Synthesis, structures and biological properties of nickel(II) phthalates with imidazole and its derivatives

Article abstract of DOI:10.1016/j.poly.2009.11.016

Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)]₆(Pht)·H₂O (1), [Ni(Pht)(Im)₃(H₂O)₂]· H₂O (2) and [Ni(Pht)(2-MeIm)₃(H₂O)₃]· H₂

Full text of DOI:10.1016/j.poly.2009.11.016

Polyhedron 29 (2010) 1102–1108
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, structures and biological properties of nickel(II) phthalates
with imidazole and its derivatives
Irina G. Filippova a, Olesea A. Gherco a, Yurii A. Simonov a, Alexandra A. Deseatnic-Ciloci b,
Steliana F. Clapco b, Janeta P. Tiurina b, Svetlana G. Baca c,
*
a Institute of Applied Physics, Academy of Sciences of Moldova, MD2028 Chisinau, Republic of Moldova
b Institute of Microbiology and Biotechnology, Academy of Sciences of Moldova, MD2028 Chisinau, Republic of Moldova
c Institute of Chemistry, Academy of Sciences of Moldova, MD2028 Chisinau, Republic of Moldova
a r t i c l e i n f o
a b s t r a c t
Article history:
Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)]6(Pht)ꢀH2O (1), [Ni(Ph-
t)(Im)3(H2O)2]ꢀH2O (2) and [Ni(Pht)(2-MeIm)3(H2O)3]ꢀH2O (3), and coordination polymer [Ni(Pht)(4-
MeIm)2(H2O)]n (4) (where Pht = dianion of o-phthalic acid, Im = imidazole, 2-MeIm = 2-methylimidazole,
4-MeIm = 4-methylimidazole) have been synthesized. The complexes 1–4 were characterised by elemen-
tal analysis, IR data, thermogravimetric, and X-ray diffraction analyses. X-ray analysis shows that the
asymmetric unit of 1 consists of [Ni(Im)]62+ cation, Pht2ꢁ anion and solvate H2O molecule. The phthalate
dianion does not take part in coordination to metal ion. The cations, anions and water molecules are
linked via N–Hꢀ ꢀ ꢀO and O–Hꢀ ꢀ ꢀO interactions forming 2D hydrogen-bonded networks. The structures of
2 and 3 are similar to other mononuclear Ni(II) phthalate complexes where Pht2ꢁ anions act as monoden-
tate ligands and uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen
bonded double-chains. The structure of 4 consists of [Ni(4-MeIm)2(H2O)] building units connected by
phthalate ions to form helical chains. The complexes 1–4 were tested for their ability to increase the bio-
synthesis of enzymes.
Received 7 October 2009
Accepted 20 November 2009
Available online 26 November 2009
Keywords:
Nickel(II) carboxylate
Phthalate complex
Crystal structure
Hydrogen bonding
Biological activity
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
while Ni(II) mainly forms mononuclear complexes with a mono-
dentate function of Pht [12–19]. Out of 27 structural investigations
o-Phthalic acid (H2Pht) is successfully used for creating an
extensive range of coordination compounds with different dimen-
sionalities: monomers, clusters and metallopolymers or coordina-
tion polymers. Bridging or chelate-bridging functions of that
ligand usually lead to the formation of coordination polymers.
The phthalate ligand also takes part in hydrogen bonding that sta-
bilizes the polymeric structures by forming two- and three-dimen-
sional networks. Despite numerous coordination modes of the
phthalate ligand (twenty six coordination modes with metal cen-
ters in complexes [1]), the 1,6-bridging function of Pht2ꢁ is the
most frequent in its metal complexes. In this case, the phthalate
anion acts as a bidentate ligand and coordinates to metal ions by
one oxygen atom from each carboxylate group. This statistics has
been persisted in metal phthalate coordination polymers with dif-
ferent aromatic amines [1]. However, each of 3d-metals has its
own preferences in coordination modes of the Pht ligand. For
example, most of Zn(II) complexes have dinuclear or polymeric
structures [2–11] with bridging function of the dicarboxylate,
of Ni(II) phthalate complexes extracted from CSD (version 5.30)
[20] the phthalate executes the bridging function only in eight
[21–27]. The combinations of the phthalate ligand and N-donor
aromatic amines often lead to the organization of mononuclear
complexes with the common formula [Ni(Pht)(amine)(H2O)3]ꢀ
nH2O [where amine – one bidentate ligand (2,20-dipyridylamine
(dpa), 1,100-phenanthroline (phen) [15] 2,20-bipyridine (bpy) [17]
or two monodentate ligands (pyridine (Py), 3-methylpyridine
(b-Pic), 1-methylimidazole (1-MeIm) [13] and n = 0, 1, 3]. The
phthalate ligand occupies only one place in the metal octahedron,
and the coordination sphere is completed by two N-atoms of aro-
matic amines and oxygen atoms of three water molecules. The
presence of numerous hydrogen atom donors and acceptors results
in extensive and similar hydrogen bonding in these compounds.
First of all, the coordinated water molecules and uncoordinated
oxygen atoms of carboxylate groups form the intramolecular
hydrogen bonds. Then, neighboring complexes are linked via
O(W)–Hꢀ ꢀ ꢀOcarb hydrogen bonds into double-chains. In some cases
the initial step in the organization of such chain is the formation of
centrosymmetric dimer unit with four R22(8) rings [28]. The
arrangement of double-chains mainly depends on the nature of
aromatic amines.
* Corresponding author. Tel.: +373 22739661; fax: +373 22739954.
