Skip to content


  • Research article
  • Open Access

Synthesis, crystallographic, spectroscopic studies and biological activity of new cobalt(II) complexes with bioactive mixed sulindac and nitrogen-donor ligands

Contributed equally
Chemistry Central Journal201711:40

  • Received: 1 March 2017
  • Accepted: 3 May 2017
  • Published:


Four novel complexes [Co(H2O)4(sul)2] 1, [Co(2-ampy)2(sul)2] 2, [Co(H2O)2(1,10-phen) (sul)2] 3 and [Co(2,9-dimephen)(sul)2] 4 (sul = sulindac, 2-ampy = 2-amino pyridine, 1,10-phen = 1,10-phenanthroline and 2,9-dimeph = 2,9-dimethyl-1,10-phenanthroline) were prepared and characterized by IR, UV–Visible spectroscopy and magnetic properties. The crystal structures of complexes 1 and 4 were determined by single-crystal X-ray diffraction. In-vitro anti-bacterial activity for the prepared complexes against Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus) and Gram-negative (Bordetella, Escherichia coli) bacteria and Yeast species (Saccharomyces and Candida) were performed using agar well-diffusion method. Only complex 4 showed reasonable activity against yeast. All compounds showed more anti-bacterial activity against Gram-positive bacteria than Gram-negative.
Graphical Abstract image
Graphical abstract

This work reports synthesis, crystallographic, spectroscopic studies and biological activity of new cobalt(II) complexes with bioactive mixed sulindac and nitrogen-donor ligands. The crystal structures of complexes 1 and 4 were determined using single-crystal X-ray diffraction. In-vitro anti-bacterial activity of the prepared complexes and their parent ligands were investigated against different Gram-positive and Gram-negative bacteria using agar diffusion method


  • Cobalt(II) complexes
  • Nitrogen donor ligands
  • Sulindac
  • Anti-bacterial activity


Cobalt has a significant role in proteins; there are at least eight cobalt-dependent proteins. Moreover, cobalt is needed at the active center of certain coenzymes that are called cobalamins especially cyanocobalamins (Vitamin B12) which regulates indirectly the synthesis of DNA [13].

The first reported study about the biological activity of cobalt compounds was in 1952, where cobalt(III) compounds of bidentate mustard seemed to act as hypoxia-selective agents [4, 5]. Several compounds showed considerable activity against bacteria strains and against leukemia and lymphoma cell lines [6]. Furthermore, cobalt complexes possess in vivo insulin-like properties [7, 8], anti-fungal and anti-oxidant activities [9]. Several Co(III) complexes with anti-microbial activities have been reported [1014]. For instance, a Co(III) complex of the known anti-ulcer drug famotidine turned out to have greater anti-microbial activity against M. lysodeikticus and Escherichia coli than the metal free drug [1014].

Recently, metal(II) carboxylate compounds with nitrogen and/or oxygen-donor ligands have attracted an increasing interest because of their potential biological and chemical activities [15]. The interaction between heterocyclic compounds and metal ions is very important in biological systems such as drugs and vitamins [16]. In previous studies cobalt(II) compounds showed anti-fungal and anti-microbial activities; for example, imidazole-2-carbaldehyde semicarbazone was active against yeasts Candida tropicalis and Saccharomyces cerevisiae. Activity was most noticeable against phytopathogenic fungi such as Alternaria or Sclerotinia [17].

{(1Z)-5-fluoro-2-methyl-1-[4-(methylsulfinyl)benzylidene]-1H-indene-3-yl}acetic acid known as Sulindac, in the form of potassium salt has a wide spectrum of activity as non-steroidal anti-inflammatory drug (NSAIDs). The chemical classes of NSAIDs comprise phenylalkanoic acids, anthranilic acids, salicylate derivatives, oxicams, furanones and sulfonamides [1824]. Sulindac belong to phenylalkanoic acids that are potent NSAIDs for the treatment of inflammatory conditions, such as pain, fever and inflammation. The transition metal coordination with NSAIDs caused many enhanced anti-inflammatory activity [2527]. Some compounds of NSAIDs that can coordinate with transition metals have been synthesized and tested for their biological and pharmacological activity [2834], to our best knowledge the synthesized cobalt complexes are the first reported structures, in addition to our previously reported zinc (Fig. 1) sulindac complexes [34].
Fig. 1
Fig. 1

Sulindac structure [37]

The synthesis, characterization and anti-bacterial activity of new cobalt(II) sulindac containing complexes with heterocyclic nitrogen based ligands (2-aminopyridine “2-ampy”, 1,10-phenanthroline “1,10-phen” and 2,9-dimethyl-1,10-phenanthroline “2,9-dimphen”) are described in the present work. The crystal structures of [Co(H2O)4(sul)2] (1) and [Co(2,9-dimephen)(sul)2] (4) are also reported.

Results and discussion

Synthesis of cobalt complexes

[Cobalt sulindac complex], 1 was prepared by mixing cobalt chloride and potassium sulindac in 1:2 molar ratios with methanol as a solvent. The desired product was obtained as a yellow solid (Scheme 1) and its structure was determined by single crystal X-ray diffraction. The novel mixed ligand cobalt(II) complexes were prepared by adding the appropriate N-donor ligand to complex 1 see (Scheme 2). The physical properties of 1–4 are summarized in Additional file 1: Table S1. Physical properties and yield of Cobalt(II) sulindac compounds.
Scheme 1
Scheme 1

Synthesis of complex 1

Scheme 2
Scheme 2

Synthesis and the proposed structures of complexes 24 (Asterisk proposed structure)

Crystallographic study

Crystallographic study of complex 1

The atomic numbering scheme and atom connectivity for complex 1 are shown in Fig. 2. The asymmetric unit of the titled complex, contains a Co(II) cation, two monodentate sulindac groups and four water molecules.
Fig. 2
Fig. 2

The molecular structure view of 1 showing the atom labeling scheme

Although the synthetic procedure and the recrystallization process of complex 1 were performed in methanol, a marked preference for coordination of water over methanol was observed and proved by single crystal X-ray determination. This phenomenon might be due to the stronger bond interaction between water and the metal center than methanol. In addition, the used methanol was not dry enough and wet, so it was possible to provide the four water molecules bonded to the metal center.

