Synthesis, structures and antimicrobial activities of nickel(II) and zinc(II) diaminomaleonitrile-based complexes

Synthesis, structures and antimicrobial activities of nickel(II) and zinc(II)... Three Ni(II) and Zn(II) complexes [Ni(L1)], [Ni(L2)], and [Zn(L3)(DMSO)] (L1 = 2,3-bis(2-hydroxybenzylideneimino)- 2,3-butenedinitrile, L2 = 2,3-bis(2-hydroxy-3-methoxybenzylideneimino)-2,3-butenedinitrile, L3 = 2,3-bis(2-hydroxy- 1-naphthylideneimino)-2,3-butenedinitrile) were obtained in DMSO by one-pot syntheses. The complexes were characterized by physicochemical and spectroscopic methods. Also, their solid-state structures were determined by single-crystal X-ray diffraction. The geometries of the Ni(II) and Zn(II) complexes were square planar and square pyramidal, respectively. The complexes were screened in vitro against a fungal species and eight species of bacteria, revealing their antimicrobial activity. Introduction DAMN with different aromatic aldehydes can form 1:1 and/ or 1:2 Schiff base ligands [ 14]. In recent studies, we have The synthesis and characterization of Schiff bases and their reported the synthesis and characterization of complexes transition metal complexes has attracted considerable atten- incorporating tridentate NNO-Schiff base ligands based on tion in recent decades [1–3]. Schiff base ligands with a vari - diaminomaleonitrile [15, 16]. In this project, our efforts were ety of donor atoms including nitrogen, oxygen and sulfur directed to the synthesis and characterization of nickel(II) can be coordinated with transition metal atoms. Depending and zinc(II) complexes with tetradentate N O -Schiff base 2 2 on the type and oxidation state of the central metal atom ligands based on diaminomaleonitrile and various aldehydes and the ligand structure, they can be bidentate, tridentate, such as 2-hydroxybenzaldehyde, 3-methoxy-2-hydroxyben- tetradentate or polydentate, and depending on the nature zaldehyde and 2-hydroxy-1-naphthaldehyde. of the possible counter ion, transition metal Schiff’s base complexes show various coordination modes with varying degree of distortion [4, 5]. Among these, the tetradentate Experimental Schiff bases with N O coordination sites belong to ligands 2 2 investigated most often in coordination chemistry [6–8]. Materials and methods The transition metal complexes formed from tetradentate Schiff bases exhibit a wide range of biological properties All reagents for synthesis and analysis were purchased from [9–12]. 2,3-Diamino-cis-2-butenedinitrile (diaminomaleoni- Merck and used without further purification. Elemental anal - trile: DAMN) is an attractive precursors to nucleotides and yses were recorded on a Thermo Finnigan Flash Elemental is considered as an intermediate in the synthesis of a wide Analyzer 1112EA. Melting points were measured on an variety of heterocyclic compounds [13]. The condensation of Electrothermal-9100 apparatus. The IR measurements were taken on a FTIR Tensor 27 infrared spectrophotometer as −1 1 KBr disks in the range of 400–4000 cm . H NMR spectra * Iran Sheikhshoaie were measured on a Bruker AVANCE BRX 250 MHz