Crystal structures and antimicrobial activities of copper(II) complexes of fluorine-containing thioureido ligands

Article abstract of DOI:10.1016/j.ica.2013.06.029

Cu(II) complexes with N-4-fluorobenzoylpiperidine-1-carbothioimidate (L1), N-2-fluorobenzoylpiperi-dine-1-carbothioimidate (L2) and 2-fluorobenzoate (L3) have been synthesized and characterized by elemental analysis, Fourier Transform infrared (FT-IR), Ul

Full text of DOI:10.1016/j.ica.2013.06.029

Inorganica Chimica Acta 405 (2013) 387–394
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Inorganica Chimica Acta
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Crystal structures and antimicrobial activities of copper(II) complexes
of fluorine-containing thioureido ligands q
a
a
b,
Huanhuan Liu a, Wen Yang a, Weiqun Zhou a, , Yunlong Xu , Juan Xie , Mengying Li
⇑
⇑
a College of Chemistry & Chemical Engineering and Material Science, Soochow University, 199 Ren’ai Road, Suzhou 215123, People’s Republic of China
b School of Biology and Basic Medical Sciences, Soochow University, 199 Ren’ai Road, Suzhou 215123, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Cu(II) complexes with N-4-fluorobenzoylpiperidine-1-carbothioimidate (L1ꢀ), N-2-fluorobenzoylpiperi-
dine-1-carbothioimidate (L2ꢀ) and 2-fluorobenzoate (L3ꢀ) have been synthesized and characterized by
elemental analysis, Fourier Transform infrared (FT-IR), Ultraviolet (UV) and fluorescence spectroscopy
methods. The crystal structures of [Cu(L1)2], [Cu(L2)2] and [Cu2(L3)4(DMF)2] (DMF: N,N-dimethylform-
amide) have been determined by X-ray diffraction method. The antimicrobial activities of the complexes
against the bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and
Shewanella sp.) and the fungi (Botrytis cinerea, Trichoderma spp., Myrothecium and Verticillium spp.) have
been investigated comparing with the corresponding ligands. The experiments showed that the com-
plexes had the stronger antibacterial and antifungal activities than the corresponding ligands had.
Ó 2013 The Authors. Published by Elsevier B.V. All rights reserved.
Article history:
Received 30 April 2013
Received in revised form 14 June 2013
Accepted 17 June 2013
Available online 28 June 2013
Keywords:
Copper complexes
Crystal structures
Antimicrobial activities
1. Introduction
ligands or the free metal ions. Some complexes such as Co(III)
and Ni(II) complexes had the weaker antibacterial activities than
The heterocyclic compounds containing nitrogen have intense
attention due to extensive biological and industrial applications
[1–3]. It is known that pyridine and morpholine exhibit broad
biological activities, such as antibacterial and antifungal activities
[4–7]. And many thiourea derivatives are explored to be pharma-
cologically active like anticancer [8,9], hypnotic, antifungal
[10,11], antibacterial [12], diuretic [13], anti-viral, anti-tubercular,
anti-thyroidal, herbicidal and insecticidal activities [14]. Moreover,
the biological activity of complexes containing thioureas has also
been successful screened for various biological processes [15–19].
Copper complexes have been much explored due to the fact that
copper is bio-essential elements responsible for numerous
bioactivities in living organism [20]. It is well known that Cu(II)
complexation plays an important role in the pharmacological
profile of the antimicrobial activities [21–27].
the corresponding ligands had [28,29]. But, in many cases, upon
the coordination to metal ions, the bioactivity of these complexes
increases, suggesting that complexation can be an interesting
strategy of dose reduction [30–34]. In consideration of the fact of
the good biological effect of copper ion, we have interest in explor-
ing the microbial activities ofcopper complexes. In this paper, we
have synthesized two new complexes, [Cu(L1)2] and [Cu(L2)2].
Moreover, when the complex of [Cu(L2)2] was heated slightly in
DMF, it transformed into a new complex of [Cu2(L3)4(DMF)2].
The crystal structures of complexes have been determined success-
fully by X-ray diffraction. The antimicrobial experiments showed
that all of the complexes had stronger controls to the studied fungi
and bacteria than their corresponding ligands and free Cu2+ had,
which indicated the three copper complexes should be the excel-
lent antibacterial reagents to application.