The two sulindaco groups are connected to the metal center in a monodentate coordination mode forming a symmetrical octahedral geometry with the additional four water molecules. The Co–O bond distances of 2.089(4), 2.100(5) and 2.141(4) Å are similar to previously reported values [38]. Selected bond angles and bond distances are listed in Table 1.
Table 1

Selected bond angles (°) and bond distances (Å) for 1 and 4

Bond distance (Å) of complex 1

Bond distance (Å) of complex 4

























Bond angle (°) of complex 1

Bond angle (°) of complex 4





O(1 W)–Co(1)–O(1W)#1




O(2 W)–Co(1)–O(2W)#1





































From the bonding angles in complex 1; O(1)#1–Co(1)–O(2W)#1 = 87.9(2)°, O(1)–Co(1)–O(2W) = 87.9(2)°, O(1)–Co(1)–O(1 W) = 92.09(17)°, O(1)#1–Co(1)–O(1W) = 87.91(17)° and O(2W)#1–Co(1)–O(1W) = 89.4(2)° a slight distortion from regular octahedral geometry was observed due to the expected JahnTeller effect which is also confirmed by the appearance of a shoulder in the dd visible transition of this and other cobalt complexes.

Crystallographic study of complex 4

The atomic numbering scheme and atom connectivity for complex 4 are shown in Fig. 3. The asymmetric unit of the titled complex, contains a Co(II) cation, two sulindac groups and one 2,9-dimephen ligand. The Co–O bond distances of 2.117(8), 2.128(6), 2.220(10) and 2.220(10) Å are similar to reported values [3947]. Co–N bond distances of 2.090(7) and 2.100(7) Å are also similar to reported values [3948]. Selected angles and distances are listed in Table 1.
Fig. 3
Fig. 3

The molecular structure view of 4 showing the atom labeling scheme

From bonding angles in complex 4, a slight deviation from octahedral geometry was observed, N(1)–Co(1)–O(1) = 108.2(3)°, N(2)–Co(1)–O(4) = 112.3(3)°, N(2)–Co(1)–O(5) = 102.5(4)°, N(2)–Co(1)–N(1) = 79.8(3)° and N(1)–Co(1)–O(2) = 104.3 (19)°.

Infrared spectra

Infrared spectral data of KBr pellet of cobalt sulindac complexes 1–4 in the 400–4000 cm−1 range are summarized in Additional files 2 and 3: Table S2. Comparison between some of principle peaks in IR for K(sul) and 1 (cm-1) and Table S3. Summary of principle peaks in IR for complexes 2, 3 and 4 (cm-1). In metal carboxylate complexes, the major characteristic of the IR spectra is the frequency of the υ asymmetric (υas) and υ symmetric (υs) of carbonyl (COO) stretching vibrations and the difference between them Δυ(COO). The frequency of these bands depends upon the coordination mode of the carboxylate ligand. Monodentate complexes exhibit Δυ(COO) values that are much greater than the ionic complexes. Chelating (bidentate) complexes exhibit Δυ(COO) values that are significantly less than the ionic values. Δυ(COO) values for bridging complexes are greater than those of chelating complexes, and close to the ionic values [49]. In complex 1; υas(COO) is at 1601 cm−1 and υs(COO) at 1397 cm−1, Δυ(COO) = 204 cm−1 which is close to that of potassium sulindac which supports a coordination mode for complex 1 as monodentate. The O–H vibration frequency at 3376 cm−1 indicates the presence of water molecules in the coordination geometry [Co(H2O)4(sul)2] as also supported by single crystal X-ray determination.

The assignments of IR frequencies for the asymmetric stretching υas(COO), the symmetric stretching υs(COO) and the difference between these two values of sulindac group in complexes 14 and those of potassium sulindac are shown in Additional file 1: Tables S2 and S3.

Complexes 2 and 3 have υas(COO) at 1599, and 1600 cm−1, but υs(COO) appear at 1390 and 1380 cm−1, so Δυ (COO) are 219 and 220 cm−1, respectively which is larger than Δυ(COO)K(sul) = 178 cm−1 and this supports monodentate coordination mode of the carboxylate groups. In addition, complex 3 has an absorption frequency at 3415 cm−1 which may indicate water molecules in the coordination geometry.

Moreover, in complex 2 two absorption frequencies υas(NH2) at 3374 cm−1 and υs(NH2) at 3268 cm−1 with Δυ(NH2) = 106 cm−1 were observed. These frequencies are assigned to the 1°-NH2 group indicating that the complexation with cobalt is through the pyridine nitrogen atom rather than the NH2 nitrogen atom [50, 51].

In complex 4 υas(COO) was observed at 1599 cm−1, and υs(COO) was at 1441 cm−1 giving a Δυ(COO) of 158 cm−1 and this supports a bidentate coordination mode of the carboxylate groups. This result was also confirmed by X-ray structure determination of complex 4.

UV–Vis spectra

Generally, three types of electronic transitions have been observed for coordination compounds: Metal to ligand (MLCT) or ligand to metal (LMCT) charge-transfer absorption bands, dd transition bands and intra-ligand (LC) transition bands [52, 53].

Co(II) metal ion with low spin d 7 electronic configuration showed two low intensity bands with small ε value (12–13 Lmol−1 cm−1) in the visible region. The source of these two bands is due to the dd transition between 2E2→T1g and 2E→2T2g. LMCT was observed at (206–213 nm) with ε values between 1800 and 3000 Lmol−1 cm−1 [20, 21, 5467]. All other bands are similar to nitrogen based ligand ΠΠ* or n→Π* transitions with small blue or red shifts for cobalt coordination complexes [20, 21, 5567]. The results are tabulated in Additional file 4: Table S4. UV-visible spectral data for compounds (14).

Complexes 3 and 4 adopted distorted octahedral geometries with different carboxylate coordination modes, e.g. monodentate, bidentate, in complex 3 the two water molecules were covalently coordinated to the central Co(II) cation which imposed monodentate coordination mode of the sulindaco groups. Whereas, the two sulindaco groups in complex 4 are both bidentately coordinated to the Co(II) center as a result of the increased steric hindrance effect by two methyl groups on the 1,10-phen ring. The electronic effect of the ligands in complexes 2–4 are almost identical.

