding author. Email: jinxudong@yahoo.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2011 Taylor & Francis
DOI: 10.1080/00958972.2011.575459

1534
X.-D. Jin et al.
C
H
N
H
R
O
L1: R= 3-OCH3; L2: R= 4-OCH3
Figure 1. Structures of L1 and L2.
1
were synthesized and the structures were characterized by IR, H NMR, elemental
analysis, molar conductance, thermal analysis, and single-crystal X-ray diffraction.
The antibacterial activities of complexes against two bacteria Escherichia coli and
Staphylococcus aureus were simultaneously investigated.
2. Experimental
2.1. Materials and methods
All chemicals and solvents were of analytical grade and used as received. Elementa1
1
analysis was carried out on a Perkin Elmer Flash EA 1112. Chemical shifts (ꢀ) for H
NMR spectra were recorded at 300 MHz on a Varian Mercury-Vx300 spectrometer in
CDCl3 containing TMS as an internal standard. Infrared spectra (IR) were scanned
from 4000 to 400 cmꢀ1 with KBr pellets on a Nicolet NEXUS FT-IR 5700
spectrophotometer. Thermal analysis was carried out on a METTLER TOLEDO
TGA/SDTA851e. Melting points were measured on a WRS-1B micro melting point
apparatus and are uncorrected. The molar conductance of the complexes in DMF
(1.0 ꢁ 10ꢀ3 mo1 Lꢀ1) was measured on a DDS-11A conductometer.
2.2. Synthesis of ligands
L1 and L2 (figure 1) were prepared by condensation of adamantaneamine and 3- or
4-methoxysalicylaldehyde in anhydrous alcohol.
Adamantaneamine 3.03 g (0.02 mo1) in 20 mL anhydrous alcohol was added to a
solution of 3- or 4-methoxysalicylaldehyde 3.04 g (0.02 mo1) in 60 mL anhydrous
alcohol. The mixture was refluxed for 2 h and cooled to room temperature. A colored
crysta1 was filtered and evaporated under reduced pressure.
L1: 4.45 g, yield 78%. Brown needles. m.p. 108.5 ꢂ 110.0ꢃC. Lit. [10]. 109ꢃC. IR (KBr):
3433(w), 3009(w), 2912(s), 2849(s), 1629(s), 1468(s), 1453(m), 1420(w), 1376(w),
1367(w), 1344(w), 1327(w), 1306(w), 1276(m), 1249(s), 1171(w), 1119(m), 1090(s),
986(w), 966(m), 940(w), 932(w), 966(w), 843(w), 814(w), 787(w), 755(w), 713(w), and
544(w). 1H NMR (CDCl3, 300 MHz): ꢀ 15.19 (s, 1H, Ar–OH); 8.24 (s, lH, CH¼N); 6.84
3
3
3
(d, J ¼ 7.5, 1H, Ar–H); 6.83 (d, J ¼ 8.1, 1H, Ar–H); 6.68 (t-like, J ¼ 7.8/8.1, 1H,
Ar–H); 3.88 (s, 3H, Ar–OCH3); 2.17 (s, 3H, CH, adamantane ring); 1.85 (s, 6H, CH2,
adamantane ring); 1.79–1.71 (m, 6H, CH2, adamantane ring). Anal. Calcd for
C18H23NO2 (285.38): C, 75.76; H, 8.12; N, 4.91. Found: C, 75.74; H, 8.15; N, 4.88.

Indium(III) complexes
1535
Cl
Cl
CH3
Cl
N
N
O
N
In
Cl
Cl
H
O
H
O
CH3
In
H
OCH3
O
Cl
N
OCH3
H3CO
1
2
Figure 2. Proposed structures of 1 and 2.