spec- i_shoaie@yahoo.com; shoaie@uk.ac.ir trometer using d -DMSO as solvent for the complexes. The Department of Chemistry, Faculty of Science, Shahid chemical shift values (δ) are given in ppm. The electronic Bahonar University of Kerman, Kerman, Iran absorption spectra in DMSO solution were recorded by a Fakultät für Chemie und Mineralogie, Universität Leipzig, Cary 50 UV–Vis spectrophotometer. Bacteria were isolated 04103 Leipzig, Germany from clinical samples or purchased from Merck Company. Department of Biology, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran Vol.:(0123456789) 1 3 556 Transition Metal Chemistry (2018) 43:555–562 –CH=N), 7.20–6.45 (m, 6H, ArH), 3.74 (s, 6H, –OCH ). Preparation of [Ni(L1)] and [Ni(L2)] −1 −1 UV–Vis spectra [λ , nm (log ε, L mol  cm ); DMSO max solution]: 270 (4.29), 355 (4.16), 375 (4.13), 395 (4.14), A solution of 2-hydroxybenzaldehyde (2.0 mmol, 0.21 ml) 520 (3.97), 600 (4.13). Anal. Calcd. for C H N NiO : C, for H L1 and 3-methoxy-2-hydroxybenzaldehyde (0.304 g, 20 18 4 6 51.2; H, 3.8; N, 11.9%. Found: C, 51.0; H, 3.7; N, 11.7%. 2.0 mmol) for H L2 and 2,3-diamino-cis-2-butenedini- trile (0.108 g, 1.0 mmol) in DMSO (5 ml) was heated for Preparation of [Zn(L3)(DMSO)] 30 min. Afterward, triethylamine (0.200 g, 2.0 mmol) and NiCl ·6H O (0.238 g, 1.0 mmol) in DMSO (5 ml) were 2 2 This complex was synthesized similar to [Ni(L1)] and added dropwise and the resulting reaction mixture was [Ni(L2)] complexes. To a solution of 2-hydroxy-1-naph- refluxed for 4 h while stirring constantly. The clear green thaldehyde (0.344  g, 2.0  mmol) in DMSO (10  ml), solution was allowed to stand several days at room tem- 2,3-diamino-cis-2-butenedinitrile (0.108 g, 1.0 mmol) was perature, providing blue single crystals suitable for X-ray added and refluxed for 30 min. A deep brown solution was crystallography (Scheme 1). obtained. After adding triethylamine (0.200 g, 2.0 mmol) [Ni(L1)]: Yield: 0.242 g (65%); m.p. > 300 °C IR (KBr, −1 and Zn(CH CO ) ·2H O (0.219 g, 1.0 mmol) to the solution, cm ): 2218 (C≡N), 1611 (C=N), 1576 (C=C) , 3 2 2 2 aliphatic the color of the solution changed to black. Dark red single 1517 (C=C) , 1195 (C–O), 754 (Ni–N), 418 (Ni–O). aromatic crystals suitable for crystallography appeared after 2 weeks H NMR (250 MHz, d -DMSO, ppm): δ = 8.57 (s, 2H, standing (Scheme 2). Yield 0.407 g (73%); m.p. > 300 °C. –CH=N), 7.45–6.24 (m, 8H, ArH). UV–Vis spectra [λ , max −1 −1 −1 IR (KBr, cm ): 3007 (C–H), 2209 (C≡N), 1601 (C=N), nm (log ε, L mol  cm ); DMSO solution]: 265 (4.46), 1571 (C=C) , 1536 (C=C) , 1267 (C–O), 1183 305 (4.30), 380 (4.25), 440 (4.08), 530 (4.09), 595 (4.08). aliphatic aromatic (S=O), 747 (Zn–N), 412 (Zn–O). H NMR (250  MHz, Anal. Calcd. for C H N NiO : C, 57.9; H, 2.7; N, 15.0%. 18 10 4 2 d -DMSO, ppm): δ  =  9.25 (s, 2H, –CH=N), 8.06- 6.94 Found: C, 57.7; H, 2.6; N, 14.9%. (m, 12H, ArH), 3.30 (s, 6H, CH ). UV–Vis spectra [λ , [Ni(L2)]: Yield 0.259 g (60%); m.p. > 300 °C. IR (KBr, 3 max −1 −1 −1 nm (log ε, L mol cm ); DMSO solution]: 265 (4.65), cm ): 2225 (C≡N), 1612 (C=N), 1580 (C=C) , aliphatic 355 (4.31), 400 (4.40), 425 (4.38), 465 (4.23), 600 (4.71). 