Synthesis, characterization, crystal structure and toxicity evaluation of Co (II), Cu (II), Mn (II), Ni (II), Pd (II) and Pt (II) complexes with Schiff base derived from 2-chloro-5-(trifluoromethyl)aniline

Article abstract of DOI:10.1002/aoc.5931

A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)imino)methyl) phenol (HL¹) and its complexes [Co(L¹)₂(H₂O)₂] (1), [Cu(L¹)₂] (2), [Mn(L¹)₂(H₂O)₂] (3), [Ni(L¹)₂(H₂O)₂] (4), [Pd₂(L¹)₂(OAc)₂·1.16H₂O] (5), [Pt(L¹)₂] (6) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, ¹H-NMR, ¹³C-NMR, UV–Vis, mass spectroscopies and X-ray powder diffraction (XRD). The molecular structures of ligand HL¹ and two complexes (2 and 5) were confirmed by X-ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square-planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R-3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells.

Full text of DOI:10.1002/aoc.5931

Received: 30 March 2020
DOI: 10.1002/aoc.5931
Revised: 15 June 2020
Accepted: 17 June 2020
F U L L P A P E R
Synthesis, characterization, crystal structure and toxicity
evaluation of Co (II), Cu (II), Mn (II), Ni (II), Pd (II) and Pt
(
5
II) complexes with Schiff base derived from 2-chloro-
-(trifluoromethyl)aniline
1
2
3
Gina Lupa s¸ cu | Elena Pahonțu | Sergiu Shova
|
4
4
5
Ștefania Felicia B aꢀ rbuceanu | Diana Carolina Ilie s¸ | Mihaela Badea
Codruța Paraschivescu | C aꢀ t aꢀ lin Ducu7 | Johny Neamțu | Mihaela Dinu
|
6
8
9
|
9
10
11
Robert Viorel Ancuceanu | Doina Dr aꢀ g aꢀ nescu
| Cristina Elena Dinu-Pîrvu
1
Physiology Department, University of
A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)
Medicine and Pharmacy “Carol Davila”,
Faculty of Pharmacy, Bucharest, Romania
1
1
1
imino)methyl) phenol (HL ) and its complexes [Co(L ) (H O) ] (1), [Cu(L ) ]
2
2
2
2
2
Inorganic Chemistry Department,
1
1
1
(
2), [Mn(L ) (H O) ] (3), [Ni(L ) (H O) ] (4), [Pd (L ) (OAc) ꢀ1.16H O] (5), [Pt
2
2
2
2
2
2
2
2
2
2
University of Medicine and Pharmacy
1
(
L ) ] (6) were synthesized and characterized by different physico-chemical
2
“Carol Davila”, Faculty of Pharmacy,
Bucharest, Romania
techniques including elemental and thermal analysis, magnetic susceptibility
3
1
13
Institute of Macromolecular Chemistry
measurements, molar electric conductivity, IR, H-NMR, C-NMR, UV–Vis,
“Petru Poni”, Iasi, Romania
mass spectroscopies and X-ray powder diffraction (XRD). The molecular
4
Organic Chemistry Department,
1
structures of ligand HL and two complexes (2 and 5) were confirmed by X-ray
University of Medicine and Pharmacy
“
Carol Davila”, Faculty of Pharmacy,
crystallography analysis on the monocrystal. In this complexes, the metal ions
are in distorted square-planar environments. The copper (II) complex is
mononuclear and crystallized in a monoclinic space group P21/c, whereas
palladium (II) complex is dinuclear and crystallized in the trigonal crystal
system R-3. The toxicity of the ligand and complexes was evaluated on both
plant and animal cells, using the plant species Triticum aestivum L. and the
crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the
compounds presented very little toxicity on Artemia franciscana Kellogg. More-
over, the palladium (II) complex was devoid of any toxicity on the plant cells.
Bucharest, Romania
5
Inorganic Chemistry Department,
University of Bucharest, Faculty of
Chemistry, Bucharest, Romania
6
Organic Chemistry Department,
University of Bucharest, Faculty of
Chemistry, Bucharest, Romania
7
Department of Fabrication and Industrial
Management, University of Pitesti,
Faculty of Mechanics and Technology,
Pitesti, Romania
8
Pharmacy Department I, University of
K E Y W O R D S
Medicine and Pharmacy Craiova,
Craiova, Romania
acute toxicity, crystal structure, metal complexes, Schiff base, spectroscopy
9
Pharmaceutical Botany and Cell Biology
Department, University of Medicine and
Pharmacy “Carol Davila”, Faculty of
Pharmacy, Bucharest, Romania
1
0
Pharmaceutical Physics Department,
University of Medicine and Pharmacy
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.
©
2020 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons Ltd
Appl Organomet Chem. 2020;e5931.
wileyonlinelibrary.com/journal/aoc
1 of 13
https://doi.org/10.1002/aoc.5931