L2: 3.71 g, yield 65%. Yellow needles. m.p. 106.7 ꢂ 108.7ꢃC. IR (KBr): 3434(w), 2907(s),
2848(m), 1625(s), 1531(w), 1452(w), 1342(w), 1309(w), 1227(s), 1210(w), 1187(w),
1169(w), 1116(m), 1088(w), 1032(w), 967(w), 939(w), 922(w), 831(m), 814(w), 787(w),
1
645(w), 585(w). H NMR (CDCl3, 300 MHz): ꢀ 11.51 (s, 1H, Ar–OH); 8.00 (s, lH,
CH¼N); 7.01 (d, 3J ¼ 9.6, 1H, Ar–H); 6.29 (s, 1H, Ar–H); 6.27 (d, 3J ¼ 8.7, 1H, Ar–H);
3.79 (s, 3H, Ar–OCH3); 2.19 (s, 3H, CH, adamantane ring); 1.89 (s, 6H, CH2,
adamantane ring); 1.79–1.71 (m, 6H, CH2, adamantane ring). Anal. Calcd for
C18H23NO2 (285.38): C, 75.76; H, 8.12; N, 4.91. Found: C, 75.77; H, 8.10; N, 4.85.
2.3. Synthesis of the complexes
Complexes 1 and 2 (figure 2) were prepared in a similar procedure with indium(III)
chloride tetrahydrate and the corresponding Schiff base in appropriate solvent.
2.3.1. Synthesis of 1. Indium(III) chloride tetrahydrate (0.29 g, 1.0 mmol) in 20 mL
anhydrous alcohol was added dropwise to a hot solution of L1 (0.29 g, 1.0 mmol) in
20 mL anhydrous alcohol. Thereafter the mixture was refluxed for 1.5 h and then kept
at room temperature overnight; powdery precipitates were crystallized in ethyl acetate/
N,N-dimethylformamide 10 : 1 (v/v) to give 1 (0.22 g, 38%) as yellow plates.
Complex 1: m.p.: 126.0 ꢂ 126.2ꢃC. IR (KBr): 3431(m), 2918(s), 2853(m), 1647(s),
1610(m), 1560(w), 1499(s), 1455(w), 1309(m), 1226(s), 1087(w), 957(w), 851(w), 781(w),
1
745(m), 721(w), 547(w), 500(w), 448(w). H NMR (CDCl3, 300 MHz): ꢀ 13.26 (s, 1H,
Ar–OH); 8.19 (d, 3J ¼ 14.7, 1H, CH¼N); 7.09 (d, 3J ¼ 7.8, 1H, Ar–H); 7.03 (d, 3J ¼ 6.6,
3
1H, Ar–H); 6.80 (t-like, J ¼ 7.8/8.1, 1H, Ar–H); 4.05 (s, 3H, Ar–OCH3); 2.30 (s, 3H,
CH, adamantane ring); 2.06 (s, 6H, CH2, adamantane ring); 1.83–1.71 (m, 6H, CH2,
adamantane ring). Anal. Calcd for C22H32Cl3InN2O3 (593.68): C, 44.51; H, 5.43;
N, 4.72. Found: C, 44.32; H, 5.55; N, 4.66.
2.3.2. Synthesis of 2. Indium(III) chloride tetrahydrate (0.29 g, 1.0 mmol) in 20 mL
anhydrous alcohol was added dropwise to a hot solution of L2 (0.59 g, 2.0 mmol) in
20 mL anhydrous alcohol. The color of the mixture changed from yellow to white
during 2 h reflux. The reactant was kept at room temperature overnight and red

1536
X.-D. Jin et al.
Figure 3. X-ray structure of 1. Hydrogens and ethanol are omitted for clarity.
powdery precipitate was filtered off; recrystallization from ethanol afforded 2 (0.43 g,
55%) as white plates.
Complex 2: m.p.: 269.5 ꢂ 270.7ꢃC. IR (KBr): 3436(m), 2908(s), 2854(m), 1647(s),
1611(m), 1540(m), 1481(m), 1458(w), 1366(w), 1303(m), 1230(s), 1216(s), 1176(w),
1122(w), 1083(w), 1026(w), 975(w), 840(w), 785(w), 608(w), 538(w), 502(w), 448(w).