We have investigated the antibacterial activity of N-(piperidyl-
thiocarbonyl) benzamides and N-(morpholinothiocarbonyl) benz-
amides and their complexes [28,29]. However, the biological
activities of metal complexes were different from those of either
2. Experimental
Melting points are determined on a Kofler melting point appa-
ratus and uncorrected. IR spectra are obtained in KBr discs using
a Nicolet 170SX FT-IR spectrometer. Elemental analyses are per-
formed on a Yannaco CHNSO Corder MT-3 analyzer. Absorption
and fluorescence spectra were recorded on a CARY50 UV–Vis
spectrophotometer and an FLS920 fluorescence spectrophotome-
ter. X-ray diffraction determination is carried out with Rigaku
Mercury CCD detector.
q
This is an open-access article distributed under the terms of the Creative
Commons Attribution-NonCommercial-No Derivative Works License, which per-
mits non-commercial use, distribution, and reproduction in any medium, provided
the original author and source are credited.
⇑
Corresponding authors. Tel.: +86 0512 65884827 (W. Zhou), +86 0512
65880421 (M. Li).
E-mail addresses: wqzhou@suda.edu.cn (W. Zhou), lmysz@126.com (M. Li).
0020-1693/$ - see front matter Ó 2013 The Authors. Published by Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2013.06.029

388
H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
O
C
O
1588.5(w,
(s, dCH2), 1341.6 (w,
893.1 (w, C–S), 764.5 (w,
[Cu(L2)2]: Yield: 65%. Green, m.p.:158.5–159.8 °C. Element Anal.
Calc. for C26H28CuF2N4O2S2: C, 52.51; H, 4.71; N, 9.42; S, 10.77.
Found: C, 51.95; H, 4.56; N, 9.65; S, 11.31%. FTIR (cmꢀ1): 3068.9
m
C@N),1523.7 (s, mC
C–F), 1211.6 (m,
ph–H).
@
C(ph)), 1486.8 (s, mC
@
C(ph)), 1423.1
KSCN
m
mC–O), 1197.5 (m, m
C–N),
Cl
C
NCS
m
c
(2)
F
F
(1)
O
S
(3)
HN
N
C
NH
C
(4)
(w,
1584.1(w,
(s, dCH2), 1357.9 (w,
920.7 (w, C–S), 849.1 (w, c
m
ph–H), 2928.9 (s,
C@N),1525.8 (m, mC
C–F), 1259.2 (m,
ph–H).
m
CH2), 2845.8 (w,
C(ph)), 1497.6 (s, mC
C–O), 1126.5 (w, m
m
CH2), 1609.6 (w, mC
C(ph)), 1423.5
C–N),
@C(ph)),
F
m
@
@
m
m
HL2: o-F
Scheme 1. The synthetic route of HL1 and HL2.
m
HL1: p-F
The transform process from [Cu(L2)2] to [Cu2(L3)4(DMF)2] was
shown in Scheme 3. Yield: 87%. m.p.:166.5–167.8 °C, Element Anal.
Calc. for C34H30Cu2F4N2O10: C, 49.04; H, 3.85 N, 3.37. Found: C,
2.1. Synthesis
48.83; H, 3.72; N, 3.25%. IR (KBr, cmꢀ1): 3036 (w,
m
ph–H), 2850
C(ph)), 1485.9 (w,
C(ph)), 1403.4 (s, dCH3), 1285.4 (w, C–F),
C–O),1181 (m, C–N), 760.1 (m, dph–H).
(w,
dCH3), 1445.0 (w, mC
1231.9 (w,
mCH3), 1628.7 (s, mC@C(ph)), 1564.2 (w, mC@
2.1.1. Synthesis of the ligands
@
m
The synthetic route given by the literature [29] of HL1 and HL2
was outlined in Scheme 1. Benzoyl isothiocyanate (2) was obtained
by the condensation of fluorobenzoyl chloride (1) with KSCN in
acetone solution. Then, the freshly solution was added dropwise
to stoichiometric amount of piperidine (3) with stirring and reflux-
ing for 1–2 h. The solids (4) was filtrated, washed with water, and
dried to yield.