Magnetic properties

The magnetic moment measurements of compounds 14 are given in Table 2. The value of magnetic moments for all complexes indicates that each compound has paramagnetic properties with one unpaired electron, which indicates that each Co(II) complex adopted a low spin, d 7 octhedral geometry. Low spin Co(II) octahedral complexes with nitrogen and/or oxygen-donor ligands are very rare [62]. Both structural, magnetic and spectral data are necessary to prove that a complex contains low spin Co(II) metal ion octahedral geometry with only few of these compounds have been structurally characterized by single crystal X-ray crystallography [6871].
Table 2

Magnetic properties of cobalt(II) compounds


Magnetic moment (μeff BM)

Unpaired electron (n)

[Co(H2O)4(sul)2] (1)

2.26 ± 0.05


[Co(2-ampy)2(sul)2] (2)

2.41 ± 0.15


[Co(H2O)2(1,10-phen)(sul)2] (3)

2.40 ± 0.12


[Co(2,9-dimephen)(sul)2] (4)

2.40 ± 0.09


Anti-bacterial activity

Before measurement of their biological activity, the solution stability of the complexes were tested, as the complexes were crystallized by slow solvent evaporation at room temperature that took several days and the same physical properties of the compounds were obtained. Moreover, the relevant X-ray structure determination of some complexes showed that the structures were remained intact.

Two Gram positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus), two Gram negative bacteria (Bordetella, E. coli) and yeast species (Saccharomyces and Candida) were used to test the compounds anti-bacterial activity. The results were obtained by the well-diffusion method using DMSO as a negative control to resist any tested microorganisms; Gentamycin as a positive control for Gram positive and Gram negative bacteria and Nystatin as a positive control for yeast. The parent ligand, potassium sulindac, did not show anti-bacterial activity against any of the tested microorganisms, but (CoCl2) showed anti-bacterial activity against all tested microorganisms (Table 3).
Table 3

In-vitro anti-bacterial activity data of complexes 14



E. coli

S. epi

S. aureus










15.3 ± 0.5

10.1 ± 0.4

21.0 ± 0.4

19 ± 1


13 ± 1

23 ± 1

11 ± 1


12 ± 2

8.5 ± 1.5

26.7 ± 0.6

21 ± 1


16 ± 2

12 ± 2

39 ± 1

25.0 ± 1.5

42 ± 1

41.12 ± 0.5


22 ± 2

12 ± 2

30.0 ± 0.5

11 ± 1

20.0 ± 0.7

22 ± 1



30 ± 1

37 ± 1

28 ± 1

32.7 ± 0.6


35.5 ± 0.2

40.5 ± 0.4

Inhibition zone diameter (IZD) in mm, all microorganisms were resistant to DMSO. The data stated as average ± standard deviation (N = 3), the concentration of the complexes and the standards was 30 mg/5 mL in DMSO (6 g/l)

— dashes indicated zero inhibition

Complex 1 showed high activity against G or G+ bacteria except against E. coli. Complexes 3 and 4 showed low activity against G bacteria and high activity against G+ bacteria. Complex 2 showed high activity against S. epidermidis and low or zero activity against other bacteria. However, in yeast all complexes didn’t show any activity except complexes 4 showed high activity. Complexes 3 and 4 were chosen for further studies because of their higher IZD values. The complexes have been studied with their parent nitrogen donor ligands “1,10-phen and 2,9-dimephen” against all tested Gram-positive, Gram-negative bacteria and yeast to determine the effect of the complexation on anti-bacteria activity (Tables 4, 5).
Table 4

Comparison of anti-bacterial activity of complex 3 with 1,10-phen

Concentration (mg/ml)


E. coli

S. epidermidis

S. aureus





IZD of 3 (mm)


11.9 ± 2

8.5 ± 1.5

26.7 ± 0.6

21 ± 1


10.3 ± 0.5

24.6 ± 1.5

18.7 ± 0.5


22.6 ± 1.6

10.9 ± 0.7

IZD of 1,10-phen


33.0 ± 0.7

33 ± 1

36 ± 0.6

38.5 ± 1.5


21.6 ± 0.5

31.5 ± 1.7

33.6 ± 0.7

35.4 ± 0.5


11.0 ± 1

29.0 ± 0.7

24 ± 1.6

28.6 ± 0.7

Table 5

Comparison of anti-bacterial activity of complex 4 with 2,9-dimephen

Concentration (mg/ml)


E. coli

S. epidermidis

S. aureus







IZD of 4 (mm)



16.2 ± 1.9

12.0 ± 2.0

39 ± 1

25.0 ± 1.5

41.12 ± 0.5


13.7 ± 0.5

34.6 ± 0.7

24.3 ± 0.5

41 ± 1


11.4 ± 1.2

30.4 ± 1.6

21.9 ± 0.7

35.9 ± 0.5

IZD of 2, 9-dimephen



14.6 ± 0.9

36.9 ± 1.5

39 ± 1

44 ± 2


9.2 ± 0.5

35.5 ± 0.7

35.4 ± 0.5

42 ± 1


8.3 ± 1.2

33.0 ± 1.6

31.3 ± 0.7

38.4 ± 0.5

Tables 4 and 5 show that the complexation process of cobalt-sulindac with 1,10-phen in complex 3 decreased the anti-bacterial activity considerably for both gram negative and gram positive bacteria, but complexation of cobalt-sulindac with 2,9-dimephen in complex 4 mostly showed similar behavior against S. epidermidis and yeast, but decreased the activity against S. aureus and increased the anti-bacterial activity against gram negative bacteria. The anti-bacterial activity of complexes 1–4 when compared with previously reported work would be considered as promising results [15, 2836, 7278].


Four new Co(II) complexes with sulindac in the presence of N-donor heterocyclic ligands (2-ampy, 1,10-phen and 2,9-dimephen) have been synthesized and characterized. Magnetic properties, infrared and UV–Vis spectrophotometric techniques were used to study the new complexes in addition to X-ray diffraction of complexes 1 and 4; which reveals distorted octahedral geometry of the Co(II) ion. In complex 1 the cobalt binds two monodentate sulindac groups and in complex 4 cobalt binds two bidentate sulindac groups and one 2,9-dimephen. The structures of the remaining complexes were proposed depending on IR, UV–Vis results and magnetic properties. Complexes 3 and 4 showed anti-bacterial activity against G+ and G bacteria. Moreover, complex 4 have demonstrated the highest efficiency against yeast.