2
of 13
LUPA S¸ CU ET AL.
“Carol Davila”, Faculty of Pharmacy,
Bucharest, Romania
1
1
Physical and Colloidal Chemistry
Department, University of Medicine and
Pharmacy “Carol Davila”, Faculty of
Pharmacy, Bucharest, Romania
Correspondence
Dr Elena Pahontu, Professor, Inorganic
Chemistry Department, Faculty of
Pharmacy, University of Medicine and
Pharmacy “Carol Davila”, Bucharest,
Romania.
Email: elenaandmihaela@yahoo.com
Dr Doina Draganescu, Professor,
Pharmaceutical Physics Department,
Faculty of Pharmacy, University of
Medicine and Pharmacy “Carol Davila”,
Bucharest, Romania.
Email: doinadraganescu@yahoo.com
1
| INTRODUCTION
in polarity and also explaining the increase of the lipo-
philic character of the complex combinations.
There has been consistent scientific interest in obtaining
and investigating Schiff bases since the nineteenth
century, when the first synthesis of this type of organic
In terms of structure activity relationship, Schiff bases
derivated from salicylaldehyde and substituted with a
halogen are well known for their efficacy against bacteria
[1]
[13]
compound was recorded. The simplicity of obtaining a
condensation reaction between a compound with a
carbonyl group, an aldehyde or ketone type, and an
aromatic primary amine, brings these azomethine-
bearing compounds into the preference of the
researchers. Also, the large and varied number of biologi-
and fungi.
In addition, it is known that fluorine-
containing organic compounds have attracted much
interest because of their unique physicochemical proper-
[
20–22]
ties and biological activity.
Introduction of fluorine
or fluoroalkyl groups into drug candidates increase their
[
23]
binding affinity at the active sites of enzymes.
[
2,3]
[4,5]
cal actions (antibacterial
anti-tumor,
antioxi-
The research in the field of coordinative chemistry
aims at the synthesis of new biologically active com-
pounds but with low toxicity. Recently, our group is
focused on the synthesis of fluorine-containing Schiff
bases. In this article, we have observed the coordination
behaviour and toxicity of the newly synthesized cobalt
(II), copper (II), manganese (II), nickel (II), palladium
(II), platinum (II) complexes with Schiff base derived
from 2-chloro-5-(trifluoromethyl)aniline. The molecular
[6,7]
[8,9]
[10,11]
dant
antiviral,
antifungal
for which they are
used reinforces the idea that Schiff bases are constantly
analyzed. These advantages are also added to the
increased stability they exhibit, the structural variety in
which they are found, and all these explain their useful-
[2,12]
ness as drug substances,
whereby the biological effect
is enhanced by aromatic and hydrophilic character. The
above-mentioned aspects add to the great ability to coor-
dinate of Schiff bases that contribute to the formation of
a large family of ligands which by the chelation process
1
1
structure of the ligand HL , complexes [Cu(L ) ] (2),
2
1
[Pd (L ) (OAc) ꢀ1.16H O] (5) were determined by X-ray
2
2
2
2
[
13]
decreases the polarity of the metal ions involved.
According to the literature, by coordinating the ligand to
crystallography technique. In view of biological proper-
ties, we evaluated the acute toxicity of these compounds
on the plant species Triticum aestivum L. and on the
crustacean Artemia franciscana Kellogg.
2+
2+
metal ions presented in biological systems (Zn , Cu ,
2
+
2+
2+
2+
2+
Co , Mn , Ni , Fe , VO ), its biological activity is
[14–16]
significantly increased,
making these metal com-
pounds the perfect candidates for pharmaceutical fields
that bring new mechanism of action.
The potentiation of the biological effect is related to
the presence of the azometinic link in the Schiff base,
supplemented by the chelation effect created with the
central metal ion, contributing to a significant decrease
2 | EXPERIMENTAL
2.1 | Materials
[15–19]
Salicylaldehyde and 2-chloro-5-(trifluoromethyl)aniline
(Sigma-Aldrich, Munich, Germany) were used as received.

LUPA S¸ CU ET AL.
3 of 13
.
.
Co (NO ) 6H O, CuSO 5H O, Mn (CH COO) ,
4.04; Co, 8.51. Found: C, 48.79; H, 2.58; N, 3.76; Co,
8.36%. IR (KBr, cm ): ν(C=N) 1,613; ν (Ar-OH) 1,253,
3
2
2
4
2
3
2
.
−1
NiCl 6H O, Pd (CH COO) , K [PtCl ] (Merck,
2
2
3
2
2
4
Darmstadt, Germany) were used as supplied. Solvents
used for the reactions were purified and dried by conven-
tional methods.
ν (CF ) 1329.
3
[24]
1
2
.3.2 | Synthesis of the complex [cu(L ) ]
2
2
.2 | Synthesis of 2-(((2-chloro-5-
(2)
(
trifluoromethyl)phenyl)imino)methyl)
1
.
phenol (HL )
The CuSO 5H O (1 mmol, 0.0250 g) dissolved in 10 ml
4 2
methanol was mixed with a 10 ml DMSO/methanol solu-
tion (1:9, v/v) of Schiff base ligand HL (1 mmol,
1
A mixture formed from 1 ml salicylaldehyde (10 mmol),
1
.36 ml 2-chloro-5-(trifluoromethyl) aniline (10 mmol)
0.0289 g) and 1–2 drops triethylamine were added. The
solution obtained was stirred for 6 hr at room tempera-
ture. The resulted brown-yellow precipitate was sepa-
rated by filtration, washed with ethanol followed by ether
and dried in vacuo.
and 10 ml ethanol was heated under reflux for 6 hr
and kept at 4 C for two weeks. The characteristic
ꢁ
yellow precipitate obtained was filtered and
recrystallized by dissolving in ethanol. Fine yellow
crystals obtained upon slow evaporation at room
temperature were characterized, including single crystal
X-ray diffraction.
ꢁ
Yield 81%; M.p. >260 C; M.wt.: 660.5 g/mol; Anal.
Calc. for C H CuN O F Cl : C, 50.87; H, 2.42; N,
28
16
2
2
6
2
4.23; Cu, 9.61. Found: C, 50.59; H, 2.26; N, 4.07; Cu,
ꢁ
−1
Yield 82%; M.p. 145 C; M.wt.: 299.5 g/mol; Anal.
9.48%. IR (KBr, cm ): ν(C=N) 1,610; ν (Ar-OH) 1,263,
Calc. for C H NOF Cl: C, 56.09; H, 3.00; N, 4.67.
Found: C, 56.35; H, 2.88; N, 4.40%. IR (KBr, cm ):
ν (CF ) 1328.
14
9
3
3
−
1
ν(C=N) 1,620; ν (Ar-OH) 1,276, ν (CF ) 1326.
3
1
H NMR (DMSO-d ; δ, ppm, J, Hz): δ = 12.78 (s,1H,
6
OH), 9.09 (s,1H, H ), 7.99 (s, 1H, H ), 7.81 (d,
2.3.3 | Synthesis of the complex [Mn
7
6
3
1
J = 10.0 Hz, 1H, H ), 7.70 (dd, J = 5, 10 Hz, 1H, H ),
(L ) (H O) ] (3)
3
10
2
2
2
7
.65 (dd, J = 5, 10 Hz, 1H, H ), 7.47 (t, J = 5, 10 Hz, 1H,
4
H ), 7.03–6.98 (overlapped signals, 2H, H , H ).
Synthesis of complex 3 was similar to preparation of com-
plex 1, using Mn (CH COO) (1 mmol, 0.0536 g). The
12
13
11
13
C RMN (DMSO-d ; δ, ppm): δ = 166.4(C-7), 160.5
6
3
2
(
1
C-9), 145.8, 134.3, 133.1, 132.5, 130.9, 129.1, 126.9, 124.3,
23.7, 119.2, 117.2, 116.8.
resulted solution after reflux was left for one week at
room temperature. The formed brown precipitate was
purified by washing with ethanol, then with ether and
dried in vacuo.
ꢁ
2
.3 | General procedure for the
Yield 78%; M.p. >260 C; M.wt.: 687.9 g/mol; Anal.
preparation of the metal complexes (1–6)
Calc. for C H MnN O F Cl : C, 48.84; H, 2.90; N,
28
20
2
4
6
2
4
.07; Mn, 7.98. Found: C, 48.96; H, 2.71; N, 3.85; Mn,
−1
Complexes 1–6 were prepared by the direct reaction
7.53%. IR (KBr, cm ): ν(C=N) 1,610; ν (Ar-OH) 1,264;
between the ligand and the corresponding metal salts.
ν (CF ) 1328.
3
1
2
.3.1 | Synthesis of the complex [co
2.3.4 | Synthesis of the complex [Ni(L ) ]
(4)
2
2
1
(L ) (H O) ] (1)
2
2
2
.
A methanol solution (10 ml) of Co (NO ) 6H O
Synthesis of complex 4 was almost the same with com-
plex 1, the NiCl 6H O (1 mmol, 0.0237 g) and HL
2 2
3
2
2
.
1
(1
mmol, 0.0290 g) was mixed with 10 ml
DMSO/methanol solution (1:9, v/v) of HL (1 mmol,
.0289 g) and 1–2 drops triethylamine. The mixture
was refluxed for 6 hr and resulted a brown precipitate
that was separated by filtration, washed with ethanol
followed by ether and dried in vacuo.
1
(2 mmoli, 0.056 g) were used. A green darken precipitate
was obtained.
0
ꢁ
Yield 84%; M.p. 164 C; M.wt.: 1311.38 g/mol;
Anal. Calc. for C H Ni N O F Cl : C, 51.24; H,
56
32
2
4
4
12
4
2.44; N, 4.27; Ni, 8.95. Found: C, 51.50; H, 2.23; N,
ꢁ
−1
Yield 74%; M.p. 229 C; M.wt.: 691.9 g/mol; Anal.
4.01; Ni, 8.67%. IR (KBr, cm ): ν(C=N) 1,609; ν (Ar-
Calc. for C H CoN O F Cl : C, 48.56; H, 2.89; N,
OH) 1,263, ν (CF ) 1328.
28
20
2
4
6
2
3