1538 (C=C) , 1253 (C–O), 735 (Ni–N), 414 (Ni–O). aromatic Anal. Calcd. for C H N O SZn: C, 60.2; H, 3.6; N, 10.0%. H NMR (250 MHz, d -DMSO, ppm): δ = 8.49 (s, 2H, 28 20 4 3 Found: C, 60.0; H, 3.3; N, 9.8%. NC CN C C H H H N NC CN Ni NiCl ·6H O 2 2 OH + CC O O H N NH 2 2 DMSO 1mmol 2mmol R= H[Ni(L1)] R= OCH3 [Ni(L2)] Scheme 1 A schematic representation of synthesis of [Ni(L1)] and [Ni(L2)] complexes NC CN C C H NC CN Zn(CH CO ) ·2H O 3 2 2 2 Zn OH + CC H N NH DMSO 2 2 2mmol1 mmol H C CH 3 3 Scheme 2 A schematic representation of synthesis of [Zn(L3)(DMSO)] complex 1 3 Transition Metal Chemistry (2018) 43:555–562 557 ATCC 27853, Staphylococcus aureus PTCC 1112, Escher- X‑ray structure determination ichia coli PTCC 1330, Bacillus cereus PTCC 1015 and Micrococcus luteus PTCC 1110) and three bacteria isolated Suitable crystals for single-crystal X-ray structure analysis were selected in mineral oil and mounted on glass fibers. from clinical samples (Klebsiella pneumoniae, Enterococcus faecalis and Listeria monocytogenes). Brain Heart Infusion Diffraction data for [Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)] were collected on an IPDS-1 diffractometer (Stoe&Cie medium (BHI-Merck) was used for L. monocytogenes and E. faecalis, whereas the other bacteria were cultured on Muel- GmbH, Darmstadt, Germany) using graphite-monochroma- tized Mo-Kα radiation, (λ = 0.71073 Å). The structures were ler–Hinton medium (Merck). Also, YGC medium (Merck) was used as the test medium for the yeast strain. solved by direct methods using SHELXS and refined using SHELXL [17]. All non-hydrogen atoms with the exception Determination of antimicrobial activity of the disordered S atom of the DMSO ligand in [Zn(L3) (DMSO)] were refined anisotropically. Hydrogen atoms The antimicrobial activities of [Ni(L1)], [Ni(L2)] were included in idealized positions. The molecular graph- ics were drawn with DIAMOND [18]. Crystallographic data and [Zn(L3)(DMSO)] complexes, NiCl ·6H O and 2 2 Zn(CH CO ) ·2H O against some Gram positive bacteria and details of the data collection and structure refinement 3 2 2 2 are listed in Table 1, selected bond lengths and angles are strains (L. monocytogenes, E. faecalis, S. aureus PTCC 1112, M. luteus PTCC 1110 and B. cereus PTCC 1015), presented in Table 2, and Scheme 3 shows packing views of the three complexes. some Gram negative bacterial strains (E. coli PTCC 1330, K. pneumoniae, P. aeruginosa ATCC 27853) and Microorganism strains and culture a fungal species (C. albicans PTCC 5027) were investi- gated using agar well diffusion plate methods [19]. The In this research, we used one yeast (Candida albicans PTCC agar media were inoculated with 100 µl of the inoculums which were prepared using an overnight culture of each 5027), five standard bacteria ( Pseudomonas aeruginosa Table 1 Crystallographic Complex [Ni(L1)] [Ni(L2)] [Zn(L3)(DMSO)] data collection parameters for [Ni(L1)], [Ni(L2)] and [Zn(L3) Formula C H N NiO C H N NiO C H N O SZn 18 10 4 2 20 18 4 6 28 20 4 3 (DMSO)] −1 Formula weight, g mol 373.01 469.09 557.91 Crystal size, mm 0.30 × 0.10 × 0.05 0.10 × 0.10 × 0.08 0.20 × 0.20 × 0.10 Crystal color Blue Blue Red Temperature, K 213 213 213 Crystal system Orthorhombic Monoclinic Triclinic Space group Pbcn I2/a P 1 Unit cell dimensions (Å, °)  a 17.133 (2) 13.291 (1) 10.4479 (5)  b 6.9752 (4) 13.0637 (6) 11.1601 (5)  c 26.088 (2) 22.605 (2) 11.8326 (6)  α 90 90.00 102.406 (6)  β 90 102.322 (7) 100.556 (6)  γ 90 90.00 111.140 (5)  Volume, Å 3117.6 (4) 3834.5 (5) 1204.22 (11)  Z 8 8 2 −3 Calculated density, g cm 1.589 1.625 1.539 −1 Absorption coefficient, mm 1.264 1.061 1.146 θ range for data collection, ° 2.0–25.0 2.2– 25.0 2.1–25.9 Reflections collected 18,304 12,828 11,951 Independent reflections (R ) 2681 (0.146) 3335 (0.165) 4372 (0.0273) int Observed reflections [I  ≥ 2σ(I)] 1003 1617 3683 Parameters 226 280 344 R1 (observed reflections) 0.0445 0.0786 0.031 wR2 (all data) 0.1028 0.1825 0.078 −3 Largest diff. peak/hole, eÅ 0.47/− 0.84 0.74/− 0.72 0.49/− 0.30 1 3 558 Transition Metal Chemistry (2018) 43:555–562 Table 2 Selected bond lengths [Ni(L1)] (Å) and angles (°) of [Ni(L1)],  Ni1–N1 1.854 (6) N1–C5 1.320 (9) Ni1–O2 1.834 (5) [Ni(L2)] and [Zn(L3)(DMSO)]  Ni1–N2 1.862 (6) N2–C2 1.406 (8) N1–C1 1.387 (7)  Ni1–O1 1.836 (5) C5–C6 1.400 (11) C1–C2 1.349 (7)  N1–Ni1–N2 86.2 (3) O2–Ni1–N2 94.19 (16) O1–Ni1–O2 85.0 (2)  N1–Ni1–O1 94.71 (15) Ni1–N1–C1 112.0 (5) O1–Ni1–N2 177.9 (2)  N1–Ni1–O2 178.4 (2) Ni1–N1–C5 127.5 (5) N1–C5–C6 124.2 (7) [Ni(L2)]  Ni1–N1 1.838 (6) N1–C5 1.327 (9) Ni1–O2 1.849 (5)  Ni1–N2 1.860 (6) C5–C6 1.382 (9) N1–C1 1.366 (9)  Ni1–O1 1.846 (4) C1–C2 1.341 (10)  N1–Ni1–N2 86.0 (3) O2–Ni1–N2 94.1 (2) O1–Ni1–O2 85.9 (2)  N1–Ni1–O1 94.0 (2) Ni1–N1–C1 112.5 (5) O1–Ni1–N2 178.8 (3)  N1–Ni1–O2 179.9 (3) Ni1–N1–C5 127.5 (5) N1–C5–C6 124.1 (8) [Zn(L3)(DMSO)]  Zn1–N1 2.0813 (14) Zn1–O3 2.0430 (16) N3–C3 1.135 (3)  Zn1–N2 2.0992 (17) N1–C1 1.378 (3) C1–C2 1.371 (3)  Zn1–O1 1.9530 (16) N1–C5 1.319 (2) C1–C3 1.450 (3)  Zn1–O2 1.9742 (13) N2–C2 1.386 (2) C5–C6 1.404 (3)  N1–Zn1–O1 87.43 (6) O1–Zn1–O3 100.55 (8) C1–N1–C5 121.68 (16)  N1–Zn1–O2 146.31 (7) O1–Zn1–N2 159.77 (7) Zn1–N1–C1 111.94 (12)  N1–Zn1–O3 108.81 (7) O2–Zn1–O3 102.96 (6) Zn1–N1–C5 126.06 (13)  N1–Zn1–N2 79.12 (6) O2–Zn1–N2 85.71 (6) N1–C5–C6 126.17 (17)  O1–Zn1–O2 97.67 (6) O3–Zn1–N2 98.08 (8) Scheme 3 The packing view of [Ni(L1)] (a), [Ni(L2)] (b) and [Zn(L3)(DMSO)] (c) microorganism (18–24 h) adjusted to a turbidity equivalent was used as a negative control. The minimum inhibitory to a 0.5-McFarland standard. Wells were cut and 50 µl of concentration (MIC) and minimal bactericidal concen- the compounds (10 mg/ml; DMSO was used as solvent) tration (MBC) were determined by microdilution assay were added. Each compound was tested in triplicate along (NCCLS, 2008). The cultures were prepared in 24 and with standard ciprofloxacin for bacteria and fluconazole 72 h broth cultures of microorganisms, respectively. The for yeast. The plates were incubated at 37 °C for 24 h. MIC was defined as the lowest concentration of compound The antimicrobial activity was assayed by measuring the to inhibit the growth of microorganisms, and the MBC was diameter of the inhibition zone formed around the well. defined as the lowest concentration of compound to kill the The diameter of the zone of inhibition was measured by microorganisms. Serial dilutions ranging from 10 mg/ml measuring scale in millimeters (mm). DMSO as solvent to 39 µg/ml were prepared in medium. 