The results of this work was Submitted in Partial Fulfillment of the Requirements for the Degree of Masters in Applied Chemistry, Faculty of Graduate Studies, Birzeit University, Ramallah, Palestine. The thesis was published in 2015 on FADA Birzeit University Open Access Repository [79].


Starting materials

Cobalt(II) chloride was purchased from Merck, sulindac, 2-aminopyridine, 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline were purchased from Sigma-Aldrich. All solvents used were of analytical reagent grade and purchased from commercial sources. E. coli, S. aureus, S. epidermidis, Bordetella and Yeast species (Saccharomyces and candida) were kindly obtained from the Drugs Department at Central Public Health Laboratory.


All Co(II) complexes were synthesized at room temperature in ambient conditions.

Synthesis of [Co(H 2 O) 4 (sul) 2 ] (1)

Sulindac (3.0 g, 8.4 mmol) was allowed to dissolve in a methanolic solution of potassium hydroxide (0.47 g, 4.2 mmol) (75 ml methanol). To this solution was added slowly CoCl2·7H2O (1.0 g, 4.2 mmol) in 15 ml of methanol. The mixture was allowed to stir for 24 h and the formed precipitate was collected, washed with cold water and air dried. Suitable crystals for X-ray structural analysis were obtained by recrystallization from hot methanol.

[Co(H 2 O) 4 (sul) 2 ] (1): 85% (3.81 g) yield; m.p. 201 °C; IR (cm−1, KBr): 3376, 3050, 2911, 2850, 1600, 1563, 1485, 1465, 1416, 1369, 1326,1268, 1217, 1203, 1171, 1133, 1086, 1024, 1008, 967, 918, 891, 891, 868, 805, 776, 717, 672, 659, 572, 473; UV–Vis [DMSO, λ (nm)(є/Lmol−1 cm−1)]: 211 (3283), 252 (828), 258 (872), 264 (850), 282 (771), 328 (514); μeff = 2.26 BM.

Synthesis of [Co(2-ampy) 2 (Sul) 2 ] (2)

Sulindac (3.0 g, 8.4 mmol) was allowed to dissolve in a methanolic solution of potassium hydroxide (0.47 g, 4.2 mmol) (40 ml methanol). To this solution was added slowly CoCl2·7H2O (1.0 g, 4.2 mmol) in 10 ml of methanol, then 2-ampy (0.79 g, 8.4 mmol) dissolved in 15 ml of methanol was added. The mixture was allowed to stir for 24 h, the solvent was evaporated then the residue was dissolved in dichloromethane which was then evaporated and the compound obtained was washed with petroleum ether and dried under vacuum.

[Co(2-ampy) 2 (Sul) 2 ] (2): 56% (2.50 g) yield; m.p. 180 °C (decomposed); IR (cm−1, KBr): 3374, 3268, 3015, 2914, 2860, 1599, 1515, 1494, 1464, 1424, 1380, 1267, 1195, 1164, 1137, 1086, 1031, 1010, 955, 915, 891, 846, 811, 727, 651, 593, 533, 474, 449; UV–Vis [DMSO, λ (nm); (є/Lmol−1 cm−1)]: 207 (1828), 286 (450), 329 (348), 655 (12.7); μeff = 2.41 BM.

Synthesis of [Co(H 2 O) 2 (1,10-phen)(sul) 2 ] (3)

Sulindac (3.0 g, 8.4 mmol) was allowed to dissolve in a methanolic solution of potassium hydroxide (0.47 g, 4.2 mmol) (40 ml methanol). To this solution was added slowly CoCl2·7H2O (1.0 g, 4.2 mmol) in 10 ml of methanol, then 1,10-phenanthroline (0.756 g, 4.2 mmol) dissolved in 15 ml of methanol was added. The mixture was allowed to stir for 24 h, the solvent was evaporated then the residue was dissolved in dichloromethane which was then evaporated and the compound obtained was washed with petroleum ether and dried under vacuum.

[Co(H 2 O) 2 (1,10-phen)(sul) 2 ] (3): 22% (1.0 g) yield; m.p. 140 °C; IR (cm−1, KBr): 3415, 3059, 2911, 2852, 1600, 1515, 1464, 1424, 1380, 1267, 1195, 1164, 1137, 1086, 1010, 956, 915, 891, 846, 811, 727, 651, 593, 533, 474, 441; UV–Vis [DMSO, λ (nm) (є/Lmol−1 cm−1)]: 208 (2152), 226 (700), 271 (535), 328 (224), 431 (16.3), 488 (13.2); μeff = 2.4 BM.

Synthesis of [Co(2,9-dimephen)(sul) 2 ] (4)

Sulindac (3.0 g, 8.4 mmol) was allowed to dissolve in a methanolic solution of potassium hydroxide (0.47 g, 4.2 mmol) (40 ml methanol). To this solution was added slowly CoCl2·7H2O (1.0 g, 4.2 mmol) in 10 ml of methanol, then 2,9-dimethyl-1,10-phenanthroline (0.875 g, 4.2 mmol) dissolved in 15 ml of methanol was added. The mixture was allowed to stir for 24 h, the solvent was evaporated then the residue was dissolved in dichloromethane which was then evaporated and the compound obtained was washed with petroleum ether and dried. Suitable crystals for X-ray structural analysis were obtained by recrystallization from 1:1 mixture of chloroform/acetonitrile.

[Co(2,9-dimephen)(sul) 2 ] (4): 34% (1.54 g) yield; m.p. 150 °C (decomposed); IR (cm−1, KBr): 3040, 2912, 2845, 1599, 1566, 1465, 1441, 1359, 1194, 1157, 1135, 1086, 1031, 954, 916, 891, 855, 812, 761, 728, 644, 533, 474; UV–Vis [DMSO, λ (nm) (є/Lmol−1 cm−1)]: 207 (2263), 229 (933), 274 (621), 328 (261), 432 (13.3); μeff = 2.4 BM.