E-mail address: sbaca_md@yahoo.com (S.G. Baca).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.11.016

I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
1103
In this paper, we report the synthesis of four new nickel(II)
phthalate compounds: mononuclear complexes [Ni(Im)]6(Pht)ꢀH2O
(1), [Ni(Pht)(Im)3(H2O)2]ꢀH2O (2) and [Ni(Pht)(2-MeIm)3(H2O)3]ꢀ
H2O (3), and coordination polymer [Ni(Pht)(4-MeIm)2(H2O)]n (4)
(where Pht = dianion of o-phthalic acid, Im = imidazole, 2-MeIm =
2-methylimidazole, 4-MeIm = 4-methylimidazole). The complexes
1–4 were characterised by elemental analysis, IR data, thermo-
gravimetric and single-crystal X-ray diffraction analyses.
The past years investigations show that coordination com-
pounds play an important role in the directed synthesis of bioac-
tive substances, including enzymes of microorganisms [29]. The
use of complexes with certain trace-metal elements is considered
effective due to their more rapid penetration in the cells and lower
toxicity in comparison with the metal ions from nonorganic com-
pounds [30,31]. Nickel plays an essential role in many microorgan-
isms in which it is incorporated into microbial enzymes (urease,
hydrogenase, acetyl coenzyme A decarbonilase/synthetase, dehy-
drogenase, metilCoM reductase, superoxide dismutase) [32,33].
For example, the coordination compounds of Ni(II) with thiosemi-
carbazones are able to increase the biosynthesis of pectolytic en-
zymes of fungal strains Penicillium viride with 13–58% [34]. The
influence of the newly synthesized Ni(II) complexes 1–4 on the
protease synthesis was checked.
radiation) with CCD (area detector). The intensity data for 1 were
collected at room temperature on Enraf Nonius CAD4 single crystal
diffractometer (Cu K
a radiation). Crystal data, details of data col-
lections and refinement for 1–4 are given in Table 1. The structures
were solved by direct methods (SHELXS-97 [35]) and refined on F2
(SHELXl-97 [36]) in anisotropic approach for non-hydrogen atoms.
The positions of H-atoms were located from the difference synthe-
ses of electronic density and were refined as rigidly bonded to the
corresponding atom. Selected bond distances and angles are listed
in Table 2.
2.3. Biological testing
To estimate the biological role of the synthesized compounds
1–4, the fungal strain, conventionally named 10 T, an active pro-
ducer of protease was used. Submerged culturing was carried out
in Erlenmeyer flasks (0.5 L capacity) with the nutritive medium
with the following composition (g/L): wheat bran – 20.0; soya bean
flour – 10.0; CaCO3 – 2.0; (NH4)2SO4 – 1.0; yeasts extract – 10 ml/L;
pH 6.25. The tested compounds were added into the nutritive med-
ium in concentrations of 5, 10 and 15 mg/L. The nutritive medium
without coordinative compounds was used as control. The dura-
tion of the cultivation process was 8–10 days. The proteolytic
activity in the culture filtrate was established with gelatin (with
the value of pH 3.6 and 7.4) as substrate according to Willstatter
[37].
2. Experimental
2.1. Materials and physical measurements
2.4. Synthesis of [Ni(Im)6](Pht)ꢀH2O (1) and [Ni(Pht)(Im)3(H2O)2]ꢀH2O
(2)
All reagents were purchased from commercial sources and used
as received. The infrared spectra were recorded on a Perkin–Elmer
Spectrum One spectrometer using KBr pellets in the region 4000–
400 cmꢁ1. TG analyses were carried out on a Mettler-Toledo TA 50
2.4.1. Method A
Nickel(II) carbonate (0.6 g, 5 mmol) and H2Pht (0.83 g, 5 mmol)
were added to a solution of Im (0.68 g, 10 mmol) in water (30 ml).
The resulting mixture was heated at reflux for two hours. The solu-
tion was filtered and allowed to slowly evaporate. Green crystals of
compound 2 suitable for X-ray diffraction studies formed after two
weeks in 50% (1.2 g) yield. Anal. Calc. for C17H22N6NiO7 (481.12): C,
42.44; H, 4.61; N, 17.47; Ni, 12.20. Found: C, 42.43; H, 4.62; N,
in dry nitrogen (60 ml minꢁ1) at a heating rate of 5 °C minꢁ1
.
2.2. X-ray crystallography
Experimental data for 2, 3 and 4 were collected at room temper-
ature on Bruker AXS Smart single crystal diffractometer (Mo K
a
Table 1
Crystal data for compounds 1–4.