1 3 Transition Metal Chemistry (2018) 43:555–562 559 Results and discussion Structure description of [Ni(L1)] and [Ni(L2)] Syntheses and spectroscopic characterization The molecular structure of [Ni(L1)] in solid state is shown in Fig. 1. This complex crystallizes in the orthorhombic space In general, metal complexes [Ni(L1)], [Ni(L2)] and group Pbcn. The Schiff base ligand coordinates to one nickel atom in a tetradentate manner via phenolate O and imine [Zn(L3)(DMSO)] were obtained from the condensation of DAMN with various aldehydes in the presence of metal N atoms. The geometry around the nickel atom is square planar, and the angle sum in the nickel plane is 360.1°. atoms. The IR spectra of the complexes exhibit absorption −1 bands at 1612, 1611 and 1601 cm respectively, which The bond distances between Ni(1) and O are 1.836(5) and 1.834(5) Å, and the Ni(1)–N bond lengths are 1.854(6) and are assigned to the (C=N) stretching vibration [20]. The absence of an OH stretching vibration suggests that the 1.862(6) Å [27]. The molecular structure of [Ni(L2)] in solid state is shown O phenolic atoms of the ligands are deprotonated and participate in coordination to the nickel and zinc atoms in Fig. 2. [Ni(L2)] crystallizes in the monoclinic space group I2/a. The nickel atom is also four-coordinated with a square [21]. The symmetric diimine nature of the complexes is proven by the single band observed in the range of planar geometry. The coordination environment of the nickel −1 atom is very similar to that of the [Ni(L1)]. 2209–2225 cm assigned to the (C≡N) stretching vibra- tion, contrary to two bands observed in monoimine Structure description of [Zn(L3)(DMSO)] compounds [22]. The absorption bands in the range of −1 −1 735–754 cm and 412–418 cm in the metal complexes The molecular structure of [Zn(L3)(DMSO)] in the solid are assigned to stretching modes of the M–N and M–O bonds, respectively [23]. In the H NMR spectra of the state is shown in Fig. 3. This complex crystallizes in the triclinic space group P1 . The zinc atom is surrounded by complexes, the signal at 9.25, 8.57 and 8.49 ppm respec- tively is attributed to azomethine protons [15]. The elec- two nitrogen atoms and two oxygen atoms from the Schiff base ligand and one oxygen atom from a DMSO ligand. tronic spectra of the complexes were recorded in DMSO. The bands at 265 and 270 nm are attributed to the elec- The zinc atom is five-coordinated with a square pyramidal coordination geometry. The tetradentate ligand occupies tronic transitions π→π* of the aromatic rings. The bands between 305 and 400 nm are due to n→π* transitions. The the equatorial plane, and one O-coordinating DMSO ligand (sulfur atom disordered on two positions with 87.8(2) and bands above 400 nm are attributed to the intense charge transfer and intraligand transitions, indicating efficient 12.2(2)%) occupies the apical position. The coordinating N and O atoms form a plane with a maximum deviation of conjugation in the metal complexes [24–26]. 