Physical measurements

Infrared (IR) spectra were recorded in the 450–4000 cm−1 region (KBr) on a Perkin Elmer FT-IR spectrometer (2004). UV–Vis spectra were recorded using Hewlett Packard 8453 photo diode array spectrophotometer in the 200–800 nm region using DMSO as solvent. Melting points were determined in capillary tubes with B-545 melt apparatus without any correction. The magnetic susceptibility measurements were determined by Gouy method using mercury cobalt-thiocyanate complex, (HgCo(NSC)4) as standard. Calculation of the effective magnetic moment was obtained by using the following: μeff = 2.83 * (χmT)1/2 (Molar susceptibility, χm, and T is the temperature with K).

X-ray crystallography

X-ray intensity data of complexes 1 and 4 was carried out at room temperature on a Bruker SMART APEX CCD X-ray diffractometer system (graphite-monochromated Mo Kα radiation λ = 0.71073 Å) by using the SMART software package [80]. The data were reduced and integrated by the SAINT program package [81]. The structure was solved and refined by the SHELXTL software package [82]. H atoms were located geometrically and treated with a riding model. The R-factor above 10% reflects the low quality of crystals obtained in the process of recrystallization and better crystals could not been found. Crystal data and details of the data collection and refinement are summarized in Table 6 and in Additional file 5: Supplementary crystallographic data for complexes 1 and 4.
Table 6

Structure refinement of crystal data for compounds (1) and (4)


Complex (1)

Complex (4)

Empirical formula

C40 H34CoF2O12S2

C53 H38CoF2N2O5S2

Formula weight




0.71073 Å

0.71073 Å


295(1) K

295(1) K

Space group



Crystal system



Unit cell dimensions

a = 5.012(3) Å

α = 81.85(1)°

a = 20.930(3) Å

α = 90°

b = 12.640(8) Å

β = 82.230(9)°

b = 14.836(2) Å

β = 101.705°

c = 16.22(1) Å

γ = 86.40(1)°

c = 15.807(2) Å

γ = 90°


1006.9(11) Å3

4806.3(11) Å3




Absorption coefficient

0.601 mm−1

0.500 mm−1

Density (calculated)

1.431 Mg/m3

1.304 Mg/m3

Crystal size

0.50 × 0.16 × 0.06 mm3

0.53 × 0.46 × 0.05 mm3




Reflections collected



Theta range for data collection



Index ranges

−6 ≤ h ≤ 6, −16 ≤ k ≤ 16, −20 ≤ l ≤ 20

−26 ≤ h ≤ 26, −18 ≤ k ≤ 18, −20 ≤ l ≤ 19

Completeness to theta = 26.99°



Independent reflections

4334[R(int) = 0.0625]

10,468 [R(int) = 0.0766]

Absorption correction






Refinement method

Full-matrix least-squares on F2

Full-matrix least-squares on F2

Largest diff. peak and hole

1.331 and −0.664 e Å−3

2.147 and −0.686 e Å−3

Goodness-of-fit on F2



R indices (all data)

R1 = 0.1355, wR2 = 0.2727

R1 = 0.2349, wR2 = 0.4718

Final R indicesa [I > 2sigma(I)]

R1 = 0.1158, wR2 = 0.2599

R1 = 0.1941, wR2 = 0.4496

a \({\text{R}}1 = \sum \left\| {{\text{F}}_{0} \left| - \right|{\text{F}}_{\text{c}} } \right\|/\sum {\text{F}}_{0} ,\;{\text{wR}}_{2} = \left\{ {\sum [{\text{w}}({\text{F}}_{0}^{2} - {\text{F}}_{c}^{2} )^{2} ]/\sum [{\text{w}}({\text{F}}_{0}^{2} )^{2} } \right\}^{1/2}\)

Anti-bacterial activity

Agar diffusion method [83] was used for screening the anti-bacterial activity measurements of the synthesized cobalt complexes. Different types of gram-negative bacteria (Bordetella, E. coli) and gram-positive (S. epidermidis, S. aureus) and Yeast species (Saccharomyces and Candida) were used in the present work.

In sterile saline single bacterial colonies were dissolved until the suspended cells reached the turbidity of McFarland 0.5 Standard. The bacterial inocula were spread on the surface of the Muller Hinton nutrient agar by means of a sterile cotton swab. Sterile glassy borer were used to make a 6 mm in diameter wells in the agar plate. Samples were dissolved in DMSO in concentration equal to (8 mg/ml), (4 mg/ml) and (2 mg/ml), then 50 μl of the test samples were introduced in the respective wells. DMSO was used as negative control while gentamycin used as positive control. Immediately the plate was incubated at 37 °C for 24 h. The anti-bacterial activity was determined by measuring the diameter inhibition zone of complete growth in millimeter (mm). The averages of two trials determined the results and are stated as average ± standard deviation.



Authors’ contributions

Both authors read and approved the final manuscript.


The authors thank the office of Vice President for Academic Affairs at Birzeit University for their financial support.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