4
of 13
LUPA S¸ CU ET AL.
2
.3.5 | Synthesis of the complex
a Jasco V-670 spectrophotometer, using MgO dilution
matrices. Magnetic susceptibility measurements were
performed at room temperature in the polycrystalline
state on a Faraday magnetic balance (home-made). The
heating curves (TG and DTA) were recorded using a
Labsys 1,200 SETARAM instrument, over the tempera-
1
[Pd (L ) (OAc) ꢀ1.16H O] (5)
2
2
2
2
1
To HL (1 mmol, 0.0289 g) dissolved in 10 ml of
chloroform/methanol solution (1:5, v/v), the Pd
(CH COO) (1 mmol, 0.0289 g) dissolved in 10 ml metha-
3 2
ꢁ
ꢁ
nol was added. The solution obtained was mixed for 6 hr
at room temperature. The resulted brown precipitate was
separated by filtration and washed with ethanol followed
by ether and dried in vacuo.
ture range of 30–900 C using a heating rate of 10 C‧
−1
min . The measurements were carried out in synthetic air
3
−1
atmosphere (flow rate 16.66 cm ‧min ), by using alumina
crucibles. The FAB mass spectra were recorded on a JMS-
AX-500 mass spectrometer. The molar conductance of the
complexes in dimethylformamide solutions (10− M), at
room temperature, were measured using a Consort type
C-533 conductivity instrument.
ꢁ
Yield 80%; M.p. >260 C; M.wt.: 691.69 g/mol;
3
Anal. Calc. for C H
Pd Cl F N O7.17: C, 48.57; H,
2 2 6 2
32
24.33
2
3
.89; N, 4.04; Ni, 8.48. Found: C, 48.82; H, 2.63; N,
.73; Ni, 8.17%. IR (KBr, cm ): ν(C=N) 1,607; ν (Ar-
−1
−
−
OH) 1,264, ν (CF ) 1328, ν (COO ) 1,484, ν (COO )
X-ray powder diffraction analysis was performed on
diffractometer Rigaku ULTIMA IV using monochromatic
Cu-kα radiation. Reflection were scanned for diffraction
3
as
s
1
,360.
1
H NMR (DMSO-d ; δ, ppm, J, Hz): δ = 8.25 (s, 1H,
6
ꢁ
ꢁ
H ), 7.80 (d, J = 10.0 Hz, 1H, H ), 7.71–7.72 (overlapped
signals, 2H, H , H ), 7.53 (d, J = 5 Hz, 1H, H ), 7.43 (t,
J = 5.0, 10.0 Hz, 1H, H ), 6.98 (d, J = 10.0 Hz, 1H, H ),
angles (2θ) ranging from 5 to 50 for complexes 4, 6 and
7
3
o
o
for diffraction angles (2θ) ranging from 5 to 80 for
complex 3.
4
6
13
11
10
6
.71 (t, J = 5.0, 10.0 Hz, 1H, H ), 1.12 (s, 3H,
12
−
CH COO ).
3
1
3
C RMN (DMSO-d ; δ, ppm): δ = 175.5, 166.2(C-7),
6
1
1
63.4(C-9), 146.6, 136.8, 136.2, 132.5, 130.3, 127.9, 124.7,
24.5, 123.3, 120.4, 119.4, 116.2, 21.1 (CH3).
2.5 | X-ray crystallography
1
X-ray diffraction measurements for HL were carried
out with an Oxford-Diffraction XCALIBUR E CCD dif-
fractometer equipped with graphite-monochromated
MoKα radiation. Single crystals were positioned at
2
.3.6 | Synthesis of the complex [Pt
1
(L ) ] (6)
2
4
0 mm from the detector 219 frames were measured
ꢁ
The aqueous solution (10 ml) of K [PtCl ] (1 mmol,
each for 5 s over 1 scan width. Intensity data for
2 and 5 were collected with Oxford Diffraction Super-
Nova diffractometer using hi-flux micro-focus Nova Mo
Ka radiation. The single crystal was positioned at
49 mm from the detector and 422 and 205 frames
2
4
0
.041 g) was added to methanol solution (10 ml) of ligand
1
HL (1 mmol, 0.0289 g). The solution obtained was
mixed for 5 hr at room temperature. The resulted brown
precipitate was separated by filtration and washed with
methanol followed by ether and dried in vacuo.
ꢁ
were measured each for 90 s and 30 s over 1 scan
ꢁ
Yield 83%; M.p. >260 C; M.wt.: 792.08 g/mol; Anal.
width, for 2 and 5 respectively. The unit cell determi-
Calc. for C H PtN O F Cl : C, 42.41; H, 2.02; N, 3.53.
Found: C, 42.70; H, 1.84; N, 3.26%. IR (KBr, cm ):
nation and data integration were carried out using the
28
16
2
2
6
2
−
1
[25]
CrysAlis package of Oxford Diffraction.
tures were solved by direct methods using Olex2
The struc-
[
26]
ν(C=N) 1,613; ν (Ar-OH) -, ν(CF ) 1329.
3
2
and refined by full-matrix least-squares on F with
[
27]
SHELXL-2015
using an anisotropic model for non-
2
.4 | Physical measurements
hydrogen atoms. All H atoms were introduced in ideal-
ized positions (dCH = 0.96 Å) using the riding model
with their isotropic displacement parameters fixed at
120% of their riding atom. The positional parameters
of disordered -groups in 2 and 5 were refined using
available tools (PART, DFIX, and SADI) of SHELXL97
and the combined anisotropic/isotropic refinement has
been applied for non-hydrogen atoms. The molecular
plots were obtained using the Olex2 program. The
crystallographic data and refinement details are quoted
in Table 1.
C, H and N analyses were performed with the Carlo-Erba
LA-118 microdosimeter and the AAS-1 N Carl-Zeiss-Jena
spectrometer was used for the determination of Co (II),
Cu (II), Mn (II) and Ni (II). The H NMR and
NMR spectra were recorded on a Bruker 400 DRX spec-
trometer in DMSO solution, using TMS as the internal
standard. Infrared spectra (4,000–400 cm ) were
recorded on a Bruker Vertex 70 spectrophotometer, using
KBr pellets. Diffuse reflectance spectra were recorded on
1
13
C
−1