1
2
3
4
Empirical formula
Formula weight
Temperature, K
k (Å)
Crystal system
Space group
a (Å)
C26H30N12O5Ni
649.33
293(2)
1.54178
monoclinic
P21/c
13.083(3)
13.032(3)
18.429(4)
90
C17H22N6O7Ni
481.12
293(2)
0.71073
monoclinic
P21/n
10.748(2)
9.3117(19)
23.125(5)
90
C16H24N4O8Ni
459.10
293(2)
C16H18N4O5Ni
405.05
293(2)
0.71073
monoclinic
P21/n
11.508(2)
9.1050(18)
16.633(3)
90
0.71073
triclinic
ꢀ
P1
7.2640(15)
10.197(2)
14.427(3)
76.31(3)
b (Å)
c (Å)
a
(°)
b (°)
105.60(3)
90
3026.3(10)
4, 1.425
103.14(3)
90
2253.8(8)
4, 1.418
87.76(3)
84.87(3)
1033.9(4)
2, 1.475
0.988
101.02(3)
90
1710.7(6)
4, 1.573
c
(°)
V (Å3)
Z, Dcalc (g cm3)
l
(mmꢁ1
)
1.416
0.909
1.171
F(0 0 0)
1352
1000
480
840
Crystal size, (mm)
hmin, hmax (°)
Limiting indices
0.12 ꢂ 0.21 ꢂ 0.09
3.51, 68.99
ꢁ15 ꢃ h ꢃ 15
0 ꢃ k ꢃ 15
0 ꢃ l ꢃ 22
5635/5463
0.1482
0.40 ꢂ 0.26 ꢂ 0.12
1.81, 26.00
ꢁ13 ꢃ h ꢃ 13
ꢁ10 ꢃ k ꢃ 11
ꢁ28 ꢃ l ꢃ 28
15266/4339
0.0776
0.33 ꢂ 0.12 ꢂ 0.05
2.06, 26.50
ꢁ9 ꢃ h ꢃ 9
ꢁ12 ꢃ k ꢃ 12
ꢁ17 ꢃ l ꢃ 18
10517/4177
0.0268
0.14 ꢂ 0.10 ꢂ 0.05
1.99, 26.50
ꢁ14 ꢃ h ꢃ 14
ꢁ11 ꢃ k ꢃ 11
ꢁ20 ꢃ l ꢃ 20
15180/3502
0.0903
Reflections collected/unique reflections
Rint
Goodness-of-fit on F2
0.826
1.084
1.035
0.890
Final R1, wR2 [I > 2
R1, wR2 (all data)
r
(I)]
0.0613, 0.1271
0.1657, 0.1579
0.0616, 0.1584
0.0747, 0.1645
0.0313, 0.0763
0.0434, 0.0792
0.0556, 0.1025
0.1474, 0.1241

1104
I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
Table 2
(20%), respectively. The identity of 2 was established by compari-
son of IR data with crystallographically characterized precipitate
from Method A, and by elemental analysis (found for compound
Selected bond lengths (Å) and angles (°) for compounds 1–4.
1
Ni–N(1B)
Ni–N(1F)
Ni–N(1E)
2.116(4)
2.119(4)
2.123(4)
Ni–N(1A)
Ni–N(1D)
Ni–N(1C)
2.124(5)
2.147(5)
2.150(4)
2
C, 42.28; H, 4.60; N, 17.24; Ni, 12.47%). Anal. Calc. for
C26H30N12NiO5 (1) (649.33): C, 48.1; H, 4.66; N, 25.89; Ni 9.04.
Found: C, 47.94; H, 4.67; N, 25.52; Ni, 8.81%. IR data (KBr, cmꢁ1):
3437br,m, 3135br,vs, 3043s, 2933s, 2849s, 2725sh, 2632sh,
1608sh, 1563vs, 1490m, 1456m, 1400sh, 1379vs, 1325s, 1259sh,
1249m, 1168sh, 1146m, 1099s, 1072vs, 941s, 914m, 896m, 842s,
822s, 784m, 769m, 754s, 719m, 694m, 668vs, 653sh, 622m, 589w.
N(1B)–Ni–N(1F)
N(1B)–Ni–N(1A)
N(1B)–Ni–N(1D)
N(1F)–Ni–N(1A)
N(1E)–Ni–N(1A)
N(1A)–Ni–N(1C)
N(1F)–Ni–N(1E)
N(1D)–Ni–N(1C)
90.6(2)
89.7(2)
91.1(2)
92.7(2)
88.2(2)
90.4(2)
89.8(2)
88.1(2)
N(1E)–Ni–N(1D)
N(1F)–Ni–N(1D)
N(1B)–Ni–N(1C)
N(1B)–Ni–N(1E)
N(1A)–Ni–N(1D)
N(1F)–Ni–N(1C)
N(1E)–Ni–N(1C)
91.1(2)
88.8(2)
88.7(2)
177.8(2)
178.3(2)
176.8(2)
91.1(2)
2.5. Synthesis of [Ni(Pht)(2-MeIm)2(H2O)3]ꢀH2O (3)
2
A solution of Ni(NO3)2ꢀ6H2O (0.58 g, 2 mmol) in water (10 ml)
was added to a warm solution of KHPht (0.4 g, 2 mmol) and 2-
MeIm (0.33 g, 4 mmol) in water (10 ml). The resulting mixture
was stirred and heated at reflux for one hour. The green crystalline
product was filtered off, washed with water and ethanol and dried
in air. Yield: 0.44 g (48%). Anal. Calc. for C16H24N4NiO8 (459.08): C,
41.86; H, 5.27; N, 12.20; Ni 12.78. Found: C, 41.30; H, 5.25; N,
11.61; Ni, 12.53%. IR data (KBr, cmꢁ1): 3395sh, 3189br,vs,
3118sh, 1610sh, 1581sh, 1552vs, 1486s, 1445m, 1404vs, 1390vs,
1295m, 1160w, 1130sh, 1117m, 1086w, 1036w, 1012w, 932w,
858m, 828m, 809m, 768s, 746s, 738sh, 714m, 691m, 682m,
675m, 654m, 610m. Single crystals of compound 3 suitable for X-
ray diffraction studies were obtained from the mother liquor after
keeping in an open flask at room temperature for two weeks.
