Multi-properties of a Cu(II) complex: Crystal structure, anion binding ability, bioactivity and cell cytotoxicity

Article abstract of DOI:10.1016/j.ica.2016.10.046

A new copper(II) complex based on Schiff bases of 3-nitrosalicylaldehyde was synthesized and the crystal was also obtained fortunately. Its structure was well characterized by single-crystal X-ray diffraction and HRMS. The complex showed the strongest bin

Full text of DOI:10.1016/j.ica.2016.10.046

Accepted Manuscript
Research paper
Multi-properties of a Cu(II) complex: crystal structure, anion binding ability,
bioactivity and cell cytotoxicity
Xuefang Shang, Kui Ren, Jie Li, Wanli Li, Jiajia Fu, Xueli Zhang, Jinlian Zhang
PII:
S0020-1693(16)30785-X
http://dx.doi.org/10.1016/j.ica.2016.10.046
ICA 17339
DOI:
Reference:
Inorganica Chimica Acta
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Accepted Date:
23 June 2016
24 October 2016
28 October 2016
Please cite this article as: X. Shang, K. Ren, J. Li, W. Li, J. Fu, X. Zhang, J. Zhang, Multi-properties of a Cu(II)
complex: crystal structure, anion binding ability, bioactivity and cell cytotoxicity, Inorganica Chimica Acta (2016),
doi: http://dx.doi.org/10.1016/j.ica.2016.10.046
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Multi-properties of a Cu(Ⅱ) complex : crystal structure, anion
binding ability, bioactivity and cell cytotoxicity
Xuefang Shanga*, Kui Rena, Jie Lia, Wanli Lib, Jiajia Fuc, Xueli Zhangc, Jinlian
Zhangc
aKey Laboratory of Medical Molecular Probes, Department of Chemistry, School of Basic
Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, China
bDepartment of Immunity, Xinxiang Medical University, Xinxiang, Henan 453003, China
cSchool of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, China
*Corresponding author: Tel +86-373-3029128, Fax +86-373-3029959
E-mail: xuefangshang@126.com
Abstract:
A new copper(Ⅱ) complex based on Schiff bases of 3-nitrosalicylaldehyde was
synthesized and the crystal was also obtained fortunately. Its structure was well
characterized by single-crystal X-ray diffraction and HRMS. The complex showed the
strongest binding ability and high selectivity for hydrogen sulfide among other anions
−
(AcO−, H2PO4 , F−, Cl−, Br− and I−) at neutral pH in organic-aqueous solutions. The
possible mechanism was the copper ion was released and combined with hydrogen
sulfide after the anion was added. In addition, the further application of the sensor was
applied to hela cells cytotoxicity. The above results indicated the copper(Ⅱ) complex
could be used as a sensor for the detection of HS− in the sample of environment,
pharmacy, and etc. More importantly, the copper(Ⅱ) complex also exhibited effective
and wide antibacterial activity.
Key words: copper( Ⅱ ) complex; crystal property; hydrogen sulfide; sensor;
antibacterial activity
1. Introduction
1

Hydrogen sulfide (H2S), notorious for the stink of rotten-eggs, was considered
merely as a toxin with no beneficial physiological significance until the initial
observations by Kimura’s group suggesting its biological relevance as a signaling
molecule [1]. Now hydrogen sulfide( H2S) is found to be the third endogenous
gasotransmitter after carbon monoxide and nitric oxide [2-6], which contributes to
various physiological processes, including relaxation of vascular smooth muscles,
mediation of neurotransmission, regulation of inflammation and O2 sensing, and it can
also protect against ischemia/reperfusion injury [7-11]. On the other hand, the
abnormal H2S level in cell is related to various diseases such as Alzheimer’s disease,
Down’s syndrome, diabetes and liver cirrhosis [12-15]. Therefore, the selective
recognition and detection of H2S in living systems is significant for better
understanding of its physiological and pathological function. And so, the detection of
H2S has become the important subject of chemical research. A variety of detection
methods
including
colorimetric,
electrochemical,
chem-luminescence,
chromatography, and methylene blue assay [16-21] are generally limited by their
invasive and destructive nature to the living organisms. While, fluorescence is
suitable for the study of H2S in biological samples due to the high sensitivity and
selectivity. What’s more, the fluorescence detection method has been widely used in
biological studies to research the physiological roles of H2S and other small molecules
because this technology provides real-time, easy-to-use, nondestructive detection in
live cells or tissues [22-33]. Lippard reported a number of mental complexes for the
fluorescent detection of NO by following the dis placement approach with a detection
limit of 50-100mM [34]. Chang et al. synthesized a cyclopalladated derivative
showed ppb level sensitivity towards CO [35].
Schiff bases have been attracted considerable attention for their wide range of
2