Department of Chemistry, Birzeit University, P.O. Box 14, West Bank, Palestine


  1. Zhang KL, Lin JG, Wang YQ, Xu WL, Chen JT (2004) Aquabis (2-nitrobenzoato-κO)(1, 10-phenanthroline-κ2N, N′) zinc (II). Acta Crystallogr Sect C 60:m454–m456View ArticleGoogle Scholar
  2. Cotton FA, Wilkinson G, Murillo CA, Bochmann M (1999) Advanced inorganic chemistry, 6th edn. Wiley, New York, pp 817–819Google Scholar
  3. Weder JE, Dillon CT, Hambley TW, Kennedy BJ, Lay PA, Biffin JR, Regtop HL, Davies NM (2002) Copper complexes of non-steroidal anti-inflammatory drugs: an opportunity yet to be realized. Coord Chem Rev 232:95View ArticleGoogle Scholar
  4. Ott I, Kircher B, Gust R (2004) Investigations on the effects of cobalt-alkyne complexes on leukemia and lymphoma cells: cytotoxicity and cellular uptake. J Inorg Biochem 98:485–489View ArticleGoogle Scholar
  5. Yesilel OZ, Mutlu A, Darcan C, Buyukgungor O (2010) Syntheses, structural characterization and antimicrobial activities of novel cobalt-pyrazine-2, 3-dicarboxylate complexes with N-donor ligands. J Mol Struct 964:39–46View ArticleGoogle Scholar
  6. Lopez-Sandoval H, Londono-Lemos ME, Garza-Velasco R, Poblano-Melendez I, Granada-Macias P, Gracia-Mora I, Barba-Behrens N (2008) Synthesis, structure and biological activities of cobalt (II) and zinc (II) coordination compounds with 2-benzimidazole derivatives. J Inorg Biochem 102:1267–1276View ArticleGoogle Scholar
  7. Lv J, Liu T, Cai S, Wang X, Liu L, Wang Y (2006) Synthesis, structure and biological activity of cobalt (II) and copper (II) complexes of valine-derived schiff bases. J Inorg Biochem 100:1888–1896View ArticleGoogle Scholar
  8. Gust R, Ott I, Posselt D, Sommer K (2004) Development of cobalt (3, 4-diarylsalen) complexes as tumor therapeutics. J Med Chem 47:5837–5846View ArticleGoogle Scholar
  9. Dimiza F, Papadopoulos AN, Tangoulis V, Psycharis V, Raptopoulou CP, Kessissoglou DP, Psomas G (2010) Biological evaluation of non-steroidal anti-inflammatory drugs-cobalt (II) complexes. Dalton Trans 39:4517–4528View ArticleGoogle Scholar
  10. Miodragovic DU, Bogdanovic GA, Miodragovic ZM, Radulovic MD, Novakovic SB, Kaluderovic GN, Kozlowski H (2006) Interesting coordination abilities of antiulcer drug famotidine and antimicrobial activity of drug and its cobalt (III) complex. J Inorg Biochem 100:1568–1574View ArticleGoogle Scholar
  11. Nomiya K, Yoshizawa A, Tsukagoshi K, Kasuga NC, Hirakawa S, Watanabe J (2004) aluminium (III) and cobalt (II) complexes with 4-isopropyltropolone (hinokitiol) showing noteworthy biological activities. Action of silver (I)-oxygen bonding complexes on the antimicrobial activities. J Inorg Biochem 98:46–60View ArticleGoogle Scholar
  12. Rodriguez-Argüelles MC, Mosquera-Vazquez S, Sanmartin-Matalobos J, Garcia-Deibe AM, Pelizzi C, Zani F (2010) Polyhedron 29:864–866View ArticleGoogle Scholar
  13. Matsumoto K, Yamamoto S, Yoshikawa Y, Doe M, Kojima Y, Sakurai H, Hashimoto H, Kajiwara MN (2005) Antidiabetic activity of Zn (II) complexes with a derivative of L-glutamine. Bull Chem Soc Jpn 78:1077–1081View ArticleGoogle Scholar
  14. Dorkov P, Pantcheva IN, Sheldrick WS, Mayer-Figge H, Petrova R, Mitewa M (2008) Synthesis, structure and antimicrobial activity of manganese (II) and cobalt (II) complexes of the polyether ionophore antibiotic Sodium Monensin A. J Inorg Biochem 102:26–32View ArticleGoogle Scholar
  15. Abu Ali H, Darawsheh MD, Rappocciolo E (2013) Synthesis, crystal structure, spectroscopic and biological properties of mixed ligand complexes of zinc (II) valproate with 1, 10-phenanthroline and 2-aminomethylpyridine. Polyhedron 61:235–241View ArticleGoogle Scholar
  16. Szunyogova E, Gyoryova K, Hudecova D, Piknova L, Chomic J, Vargova Z, Zelenak V (2007) Thermal, spectral and biological properties of Zn (II) complex compounds with phenazone. J Therm Anal Calorim 88:219–223View ArticleGoogle Scholar
  17. Rodriguez-Arguelles MC, Mosquera-Vazquez S, Sanmartin-Matalobos J, Garcia-Deibe AM, Pelizzi C, Zani F (2010). Polyhedron: 867–870Google Scholar
  18. Fountoulaki S, Perdih F, Turel I, Kessissoglou DP, Psomas G (2011) Non-steroidal anti-inflammatory drug diflunisal interacting with Cu (II). Structure and biological features. J Inorg Biochem. 105:1645–1655View ArticleGoogle Scholar
  19. Hwu JR, Tsay SC, Chuang KS, Kapoor M, Lin JY, Yeh CS, Su WC, Wu PC, Tsai TL, Wang PW, Shieh DB (2016) Syntheses of platinum–sulindac complexes and their nanoparticles as targeted anticancer drugs. Chem-A Eur J. 22:1926–1930View ArticleGoogle Scholar
  20. Dimiza F, Papadopoulos A, Tangoulis V, Raptopoulou C, Kessissglou D, Psomas G (2012) Biological evaluation of cobalt (II) complexes with non-steroidal anti-inflammatory drug naproxen. J Inorg Biochem 107:54–64View ArticleGoogle Scholar
  21. Tsiliou S, Kefala L, Perdih F, Turel I, Kessissoglou D, Psomas G (2012) Cobalt (II) complexes with non-steroidal anti-inflammatory drug tolfenamic acid: Structure and biological evaluation. Eur J Med Chem 48:132–142View ArticleGoogle Scholar
  22. Tsiliou S, Kefala Hatzidimitriou A, Kessissoglou D, Perdih F, Papadopoulos A, Turel I, Psomas G (2015) J Inorg Biochem: 1–15Google Scholar