0.1254(9) Å. Zn(1) is positioned 0.4381(9) Å below this plane (Fig. 3), the angle sum in the zinc plane amounts to Fig. 1 ORTEP view of [Ni (L1)]; thermal ellipsoids are drawn at the 50% probability 1 3 560 Transition Metal Chemistry (2018) 43:555–562 Fig. 2 ORTEP view of [Ni(L2)] (50% ellipsoids) Fig. 3 ORTEP view of [Zn(L3) (DMSO)] (50% ellipsoids) 349.9°. The average bond length of Zn–N is 2.0902 Å. The in vitro antimicrobial activities (Table 3). Results showed Zn(1)–O(3) bond distance [2.0430(16) Å] to the DMSO that all three complexes have potential as antimicrobial ligand is slightly longer than those of Zn(1)–O(1) and agents. The complex [Ni(L1)] has activity against three Zn(1)–O(2) to the tetradentate ligand (av, 1.9636 Å) [28–30]. Gram positive bacteria. The rest of the compounds show no selectivity between Gram positive and Gram negative Antimicrobial activities bacterial strains. NiCl ·6H O and complex [Ni(L2)] have an 2 2 antifungal effect against Candida albicans PTCC 5027. As [Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)] as well as shown in Table 3, while E. faecalis and L. monocytogenes NiCl ·6H O and Zn(CH CO ) ·2H O were tested for their isolated from clinical samples are resistant to the antibiotics 2 2 3 2 2 2 1 3 Transition Metal Chemistry (2018) 43:555–562 561 Table 3 In vitro antimicrobial activity of the compounds, 10 mg/ml (IZ) Microorganism Inhibition zone (mm) [Ni(L1)] [Ni(L2)] [Zn(L3) NiCl ·6H O Zn(CH CO ) ·2H O Ciprofloxacin Fluconazole 2 2 3 2 2 2 (DMSO)] P. aeruginosa 0 10 11 9 9 22 0 K. pneumonia 0 0 0 11 11 0 0 E. faecalis 8 11 0 9 8 0 0 S. aureus 9 9 0 8 9 25 0 E. coli 0 16 0 9 10 27 0 B. cereus 0 10 0 10 18 24 0 M. luteus 10 8 7 10 16 31 0 C. albicans 0 9 0 11 0 0 35 L. monocytogenes 0 9 8 8 10 0 0 Bacteria isolated from clinical samples ciprofloxacin and fluconazole, E. faecalis is sensitive to to the metal atoms through both the azomethine N atoms [Ni(L1)], [Ni(L2)], NiCl ·6H O and Zn(CH CO ) ·2H O and phenolic O atoms. The nickel(II) complexes had four- 2 2 3 2 2 2 and L. monocytogenes is sensitive to [Ni(L2)], [Zn(L3) coordinate square planar geometries, while the zinc(II) (DMSO)], NiCl ·6H O and Zn(CH CO ) ·2H O. The results complex was five-coordinated with square pyramidal coor - 2 2 3 2 2 2 of minimum inhibitory concentration (MIC) and mini- dination geometry. In the zinc(II) complex, the tetradentate mum lethal concentration (MBC) experiments are shown ligand occupied the equatorial plane and one O-coordinating in Table 4. As can be seen, the MIC and MBC values for DMSO ligand occupied the apical position. The antimicro- [Ni(L1)] and [Ni(L2)] are considerably lower than that for bial activities of the three complexes and NiCl ·6H O and 2 2 NiCl ·6H O and also, for [Zn(L3)(DMSO)] is lower than Zn (CH CO ) ·2H O were also studied against different 2 2 3 2 2 2 that for Zn(CH CO ) ·2H O. It means that low concentra- microorganisms. The results showed that all three complexes 3 2 2 2 tions