biological activities, such as antibacterial, antifungal, antitumor, antiflammatory, and
cytotoxic [36]It was reported that Schiff bases bearing electron-withdrawing groups
can improve their antimicrobial activities [37]. Antibacterial tests for schiff base and
their copper complex reveal that the antibacterial activity of the schiff bases is
enhanced when they are chelated with a copper(Ⅱ) ion [38].
Based on the above considerations, we synthesized a copper(Ⅱ) complex (scheme
1) to research the anion binding ability, especially for HS-. Fortunately, the crystal of
copper complex was also obtained. As expected, the complex showed the strongest
−
binding ability for HS− among the tested anions (HS−, AcO−, H2PO4 , F−, Cl−, Br− and
I−). In addition, the copper(Ⅱ) complex also exhibited stronger antibacterial activity
in the bactericidal test.
Scheme 1
2. Experimental
All reagents and solvents used were of analytical grade. Sodium hydrosulfide
hydrate, all anions in the form of tetrabutylammonium salts (such as (n-C4H9)4NCl,
(n-C4H9)4NBr, (n-C4H9)4NI, (n-C4H9)4NAcO and (n-C4H9)4NH2PO4) were purchased
from Aladdin Chemistry Co. Ltd (Shanghai, China). All anions were stored in a
desiccator under vacuum, and used without any further purification. Dimethyl
1
sulfoxide (DMSO) was distilled in vacuum after being dried with CaH2. H NMR
spectra were recorded on a Unity Plus-400-MHz spectrometer. HRMS was performed
with a Mariner apparatus. UV-vis titration experiments were made on a Shimadzu
UV2550 Spectrophotometer at 298 K. The binding constant, Ks, was obtained by
non-linear least squares calculation method for data fitting.
3

The copper(Ⅱ) complex was synthesized according to the route shown in Scheme 1.
The condensation product of 3-nitrosalicylaldehyde and phenylamine was synthesized
according to the literature [39]. 3-Nitrosalicylaldehyde (10 mmol) was resolved in
ethanol solution (40 mL) and phenylamine (10 mmol) was added to the above
solution. Then, the mixture was refluxed for 4 h and the red precipitate was obtained
and recrystalled by ethanol, washed, dried under vacuum. Yield: 85%.
mp.133-134 .1H NMR (400 MHz, DMSO) δ 15.75 (s, 1H, -OH), 9.23 (s, 1H,
-CH=N- C7-H), 8.12 (dd, J = 8.1, 1.7 Hz, 1H, C4-H), 7.95 (dd, J = 7.7, 1.7 Hz, 1H,
C6-H), 7.59 (d, J = 8.0 Hz, 2H, C9-H), 7.53 (t, J = 7.8 Hz, 2H, C10-H), 7.40 (t, J = 7.2
Hz, 1H, C11-H), 7.03 (t, J = 7.9 Hz, 1H, C5-H)(S1). 13C NMR (DMSO-d6, δ, ppm):
163.10(C7), 158.73(C2), 144.50(C8), 139.36(C6), 138.94(C3), 130.40(C4), 130.17(C10),
128.57(C11), 121.75(C9), 121.11(C1), 117.17(C5)(S2). Elemental analysis: Calc. for
C13H10N2O3: C, 64.46; H, 4.16; N, 11.56; Found: C, 64.63; H, 4.08; N, 11.37. ESI-MS
(m/z): 241.3 (M-H)-.
The copper(Ⅱ) complex was synthesized according to the above literature [37]. To
a stirred ethanol solution (20 mL) of N-3-nitrosalicylaldehyde-aniline (242 mg, 1
mmol) copper nitrate trihydrate (121 mg, 0.5 mmol) was added. The mixture was
refluxed for 8 h and then stood overnight at room temperature. Suitable brown single
crystal for X-ray crystal structural analysis was obtained, separated by filtration,
washed with petroleum ether. Elemental analysis: Calc. for C26H18CuN4O6: C, 57.19;
H, 3.32; N, 10.26; Found: C, 57.45; H, 3.61; N, 10.52. ESI-HRMS in
DMSO/methanol (1:20, v/v, 1×10-4 mol·L-1 ) (m/z): 568.0408 (M+Na)+(S5).
Antibacterial activity of Cu(Ⅱ) complex
4