LUPA S¸ CU ET AL.
5 of 13
1
TABLE 1 Crystal data and structure refinement parameters for HL , 2 and 5
1
1
1
Compound
Chemical formula
Fw
HL
[Cu(L )
2
] (2)
[Pd
2
(L )
2
(OAc)
2
]ꢀ1.16H
2
O (5)
C
14
H
9
ClF
3
NO
C
28
H
16CuCl
2
F
6
N
2
O
2
32 2 6 2 7.172
C H24.33PdCl F N O
299.67
160
660.87
293
949.23
293
Temperature (K)
Wavelength (Å)
Space group
a (Å)
0.71073
0.71073
0.71073
R-3
P2
1
/c
1
P2 /c
12.9383(5)
7.2504(3)
13.7824(6)
90
12.824(2)
7.2517(15)
14.168(2)
90
20.5107(8)
20.5107(8)
46.6892(19)
90
b (Å)
c (Å)
ꢁ
α ( )
ꢁ
β ( )
101.537(4)
90
99.216(16)
90
90
ꢁ
γ ( 0
120
3
V (Å )
1266.77(10)
1300.6(4)
2
17010.1(15)
18
Z
4
calcd (g cm−
3
)
1.571
1.688
1.668
ρ
Crystal size (mm)
0.30 × 0.30 × 0.15
0.50 × 0.20 × 0.20
1.120
0.30 × 0.15 × 0.04
1.168
μ (mm−
1
)
0.332
2
Θ range
6.034 to 50.046
6.188 to 50.046
3,615
6.572 to 50.036
12,049
Reflections collected
4,954
Independent reflections
2,237 [Rint = 0.0290] Rsigma = 0.0463]
3,615 [Rint = 0.0743]
3615/0/188
0.0450
6,672 [Rint = 0.0636]
6672/34/458
0.0636
Data/restraints/parameter
2237/0/182
0.0394
a
R
1
b
wR
2
0.0967
0.1017
0.1736
c
GOF
0.19/−0.19
0.56/−0.33
0.66/−0.62
a
b
2
2 2
2 2 1/2
c
2
2 2
1/2
R
1
= Σ||F
o
|-|F
c
||/Σ|F
o
|. wR
2
= {Σ[w (F
o
- F
c
) ]/Σ[w (F
o
) ]}
.
GOF = {Σ[w (F
o c
- F ) ]/(n - p)} , where n is the number of reflections
and p is the total number of parameters refined.
2
2
.6 | Toxicity evaluation
germinating pots, the interior of which was lined with a
uniform and thin layer of cotton wool, over which a filter
paper was subsequently moistened with a sufficient
quantity of distilled water. The kernels were placed row
by row in these vessels at a distance of about one centi-
meter apart and let to germinate for approximately 24 hr
in a dark germinating chamber (Sanyo MLR351H;
.6.1 | Phytotoxicity evaluation
1
The evaluation of acute toxicity of HL ligand and its
complex combinations with Co (II), Cu (II), Ni (II) and
Pd (II) ions was performed on the plant species Triticum
aestivum L. in order to investigate their potential effects
on plant cells.
ꢁ
Sanyo), at 25 C. Subsequently, kernels with a root length
of 1 cm were selected and then 10 such specimens (plus
an additional sample for the microscopic examination)
were placed in Petri dishes with a diameter of 10 cm and
in which the test solution was brought. For the micro-
scopic examination of the nuclei, the staining of the
genetic material with acetic orcein followed by the
As it is described in literature, the key idea of the
[28,29]
Constantinescu test method,
consists in identifying
the concentration of solutions or suspensions of the test
compounds that, depending on the duration of action,
affects the root growth of the plant species Triticum
aestivum L.
[
30]
squash of the root tip was used.
The examination was
performed under the 100 x objective lens using cedar oil
for immersion, and nuclei were observed for changes in
the karyokinetic film.
Before being soaked in distilled water for a period of
2
4 hr, wheat kernels were selected for healthy aspect and
The experiment was performed on a total of 25 Petri
dishes - 5 dishes corresponding to dilutions of the ligand
uniform size. After 24 hr they were placed in Linhart