Ni(1)–N(1A)
Ni(1)–N(1B)
Ni(1)–N(1C)
2.100(3)
2.113(3)
2.140(3)
Ni(1)–O(1W)
Ni(1)–O(4)
Ni(1)–O(2W)
2.147(3)
2.154(2)
2.158(3)
N(1A)–Ni(1)–N(1B)
N(1A)–Ni(1)–N(1C)
N(1B)–Ni(1)–N(1C)
N(1A)–Ni(1)–O(1W)
N(1B)–Ni(1)–O(1W)
N(1C)–Ni(1)–O(1W)
O(4)–Ni(1)–O(2W)
95.3(1)
98.0(1)
89.4(1)
169.6(1)
94.0(1)
86.7(1)
91.2(1)
N(1A)–Ni(1)–O(4)
N(1B)–Ni(1)–O(4)
N(1C)–Ni(1)–O(4)
O(1W)–Ni(1)–O(4)
N(1A)–Ni(1)–O(2W)
N(1B)–Ni(1)–O(2W)
N(1C)–Ni(1)–O(2W)
O(1W)–Ni(1)–O(2W)
88.1(1)
176.5(1)
91.0(1)
82.5(1)
87.8(1)
88.2(1)
173.9(1)
87.8(1)
3
Ni(1)–N(1A)
Ni(1)–O(4)
Ni(1)–N(1B)
2.055(2)
2.069(2)
2.071(2)
Ni(1)–O(2W)
Ni(1)–O(3W)
Ni(1)–O(1W)
2.081(2)
2.110(2)
2.164(2)
N(1A)–Ni(1)–O(4)
N(1A)–Ni(1)–N(1B)
O(4)–Ni(1)–N(1B)
N(1A)–Ni(1)–O(2W)
O(4)–Ni(1)–O(2W)
N(1B)–Ni(1)–O(2W)
N(1A)–Ni(1)–O(3W)
172.78(7)
95.63(7)
89.91(7)
93.70(7)
81.57(6)
90.76(7)
94.95(7)
O(4)–Ni(1)–O(3W)
N(1B)–Ni(1)–O(3W)
O(2W)–Ni(1)–O(3W)
N(1A)–Ni(1)–O(1W)
O(4)–Ni(1)–O(1W)
N(1B)–Ni(1)–O(1W)
O(2W)–Ni(1)–O(1W)
O(3W)–Ni(1)–O(1W)
89.70(6)
89.64(7)
171.26(6)
88.82(7)
85.85(6)
174.93(7)
91.37(7)
87.57(6)
2.6. Synthesis of [Ni(Pht)(4-MeIm)2(H2O)]n (4)
A solution of Ni(CH3COO)2ꢀ4H2O (1.24 g, 5 mmol) in water
(10 ml) was added to a warm solution of KHPht (1.02 g, 5 mmol)
and 4-MeIm (0.82 g, 10 mmol) in ethanol (10 ml). The resulting
mixture was stirred and heated for one hour. The green crystalline
product was filtered off, washed with water and ethanol and dried
in air. Yield: 3.63 g, (90%). Anal. Calc. for C16H18N4NiO5 (405.03): C,
47.45; H, 4.48; N, 13.83; Ni 14.49. Found: C, 47.18; H, 4.33; N,
13.49; Ni, 13.78%. IR data (KBr, cmꢁ1): 3219br,vs, 3184sh, 3008m,
2870m, 1598sh, 1558vs, 1538vs, 1493s, 1444s, 1416vs, 1397vs,
1258w, 1234m, 1158m, 1149sh, 1108s, 1088m, 1041w, 1012w,
964s, 889w, 872m, 844s, 815s, 770s, 726s, 702m, 663s, 623m,
574m. Single crystals of 4 suitable for X-ray diffraction studies
were obtained from the mother solution.
4
Ni(1)–N(1A)
Ni(1)–N(1B)
Ni(1)–O(1W)
2.036(4)
2.060(4)
2.093(4)
Ni(1)–O(4)a
Ni(1)–O(2)
Ni(1)–O(1)
2.105(3)
2.109(3)
2.208(3)
Ni(1A)–Ni(1)–N(1B)
N(1A)–Ni(1)–O(1W)
N(1B)–Ni(1)–O(1W)
N(1A)–Ni(1)–O(4)a
N(1B)–Ni(1)–O(4)a
O(1W)–Ni(1)–O(4)a
N(1A)–Ni(1)–O(2)
N(1B)–Ni(1)–O(2)
O(1W)–Ni(1)–O(2)
O(4)a–Ni(1)–O(2)
177.9(2)
89.5(2)
88.3(2)
91.7(1)
88.5(1)
94.0(1)
90.0 (1)
92.1(2)
170.0(1)
96.1(1)
N(1A)–Ni(1)–O(1)
N(1B)–Ni(1)–O(1)
O(1W)–Ni(1)–O(1)
O(4)1–Ni(1)–O(1)
O(2)–Ni(1)–O(1)
N(1A)–Ni(1)–C(11)
N(1B)–Ni(1)–C(11)
O(1W)–Ni(1)–C(11)
O(4)1–Ni(1)–C(11)
O(2)–Ni(1)–C(11)
O(1)–Ni(1)–C(11)
87.3(2)
93.3(2)
109.0(1)
157.0(1)
61.0(1)
86.4(2)
95.2(2)
139.8(2)
126.1(2)
30.2(1)
31.0(1)
3. Result and discussion
a
ꢁx + 1/2, y ꢁ 1/2, ꢁz + 3/2.
3.1. Syntheses and preliminary characterization
The reaction of nickel(II) carbonate with imidazole and o-phtha-
lic acid or KHPht in water or water:ethanol solution in a 1:2:1 ratio
under heating leads to crystalline products with the formulae
[Ni(Im)6](Pht)ꢀH2O (1) and [Ni(Pht)(Im)3(H2O)2]ꢀH2O (2) in ca.
50% and 11% yield, respectively. The reaction of KHPht with nicke-
l(II) nitrate and nickel(II) acetate and 2-MeIm or 4-MeIm in water
or water:ethanol in 1:1:2 ratio results in [Ni(Pht)(2-MeIm)2(H2O)3]
H2O (3) and [Ni(Pht)(4-MeIm)2(H2O)]n (4) in ca. 50% and 90%,
respectively. The crystals 1–4 were characterised by elemental
analysis, IR data, and thermogravimetric and single-crystal X-ray
diffraction analyses.