The kinds of bacteria were Bacillus subtilis, Staphylococcus aureus,
Staphylococcus albus, Escherichia coli, Salmonella typhi and Pseudomonas
aeruginosa. Antibacterial activity was determined by filter paper method. The
qualitative filter paper was made into small round pieces (d = 6 mm) which was used
after high pressure sterilization. Under the sterile conditions, the appropriate culture
medium (20 ~ 25 mL) was dished into the sterilized Petri and made into solid plate
after solidifying. The prepared bacterial suspension (200 µL) was poured into the
appropriate solid medium using coated rods liquid coating. The filter paper was
pasted on bacterial plate. The essential oils (5 µL) were added in each piece of filter
paper. Bacillus subtilis, Staphylococcus aureus, Staphylococcus albus, Escherichia
coli, Salmonella typhi and Pseudomonas aeruginosa were stood in culture incubator
(37 ℃) for 24 h. Then the clear the plate diameter size of inhibition zone was
selected and the average value of repeat test results was obtained. Each test was
carried out for eight times to minimize the error. In order to clarify any effect of
DMSO in the biological screening, blank studies were carried out, and no activity was
observed against any bacterial strain in pure DMSO.
Cell cytotoxicity of Cu(Ⅱ) complex
In the experiment, the cells used were Hela cell which were seeded into a 96-well
plate at a density of 5 × 104 cells/well. After the cells form monolayer, the culture
media were replaced by solutions of complex at concentration in a range of 5-200
µg·mL-1. After further 24 h incubation, complex solutions were then replaced with
fresh media after several washing steps, and 20 µL MTT with concentration of
5 mg·mL-1 was added to each well and incubated for a further 4 h. After that, the
culture media were removed and 150 µL of DMSO were then added. Finally, the
absorbance of cells were detected at 490 nm using the microplate reader (Thermo
5

Multiscan MK3, Thermo Fisher Scientific, MA, USA) with the plain cell culture
media as the control. Cell viability was expressed by the ratio between the absorbance
of the cells incubated with complex to that of the cells incubated with blank culture
media only.
3. Results and discussion
3.1 X-ray crystal structure
Single crystal for X-ray analysis was prepared fortunately in order to determine
the structure of the copper(Ⅱ) complex. The measurement of X-ray structure was
performed at room temperature using a BRUKER APEX II. The structure were
solved by SHELXL-97. Software packages APEX II (data collection), saint(cell
refinement and date reduction), SHELXTL (data reduction, molecular graphics and
publication material) were also used [40-41] An ORTEP view of complex with the
atoms numbering was shown in Fig. 1. A summary of the detailed crystal data, data
collection and refinement details were all listed in Table 1. Selected bond lengths and
bond angles were listed in Table 2. The crystallographic data revealed that the metal
center was four-coordinated by two oxygen atoms in phenolate and two nitrogen
atoms in imine of the ligand. Two ligands coordinated with the copper center
in trans- orientation with respect to each other and the distance (Cu-O) was shorter
than the distance (Cu-N). The geometry around the metal center was a distorted
square-planar and space group of the unit cell is P21/c. There were also
five-coordinated complexes with a distorted square pyramidal geometry in the central
copper atom [42] and six-coordinated complexes which forming an octahedron
geometry with copper atom [43]. Tri-dentate or tetra-dentate ligands were involved in
the formation of the complexes. To the best of our knowledge, almost
bi-dentate ligands was constructed to form four-coordinated complex due to the steric
6