  23. Psomas G, Kessissoglou D (2013) Dalton Trans: 1–52Google Scholar
  24. Patil A, Donde K, Raut S, Patil V, Lokhande R (2012) J Chem Pharm Res 4:1413–1425Google Scholar
  25. Kovala-Demertzi D (2000) J Inorg Biochem 79:153–157View ArticleGoogle Scholar
  26. Krstic NS, Nikolic RS, Stankovic MN, Nikolic NG, Dordevic DM (2015) Coordination compounds of M (II) biometal Ions with acid-type anti-inflammatory drugs as ligands—a review. Trop J Pharm Res 14:337–349View ArticleGoogle Scholar
  27. Konstandinidou M, Kourounakis A, Yiangou M, Hadjipetrou L, Kovala-Demertzi D, Hadjikakou S, Demertzis M (1998) Anti-inflammatory properties of diclofenac transition metalloelement complexes. J Inorg Biochem 70:63–69View ArticleGoogle Scholar
  28. Abu Ali H, Fares H, Darawsheh M, Rappocciolo E, Akkawi M, Jaber S (2015) Synthesis, characterization and biological activity of new mixed ligand complexes of Zn (II) naproxen with nitrogen based ligands. Eur J Med Chem 89:67–76View ArticleGoogle Scholar
  29. Darawsheh M, Abu Ali H, Abuhijleh AL, Rappocciolo E, Akkawi M, Jaber S, Maloul S, Hussein Y (2014) New mixed ligand zinc (II) complexes based on the antiepileptic drug sodium valproate and bioactive nitrogen-donor ligands. Synthesis, structure and biological properties. Eur J Med Chem 82:152–163View ArticleGoogle Scholar
  30. Abu Ali H, Jabali B (2016) Polyhedron 107:97–106View ArticleGoogle Scholar
  31. Jabali B, Abu Ali H (2016) Non-steroidal Anti-Inflammatory Drug (indomethacin) and various nitrogen donor ligands. Synthesis, characterization and biological activity. Polyhedron 117:249–258View ArticleGoogle Scholar
  32. Abu Ali H, Omar S, Darawsheh M, Fares H (2016) Synthesis, characterization and antimicrobial activity of zinc (II) ibuprofen complexes with nitrogen-based ligands. J Coord Chem 69:1110–1122View ArticleGoogle Scholar
  33. Abu Ali H, Maloul S, Abu Ali I, Akkawi M, Jaber S (2016) Dichloro-bis-(pyridine-2-yl-undecyl-amine) zinc (II),[ZnCl2 (C16N2H26) 2]: Synthesis, characterization and antimalarial activity. J Coord Chem 69:2514–2522View ArticleGoogle Scholar
  34. Abu Ali H, Shalash A, Akawi M, Jaber S (2017) Synthesis, characterization and in vitro biological activity of new zinc (II) complexes of the nonsteroidal anti-inflammatory drug sulindac and nitrogen-donor ligands. Appl Organomet Chem. doi:10.1002/aoc.3772 Google Scholar
  35. Abu Ali H, Kamel S, Abu Shamma A (2017) Novel structures of Zn (II) biometal cation with the biologically active substituted acetic acid and nitrogen donor ligands: Synthesis, spectral, phosphate diester catalytic hydrolysis and anti-microbial studies. Appl Organomet Chem. doi:10.1002/aoc.3829 Google Scholar
  36. Abu Ali H, Abu Shamma A, Kamel S (2017) New mixed ligand cobalt (II/III) complexes based on the drug sodium valproate and bioactive nitrogen-donor ligands. Synthesis, structure and biological properties. J Mol Struct. doi:10.1016/j.molstruc.2017.04.048 Google Scholar
  37. Accessed 20 Jan 2015
  38. Accessed 15 Mar 2015
  39. Viossat V, Lemoine P, Dayan E, Dung N, Viossat B (2005) Synthesis, crystal structures and IR spectra of isotypic pseudopolymorphs complexes of Zn (II) by indole-2-carboxylic acid and 2, 9-dimethyl-1, 10-phenanthroline with different solvates (DMA, DMF or DMSO). J Mol Struct 741:45–52View ArticleGoogle Scholar
  40. Kadhiravan S, Sivajiganesan S (2015) J Appl Chem 8:73–84Google Scholar
  41. Waizump K, Takuno M, Fukushima N, Masuda H (1998) Structures of pyridine carboxylate complexes of cobalt (II) and copper (II). J Coord Chem 44:269–279View ArticleGoogle Scholar
  42. Liu Z, Chen Y, Liu P, Wang J, Huang M (2005) Cadmium (II) and cobalt (II) complexes generated from benzimidazole-5-carboxylate: self-assembly by hydrogen bonding and π–π interactions. J Solid State Chem 178:2306–2312View ArticleGoogle Scholar
  43. Bu XH, Tong ML, Xie YB, Li JR, Chang HC, Kitagawa S, Ribas J (2005) Synthesis, structures, and magnetic properties of the copper (II), cobalt (II), and manganese (II) complexes with 9-acridinecarboxylate and 4-quinolinecarboxylate ligands. Inorg Chem 44:9837–9846View ArticleGoogle Scholar
  44. Rettig SJ, Thompson RC, Trotter J, Xia S (1999) rystal structure and magnetic properties of polybis (formamide) bis (μ-formato) cobalt (II): an extended two-dimensional square lattice material which exhibits spontaneous magnetization below 9 K. Inorg Chem 38:1360–1363View ArticleGoogle Scholar
  45. Greiner BA, Marshall NM, Narducci Sarjeant AA, McLauchlan CC (2007) Imidazole-based nickel (II) and cobalt (II) coordination complexes for potential use as models for histidine containing metalloproteins. Inorg Chim Acta 360:3132–3140View ArticleGoogle Scholar
  46. Singh UP, Aggarwal V, Sharma AK (2007) Mononuclear cobalt (II) carboxylate complexes Synthesis molecular structure and selective oxygenation study. Inorg Chim Acta 360:3226–3232View ArticleGoogle Scholar
  47. Khandar AA, Shaabani B, Belaj F, Bakhtiari A (2007) Synthesis, characterization, electrochemical and spectroscopic investigation of cobalt (III) Schiff base complexes with axial amine ligands: The layered crystal structure of [Co III (salophen)(4-picoline) 2] ClO 4· CH 2 Cl 2. Inorg Chim Acta 360:3255–3264View ArticleGoogle Scholar