m
m
2.2. Preparation of microorganism and determination of inhibition
zone
The antimicrobial activities were investigated against fungi and
bacterium by using agar filter paper diffusion method [35,36]. The
cultures of microorganism were grown in autoclaved LB (Luria–
Bertani) media (typetone 10 g, yeast extract 5 g, NaCl 10 g, agar
15 g and 1000 mL of distilled water) at 37 °C for 48 h and stored
in LB media at 4 °C. The filter paper with thickness of 2.0 mm
was made into wafers with diameter of 6 mm by punch. After
dry heat sterilization, the wafers were placed on the agar plates
which had been cultured with selected fungi and bacteria. The test
samples were dissolved in DMSO and confected into the concentra-
tion of 500 mg/L. Then, the wafers immerged in test samples for
5 min in advance (the DMSO as reference and the CuCl2 as compar-
ison). The media was inverted in the incubator and cultured for
48 h under 37 °C. The antimicrobial activities were evaluated by
2.1.2. Synthesis of the complexes
The synthetic reactions of the complexes [Cu(L1)2] and
[Cu(L2)2] were depicted in Scheme 2. The complexes were ob-
tained by the reaction of CuCl2ꢁ2H2O (0.1 mmol/L, 5.0 mL) with
the corresponding ligands (0.1 mmol/L, 10.0 mL) in aqueous solu-
tion under the presence of sodium hydroxide (1.0 mmol/L,
1.0 mL). The complexes were isolated as the green solids and then
the green solid was washed with water and dried.
[Cu(L1)2]: Yield: 74%. Green, m.p.:179.3–179.8 °C. Element Anal.
Calc. for C26H28CuF2N4O2S2 C, 52.51; H, 4.71; N, 9.42; S, 10.77.
Found: C, 51.83; H, 4.45; N, 9.82; S, 10.15%. FTIR (cmꢀ1): 3042.6
(w,
mph–H), 2934.9 (s,
m
CH2), 2851.8 (m, mCH2), 1604.2 (w, mC@C(ph)),
O
S
O
S
NaOH
N
H
N
N
N
H2O
F
F
.
CuCl2
2O
N
N
F
O
O
S
HL2: o-F
HL1: p-F
Cu
S
N
N
F
Scheme 2. The synthetic route of [Cu(L1)2] and [Cu(L2)2].
F
N
N
N
C
S
O
F
F
O
O
2DMF/50
S
O
O Cu
F
2
O
+
4
N
NH2
Cu
evaporate
O Cu
O
F
and hydrolyze
O
O
S
O
F
N
N
N
Scheme 3. The transform route from [Cu(L2)2] to [Cu2(L3)4(DMF)2].

H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
389
Table 1
Summary data of X-ray diffraction.
Molecules
[Cu(L1)2]
26H28CuF2N4O2S2
594.18
Tetragonal
I 41/a
19.894(3)
19.894(3)
13.562(2)
90
[Cu(L2)2]
[Cu2(L3)2(DMF)2]
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C
C26H28CuF2N4O2S2
594.18
C34H30Cu2F4N2O10
829.68
Monoclinic
P 21/n
10.575(3)
10.434(3)
16.122(4)
90
Triclinic
ꢀ
P1
8.346(8)
8.575(7)
10.271(9)
100.237(7)
107.28(3)
106.761(13)
1
b (Å)
c (Å)
a
(°)
b (°)
90
90
8
93.338(6)
90
2
c
(°)
Z
Dcalc (g/cm3)
1.471
1.533
1.552
Radiation (Mo K
a
) (Å)
0.71070
1.014
0.71070
1.058
0.71070
1.277
l
(Mo K
a )
) (mmꢀ1
h (°)
3.33–24.49
21012
2187
0.0842
2187
3.01–24.50
5226
2039
0.0915
2039
3.07–24.50
13064
2895
0.0662
2895
Reflections collected
Independent reflections
Rint
Data
Restraints
0
0
0
Parameters
178
1.004
179
0.917
238
1.000
Goodness-of-fit GOF on F2
R1[I > 2
wR2 [I > 2
R1(all data)
r
(I)]
0.0764
0.1448
0.1062
0.1601
0.221 and ꢀ0.335
0.0698
0.1194
0.1375
0.1606
0.634 and ꢀ0.725
0.0708
0.1356
0.0995
0.1515
0.440 and ꢀ0.389
r(I)]
wR2 (all data)
Largest difference peak (e Aꢀ3
)
measuring the breadth of the inhibition zones,
determined by the following equation:
Dr, which was
Table 2
Some structure parameters of three complexes.