hindrance [44]. Similarly, four-coordinated complex formed due to the bi-dentate
ligand in this paper.
Fig.1
Table 1
Table 2
3.2 UV-vis titration
The binding ability of copper complex with anions was investigated using UV-vis
absorption spectra in DMSO and DMSO/HEPES (pH=7.4) at 298 K. The UV-vis
spectral responses of copper complex in DMSO were shown in Fig.2 during the
titration with various anions. The free complex (8.0×10−5 mol·L-1 in DMSO) revealed
a strong band with the maximum absorption peak at about 400 nm. The absorption
peak was gradually turned into a valley with the stepwise addition of HS− and a new
absorption peak developed at about 487 nm. The red-shift phenomenon was observed
which induced the color change of the copper complex solution from yellow to pink.
In addition, four clear isosbestic points at 270, 325, 362 and 430 nm appeared which
indicated the stable complex formed and had a certain stoichiometric ratio between
the Cu(Ⅱ) complex and HS−. Analogous investigations were carried out on other
−
normal anions. The additions of H2PO4 , AcO− and F− to Cu(Ⅱ) complex induced
−
similar red shift of the peak, but only the addition of H2PO4 transformed the peak
into valley with ten times the concentration compared with HS- which indicated Cu(Ⅱ)
complex also interacted with the above anions (Fig. 2). However, the additions of
Cl−, Br− and I− did not induce any spectral responses. The above results indicated that
Cu(Ⅱ) complex showed almost no binding ability toward these anions (Fig. 3).
Fig. 2 Fig. 3
7

In order to further study the binding ability of
Cu( Ⅱ ) complex in
aqueous solution, a solution of Cu(Ⅱ) complex (8.0×10-5 mol·L-1) was prepared in
DMSO/H2O(6:4, v/v, 0.04mol·L-1 HEPES buffer at pH 7.4). The UV-vis absorption
spectra of each solution were recorded after the investigated anions were added. As
shown in the Fig. 4, the absorption peak shifted from 413 to 447 nm and the valley
shifted from 327 to 386 nm with the concentration of NaHS increasing from 0 to
2.5×10-4 mol·L-1. What’s more, two isosbestic points at 369 and 423 nm were
appeared which indicated the interaction of HS- and complex. However other anions
did not induce any spectral response and the anion binding ability could be ignored.
The reason probably was the displacement reaction which the Cu2+ was captured by
HS− and free ligand was released from the complex. However, other anions could
only coordinate with complex probe to form a six-coordinated complex. Besides, the
HS- selective sensor was not affected by the presence of other anions (Fig. 4c). The
remarkable response of UV-vis absorption was fast enough to complete within
seconds indicated the synthesized copper complex could be used as a sensor for the
detection of HS− in aqueous solution.
Fig. 4
3.3 Fluorescent response
The fluorescence properties of the copper(Ⅱ) complex were also investigated in
DMSO. The free probe displayed weak fluorescence intensity upon excitation at 466
nm. As shown in Fig. 5, the fluorescence emission intensity was gradually
strengthened at about 550 nm with the increasing concentration of HS-. The interacted
process completed within 20 min and very quick. The reason may be that the addition
of HS- could coordinate with Cu2+ and release the free ligand. A 4-fold fluorescence
enhancement suggested that the probe could be a good candidate for the detection of
8