The IR spectra of compounds 1–4 show characteristic bands of
carboxylate groups in the usual region 1610–1538 cmꢁ1 for asym-
metric stretching and in 1416–1379 cmꢁ1 region for symmetric
stretching. Their positions and intensities are similar to those re-
ported for other Ni(II) phthalates [13,15,17–19,21] and carboxylate
complexes [38–40]. The infrared spectra also show broad bands in
17.47; Ni, 12.39%. IR data (KBr, cmꢁ1): 3412br, 3148vs, 3067vs,
2962vs, 2873sh, 1667sh, 1602sh, 1546vs, 1486sh, 1445s, 1407vs,
1392sh, 1328s, 1262m, 1180w, 1145m, 1105m, 1087m, 1070vs,
1036w, 945m, 938sh, 921w, 879w, 845s, 750vs, 694s, 667s, 618s,
548m.
2.4.2. Method B
Nickel(II) carbonate (0.6 g, 5 mmol) and KHPht (1.02 g, 5 mmol)
were added to a solution of Im (0.68 g, 10 mmol) in water:metha-
nol (1:1) (20 ml). The resulting mixture was heated at reflux for
two hours. The solution was filtered and allowed to slowly evapo-
rate. The violet crystals of compound 1 and the green ones of com-
pound 2 suitable for X-ray diffraction studies crystallized after
several days, then were filtered off, washed with methanol, ether
and dried in air. The crystals of 1 and 2 were separated by hand.
The yields of compounds 1 and 2 were 0.25 g (11%) and 0.6 g

I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
1105
the 3541–3071 cmꢁ1 region, which can be assigned to water
molecules.
onated phthalate anions in [Co(1-MeIm)6](HPht)2ꢀ2H2O and [Ni(1-
MeIm)6](HPht)2ꢀ2H2O [1], but with additional intramolecular
hydrogen bonds in counter-ion. The geometry of Pht2ꢁ residue sig-
nificantly differs from the above mentioned hydrogen phthalate
monoanion HPhtꢁ. The monoanion in [1] has an almost planar
geometry, while in Pht2ꢁ the dihedral angles between the planes
of the carboxylate group and the aromatic ring are 1.5° and
32.2°. Each oxygen atom of the chain participates in the formation
of at least one N–Hꢀ ꢀ ꢀO hydrogen bond with Im ligands (Fig. S1 in
Supporting Information). As a result, the columns of cations occupy
the cavities between chains and each cation is connected to four
different chains of anions.
Thermal analyses of 1–4 carried out in the temperature range
25–600 °C under a nitrogen atmosphere revealed that the first
weight loss corresponds to the removal of water molecules in all
compounds. For 1 and 2, the weight losses of 3.69% and 11.91% be-
fore 160 °C is attributed to the loss one solvate water molecule for
1 (calculated 2.78%) and one solvate and three coordinated water
molecules for 2 (calculated 11.24%). The first weight loss of about
16.93% for compound 3 occurred in the temperature range of 70–
150 °C, which corresponds to the loss of four water molecules
per formula (calculated 17.7%). For coordination polymer 4 about
6.2% weight loss was observed, which corresponds to the release
of one water molecule (calculated 4.45%). On further heating, the
decomposition of the organic ligands takes place in two unidenti-
fied steps: for 1 – with the total weight loss of 84.97% (calculated
78.13%) in the temperature range of 170–430 °C and for 2 – with
the total weight loss of 72.97% (calculated 76.56%) in the temper-
ature range of 170–415 °C. In compound 3 the decomposition of
the organic Pht and 2-MeIm ligands was completed before 400 °C
(observed 66.84%, calculated 72.39%). In the coordination polymer
4 the weight loss of 78.09% occurred between 220 and 420 °C,
which agrees with calculated values of 82.05% for the release of
the Pht and 4-MeIm ligands, to give the expected oxide.
The structures of (Ni(Pht)(Im)3(H2O)2]ꢀH2O (2) and [Ni(Pht)(2-
MeIm)2(H2O)3]ꢀH2O (3) are similar to those of mononuclear com-
3.2. Crystal structure description
In the crystal structure of [Ni(Im)6](Pht)ꢀH2O (1), the asymmet-
ric unit consists of [Ni(Im)]62+ cation, Pht2ꢁ anion and solvate H2O
molecule (Fig. 1). Six Im ligands coordinate to a Ni(II) center. The
Ni–N distances vary from 2.116(4) to 2.150(4) Å, and the N–Ni–N
angles range from 88.1(2)° to 92.7(2)° (Table 2). The phthalate
dianion does not take part in coordination to metal ion. The
cations, anions and water molecules are linked via N–Hꢀ ꢀ ꢀO and
O–Hꢀ ꢀ ꢀO interactions. Pht2ꢁ and H2O molecules form one-dimen-
sional chains running along the c-axis by (O(1W)–Hꢀ ꢀ ꢀO(1) =
2.700(7) Å and O(1W)–Hꢀ ꢀ ꢀO(4)[x, ꢁy + 1/2, z + 1/2] = 2.763(5) Å
hydrogen bonds (Table S1 in Supporting Information). Similar
chains were observed in the related compounds with monodeprot-
Fig. 2. Crystallographically independent structure fragments with numbering
scheme and displacement ellipsoids drawn at the 50% probability level in
compounds 2 (a) and 3 (b) Hydrogen bonds are indicated by dotted lines.
Fig. 1. The fragment of structure in 1 with a numbering scheme.