3
1H NMR (CDCl3, 300 MHz): ꢀ 12.67 (s, lH, Ar–OH); 7.78 (d, J ¼ 13.8, 1H, CH¼N);
3
3
7.36 (d, J ¼ 8.4, 1H, Ar–H); 6.29 (d, J ¼ 8.4, 1H, Ar–H); 6.97 (s, 1H, Ar–H); 3.86 (s,
3H, Ar–OCH3); 2.22 (s, 3H, CH, adamantane ring); 2.05 (s, 6H, CH2, adamantane
ring); 1.72 (s, 6H, CH2, adamantane ring). Anal. Calcd for C36H44Cl3InN2O4 (789.92):
C, 54.74; H, 5.61; N, 3.55. Found: C, 55.12; H, 5.78; N, 3.47.
2.4. X-ray crystallography
The crystallographic data collections for 1 and 2 were conducted on a Bruker Smart
˚
Apex II CCD with graphite monochromated Mo-Kꢁ radiation (ꢂ ¼ 0.71073 A) at
296(2) K using the !-scan technique. The data were integrated using the SAINT
program, which also corrected the intensities for Lorentz and polarization effects [11].
An empirical absorption correction was applied using SADABS [12]. The structures
were solved by direct methods using SHELXS-97 and all non-hydrogen atoms were
refined anisotropically on F2 by full-matrix least-squares using the SHELXL-97
crystallographic software package [13]. The hydrogens were generated geometrically.
All calculations were performed on a personal computer with the SHELXL-97
crystallographic software package. X-ray structures are shown in figures 3 and 4. The
details of the crystal parameters, data collection and refinement for 1 and 2 are
summarized in table 1. Selected bond lengths and angles with their estimated standard
deviations are given in table 2.

Indium(III) complexes
1537
Figure 4. X-ray structure of 2. Hydrogens are omitted for clarity.
3. Results and discussion
3.1. Elemental analysis and molar conductance
The C, H and N contents are in agreement with the formulas of C22H32Cl3InN2O3 for 1
and C36H44Cl3InN2O4 for 2. The molar conductance values (ÃM) are 5.13 and
6.88 S cm2 molꢀ1 for 1 and 2, indicating non-electrolytes [14].
3.2. IR spectra
IR data for 1 and 2 are given in table 3. Broad and intense absorptions at 3431 cmꢀ1 for
1 and 3436 cmꢀ1 for 2 can be identified as OH stretching vibration, indicating that
phenolic hydroxyl was not deprotonated when the complexes were formed, and oxygens
of phenolic hydroxyl participate in coordination. The strongest absorption at
1647 cmꢀ1 for 1 and 2 is characteristic of the C¼N. The strong absorptions at
1226 cmꢀ1 for 1 and 1230 cmꢀ1 for 2 are C–O stretch of phenolic hydroxyls. The
absorption at 500 cmꢀ1 for 1, 502 cmꢀ1 for 2, are attributed to In–O vibration,
indicating that oxygens of the Schiff bases are coordinated to In.

1538
X.-D. Jin et al.
Table 1. Crystallographic data for 1 and 2.