HS- (Fig. 5). The fluorescence titration of the probe with various anions was
conducted to examine the selectivity. As shown in Fig. 5(b), the addition of 100 equiv.
of Cl−, Br− and I− produced a nominal change in the fluorescence spectra of the sensor
−
and AcO−, H2PO4 and F− showed a decrease of fluorescence intensity. All these results
suggested that the complex probe was a practical probe for detection of HS- with high
selectivity.
Fig. 5
3.4 HRMS titration of complex with NaHS
In order to study the mechanism of HS- interact with complex, further insight into the
interaction of HS- with complex was investigated by performing HRMS titration in
DMSO/methanol (1:20, v/v, 1×10-4 mol·L-1 ). Figure S5-7 illustrate the change in
HRMS signal of complex upon addition of NaHS. The singlet 568.0408 (complex +
Na)+ gradually vanished from spectral window and a new signal at 265.0681 (ligand +
Na)+ appeared after addition of NaHS. The reason probably was the displacement
reaction which the Cu2+ was captured by HS− and free ligand was released from the
complex.
3.5 Affinity constant
Affinity constants for the sensor with anionic species are calculated according to
the equation (1) of 1:2 host-guest complexation [45-47].
∆εcG cH2
X = X 0 +
1 + K s cH2
(1)
where, cG and cH are the concentration of guest and host, respectively. X is the
absorbance intensity at certain concentration of host and guest. X0 is the absorbance
intensity of the host alone. Ks is the affinity constant for the host-guest complexation.
∆ԑ is the change in molar extinction coefficient. According to the non-linear fitting
9

curves (Fig. 6), copper(Ⅱ) complex interacted with anions as the ratio of 1:2. The
affinity constants could be obtained and listed in Table 3 based on the UV–vis data.
Obviously, the affinity constants of copper(Ⅱ) complex were in the order: HS− >
−
AcO− > H2PO4 > F− >> Cl− ~ Br− ~ I−. The copper(Ⅱ) complex showed the strongest
binding ability for HS− among anions tested. The reason probably was the
displacement reaction that the Cu2+ was captured by HS− and free ligand was released
from the complex. However, other anions could only coordinate with complex probe
to form a six-coordinated complex. In DMSO/H2O (e, 6:4, v/v, 0.5mol·L-1HEPES
buffer at pH 7.4) solution, only the addition of HS− could induce the spectral change
of copper complex. The affinity constant was listed in Table 1 with a value of
6.07 0.1×107. The above results indicated the synthesized copper complex could be
used as a sensor for the detection of HS− in aqueous solution.
Fig. 6
Table 3
3.6 Mechanism
Many literatures have been reported on the anion recognition. However, a full
understanding of the interacted principles has not yet been achieved. Similar to
previously reported H2S probe containing metal ion, the interacted mechanism of
host-guest was linked with the red shift phenomenon in absorption spectra. The added
NaHS could snatch the copper ions from the complex and the free ligand was released
due to the much higher affinity constant between sulfide and copper ions (Scheme 2).
However, other anions could only axial coordinate with complex probe to form a
six-coordinated complex. The binding ratio and affinity constants also could illustrate
it. As showed in Table 3, the copper complex interacted with HS− as the ratio of 1:2 in
DMSO solution and DMSO/H2O (6:4, v/v, 0.04 mol·L-1 HEPES buffer at pH 7.4)
10

solution which indicated the copper atom was released from the host. In DMSO/H2O
(6:4, v/v, 0.04mol·L-1 HEPES buffer at pH 7.4) solution, the water molecule
competed the interaction with copper complex and so the affinity constants was much
lower and no coordination with other anions.
Scheme 2
3.7 Antibacterial activity
The antibacterial activity of the Cu(Ⅱ) complex was shown in Fig. 7. The complex
was subjected to antibacterial activity tests against Bacillus subtilis, Staphylococcus
aureus, Staphylococcus albus, Escherichia coli, Salmonella typhi and Pseudomonas
aeruginosa. The experiment demonstrated that Cu(Ⅱ) complex exhibited effective
and wide antibacterial activity. Staphylococcus aureus and Staphylococcus albus
group were different from Bacillus subtilis (*P < 0.05, n = 8). Significant differences
were founded in Escherichia coli, Salmonella typhi and Pseudonym aeruginosa group
compared with Bacillus subtilis (**P < 0.01, n = 8).
Fig. 7
3.8 Cell cytotoxicity
For further biological application point of view, a quantitative in vitro cytotoxicity
study of the complex was conducted using the MTT assay. In this experiment, we
used Hela cell. Cell viability was expressed by the ratio between the absorbance of the
cells incubated with complex to that of the cells incubated with blank culture media
only. As shown in Fig. 8, the complex showed almost no cytotoxicity to Hela cell at a
concentration of 100 µg·mL-1 indicating that the complex have the potential to detect
H2S outside the cells. Further in vivo studies are currently under way in our
laboratory.
Fig. 8
11