1106
I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
pounds with a monodentate coordination mode of o-phthalic acid
[13,15,17,41]. The former differ from each other by the stoichiom-
etric ratio metal:acid:heterocyclic amine, which is 1:1:3 in 2 and
1:1:2 in 3. Fig. 2a and b shows a view of the coordination environ-
ment in these complexes with the atom numbering scheme. Nickel
atoms have a distorted octahedral geometry. The phthalate ligand
is coordinated to the nickel atom in a monodentate fashion with
bond distances 2.154(2) (for 2) and 2.069(2) Å (for 3).Two cis-posi-
tion in 3 and three cis-position in 2 are occupied by nitrogen atoms
of aromatic amines with the average distances 2.063 Å in 3 and
2.117 Å in 2. The coordination sphere is completed by oxygen
atoms of water molecules (two water molecules in 2 and three
water molecules in 3, Table 2). Similar to other mononuclear Ni(II)
complexes [13], the uncoordinated oxygen atoms of Pht2ꢁ form
two intramolecular O–Hꢀ ꢀ ꢀO hydrogen bonds with water mole-
cules, giving rise to 6-membered and 9-membered hydrogen
bonded rings as shown in Fig. 2a and b.
Despite the changes in the equatorial plane of Ni(II) atom in 2,
as compared with 3, the supramolecular structure of them has
many common features and is very similar to that of [Ni(Pht)(ami-
ne)(H2O)3] complexes [13]. As mentioned previously, the structure
of all these compounds consists of hydrogen bonded double-
chains. Analogous structural motifs can be observed in 2 and 3.
In complex 2, the adjacent complexes are connected into zigzag
chains through hydrogen bonds between the coordinated water
molecules and both oxygen atoms of uncoordinated carboxylate
group O(1W)–Hꢀ ꢀ ꢀO(1) and O(2W)–Hꢀ ꢀ ꢀO(2)[ꢁx + 1/2, y ꢁ 1/2,
Fig. 5. The fragment of structure in 4.
ꢁz + 1/2] (Table S1 in Supporting Information). This leads to orga-
nization of R22(8) motif. The solvate water molecule O(3W) and
imidazole nitrogen atom also connect nearby complexes via O–
Fig. 3. Hydrogen bonding pattern in double-chain in 2. Hydrogen atoms are omitted for clarity and hydrogen bonds are indicated by dotted lines.
Fig. 4. A view of a double-chain in compound 3. Hydrogen atoms are omitted for clarity and hydrogen bonds are indicated by dotted lines.

I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
1107
Hꢀ ꢀ ꢀO(2) hydrogen bonds into centrosymmetric dimers. The sol-
vate water molecule O(4W) gives rise to hydrogen bonds in the di-
mer. The hydrogen bonds O(1W)–Hꢀ ꢀ ꢀO(1) and O(3W)–Hꢀ ꢀ ꢀO(1)
join adjacent dimers in double-chains along the a-axis of the unit
cell. These interactions lead to the formation of R21(6) ring. Niꢀ ꢀ ꢀNi
distance in the dimer is 6.654(2) Å and that one between dimers is
7.264(2) Å. N(3A)–Hꢀ ꢀ ꢀO(4W) and N(3B)–Hꢀ ꢀ ꢀO(3) hydrogen bonds
realize the 3D network in 3.
Compound [Ni(Pht)(4-MeIm)2(H2O)]n (4) represents a 1D coor-
dination polymer due to 1,3-chelate-bridging function of the Pht
molecule (Fig. 5). It is necessary to note that 4 is isostructural with
[M(Pht)(4-MeIm)2(H2O)]n (where M = Co(II) and Cu(II) [21]). The
structure of this compound consists of [Ni(4-MeIm)2] building
units connected by phthalate ions to form helical chains (Fig. 6).
Polymeric chains run along the b-direction in the unit cell. The
closest Niꢀ ꢀ ꢀNi distance is 6.254(2) Å. The Ni(II) coordination
sphere includes two nitrogen atoms N(1A) and N(1B) of 4-MeIm
(2.037(4), 2.060(4) Å), three oxygen atoms (O(1), O(2) and O(4)*)
from two Pht2ꢁ residues (2.208(3), 2.109(3), 2.105(3) Å) and one
water molecule O(1W) at the distance 2.093(4) Å). The Pht2ꢁ anion
behaves as a tridentate ligand. One carboxylate group coordinates
to Ni(II) atom in a 1,3-chelating mode, while the other one in a
monodentate fashion. The uncoordinated nitrogen atoms of 4-
Meim molecules N(3A) and N(3B) form intra-chain hydrogen
bonds N–Hꢀ ꢀ ꢀOcarb. (Table S1 in Supporting Information). The
O(1W)–Hꢀ ꢀ ꢀO(1) and O(1W)–Hꢀ ꢀ ꢀO(3) interactions connect the
chains into layers along [1 0 1] direction. The inter-helix Niꢀ ꢀ ꢀNi
distance is 5.197(1) Å.
Fig. 6. A space filling representation of the helical chain in 4. Color scheme: red,
oxygen; blue, nitrogen; grey, carbon. Hydrogen atoms are omitted for clarity. (For
interpretation of the references to colour in this figure legend, the reader is referred
to the web version of this article.)
Hꢀ ꢀ ꢀO and N–Hꢀ ꢀ ꢀO hydrogen bonds on the both sides of the chain.
As a result, this chain may be described as a double chain. (Fig. 3).
The shortest Niꢀ ꢀ ꢀNi distance is 7.479(2) Å. The chains are held to-
gether by N(3A)–Hꢀ ꢀ ꢀO(4) hydrogen bonds in layers parallel to the
a-axis and then in a 3D network via N(3B)–Hꢀ ꢀ ꢀO(3W) interactions
(Table S1, Fig. S2 in Supporting Information).
3.3. Biological studies
The influence of the studied metal complexes was different,
being dependent on both the composition of complexes and their
concentration (Table 3). Three (complexes 1, 3 and 4) out of four
tested coordination compounds had a negative influence on the
protease synthesis, causing attenuation of the neutral protease
The double-chain in compound 3 is organized in a different way
(Fig. 4). Individual molecules are connected by two O(1W)–
Table 3
The influence of compounds 1–4 on proteolytic activity at fungal strain 10 T.
No.