[Cu(L1)2]
[Cu(L2]2]
[Cu2(L3)4(DMF)2]
ðd1 ꢀ d2Þ
D
r ¼
Bonds
(Å)
(Å)
Bonds
Cu1–O1
Cu1–O4#1
Cu1–O2#1
Cu1–O3
Cu1–O5
Cu1–Cu1#1
O1–C1
O2–C1
O3–C8
(Å)
2
Cu–O1
Cu–O1 #1
Cu–S1
Cu–S1#1
S1–C8
O1–C1
N1–C1
N1–C8
N2–C8
1.918(4)
1.918(4)
2.193(17)
2.193(17)
1.683(13)
1.273(6)
1.320(7)
1.340(7)
1.342(7)
1.896(5)
1.896(5)
2.249(3)
2.249(3)
1.745(7)
1.274(8)
1.326(8)
1.324(8)
1.332(8)
1.948(4)
1.958(4)
1.959(4)
1.972(4)
2.142(4)
2.633(14)
1.268(7)
1.252(7)
1.245(7)
1.257(7)
1.215(7)
(°)
where d1 was the diameter of the inhibition zones and d2 was the
diameter of the wafer. The tests were performed three times for
each sample. Differences between the experimental group and the
control group were analyzed by LSD (Least Significant Difference)
t-test. P < 0.05 was considered to indicate a statistically significant
difference. In this paper, all results of experiments were measured
up to P < 0.05.
O4–C8
O5–C15
Angles
2.3. X-ray determination
Angles
(°)
(°)
O1–Cu–O1 #1
O1–Cu–S1 #1
O1–Cu–S1
O1#1–Cu–S1
O1#1–Cu–S1#1 92.2(4)
90.7(2)
154.3(5)
92.2(4)
154.3(5)
180.0 (2)
86.18(16)
93.82(16)
86.18(16)
93.82(16)
O1–Cu1–O3
O1–Cu1–O5
O3–Cu1–O5
O1–Cu1–O4#1
O1–Cu1–O2#1
90.64(19)
95.23(17)
91.07(17)
88.79(19)
168.72(17)
167.96(17)
88.08(19)
100.96(17)
96.00(16)
(°)
The single crystals of [Cu(L1)2] and [Cu(L2)2] were grown by dif-
fusion method. 2 mL ethanol solution of the complex (0.1 mmol/L)
was added in a glass tube, and then 8 mL diethyl ether was added.
Finally, the glass tube was sealed and stood. After 15 days, the
green single crystals suitable for X-ray diffraction analysis were
observed. The single crystal of [Cu2(L3)4(DMF)2] was grown by sol-
vent evaporation method at constant temperature. The powder of
the pure [Cu(L2)2] was dissolved in DMF. A blue-green block-
shaped crystal of [Cu2(L3)4(DMF)2] was obtained at the tempera-
ture of 50 °C after 14 days. X-ray diffraction experiments were
carried out on a Rigaku Mercury CCD X-ray diffractometer by using
S1–Cu–S1#1
98.0(6)
180.00(11) O4#1–Cu1–O3
O2#1–Cu1–O3
O4#1–Cu1–O5
O2#1–Cu1–O5
Dihedral angles
S1–C8–N1–C1
(°)
(°)
Dihedral angles
O3–Cu1–O1–C1
O5–Cu1–O1–C1
O1–Cu1–O3–C8
O5–Cu1–O3–C8
ꢀ12.1(13) ꢀ6.2(12)
82.5(5)
173.6(5)
ꢀ83.8(5)
ꢀ179.1(5)
O1–Cu1–O5–C15 ꢀ122.0(5)
graphite monochromated Mo K
a radiation (k = 0.71070 Å). Single
crystals were mounted with grease at the top of a glass fiber. Cell
parameters were refined on all observed reflections by using the
program of CrystalClear (Rigaku and MSC, Ver. 1.3, 2001). The col-
lected data were reduced by the program of CrystalClear and an
absorption correction (multiscan) was applied.