Empirical formula
Formula weight (g molꢀ1
Crystal size (mm3)
Crystal system
C
593.68
0.22 ꢁ 0.21 ꢁ 0.20
Monoclinic
P21/n
22H32Cl3InN2O3 (1)
C36H44Cll3InN2O4 (2)
789.92
)
0.20 ꢁ 0.16 ꢁ 0.10
Triclinic
ꢀ
P1
Space group
Unit cell dimensions (A, )
ꢃ
˚
a
b
c
ꢁ
ꢃ
ꢄ
9.5789(6)
10.072(2)
13.589(3)
14.027(3)
72.68(3)
81.42(3)
76.20(3)
1773.6(6), 2
1.53–25.02
ꢀ10 ꢅ h ꢅ 11,
ꢀ16 ꢅ k ꢅ 16,
ꢀ13 ꢅ l ꢅ 16
1.479
23.2272(15)
12.5084(9)
90.00(2)
101.0100(10)
90.00(2)
2731.8(3), 4
2.41–25.01
ꢀ11 ꢅ h ꢅ 11,
ꢀ15 ꢅ k ꢅ 27,
ꢀ14 ꢅ l ꢅ 14
1.463
3
˚
V (A ), Z
ꢅ range for data collection (ꢃ)
Limiting indices
ꢆ (g cmꢀ3
ꢇ (mmꢀ1
)
)
1.185
0.933
Reflections collected/unique
Data/restraints/parameters
Goodness-of-fit
F(000)
T(K)
R1a/wR2b(I 4 2ꢈ(I ))
R1/wR2 (all data)
13,644/4790 [R(int) ¼ 0.0332]
4790/32/393
1.059
1224
296(2)
12,935/6203 [R(int) ¼ 0.0299]
6203/0/418
1.062
812
296(2)
0.0328/0.0912
0.0353/0.0928
0.0361/0.0980
0.0423/0.1032
b
2
2
1=2
aR1 ¼ Æ||Fo|ꢀ|Fc||/|Fo|; wR2 ¼ ½ÆwðFo2 ꢀ Fc2Þ =ÆwðFo2Þ ꢆ
:
3.3. 1H NMR analysis
1H NMR data for 1 and 2 in CDCl3 are given in table 4. Singlets at 13.26 for 1 and
12.67 for 2 are assigned to the phenolic hydroxyl proton because of intramolecular
hydrogen bond formation of –CH¼Nꢄ ꢄ ꢄHO– between imino nitrogen and
phenolic hydroxyl hydrogen. A sharp singlet at 8.19 for 1 and 7.78 for 2 is assigned
to the –CH¼N proton. A couple of peaks at 7.09–6.80 for 1 and 7.36–6.97 for 2 are
assigned to Ar–H. An intense singlet at 4.05 for 1 and 3.86 for 2 was assigned to OMe.
The CH and CH2 from adamantane were identified in the range of 2.30–1.71.
3.4. Crystal structure of 1 and 2
The single-crystal X-ray analysis reveals 1 crystallizes in the monoclinic system, P21/n
space group. As shown in figure 3, the asymmetric unit consists of one indium(III), one
L1, three chlorides and one DMF. The indium is six-coordinate with reversed
triangular-prism geometry via three oxygens (O1, O2, O3) as a bottom plane and three
chlorides as another plane. The dihedral angle of two approximately parallel planes is
4.700(73)ꢃ. O1 and O2 are from bidentate ligand L1 and O3 is from coordinated DMF.
˚
The In–O bond lengths are 2.162(2), 2.425(3) and 2.273(2) A and In–Cl are 2.3960(11),
˚
2.4317(9) and 2.4134(10) A. The longest bond length between indium and oxygen is
In1–O2 due to the effect of methyl. For a similar reason the longest bond length
between indium and chloride is In1–Cl2.

Indium(III) complexes
1539
ꢃ
˚
Table 2. Selected bond lengths (A) and angles ( ) in 1 and 2.