6
of 13
LUPA S¸ CU ET AL.
suspension and the solutions for its complexes and a con-
trol box with distilled water and another with distilled
water and DMSO (1%).
ligand suspensions and complex assay combinations
obtained with 0.1% DMSO (50 μM - C , 5 μM - C , 1 μM -
l
2
C , 0.1 μM - C , 0.01 μM - C ).
3
4
5
The 5 concentrations of the solutions varied from
0
(for the control) to 100 μM.
Linear measurements of the primary roots were per-
3 | RESULTS AND DISCUSSION
formed over 3 consecutive days at 24, 48- and 72-hr inter-
vals, and the results obtained were reported in the control
values. Statistical comparisons among Triticum groups
were analyzed through robust linear regression with two
variables (substance and concentration as factors), using
1
The Schiff base HL (Scheme 1) was synthesized in good
1
13
yield and characterized by IR, UV–Vis, H NMR, C NMR
spectroscopy and X-ray diffraction. All compounds were
prepared by direct reaction between ligand and the
corresponding metal salts, the molar ratio used was 1:1
[M:L] for the cobalt (II), copper (II), manganese (II), palla-
dium (II) and platinum (II) complexes and 1:2 [M:L] for
the nickel (II) complex. The metal complexes are micro-
crystalline solids which are stable in air. They are insolu-
ble in organic solvents such as acetone, methanol, ethanol,
but soluble in DMF and DMSO, with the exception of the
platinum complex which is also soluble in ethanol. The
synthesis of the complexes is reproducible and the Schiff
base coordinates as a mononegative bidentate ligand.
[
31]
MM-type estimators as described by Koller and Stahel
(
‘robustbase’ R package). IC50 concentrations were deter-
[
32]
mined using non-linear regression (‘drc’ R package).
2.6.2 | Animal toxicity evaluation
1
The evaluation of the acute toxicity of HL ligand and its
complex combinations was performed on the crustacean
Artemia franciscana Kellogg.
−
1
2
−1
The aim was to analyse the potential modifications
that these substances can make on animal cell.
The molar conductivity values (4–17 Ω ‧cm ‧ mol )
of the complexes 1–6 in 10 M DMF solution show that
they are non-electrolytes.
(reported in Section 2) confirm the stoichiometry of the
ligand and the corresponding coordination compound.
−3
[
38]
The principle of the lethality test on native species of
Artemia species is to identify the concentration of the stud-
ied substances, which, depending on the duration of
action, influences causes the death of 50% of the ani-
The elemental analyses data
[33]
[34,35]
mals. The method was applied as reported by
with
1
some minor adaptations as reported by other
3.1 | Crystal structure description of HL ,
[cu(L ) ] (2), [Pd (L ) (OAc) ꢀ1.16H O] (5)
[36,37]
1
1
researchers.
2
2
2
2
2
Artificial see water was obtained from a commercially
available salt mixture (CoralMarine, Grotech) dissolved
in distilled water at a concentration of 33.4 g/l. As for the
Artemia franciscana (Kellog, 1906), they come from Great
Salt Lake in the United States, marketed by Ocean Star
International and repackaged by S. K. Trading from
Thailand. The hatching process was initiated by about
According to X-ray diffraction study all the investigated
compounds have a molecular crystal structure, as shown
in Figures 1, 2 and 3 respectively. The bond distances and
angles are quoted in Tables 2, 3. There are no co-
1
crystallized solvent molecules in crystals of HL and 2,
while compound 5 crystallizes with 1.16 water molecules,
disordered between several positions, per copper
(II) complex.
4
8 hr before the test, placing approximately 2 g of cysts in
a volume of 500 ml of previously prepared artificial sea
ꢁ
1
water at a temperature of 25 C under constant oxygena-
The molecule of HL in the solid state are nonplanar:
tion. Nauplii (recently hatched organisms) were sampled
using micropipettes and used for testing. The test was
performed on 4 x 6 well plates, 2 ml from each concentra-
tion being transferred in each well, after which 12–15
animals were added. The experiment was performed in
triplicate (three wells for each concentration and control
group). The plates were covered and kept in the dark at
two planar fragments are rotated around the N1-C8 bond
at 46.84(7) . This configuration is stabilized by strong
ꢁ
intramolecular O-HꢀꢀꢀN hydrogen bonding (Figure 1).
1
Compound [Cu(L ) ] (2) exhibits a mononuclear
2
centrosymmetric structure (Figure 2) The copper
ꢁ
the temperature of 25 C. After 24 and 48 hr the samples
were examined for the presence of dead nauplii or slow
movement during an observation period of 10 seconds.
The test groups were made up of two controls (1%
DMSO in sea water and DMSO-free control consisting of
artificial sea water) and 5 increasing concentrations of
1
SCHEME 1 Schiff base ligand HL

LUPA S¸ CU ET AL.
7 of 13
1
FIGURE 1 X-ray molecular structure of HL with atom
labelling scheme and thermal ellipsoids at 50% probability level.
H-bond parameters: O1-HꢀꢀꢀN1 [O1-H 0.82 Å, HꢀꢀꢀN1 1.87 Å,
ꢁ
O1ꢀꢀꢀN1 2.590(2) Å, <O1HN1 146.8 ]
1
FIGURE 3 a) X-ray molecular structure of [Pd
2 2 2
(L ) (OAc) ]
(5) with atom labelling scheme and thermal ellipsoids at 30%
probability level; b) view along Cu1ꢀꢀꢀCu2 line. Fluorine atoms are
not shown for clarity. H-bond parameters: C17-HꢀꢀꢀO6 [C17-H
ꢁ
0
.93 Å, HꢀꢀꢀO6 2.49 Å, C17ꢀꢀꢀO6 3.36(1) Å, <C17HO6 155.7 ];
C31-HꢀꢀꢀO1 [C31-H 0.93 Å, HꢀꢀꢀO1 2.51 Å, C31ꢀꢀꢀO1 3.36(1) Å,
ꢁ
<
C31HO1 151.4 ]
(
II) atom occupies a special position on the centre of sym-
metry exhibiting N O coordination in a slightly distorted
2
2
square planar geometry. Two Schiff base moieties behave
as deprotonate bidentate chelating ligands with Cu1-O1
1.861(3) Å and Cu1-N1 2.017(3) Å distances. The coordi-
nated ligand keeps the same configuration as in free
state, but the dihedral angle between two planar frag-
ꢁ
ments increases up to 51.6(3) (Figure 2b) due to addi-
tional steric effect in the complex molecule.
1
FIGURE 2 a) X-ray molecular structure of [Cu(L )
2
] (2) with
1
Compared
with
[Cu(L ) ]
(2)
complex
2
atom labelling scheme and thermal ellipsoids at 50% probability
level; b) a view showing the configuration of the ligands
in the complex
1
[
Pd (L ) (OAc) ] (5) exhibits a dinuclear structure, as
2 2 2
shown in Figure 3a, b. Two paladium (II) atoms are
bridged, at distance of 2.86175(8) Å, by two carboxylate
Symmetry code: (i) 1 – x, 1 – y, 1 – z
2
0
groups acting as bidentate μ -к O:O ligands. It is also to
2
note the presence of two inramolecular C-HꢀꢀꢀO hydrogen
1
−
bonds, towards the oxygen atoms of the (L ) ligands as