The reflection data of crystals were corrected based on Lorentz
and polarization effects. The crystal structures were solved by the
direct methods and refined on F2 by the full-matrix least-squares
methods using the software package of SHELXTL [37,38]. All of the
non-hydrogen atoms were refined anisotropically. The hydrogen
atoms were placed at the calculated positions. The structure of
[Cu(L1)2] involved a orientation disorder of atom S. The molecule
was refined in two positions with the main position of the atom
S1A (61%) and the secondary position of the atom S1B (39%). In
[Cu(L2)2], the atom F1 was disordered by bonding to C7 (69.8%)
and C3 (30.2%). A summary of the key crystallographic information,
the selected bond lengths and the bond angles of three crystals
were listed in Tables 1 and 2. The other information of the crystals,
such as the final fractional coordinates, the temperature parame-
ters, the bond distances and the bond angles have been deposited

390
H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
Fig. 1. Crystal structures of the complexes [Cu(L1)2] (a) and [Cu(L2)2] (b).
were consisted with those of in trans-bis [N, N-diethyl-N-(p-nitro-
Table 3
The intramolecular interactions of [Cu(L1)2].
benzoyl) thioureato] copper (II) [39]. As the Jahn–Teller’s effect
shown [45], the bond lengths were longer than those of in
Ni(MTCB)2 [46]. The other bond lengths and angles were in agree-
ment with the reported structures. As shown in the crystal struc-
tures, the metal ion was located in the basal plane. The bond
angles of both O–Cu–O and S–Cu–S in the equatorial plane were
180°. The bond angles of the O–Cu–S were 93.82° and 86.18°, lead-
ing to slightly distorted quadrangle geometry. Neither intermolec-
ular hydrogen bond nor short contact interaction was observed in
the crystal. It indicated that the complex was self-assembled only
by Van der Waals’s interactions.
D–Hꢁ ꢁ ꢁA
d(D–H)
d(Hꢁ ꢁ ꢁA)
2.416
2.445
2.311
d(Dꢁ ꢁ ꢁA)
2.735(7)
2.764(7)
2.739(8)
\(DHA)
C3–H3ꢁ ꢁ ꢁO1
C7–H7ꢁ ꢁ ꢁN1
C13–H13ꢁ ꢁ ꢁN1
0.93
0.93
0.97
99.69°
99.80°
106.05°
in the Cambridge Crystallographic Data Centre as CCDC 912040
([Cu(L1)2]), 912039 ([Cu(L2)2]) and 882187 ([Cu2(L3)4(DMF)2)]).
According to Congdon’s suggestion for hydrolyzation of ben-
zoylthioureas in sulfuric acid [47], the complex of [Cu2(L3)4
(DMF)2)] might derive from the decomposition of [Cu(L2)2] in
DMF (Scheme 3). The crystal data and parameters of [Cu2(L3)4
(DMF)2] were given in Table 1 and the selected bond lengths and
angles were collected in Table 2. The molecular structure of crystal
was shown in Fig. 2. The structure consisted of a quadruply bridged
neutral molecule lying on a crystallographic mirror. Similar to
binuclear copper(II) complexes of tolfenamic, four carboxylato
groups from four ligands were in the familiar bidentate syn.,
3. Results and discussion
3.1. Structure characteristic
The crystal structures of two fluorobenzoylthiourato complexes
were presented in Fig. 1. [Cu(L1)2] presented a symmetric cis-tetra-
coordinate planar square structure in
a relatively distorted
manner, which was similar to the cis-bis (N,N-diethyl -N0-pivaloyl-
thioureato) copper(II) [39], cis-bis [N,N-diethyl-N-(p-nitrobenzoyl)
thioureato] copper(II) [40], cis-bis [N-(4-morpholinothiocarbonyl)-
N-1-naphthylbenzamidin] copper(II) [41] and cis-bis [1,1-bis(2-
hydroxyethyl)-3-benzoylthioureato] copper(II) [42]. The Cu–O
bonds (average length, 1.918 Å) were obviously shorter than the
Cu–S bonds (average length, 2.193 Å). The divergent geometry of
the two arms benefited to allow the sulfur atom to approach the
metal atom within a reasonable bonding distance. The angles of
O–Cu–O and S–Cu–S were 90.7° and 98.0° while the bond angles
of O1–Cu–S1 and O1#1–Cu–S1 were 92.2° and 154.3°, which re-
sulted in slightly distorted quadrangle geometry. The intramolecu-
lar interactions of [Cu(L1)2] were C3–H3ꢁ ꢁ ꢁO1, C7–H7ꢁ ꢁ ꢁN1 and
C13–H13Bꢁ ꢁ ꢁN1 and their main information were listed in Table 3.