1
In(1)–O(1)
In(1)–Cl(1)
In(1)–O(2)
N(1)–C(7)
N(2)–C(19)
O(1)–C(2)
O(2)–C(18)
O(1)–In(1)–O(3)
O(3)–In(1)–Cl(1)
O(3)–In(1)–Cl(3)
O(1)–In(1)–O(2)
Cl(1)–In(1)–O(2)
O(1)–In(1)–Cl(2)
Cl(1)–In(1)–Cl(2)
O(2)–In(1)–Cl(2)
C(3)–O(2)–In(1)
C(19)–O(3)–In(1)
2.162(2)
2.3960(11)
2.425(3)
1.289(5)
1.304(5)
1.317(4)
1.415(5)
77.94(10)
91.97(8)
88.07(7)
69.60(9)
160.48(7)
94.16(7)
102.83(4)
86.20(7)
111.2(2)
122.8(2)
In(1)–O(3)
In(1)–Cl(3)
In(1)–Cl(2)
N(1)–C(8)
N(2)–C(20)
O(2)–C(3)
O(3)–C(19)
O(1)–In(1)–Cl(1)
O(1)–In(1)–Cl(3)
Cl(1)–In(1)–Cl(3)
O(3)–In(1)–O(2)
Cl(3)–In(1)–O(2)
O(3)–In(1)–Cl(2)
Cl(3)–In(1)–Cl(2)
C(2)–O(1)–In(1)
C(18)–O(2)–In(1)
C(7)–N(1)–C(8)
2.273(2)
2.4134(10)
2.4317(9)
1.496(4)
1.460(6)
1.390(4)
1.254(4)
92.27(7)
157.39(7)
106.01(4)
77.56(10)
90.23(7)
163.56(8)
94.58(4)
117.9(2)
129.1(3)
127.0(3)
2
In(1)–O(3)
In(1)–Cl(3)
In(1)–Cl(1)
O(2)–C(3)
N(1)–C(8)
N(2)–C(26)
Cl(2)–In(1)–Cl(1)
O(3)–In(1)–O(1)
O(1)–In(1)–Cl(3)
O(1)–In(1)–Cl(2)
O(3)–In(1)–Cl(1)
O(1)–C(1)–C(2)
C(19)–O(3)–In(1)
C(26)–N(2)–C(27)
2.161(2)
2.3827(11)
2.3941(13)
1.362(4)
1.296(4)
1.299(4)
134.54(6)
157.63(9)
101.45(7)
88.55(8)
81.73(7)
123.2(3)
136.7(2)
126.1(3)
In(1)–O(1)
In(1)–Cl(2)
O(1)–C(1)
O(2)–C(7)
N(1)–C(9)
N(2)–C(27)
Cl(3)–In(1)–Cl(1)
O(3)–In(1)–Cl(3)
O(3)–In(1)–Cl(2)
Cl(3)–In(1)–Cl(2)
O(1)–In(1)–Cl(1)
C(1)–O(1)–In(1)
C(8)–N(1)–C(9)
O(1)–C(1)–C(6)
2.166(2)
2.3849(10)
1.307(4)
1.432(4)
1.483(4)
1.486(4)
115.50(6)
99.23(7)
92.37(7)
109.95(5)
81.75(7)
136.8(2)
127.4(3)
118.7(3)
Table 3. Main IR data for 1 and 2 (cmꢀ1).
Complex
ꢄO–H
ꢄCH
ꢄCH2
ꢄC¼N
ꢄC–O
ꢄM–O
1
2
3431(m)
3436(m)
2918(s)
2908(s)
2853(m)
2854(m)
1647(s)
1647(s)
1226(s)
1230(s)
500(w)
502(w)
s, strong; m, medium; w, weak.
ꢀ
Complex 2 crystallizes in the triclinic system, P1 space group. As shown in figure 4,
the asymmetric unit consists of one indium(III), two L2 and three chlorides. The indium
is five-coordinate with distorted trigonal-bipyramidal geometry via two oxygens and
three chlorides. The equatorial coordination sites of In1 are occupied by three chlorides
˚
(Cl1, Cl2, Cl3) with bond lengths of 2.3941(13), 2.3849(10) and 2.3827(11) A for
In1–Cl1, In1–Cl2 and In1–Cl3, respectively. Axial positions of In1 are occupied by two
oxygens (O1, O3) from two monodentate L2 with bond lengths of 2.166(2) and
˚
2.161(2) A for In1–O1 and In1–O3. The distance between two adamantane rings from

1540
X.-D. Jin et al.
Table 4. 1HNMR data for 1 and 2 (ꢀ in ppm, J in Hz).