8
of 13
LUPA S¸ CU ET AL.
ꢁ
1
TABLE 2 Bond distances (Å) and angles ( ) for ligand HL
and complex 2
indicating coordination with the central metal ion by the
oxygen atom of the phenolic hydroxyl group
[
40]
(
Figures S2–7).
Bonds Lengths (Å)
The spectrum of complex 5 shows two bands at
1
1
484 and 1,360 cm− corresponding to the vibration
1
HL
2
−
−
Cl1-C13
F1-C14
F2-C14
F3-C14
O1-C1
N1-C7
N1-C8
C6-C7
C8-C13
1.730(2)
1.335(2)
1.343(2)
1.334(2)
1.347(2)
1.285(2)
1.407(2)
1.448(3)
1.394(3)
Cu1-O1
Cu1-O1
Cu1-N1
Cu1-N1
Cl1-C9
F1-C14
F2-C14
F3-C14
O1-C1
N1-C7
N1-C8
1.861(3)
1.861(3)
2.017(3)
2.017(3)
1.722(4)
1.244(7)
1.268(7)
1.308(7)
1.318(5)
1.301(5)
1.438(5)
frequencies νas (COO ) and νs (COO ) respectively.
The difference between the two frequencies Δ = [ν
COO ) - ν (COO )] is 125 cm and confirms the
1
1
as
−
−
−1
(
s
bridging coordination of the acetate ion to the palla-
[
41]
dium (II) ion.
In the IR spectra of complexes 1, 3 and 5 a consider-
−1
able peak observed in the 3,450–3,435 cm .
range, which are indicative of coordinated water in
[
42]
the complexes.
The electronic spectra recorded on polycrystalline
powder provide information on metal ion stereochemis-
try in complex combinations. The spectral data from the
electronic spectra recorded for the complexes of Co (II),
Cu (II), Ni (II), Pd (II) and Pt (II) obtained with ligand
ꢁ
Angles ( )
1
1
HL 2
HL and magnetic moment values are shown in Table 4.
1
C7-N1-C8
O1-C1-C2
O1-C1-C6
C2-C1-C6
C1-C6-C7
C5-C6-C1
C5-C6-C7
N1-C7-C6
C9-C8-N1
C13-C8-N1
119.88(16)
118.12(18)
122.14(18)
119.75(18)
121.37(17)
119.09(18)
119.54(17)
120.88(17)
123.01(16)
118.75(17)
O1-Cu1-N1
O11-Cu1-N1
C1-O1-Cu1
C7-N1-Cu1
C7-N1-C8
C8-N1-Cu1
O1-C1-C2
O1-C1-C6
N1-C7-C6
C9-C8-N1
C13-C8-N1
92.06(14)
87.94(14)
127.5(3)
121.6(3)
116.7(3)
121.4(3)
119.1(4)
123.2(4)
127.0(4)
120.9(4)
120.5(4)
The electronic spectrum of ligand HL (Figure S8)
−
1
has two absorption maxima at 33330 and 26,650 cm ,
the maxima were attributes to intraligand transitions
n ! π * and π ! π * , respectively.
These absorption bands are shifted to smaller energies
in the electronic spectra of the complex combinations as
a result of coordination of the ligand to the metal ion.
For complex 1, the electronic spectrum has two absorp-
−
1
−1
tion bands at 15000 cm and 21,500 cm assigned to
4
4
4
4
T (F) ! A (F) and T (F) ! T1g(P) transitions,
1g
2g
1g
respectively. These transitions suggest typical behaviours
for the spin-high Co (II) complexes. The magnetic moment
value (5.10 MB) and the brown color of this complex sup-
(
1)
[43,44]
Symmetry code: 1 - x, 1 - y, 1 - z.
port octahedral geometry.
The electronic spectrum of complex 2 shows a broad
1
−1
acceptors of protons. As expected, the dihedral angle
between two planar fragments reaches a much higher
value of 80.675(3) and 80.702(3) (Figure 3b) for the
ligands denoted by N1O1 and N2O2 atoms, respectively.
band at 14490 cm− and a number at 23800 cm , which
2
2
2
2
were assigned to transitions B1g ! B and B ! E
2g
1g
g
ꢁ
ꢁ
for square-planar stereochemistry. The magnetic moment
(1.80 MB) suggests the antiferromagnetic coupling of para-
magnetic Cu (II) ions with S = 1/2 at room temperature.
They also indicate the existence of monomer copper
[
45]
3.2 | Spectral characterisation
(II) species.
In the spectrum of complex 4 there are three absorp-
tion bands at 9500 cm , 15,260 cm and 20,600 cm-1
−
1
−1
−1
The intense band of 1,620 cm of the IR spectrum of the
1
3
3
HL ligand attributed to the ν(C=N) vibration is shifted
assigned
to
transitions
A (F)
!
T (F),
2g
2
g
3
3
3
3
in the spectra of the complexes to lower frequencies by
A (F) ! T (F) and A (F) ! T (P) respectively.
2g
1g
2g
1g
−
1
8
–11 cm , suggesting the coordination of the Schiff base
These transitions are characteristic to octahedral
stereochemistry. The magnetic moment value of 3.40 MB
corresponds to two non-paired electrons on nickel ion for
2+
2+
2+
2+
2+
on the metal ions Co , Cu , Ni , Pd and Pt via the
azometinic nitrogen atom.
[39]
The narrow band of medium intensity at 1276 cm−1
of the IR spectrum of the ligand (Figure S1) attributed to
the ν(C-OH) phenolic vibration is shifted to lower fre-
quencies or disappears in IR spectra of the complexes
their six-coordinated configuration.
The electronic spectra of complexes 5 and 6 indicate a
square-planar geometry for Pd (II) ions and Pt (II) ions.
[46,47]
−
1
The very intense bands at 22980 and 24,300 cm