4. Conclusion
In conclusion, we have successfully designed and synthesized a copper complex
crystal. The copper complex prepared in 60% DMSO aqueous solution were relatively
stable and showed high selective and sensitive for HS− among various anions tested.
The complex could be used as a new colorimetric sensor for the detection of H2S at
neutral pH in aqueous condition. The above method was advantage for the simplicity
analysis and low cost of the starting material. Antimicrobial tests showed that
copper( Ⅱ) complex exhibited wide antibacterial activity. In addition, the cell
cytotoxicity of the sensor also conducted in hela cell. The complex holds a great
potential for environmental analysis of HS−, S2−, H2S and the application in
bio-analysis is still challenging. Preparation of highly water soluble and highly
fluorescent copper complex is under investigation.
Acknowledgment
This work was supported by the National Natural Science Foundation of China
(81301269) , Program for Science & Technology Innovation Talents in Universities of
Henan Province (15HASTIT039) and Fund of Fluorescence Probe and Biomedical
Detection Research Team of Xinxiang City (CXTD16001).
Supplementary Material
Crystallographic data as cif file for the structure reported in this paper have been
deposited at the Cambridge Crystallographic Data Center with CCDC 1416108.
Copies
of
the
data
can
be
obtained
free
of
charge
at
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic
Data Center, 12, Union Road, Cambridge CB2 1EZ, UK). Email:
12

deposit@ccdc.cam.ac.uk.
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18

Scheme 1 Synthesis route for Copper(Ⅱ) Complex
Fig.1 The molecular structure of copper complex
HS-
AcO-
-
F-
H2PO4
19

Ligand
Fig. 2 UV-vis spectral changes of Cu(Ⅱ) complex upon the addition of various anions.
[complex] = 8.0×10-5 mol·L-1 in DMSO. Arrows indicate the direction of increasing
anions concentration. And the spectrum of free ligand (2.0×10−5 mol·L-1 in DMSO).
Fig. 3 UV-vis spectral changes of Cu(Ⅱ) complex (8×10-5 mol·L-1) upon the additions
of various anions.
b
a
c
20

Fig. 4 UV-vis spectral of the complex solution [complex] = 8.0×10-5 mol·L-1 in
DMSO/H2O(6:4, v/v 0.04mol·L-1 HEPES buffer at pH 7.4) and the complex solution
after addition of different anions. (a) HS- (0 - 2.5×10−4 mol·L-1), Arrows indicate the
direction of increasing HS- concentration. (b) the complex and the complex after the
addition of different anions. (c ) Change in absorbance at 445nm in the presence of
anions and mixed with NaHS.
b
a
Fig. 5 (a) Fluorescence response (λex, 466nm) of copper probe (4.0×10−5 mol·L-1, slit
widths: 10 nm/10 nm) upon the addition of NaHS. Arrows indicate the increase
direction of NaHS concentration. All the spectra were acquired after reaction of the
probe with NaHS for 20 min. (b) Fluorescence spectra (λex, 466 nm, slit widths:
10 nm/10 nm) of probe (4.0×10−5 mol·L-1in DMSO) upon the addition of NaHS (20
21

equiv.) and various anions (50 equiv.) and fluorescence spectra (λex, 466 nm, slit
widths: 10 nm/10 nm) of free ligand (2.0×10−5 mol·L-1 in DMSO).
c
a
b
d
e
Fig. 6 Non-linear fitting curves of Cu(Ⅱ) complex in DMSO (a, b, c, d) or
H2O/DMSO(e, 6:4, v/v, 0.04 mol·L-1HEPES buffer at pH 7.4) upon the addition of
HS-.
Scheme 2 The possible binding mode of complex with hydrogen sulfide ion
22

Fig. 7 Antimicrobial activity of Cu(Ⅱ) complex against bacteria. All the data were
presented as means ± SDs (n =8), compared with that of B. subtilis *P<0.05; **
P<0.01.
Fig. 8 Cell viability values (%) estimated by MTT proliferation test versus
concentrations of complex after 24h incubation at 37℃. Hela cell was cultured in the
5-200 µg/mL complex solution at 37℃ for 24 h (n=6).
23