Compound Ar–OH
1a
CH¼N
Ar–H
OCH3
4.05
Adamantane ring
2.30
13.26
8.19
7.09
(s, lH) (d, 3J ¼ 14.7, 1H) (d, 3J ¼ 7.8, 1H);
(s, 3H) (s, 3H, CH);
2.06 (s, 6H, CH2);
1.83-1.71 (m, 6H, CH2)
7.03 (d, 3J ¼ 6.6, 1H);
6.80 (t-like, 3J ¼ 7.8/8.1, 1H)
2
12.67
7.78
7.36
3.86
2.22
(s, lH) (d, 3J ¼ 13.8, 1H) (d, 3J ¼ 8.4, 1H);
(s, 3H) (s, 3H, CH);
2.05 (s, 6H, CH2);
1.72 (s, 6H, CH2)
6.29 (d, 3J ¼ 8.4, 1H); 6.97 (s, 1H)
a8.05(s, 1H, CHO of DMF); 2.97(s, 3H, CH3 of DMF); 2.87(s, 3H, CH3 of DMF).
Figure 5. The packing diagram of 1 viewed along the a-axis.
˚
two ligands is 4.492 A for C32–C11, indicating cis-coordination of two ligands to
indium. Dihedral angle of two phenyl planes is 16.004(3)ꢃ.
The molecular packing in the unit cell demonstrates no significant intermolecular
hydrogen bonding interactions or ꢉ–ꢉ stacking for 1 and 2; molecules are arranged by
weak van der Waals interactions to form network structures (figures 5 and 6). Ethanol
was found in the crystal of 1.
3.5. Thermal analysis
Thermal gravimetric analysis was carried out with a heating rate of 20ꢃC minꢀ1 in argon
from 25 ꢂ 900ꢃC. The TG-DTG curves of 1 and 2 are provided in ‘‘Supplementary
material’’. A difference of thermal decomposition was observed with four stages for 1

Indium(III) complexes
1541
Figure 6. The packing diagram of 2 viewed along the c-axis.
and three stages for 2. The starting decomposition and weight losses were approx-
imately 120ꢃC for 1 and 250ꢃC for 2. When the complexes were heated above 550ꢃC, the
residues were deduced as oxides.
3.6. Antibacterial activity
Complexes 1 and 2 were tested in vitro to assess their growth inhibitory activity against
E. coli and S. aureus by Kirby methods [15, 16]; the corresponding Schiff bases were
also investigated. The compounds were prepared with four concentrations of
1.0 ꢁ 10ꢀ1, 1.0 ꢁ 10ꢀ2, 1.0 ꢁ 10ꢀ3, 1.0 ꢁ 10ꢀ4 mo1 Lꢀ1 in DMF. The diameters of
inhibition zone were measured after 48 h and the results are presented in table 5.
Both complexes exhibit antibacterial activities against E. coli and S. aureus compared
with the corresponding ligands; the antibacterial abilities of the complexes were
concentration-dependent. Complex 2 was more active against E. coli than S. aureus in
concentrated solution, while 1 displayed almost the same activities against both bacteria
at 1.0 ꢁ 10ꢀ1 and 1.0 ꢁ 10ꢀ2. In contrast with complexes, L2 exhibited relatively poor
antibacterial activity against Escherichia coli at any concentrations.
4. Conclusions
Single-crystal X-ray diffraction revealed that 1 consists of one indium(III), one
Schiff-base ligand, three chlorides and one DMF. The indium is six-coordinate with
reversed triangular-prism. Complex 2 consists of one indium(III), two Schiff-base

1542
X.-D. Jin et al.

Indium(III) complexes
1543
ligands and three chlorides. The indium is five-coordinate with distorted
trigonal-bipyramidal geometry.
Antibacterial activity showed both complexes exhibited activities against E. coli and
S. aureus. Antibacterial activities of both complexes were better than that of the
corresponding ligand.
Supplementary material
Supplementary X-ray crystallographic data for
1
(CCDC 761183) and
2
(CCDC 797037) can be obtained free of charge via www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge
CB2
deposit@ccdc.cam.ac.uk).
1EZ,
UK;
Fax:
(þ44)
1223-336-033;
or
E-mail:
Acknowledgments
This work was financially supported by Foundation of Liaoning Educational
Committee (no. 2008T065), Science and Technology Foundation of Liaoning
Province (no. 20071027) and the Scientific Research Foundation for the Returned
Overseas Chinese Scholars (no. 2005546), China.
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