  48. Lai CS, Tiekink ERT (2003) Appl Organomet Chem 17:255–256View ArticleGoogle Scholar
  49. Nakamoto K (2009) Infrared and Raman spectra of inorganic and coordination compounds, 6th edn. Wiley, HobokenGoogle Scholar
  50. Badshah KD (2011) Synthesis and characterization of zinc complexes with N- and O- donor ligands. AIOU, IslamabadGoogle Scholar
  51. Zeleňák V, Vargová Z, Györyová K (2007) Correlation of infrared spectra of zinc (II) carboxylates with their structures. Spectrochim Acta, Part A 66:262–272View ArticleGoogle Scholar
  52. Zhang X, Yi ZH, Xue M, Xu Y, Yu JH, Yu XY, Xu JQ (2007) Chem Res Chin Univ 23:631–634View ArticleGoogle Scholar
  53. Yu HL, Yang J, Fu Q, Ma JC, Li WL (2008) Chem Res Chin Univ 24:123View ArticleGoogle Scholar
  54. Hasanvanda F, Hoseinzadeh A, Zolgharnein J, Amania S (2010) J Coord Chem 63:346–352View ArticleGoogle Scholar
  55. Ahmadia RA, Hasanvanda F, Brunob G, Rudbarib HA, Amania S (2013) Russ J Coord Chem 39:867–871View ArticleGoogle Scholar
  56. Komaei SA, Albada G, Reedijk AV (1999) J Trans Met Chem 24:104–107View ArticleGoogle Scholar
  57. Rodríguez L, Labisbal E, Sousa-Pedrares A, García-Vázquez JA, Romero J, Durán ML, Real A, Sousa A (2006) Coordination chemistry of amine bis (phenolate) cobalt (II), nickel (II), and copper (II) complexes. Inorg Chem 45:7903–7914View ArticleGoogle Scholar
  58. Shaker SA, Farina Y, Mahmmod S, Eskender M (2009) Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) mixed ligand complexes of theophylline and cyanate: synthesis and spectroscopic characterization. Mod Appl Sci 3:88–93View ArticleGoogle Scholar
  59. Sunita Devi O, Manihar Singh AK (2011) J Chem Pharm Res 3:1055–1060Google Scholar
  60. Al-Nahary TT (2009) Synthesis and characterization of metal complexes of Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Ru (III), Rh (III) and Pd (II) with derivatives of 1, 3, 4-thiadiazole-2, 5-dithiol as new ligands. J Saudi Chem Soc 13:253–257View ArticleGoogle Scholar
  61. Al-Nahary TT (2007) ISESCO J Sci Technol Vis 3:16–22Google Scholar
  62. Faus J, Julve M, Lloret F, Muiioz MC (1993) Bis (dimethylviolurato)(phenanthroline) cobalt (II), a low-spin octahedral cobalt (II) complex. Crystal structure of [Co (dmvi) 2phen]. 2CHCl3. Inorg Chem 32:2013–2017View ArticleGoogle Scholar
  63. Çukurovali A, Yilmaz I, Özmen H, Ahmedzade M (2002) Cobalt (II), copper (II), nickel (II) and zinc (II) complexes of two novel Schiff base ligands and their antimicrobial activity. Trans Met Chem 27:171–176View ArticleGoogle Scholar
  64. Pal S, Sengupta P, Ghosh S, Mukherjee G, Mostafa G (2002) Cobalt (III) and Low Spin Cobalt (II) Complexes of the Two Highly Flexible Hexadentate Ligands 1, 3-di (o-salicylaldiminophenylthio) propane and 1, 2-di (o-salicylaldiminophenylthio) xylene. J Coord Chem 55:271–280Google Scholar
  65. Hitchman MA (1977) Electronic structure of low-spin cobalt (II) Schiff base complexes. Inorg Chem 16:1985–1993View ArticleGoogle Scholar
  66. Hartman JR, Hintsa EJ, Cooper SR (1986) J Am Chem Soc 108:1202–1208View ArticleGoogle Scholar
  67. Marques LF, Marinho MV, Speziali NL, Visentin LC, Machado FC (2011) Inorg Chim Acta 365:454–457View ArticleGoogle Scholar
  68. Bertrand JA, Carpenter DA, Kalyanaraman AR (1971) The structure of K2BaCo (NO2) 6 at 233° K.: a static Jahn-Teller distortion. Inorg Chim Acta 5:113–114View ArticleGoogle Scholar
  69. Hartman JR, Hintsa EJ, Cooper SR (1984) J Chem Soc Chem Commun: 287–386Google Scholar
  70. Setzer WN, Ogle CA, Wilson GS, Glass RS (1983) Inorg Chem 22:266–271View ArticleGoogle Scholar
  71. Wilson GS, Swanson DD, Glass RS (1986) Inorg Chem 25:3827View ArticleGoogle Scholar
  72. Dimiza F, Perdih F, Tangoulis V, Turel I, Kessissoglou DP, Psomas G (2012) Eur J Med Chem 48:132–142View ArticleGoogle Scholar
  73. Tsiliou S, Kefala LA, Perdih F, Turel I, Kessissoglou DP, Psomas G (2013) Dalton Trans 42:6252–6276View ArticleGoogle Scholar
  74. Psomas G, Kessissoglou DP (2002) J Enzyme Inhib Med Chem 17:87–91View ArticleGoogle Scholar
  75. Chohan ZH, Iqbal MS, Iqbal HS, Scozzafava A, Supuran CT (2012) Eur J Med Chem 48:132–142View ArticleGoogle Scholar
  76. Tsiliou S, Kefala LA, Perdih F, Turel I, Kessissoglou DP, Psomas G (2012) J Inorg Biochem 107:54–64View ArticleGoogle Scholar
  77. Geraghtya M, Sheridana V, McCanna M, Devereuxb M, McKeec V (1999) Polyhedron 18:2931–2939View ArticleGoogle Scholar
  78. Podunavac-Kuzmanovic S, Vojinovic L, Cvetkovic D (2003) ISIRRGoogle Scholar
  79. Shalash A, Abu Ali H (2015) Non-steroidal Zn(II) and Co(II) sulindac drugs and bioactive Nitrogen-donor ligands: synthesis, characterization, anti-bacterial effect, anti-malarial effect and the use as phosphate hydrolyzing enzymes, Master Thesis, Birzeit UniversityGoogle Scholar
  80. SMART-NT V5.6, B. A. G. (2002) KarlsruheGoogle Scholar
  81. SAINTL-NT V5.0, B. A. G. (2002) KarlsruheGoogle Scholar
  82. SHELXTL-NT V6.1, B. A. G. (2002) KarlsruheGoogle Scholar
  83. Rahman A, Choudhary MI, Thomsen WJ (2001) Bioassay techniques for drug development. Harwood Academic, AmsterdamView ArticleGoogle Scholar


© The Author(s) 2017