Moreover, a pair of intermolecular interactions were C3–H3ꢁ ꢁ ꢁO1#
and O1ꢁ ꢁ ꢁH3#–C3#, symm., (3/4 ꢀ y, ꢀ1/4 + x, ꢀ1/4 ꢀ z), the
distance of H3#ꢁ ꢁ ꢁO1, 2.591 Å. The complex was self-assembled
by intermolecular interactions mainly.
g1 g1 l2 bridging mode [48], two Cu atoms were linked by four
: :
benzoate groups. Each DMF molecule was bound to the Cu–Cu vec-
tor on each of Cu atom. The complex had a Jahn–Teller distorted
and an octahedral geometry with four short Cu–O (fluorobenzoate)
bonds (1.948–1.972 Å) and a long Cu–O (DMF) bond (2.142 Å). The
distance of two copper atoms in a same dimer was 2.633 Å, which
was longer than that found in [Cu(CH3COO) 2H2O]2 (2.608 Å) [49].
There was an obviously movement of copper atom out of the basal
plane of its square pyramidal coordination polyhedron. The Cu-
basal plane distance, 0.401 Å, was longer than that of in [Cu
(diclofenac)2(DMF)]2 (0.203 Å) [50] and [Cu(CF3COO)2quinoline]2
(0.32 Å) [51]. The carboxylato portion of each ligand was not
co-planar enough to decrease the intensity of Fꢁ ꢁ ꢁO interactions.
The dihedral angle between the aromatic ring of fluorobenzoate
and the carboxylato portion was 39.6°.
A C–Hꢁ ꢁ ꢁ interaction was found in [Cu2(L3)4ꢁ(DMF)2]. C11–H11
p
[Cu(L2)2] presented a symmetric trans-tetra-coordinate planar
square structure, which was similar to trans-bis [N,N-diethyl-N-
(p-nitrobenzoyl) thioureato] copper(II) [39], trans-[Cu(SON
(CNiPr2)2)2] [43] and trans-[Cu(3-OHFT)2] [44]. The bond lengths
of Cu–O (1.896 Å) and Cu–S (2.249 Å) were shorter than that of
Cu–O (1.918 Å) and longer than Cu–S (2.193 Å) in [Cu(L1)2], which
was directed towards the symmetry related (ꢀ1/2 ꢀ x, ꢀ1/2 + y, 1/
2 ꢀ z) aromatic ring containing the C2–C7 atoms. A couple of inter-
molecular hydrogen bondings were C4–H4ꢁ ꢁ ꢁO5 (#), symm., (1/
2 ꢀ x, ꢀ1/2 + y, 1/2 ꢀ z) and O5ꢁ ꢁ ꢁC4–H4, symm., (1/2 ꢀ x, 1/2 + y,
1/2 ꢀ z). The short contact of H14ꢁ ꢁ ꢁH14 (#), symm., (ꢀx, 2 ꢀ y,
ꢀz) was 2.369 Å.

H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
391
Fig. 2. Crystal structure of the complex [Cu2(L3)4(DMF)2].
Fig. 3. IR spectra of the ligands and the complexes (a) HL1 and [Cu(L1)2], (b) HL2 and [Cu(L2)2], (c) HL3 and [Cu2(L3)4(DMF)2].

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H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
Fig. 4. UV spectra (a) and fluorescence emission spectra (b) in THF solutions for three complexes and their corresponding ligands.
HL3
Fungi
CuCl2
HL1
[Cu(L1)2]
HL2
[Cu(L2)2]
[Cu2(L3)4(DMF)2]
Botrytis cinerea
Trichoderma spp.