Table 1. Crystallographic and experimental data for the Cu(Ⅱ) Complex
Empirical formula
C26H18CuN4O6
545.98
296(2) K
0.71073 Å
Monoclinic
P 21/c
Formula weight
Temperature
Wavelength
Crystal system
Space group
Unit cell dimensions
a = 11.9215(11) Å
b = 7.9662(8) Å
c = 12.1770(12) Å
α= 90°
β= 112.269(3)°
γ = 90°
Volume
Z
1156.42(7) Å3
2
3
Density (calculated)
1.568 Mg/m
-1
Absorption coefficient
F(000)
0.997 mm
558
3
Crystal size
Theta range for data collection
Index ranges
0.503 x 0.479 x 0.160 mm
3.112 to 27.570°.
-10<=h<=11, -13<=k<=13, -16<=l<=17
17283
Reflections collected
Independent reflections
Completeness to theta = 25.242°
Absorption correction
Max. and min. transmission
2656 [R(int) = 0.0736]
99.8 %
Semi-empirical from equivalents
0.853 and 0.612
2
Refinement method
Data / restraints / parameters
Full-matrix least-squares on F
2656 / 0 / 169
2
Goodness-of-fit on F
1.016
Final R indices [I>2sigma(I)]
R indices (all data)
Extinction coefficient
R1 = 0.0372, wR2 = 0.1337
R1 = 0.0424, wR2 = 0.1413
n/a
-3
Largest diff. peak and hole
0.461 and -0.368 e.Å
24

Table 2. Selected bond lengths (Å) and angles (°) for the complex
Cu(1)-O(1)
1.8909(17)
1.9770(15)
180.0
Cu(1)-O(1)#1
1.8909(17)
1.9771(15)
180.0
Cu(1)-N(1)
Cu(1)-N(1)#1
O(1)#1-Cu(1)-O(1)
O(1)#1-Cu(1)-N(1)
O(1)-Cu(1)-N(1)
N(1)-Cu(1)-N(1)#1
O(1)-Cu(1)-N(1)#1
O(1)#1-Cu(1)-N(1)#1
88.97(7)
91.03(7)
88.97(7)
91.03(7)
Symmetry transformations used to generate equivalent atoms: #1 -x+2,-y,-z+2
25

Table 3 Affinity constants of Cu(Ⅱ) complex with various anions
anions
HS-
Ks(DMSO)
Ks(DMSO/HEPES)
(8.85 0.5)×108b
(6.07 0.07)×107b
-
HPO4
(3.55 0.06)×107b
ND
F-
AcO-
Br-
Cl-
(2.76 0.8)×107b
ND
ND
ND
ND
ND
(1.13 0.1)×108b
NDa
ND
ND
I-
aThe binding constant could not be determined
bThe binding ratio of host-guest is 1:2
26

Graphical abstract
A new copper(Ⅱ) complex crystal based on Schiff bases of 3-nitrosalicylaldehyde
was synthesized. The complex showed the strongest binding ability and high
−
selectivity for hydrogen sulfide among other anions (AcO−, H2PO4 , F−, Cl−, Br− and
I−). The above results indicated the copper(Ⅱ) complex could be used as a biosensor
for the detection of HS−. More importantly, the copper(Ⅱ) complex also exhibited
effective and wide antibacterial activity and lower cytotoxicity.
Multi-properties of a Cu(Ⅱ) complex crystal: anion binding ability,
bioactivity and cell cytotoxicity
Xuefang Shang*, Kui Ren, Jie Li, Wanli Li, Jiajia Fu, Xueli Zhang, Jinlian Zhang
27

Highlights
A new copper(Ⅱ) complex crystal based on Schiff bases of 3-nitrosalicylaldehyde
was synthesized.
The complex showed the strongest binding ability and high selectivity for hydrogen
sulfide among other anions.
The copper(Ⅱ) complex exhibited effective and wide antibacterial activity and lower
cytotoxicity.
28