Compound
Days
Concentration mg/l
Activity of neutral proteases, u/ml
Activity of acid proteases, u/ml
8
9
10
8
9
10
1.
[Ni(Im)6]PhtꢀH2O (1)
5
3.37
2.95
2.46
3.11
3.96
4.49
3.19
2.81
2.39
2.84
2.77
1.96
3.57
1.42
1.39
1.29
2.31
2.34
4.03
1.99
1.54
1.55
1.43
1.26
1.30
3.74
1.03
0.80
0.79
1.37
2.03
3.11
1.40
1.23
1.44
1.30
1.32
1.30
2.00
0.00
0.36
0.37
0.30
0.40
0.28
0.48
0.62
0.77
0.63
0.27
0.89
1.08
0.14
0.64
0.83
0.84
0.53
1.07
1.28
1.28
1.11
0.85
0.94
1.09
1.37
0.14
0.57
0.53
0.69
0.74
1.06
0.77
1.06
0.89
0.62
0.49
0.38
1.13
10
15
5
10
15
5
10
15
5
10
15
0
2.
[Ni(Pht)(Im)3(H2O)2]ꢀH2O (2)
[Ni(Pht)(2-MeIm)2(H2O)3]ꢀH2O (3)
[Ni(Pht)(4-MeIm)2(H2O)]n (4)
3.
4.
Control
Table 4
The influence of different concentration of [Ni(Pht)(Im)3(H2O)2]ꢀH2O on proteolytic activity of strain 10 T.
Concentration of compound, mg/l
Activity of neutral proteases, u/ml
7 days
u/ml
8 days
u/ml
9 days
u/ml
10 days
11 days
%, to control
%, to control
%, to control
u/ml
%, to control
u/ml
%, to control
15
20
Control
1.73
1.65
1.35
128.1
122.2
100.0
3.92
3.78
3.08
127.3
122.7
100.0
4.66
4.53
3.69
126.3
122.8
100.0
3.38
3.19
2.70
125.2
118.1
100.0
1.97
1.99
1.57
125.5
126.8
100.0

1108
I.G. Filippova et al. / Polyhedron 29 (2010) 1102–1108
[2] S.G. Baca, Yu.A. Simonov, N.V. Gerbeleu, M. Gdaniec, P.N. Bourosh, G.A. Timco,
Polyhedron 20 (2001) 831.
[3] A.D. Burrows, R.W. Harrington, M.F. Mahon, C.E. Price, J. Chem. Soc., Dalton
Trans. (2000) 3845.
[4] S.G. Baca, I.G. Filippova, N.V. Gerbeleu, Yu.A. Simonov, M. Gdaniec, G. A Timco,
O.A. Gherco, Yu.L. Malaestean, Inorg. Chim. Acta 344 (2003) 109.
[5] J.-C. Yao, W. Huang, B. Li, S. Gou, Y. Xu, Inorg. Chem. Commun. 5 (2002) 711.
[6] X. Liang, M. Weishaupl, J.A. Parkinson, S. Parsons, P.A. McGregor, P.J. Sadler,
Chem.-Eur. J. 9 (2003) 4709.
[7] N.J. Burke, A.D. Burrows, A.S. Donovan, R.W. Harrington, M.F. Mahon, C.E. Price,
Dalton Trans. (2003) 3840.
[8] B. Li, B. Li, X. Zhu, X. Lu, Y. Zhang, J. Coord. Chem. 57 (2004) 1361.
[9] Y.-B. Chen, J. Zhang, J.-K. Cheng, Y. Kang, Z.-J. Li, Y.-G. Yao, Inorg. Chem.
Commun. 7 (2004) 1139.
[10] S.-C. Zhang, J. Sun, Acta Crystallogr., Sect. E 62 (2006) m3107.
[11] Yu.A. Simonov, S.G. Baca, I.G. Filippova, M. Gdaniec, O.A. Gherco, N.V. Gerbeleu,
Russ. J. Coord. Chem. 30 (2004) 727.
activity by 45–67.0% against the control. In case of the acid prote-
ase, all compounds had a negative influence.
The maximum proteolytic activity (4.49 u/ml) was determined
in the variant that had compound 2 in the maximal tested concen-
tration (15 mg/L). The enhance of the activity was 25.8% against
the control.
In order to establish the optimal concentration of compound
[Ni(Pht)(Im)3(H2O)2]ꢀH2O (2), which ensures the stimulatory effect
in the following experiment, the range of concentration was wid-
ened (Table 4). It was found out that the stimulatory effect of com-
pound 2 in the concentration 20 mg/L was less than in the variants
cultivated in the presence of 15 mg/L complex, i.e. 22.7%.
[12] N.P. Kozlova, V.M. Agre, V.K. Trunov, S.S. Makarevich, N.N. Barkhanova, Zh.
Strukt. Khim.(Russ.) (J. Struct. Chem.) 23 (1982) 108.
4. Conclusion
[13] S.G. Baca, I.G. Filippova, P. Franz, C. Ambrus, M. Gdaniec, H. Stoeckli-Evans,
Yu.A. Simonov, O.A. Gherco, T. Bejan, N. Gerbeleu, S. Decurtins, Inorg. Chim.
Acta 358 (2005) 1762.
[14] J.-H. Bi, X.-L. Cheng, Z.-X. Huang, N.-L. Hu, Asian J. Chem. 18 (2006) 2371.
[15] D. Poleti, D.R. Stojakovic, B.V. Prelesnik, Lj. Manojlovic-Muir, Acta Crystallogr.,
Sect. C 46 (1990) 399.
[16] Y.-W. Xuan, W. Wu, D.-P. Xie, N.-X. Yuan, Acta Crystallogr., Sect. E: Struct. Rep.
Online 64 (2008) m101.
[17] D. Poleti, L. Karanovic, B.V. Prelesnik, Acta Crystallogr., Sect. C 46 (1990) 2465.