LUPA S¸ CU ET AL.
9 of 13
ꢁ
TABLE 3 Bond distances (Å) and angles ( ) for complex 5
ꢁ
Bonds Lengths (Å)
Angles ( )
Pd1-O1
Pd1-O2
Pd1-O4
Pd1-N1
Pd2-O3
Pd2-O5
Pd2-O6
Pd2-N2
Cl1-C13
Cl2-C27
F1-C18
F2-C18
F3-C18
F4-C32
1.964(5)
2.026(5)
2.047(5)
1.977(6)
2.046(5)
2.013(5)
1.965(6)
2.000(6)
1.719(10)
1.701(10)
1.341(10)
1.346(10)
1.349(9)
1.363(10)
F5-C32
F6-C32
O2-C1
O3-C1
O4-C3
O5-C3
C1-C2
C3-C4
1.358(9)
1.361(10)
1.236(9)
1.265(9)
1.256(9)
1.254(10)
1.519(11)
1.494(11)
O1-Pd1-O2
O1-Pd1-O4
O1-Pd1-N1
O2-Pd1-O4
N1-Pd1-O2
N1-Pd1-O4
O5-Pd2-O3
O6-Pd2-O3
O6-Pd2-O5
O6-Pd2-N2
N2-Pd2-O3
N2-Pd2-O5
C5-O1-Pd1
C1-O2-Pd1
C1-O3-Pd2
172.6(2)
87.0(2)
92.8(2)
87.3(2)
93.0(2)
179.4(3)
86.9(2)
87.8(2)
174.3(2)
93.3(2)
178.8(3)
92.0(2)
124.4(5)
126.7(5)
122.4(5)
C3-O4-Pd1
C3-O5-Pd2
C19-O6-Pd2
C11-N1-Pd1
C11-N1-C12
C12-N1-Pd1
C25-N2-Pd2
C25-N2-C26
C26-N2-Pd2
O2-C1-O3
123.9(5)
124.2(5)
124.8(5)
123.3(6)
118.2(7)
118.4(5)
124.1(5)
117.9(7)
118.0(5)
127.2(8)
116.2(8)
116.5(8)
115.8(9)
128.0(8)
116.2(8)
O2-C1-C2
O3-C1-C2
O4-C3-C4
O5-C3-O4
O5-C3-C4
TABLE 4 Electronic spectral assignments (cm−1) of complexes 1, 2, 4–6
Transitions d–d (cm−
1
)
μ ef (MB)
Geometry
Compounds
1
4
4
4
4
[
Co(L )
2
(H
2
O)
2
] (1)
T
4
1g(F) ! T2g(P) T1g(F) ! A2g(F)
5.10
Octahedral
4
T
1g(F) ! T1g(P)
-
21,500 15,000
1
2
2
2
2
2
2
[
[
[
[
Cu(L )
2
] (2)
B
-
1g ! B2g
B
1g ! E
g
B
1g ! A1g 14,490 23,800
1.80
3.40
*
Square-planar
Octahedral
1
3
1
3
3
3
Ni(L )
2
] (4)
A
3
2g(F) ! T2g(F) A2g(F) ! T1g(F)
3
A
2g(F) ! T1g(P) 9500 15,260 20,618
1
1
1
1
1
1
Pd
2
(L )
2
(OAc)
2
ꢀ1.16H
2
O] (5)
A
1g ! B1g
A
A
1g ! A2g
A
1g ! E
g
Square-planar
Square-planar
-
1
22,980 -
1
1
1
1
1
1
Pt(L )
2
] (6)
A
1g ! B1g
1g ! A2g
A
1g ! E
g
*
-
22,900 -
*
diamagnetic.
respectively are a combination of metal–ligand charge
(δ = 8.25 ppm) in the spectrum of complex 5. This
information indicates the coordination of the metal
centre to the imine and phenoxo groups.
[48,49]
transfer and d–d bands.
1
1
H-NMR spectra of the ligand HL and its palladium
complex (5) were recorded at 298 K in DMSO-d6
The FAB mass spectra of Co (II), Cu (II), Mn (II),
Ni (II), Pd (II) and Pt (II) complexes with Schiff base
HL were recorded to determine molecular species in
(
Figures S9–12).
1
1
The H-NMR spectrum of the Schiff base shows
distinct
resonance
aromatic
OH
group
at
solution (Figure S13).
δ = 12.78 ppm. The chemical shift of imine carbon
proton was δ = 9.09 ppm for the free ligand. The
absence of singlet belonging to OH proton in the H-
NMR spectrum of the Pd (II) complex suggests the
replacement of this proton during complexation with
the metal ion. Also, the coordination of imine nitrogen
to the metal centre was signalled by an appreciable
downfield shift of the resonance signal of imine proton
The mass spectra of these complexes show peaks
assignable to various fragments arising from the thermal
cleavage of the complexes (Table S1). The molecular ion
1
+
[M] peaks obtained from complexes are as follow:
m/z = 673.4 (1), m/z = 663.4 (2), m/z = 683.8 (3),
m/z = 1089.9 (4), m/z = 868.8 (5), m/z = 790.4 (6).
The data obtained provide good agreement for the
molecular formula of these complexes.

10 of 13
LUPA S¸ CU ET AL.
3.3 | Thermal behaviour of complexes
The thermal analysis was used in order to obtain infor-
mation concerning both the composition and stability of
[50]
complexes.
Thermogravimetric analyses data reveal
that compounds 1, 3 and 5 are hydrated while com-
pounds 2, 4 and 6 are anhydrous. Complexes 1 and 3 hav-
ꢁ
ꢁ
ing a weight loss between 130 C and 200 C which
corresponds to two water molecules directly bonded to
the metal centre and in the case of the complex 5, a loss
of mass corresponding to a crystallization water molecule
is confirmed in the first step (Figure 4).
According to TG and DTA curves, complex 4 is stable
ꢁ
up to 275 C when it starts to decompose in several exo-
thermic steps. This high thermal stability is in accord with
its anhydrous nature. The thermal decomposition
ꢁ
(
Figure S14) starts with melting at 275 C followed by the
ligand thermolysis and oxidative degradation. The final
ꢁ
residue obtained at 825 C is NiO. The complex 6 is stable
ꢁ
up to 140 C indicating the absence of any lattice or coordi-
nated water/solvent molecules (Figure S15). The first mass
loss step corresponds to both ligands thermolysis with par-
ꢁ
achlorobenzotrifluoride evaporation (b.p. 138 C). This
ꢁ
endothermic step undergoes in 140–320 C temperature
FIGURE 5 X-ray diffraction patterns of complexes 3, 4 and 6
ꢁ
range with a maximum rate at 230 C. The second decom-
position step (320–500 C), an exothermic ones, corre-
ꢁ
sponds to oxidative degradation of the remaining
compound to metallic platinum as powder XRD indicates.
After the decomposition of the patterns of the com-
plexes, the indexation was made by DICVOL06 pro-
gram for complex 3, by N-TREOR program for
[51–53]
complex 4, and by ITO13 program for complex 6.
3
.4 | Powder X-ray diffraction
The results given by this software indicate that the
complex 3 was crystallized in the tetragonal system (P4);
it unit cell parameters are a = 5.7761 Å, b = 5.7761 Å,
The X-ray diffraction diagrams for ground powder of
complexes (Figure 5) were collected at room tempera-
ture with diffractometer Rigaku ULTIMA IV using
monochromatic Cu-kα radiation. Reflection were
ꢁ
ꢁ
c = 9.4703 Å with β ( ) = 90.000 , and the complex
4 was crystallized in monoclinic system (P12 1); it unit
1
cell parameters are a = 13.9546(17) Å, b = 7.3262(8) Å,
ꢁ
ꢁ
ꢁ
scanned for diffraction angles (2θ) ranging from 5 to
c = 12.7993(17) Å with β( ) = 99.019(4) . Also, the com-
plex 6 was crystallized in triclinic system (P1); it unit cell
parameters are a = 11.844(3) Å, b = 15.046(6) Å,
ꢁ
5
0 for complexes 1, 4 and 6 and for diffraction angles
o
o
(2θ) ranging from 5 to 80 for complex 3. The collec-
ꢁ
ꢁ
tion of resolution data are summarized in Table S2.
c = 8.462(2) Å with β( ) = 93.37(2) .
FIGURE 4 Thermogravimetric analysis
of complex 5