Myrothecium
Verticillium.spp
Bacteria
Shewanella
Pseudomonas
aeruginosa
E. coli
Staphylococcus
aureus
Bacillus subtilis
Fig. 5. The photos of the complexes against the studied fungal and bacteria strains corresponding to the ligands and CuCl2.

H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
393
Table 4
Average values of the breadth of inhibition zones (4r) of the ligands and the complexes against the studied fungi and bacteria (the concentration of test sample is 500 mg/L).
4r (mm)
CuCl2
HL1
[Cu(L1)2]
HL2
[Cu(L2)2]
HL3
[Cu2(L3)4(DMF)2]
Fungi
Botrytis cinerea
Trichoderma spp.
Myrothecium
Verticillium.spp
0.9
0.4
1.0
1.3
1.2
1.5
1.7
2.3
2.6
3.5
2.4
3.0
1.5
1.1
0.6
1.6
2.8
3.5
3.5
3.0
0.0
1.5
0.8
0.2
7.5
8.0
6.0
2.1
Bacteria
Shewanella
Pseudomonas aeruginosa
E. coli
Staphylococcus aureus
Bacillus subtilis
0.9
1.0
1.1
2.3
0.5
1.7
3.6
2.8
2.1
1.8
1.0
1.2
3.2
3.5
1.6
1.6
1.8
1.7
1.5
1.7
1.1
2.6
2.8
4.0
3.0
0.1
1.0
0.9
2.6
0.4
1.5
2.4
4.1
3.7
2.3
3.2. Electronic spectra
3.2.1. FI-IR spectra
wavelength, HL1 emitted double fluorescence bands with the max-
ima emissions at 394 nm and 475 nm. Both bands were attributed
to the normal fluorescence (p⁄
? p) and charge transfer fluores-
The products were stable in air at room temperature, insoluble
in water and soluble in organic solvents such as alcohol, DMF and
DMSO (dimethylsulfoxide). The FT-IR spectra of two ligands, HL1
and HL2, together with their copper complexes were shown in
Fig. 3(a)–(b). In the IR spectra of [Cu(L1)2] and [Cu(L2)2], the
stretching vibrations of N–H (3200–3400 cmꢀ1) existed in the li-
gands disappeared, which indicated that the ligands participated
in the coordination reaction as the enamine anion. The stretching
vibrations of C@O at 1650.9 cmꢀ1, 1680.4 cmꢀ1 and the stretching
vibrations C@S at 1156.7 cmꢀ1, 1170.7 cmꢀ1 in HL1 and HL2
shifted to the smaller value and appeared at 1211.6, 1259.2 cmꢀ1
and 893.1, 920.7 cmꢀ1 in [Cu(L1)2] and [Cu(L2)2 respectively. It
indicated that the C@O bond and C@S bond transformed to the
C–O bond and C–S bond upon the coordination reaction. Moreover,
the C@S and C@O bond coordinating to Cu2+ enhanced the reso-
nance delocalization of nitrogen atom lone pair electrons, provided
more double bond character for C–N–C. Thus, both symmetric and
asymmetric C–N–C stretching was shifted to higher values. The
vibrational bands at about 1585 cmꢀ1 are attributed to C@N double
bonded in both complexes. The IR spectra of [Cu2(L3)4(DMF)2] was
exhibited in Fig. 3(c). The stretching vibrations of C@C (-ph) ap-
peared at about 1609.6, 1525.8 and 1497.6 cmꢀ1. The band at
cence, which were consistent of that of the UV absorptions. HL2
emitted a charge transfer fluorescence band with the maximum
emission at 481 nm. The normal fluorescence bands wasn’t ob-
served due to the intramolecular hydrogen bond interaction
Fꢁ ꢁ ꢁH–N. The maxima fluorescence emission wavelength were lo-
cated at 445 and 434 nm for [Cu(L1)2] and [Cu(L2)2] respectively.
Because the coordination reaction decreased the delocalization of
p
electrons, the fluorescence bands of [Cu(L1)2] and [Cu(L2)2]
shifted blue, which corresponded to that of UV absorption. HL3
didn’t emitted fluorescence. However, a strong fluorescence emis-
sion band was detedcted with the maximum emission wavelength
of 424 nm in [Cu2(L3)4(DMF)2]. It may be a new fluorescence meth-
od to determine Cu2+ by o-fluorobenzoic acid.