[18] G. Adiwidjaja, H. Kuppers, Acta Crystallogr., Sect. B 32 (1976) 1571.
[19] F.-C. Xue, Z.-H. Jiang, D.-Z. Liao, S.-L. Ma, S.-P. Yan, G.-L. Wang, X.-K. Yao, R.-J.
Wang, Polyhedron 12 (1993) 2787.
[20] F.H. Allen, Acta Crystallogr., Sect. B 58 (2002) 380.
[21] H. Endres, Z. Anorg. Allg. Chem. 513 (1984) 78.
[22] L. Tian, L. Chen, Sh.-H. Shen, Ch.-L. Wen, Sh.-L. Liu, J. Coord. Chem. 60 (2007)
683.
[23] S.-Y. Yang, L.-Sh. Long, R.-B. Huang, L.-S. Zheng, S.W. Ng, Acta Crystallogr., Sect.
E: Struct. Rep. Online 59 (2003) m507.
[24] Y. Qi, F. Luo, Y. Che, J. Zheng, Cryst. Growth Des. 8 (2008) 606.
[25] X. Zhang, Z. Yi, W. Xia, Ch. Yang, B. Li, Acta Crystallogr., Sect. E: Struct. Rep.
Online 64 (2008) m345.
Ni(II) coordination compounds with o-phthalic acid and imidaz-
ole ligand and its derivatives such as 2-methylimidazole and 4-
methylimidazole, namely mononuclear complexes [Ni(Im)]6(Pht)ꢀ
H2O (1), [Ni(Pht)(Im)3(H2O)2]ꢀH2O (2) and [Ni(Pht)(2-MeIm)3-
(H2O)3]ꢀH2O (3), and coordination polymer [Ni(Pht)(4-MeIm)2-
(H2O)]n (4), have been synthesized. The structural properties of
the complexes were investigated. Complexes 1–3 represent mono-
nuclear compounds, whereas complex 4 has a polymeric structure.
The structural patterns displayed in 1–4 illustrate the rich binding
facilities of carboxylate groups of the o-phthalate ligand and their
ability to form extensive hydrogen-bonding interactions and build-
ing up supramolecular aggregates. The ability of the complexes to
increase the biosynthesis of enzymes was tested. Our present re-
sults show that complex [Ni(Pht)(Im)3(H2O)2]ꢀ2H2O (2) can be
used as a biostimulator incresing the protease synthesis ca. 22–
28% as compared with the control.
[26] X.-L. Wang, B.-K. Chen, H.-Y. Lin, Y.-F. Bi, G.-Ch. Liu, J. Chem. Cryst. 38 (2008)
339.
[27] M. Fondo, A.M. Garcia-Deibe, N. Ocampo, J. Sanmartin, M.R. Bermejo, A.L.
Llamas-Saiz, Dalton Trans. (2006) 4260.
Acknowledgments
[28] M.C. Etter, Israel J. Chem. 25 (1985) 312.
This work was supported by the Swiss National Science Founda-
tion (SCOPES 7MDPJ065712.01/1 and IB7320-110976/1) and grant
No. P.A. 33433/03 of Ministry for Foreign Affairs, Italy for O.A.G.
The authors acknowledge the assistance of Prof. Gabriele Bocelli
in the collection of crystallographic data sets for compounds 1–4.
[29] A.A. Desyatnik, N.V. Gerbeleu, E.B. Koropchanu, Z.P. Tyurina, S.V. Lablyuk, O.A.
Bologa, S.I. Klapko, Russ. J. Coord. Chem. 28 (2002) 135.
[30] N. Parpiev, A. Kushakbaev, M. Azimov, The coordinative compounds of metals
applied in medicine. Tashkent (1982) 138.
[31] H. Dugas, Bioorganic chemistry.
Springer-Verlag, New York, 1996.
A chemical approach to enzyme action,
[32] R.P. Hausinger, Microbiol. Rev. 51 (1987) 22.
[33] S.B. Mulrooney, R.P. Hausinger, Microbiol. Rev. 27 (2003) 239.
[34] A. Deseatnic, S. Clapco, V. Drußta, J.Tiurin, S. Labliuc, J. Gra˘dinaru, N. Ga˘rba˘la˘u,
Nutritive Medium for Penicillium viride Cultivation, Variants, Patent, MD 2837,
BOPI nr. 8/2005.
[35] G.M. Sheldrick, SHELXS-97, Program for the solution of crystal structures,
University of Goettingen, Germany, 1997 (b).
[36] G.M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal Structures,
University of Goettingen, Germany, 1997(a).
[37] V. Bilai, Methods of Experimental Mycology, Kiev, 1973, pp. 41–43.
[38] G.B. Deacon, R.J. Phillips, Coord. Chem. Rev. 33 (1980) 227.
[39] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination
Compounds, Wiley, New York, 1986. p. 236.
Appendix A. Supplementary data
CCDC 749812, 749813, 749814 and 749815 contain the supple-
mentary crystallographic data for 1–4. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data associated
with this article can be found, in the online version, at doi:10.1016/
j.poly.2009.11.016.
[40] R.C. Mehrotra, R. Bohra, Metal Carboxylates, Academic Press, New York, 1983.
p. 48.
[41] S.G. Baca, I.G. Filippova, Ch. Ambrus, M. Gdaniec, Yu.A. Simonov, N. Gerbeleu,
O.A. Gherco, S. Decurtins, Eur. J. Inorg. Chem (2005) 3118.
References
[1] S.G. Baca, I.G. Filippova, O.A. Gherco, M. Gdaniec, Yu.A. Simonov, N.V. Gerbeleu,
P. Franz, R. Basler, S. Decurtins, Inorg. Chim. Acta 357 (2004) 3419.