LUPA S¸ CU ET AL.
11 of 13
FIGURE 9 Prophase of a plant cell treated with complex 4 (C
1
concentration)
FIGURE 6 Response-concentration plots describing the root
growth of Triticum aestivum L. under the influence of the metal
complexes at the concentrations tested (varying between 0 and
At the microscopic scale, the results obtained were in
line with the ones seen at macroscopic level by measuring
the root length of Triticum aestivum L. treated with various
1
00 μM)
1
test solutions. For the ligand HL , at each concentration
all division phases (prophases, metaphases, anaphases,
telopheses) could be observed (Figure 7, Figure S16).
In the case of complex 2, for the C concentration no
1
division process was observed, the interphase nuclei had
polygonal forms and the walls of the cells were corru-
gated (Figure S17). On the other side, at C concentration
5
the microscopic images were very similar to those seen
1
with HL and the control group, with telophases seen rel-
atively frequently, and interphases with visible nucleoli
(Figure 8, Figure S18).
1
FIGURE 7 Division phases seen with the lowest HL (C
5
concentration)
Similar microscopic observations were done for the
complex 2, regarding the division process (Figure S19).
At C concentration the nuclei from interphase were con-
1
densed, nucleoli not being generally visible. At the
highest concentration for complex 4, C1 presented
numerous cells in interphase, with a number of cells in
the initial stage of prophase, with no nucleoli and con-
densed nuclear material (Figure 9). As the concentrations
decreased, more cells in different division phases could
be observed for C concentration (Figure 10).
3
In the case of complex 5, at all concentrations evalu-
ated the root cell division seemed unaffected by the treat-
ment and were very similar with those seen in the
control (Figure S20).
FIGURE 8 Division phases for the complex 1 (C
concentration) – telophases and visible nucleol
5
3
3
.5 | Toxicity evaluation
.5.1 | Plant toxicity evaluation
The test substances showed dose-dependent toxicity
between 0 and 100 μM) on the monocotyledonous
(
species (Figure 6). The most pronounced toxicity was
observed for the complex 4 with Ni (II), intermediate
toxicity was seen for the complexes 1 with Co (II) and
2
with Cu (II), and the lowest toxicity was observed for
1
ligand HL . Complex 5 with Pd (II) was devoid of
toxicity, with no change in radicular elongation at any of
the tested concentrations.
FIGURE 10 Hypertrophied nucleoli and bridge telophase
observed with complex 4 (C1 concentration)

12 of 13
LUPA S¸ CU ET AL.
1
TABLE 5 Results from lethality test for the ligand HL and its
complexes 1–6
distorted octahedral geometry, while the copper (II), palla-
dium (II) and platinum (II) complexes having square–
planar geometry.
Lethality recorded after a
X-ray crystallographic studies reveal that copper
certain amount of time
Compounds
(
II) complex exhibits a mononuclear centrosymmetric
tested/concentrations
24 hr
48 hr
structure and palladium (II) complex presents a din-
uclear structure in which the two paladium (II) atoms
are bridged, at distance of 2.86175(8) Å, by two car-
1
HL – C
1
, C
2
, C
3
, C
4
, C
5
0%
0% *Slowed
movements
2
0
Complex 1 - C
, C
Complex 2 - C
, C
Complex 3 - C
, C
Complex 4 - C
, C
Complex 5 - C
, C
Complex 6 - C
, C
Martor with DMSO
Martor without DMSO
1
1
1
1
1
1
, C
, C
, C
, C
, C
, C
2
2
2
2
2
2
, C
, C
, C
, C
, C
, C
3
3
3
3
3
3
,
,
,
,
,
,
0% *Slowed
movements
2,5% - C
1
boxylate groups acting as bidentate μ -к O:O ligands.
2
C
4
5
At concentrations up to 100 μM the ligand and com-
plexes showed very little toxicity, if at all on Artemia
franciscana Kellogg. Triticum aestivum L. root growth
was most affected by the nickel (II) complex, the cop-
per (II) and cobalt (II) complexes had inhibitory effects
only at 50 μM concentrations or higher, whereas the
palladium (II) complex was devoid of any toxicity on
the plant cells. These promising results are encourag-
ing for further research in this field.
0%
0%
0%
0%
0%
5% - C
5% - C
1
1
C
4
5
C
4
5
2,5% – C
1
C
4
5
2,5% - C
1
C
4
5
5% - C
1
C
4
5
ACKNOWLEDGEMENTS
This work was financially supported by “Carol Davila”
University of Medicine and Pharmacy through
Contract no. 23PFE/17.10.2018 funded by the Ministry
of Research and Innovation within PNCDI III,
Program 1 – Development of the National RD system,
Subprogram 1.2 – Institutional Performance – RDI
excellence funding projects.
0%
0%
5%
0%
3.5.2 | Animal toxicity evaluation
The results in the Table 5 indicate a minimal acute toxic-
ity on Artemia nauplii (0% to 24-hr lethality for all tested
substances and lethality below 5% at 48 hr). Signs of tox-
icity were observed only for cobalt (II) complex 1, at
which the shellfish showed slowed movements in the
first 24 hr.
CONFLICT OF INTEREST
All authors express that they have no conflict of inter-
est to declare.
SUPPLEMENTARY DATA
CCDC 1957150, 1,957,156, 1,957,157 contains the supple-
1
mentary crystallographic data for HL , 2 and 5. These
4
| CONCLUSION
data can be obtained free of charge via http://www.ccdc.
cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: +441,223 336,033; or e-mail:
deposit@ccdc.cam.ac.uk.
The transition metal complexes with 2-(((2-chloro-
1
(trifluoromethyl)phenyl)imino)methyl)phenol (HL ) were
synthesized. The compounds have been investigated by
spectroscopic methods, elemental and thermal analysis,
magnetic susceptibility measurements, molar electric
conductivity, X-ray powder diffraction (XRD) and X-ray
crystallography on the monocrystal.
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