3.3. Antimicrobial activities
The photos and the diameter of inhibition zones against the
bacteria and the fungal strains were depicted in Fig. 5 and Table.
4. The three complexes showed stronger inhibiting fungi abilities
than the corresponding ligands and CuCl2. As we known, CuCl2 also
exhibited the considerable inhibition activities against the studied
fungi and bacteria. The breadth of the inhibition zones (Dr, mm) is
1695.7 cmꢀ1
(m
C@O) of ligand shifted to 1231.9 cmꢀ1
(mC–O) in the
0.9 (Botrytis cinerea), 0.4 (Trichoderma spp.), 1.0 (Myrothecium), 1.3
(Verticillium spp.), 0.9 (Shewanella), 1.0 (Pseudomonas aeruginosa),
1.1 (Escherichia coli), 2.3 (Staphylococcus aureus) and 0.5 (Bacillus
subtilis). The antibacterial and antifungal activities of [Cu(L1)2]
were superior to that of the ligand and free Cu2+. For example,
complex, which showed that the ligand was coordinated by the
O atoms of C@O.
3.2.2. UV–Vis spectra
UV–visible spectra of the ligands and the complexes were
shown in Fig. 4(a). In ligands of HL1 and HL2, the weak absorption
band at about 350 nm resulted from the charge transfer transition
and a strong absorption band at about 285 nm was assigned to
the Dr of [Cu(L1)2], 2.6 mm and 3.5 mm were larger than those
of HL1, 1.2 mm and 2.1 mm against B. cinerea and S. aureus. The
antibacterial and antifungal activities of [Cu(L2)2] were similar to
[Cu(L1)2]. It suggested that the substituted positions of fluorine
p
?
p⁄ transitions. Because of d–d transition of Cu(II), the absorp-
did not affect antibacterial and antifungal activities. The
[Cu2(L3)4(DMF)2] was 7.5, 8.0, 6.0 and 2.1 mm, respectively, larger
than the r of HL3, 0.0, 1.5, 0.8, 0.2 mm against Botrytis cinerea,
Trichoderma spp., Myrothecum and Verticillium spp. respectively.
For the bacteria, the r of [Cu2(L3)4(DMF)2], 1.5 mm (Shewanella),
Dr of
tion bands at about 350 nm shifted red to 364 nm in complexes,
and accompanied with the absorption bands broadening and
increasing. The absorption bands at about 285 nm shifted blue
slightly in complexes and the absorptions intensity increase com-
paring with that of the ligands. The absorption of [Cu2(L3)4(DMF)2]
was observed as a new broad band centered at about 690 nm,
which was attributed to the d–d transition of Cu(II). The strong
absorption band of HL3 at about 266 nm shifted blue to 248 nm
D
D
2.4 mm (P. aeruginosa), 4.1 mm (E. coli), 3.7 mm (S. aureus) and
2.3 mm (B. subtilis) also larger than that of HL3, 0.1 mm (Shewanel-
la), 1.0 mm (P. aeruginosa), 0.9 mm (E. coli), 2.6 mm (S. aureus) and
0.4 mm (B. subtilis) respectively. It indicated that both antifungal
and antibacterial abilities of the [Cu2(L3)4(DMF)2] were stronger
than that of HL3. For bacteria, Shewanella and P. aeruginosa, the
in [Cu2(L3)4(DMF)2], which was assigned to
The blue shift of the bands in the complexes indicated that the
coordination reaction decreased the delocalization of electrons
p⁄ transition.
p ?
p⁄ transitions.
p
antibacterial abilities of complexes were weak, the Dr were close
and resulted in the increase of the energy of
p
?
to the ligands and CuCl2. Anyway, three complexes with Cu2+
exhibited stronger antifungal abilities than the ligands and CuCl2.
It pronounced the increasing of activity may be attributed to the
formation of chelate, a less polar form of the metalloelement,
which increases the lipophilic character. The increased lipophilic
3.2.3. Fluorescence spectra
HL1 and HL2 exhibited the weakly fluorescnece emissions in
THF. As shown in Fig. 4(b), selecting 285 nm as the excitation

394
H. Liu et al. / Inorganica Chimica Acta 405 (2013) 387–394
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