of the complexes not only inhibit the growth of micro- have some potential as antimicrobial agents. Also, accord- organisms, but also kill them. So, they have both bacterio- ing to the results of MIC and MBC, these complexes have static and bactericidal effects. both bacteriostatic and bactericidal effects. Further studies on the antimicrobial activities of diaminomaleonitrile-based complexes are planned for the future. Conclusion Acknowledgements The authors gratefully acknowledge the financial support provided for this work by the Shahid Bahonar University of In conclusion, three metal Schiff base complexes have been Kerman and also by the Universität of Leipzig, Germany, 04103 Leip- synthesized and structurally characterized. The results indi- zig, Germany. cated that the ligands were N O -tetradentate coordinated 2 2 Table 4 In vitro antimicrobial Microorganisms [Ni(L1)] [Ni(L2)] [Zn(L3) NiCl ·6H O Zn(CH CO ) · 2 2 3 2 2 activity of the compounds, (DMSO)] 2H O (MIC and MBC, mg/ml) MIC MBC MIC MBC MIC MBC MIC MBC MIC MBC P. aeruginosa – – 2.5 5 1.25 – 2.5 5 0.156 2.5 K. pneumonia – – – – – – 1.25 2.5 2.5 10 E. faecalis 2.5 5 1.25 5 – – 5 10 0.625 5 S. aureus 0.625 2.5 2.5 5 – – 5 10 2.5 5 E. coli – – 0.625 2.5 – – 2.5 5 0.625 2.5 B. cereus – 5 2.5 5 – – 5 10 0.039 1.25 M. luteus 0.16 2.5 1.25 2.5 0.13 1.25 1.25 5 0.156 2.5 C. albicans – – 1.25 2.5 – – 2.5 5 – – L. monocytogenes – – 2.5 5 0.25 2.5 5 10 0.625 2.5 1 3 562 Transition Metal Chemistry (2018) 43:555–562 Open Access This article is distributed under the terms of the Crea- 13. Al-Azmi A, Elassar AZA, Booth BL (2003) Tetrahedron tive Commons Attribution 4.0 International License (http://creat iveco 59:2749–2763 mmons.or g/licenses/b y/4.0/), which permits unrestricted use, distribu- 14. MacLachlan MJ, Park MK, Thompson LK (1996) Inorg Chem tion, and reproduction in any medium, provided you give appropriate 35:5492–5499 credit to the original author(s) and the source, provide a link to the 15. Sheikhshoaie I, Ebrahimipour SY, Lotfi N, Mague JT, Khaleghi Creative Commons license, and indicate if changes were made. M (2016) Inorg Chim Acta 442:151–157 16. Lotfi N, Sheikhshoaei I, Ebrahimipour SY, Krautscheid H (2017) J Mol Struct 1149:432–438 17. Sheldrick GM (2008) Acta Crystallogr Sect A Found Crystallogr References 64:112–122 18. Brandenburg K (2010) DIAMOND Version 3.2f Crystal Impact 1. Ray MS, Chattopadhyay Sh, Drew MGB, Figuerola A, Ribas J, GbR Bonn, Germany Diaz C, Ghosh A (2005) Eur J Inorg Chem 2005:4562–4571 19. Irshad S, Mahmood M, Perveen F (2012) Res J Biol 2:1–8 2. Costes JP, Dahan F, Laurent JP (1986) Inorg Chem 25:413–416 20. Kumar V, Mishra RK, Shukla S, Mishra R, Singh M, Tiwari I, 3. Bian HD, Xu JY, Gu W, Yan SP, Cheng P, Liao DZ, Jiang ZH Thapliyal K, Upadhyay KK (2013) J Mol Struct 1047:66–72 (2003) Polyhedron 22:2927–2932 21. Ebrahimipour SY, Ranjabr ZR, Kermani ET, Amiri BP, Rudbari 4. Losada J, Del Peso I, Beyer L (2001) Inorg Chim Acta HA, Saccá A, Hoseinzade F (2015) Transit Metal Chem 40:39–45 321:107–115 22. Lacroix PG, Di Bella S, Ledoux I (1996) Chem Mater 8:541–545 5. Santos MLP, Bagatin IA, Pereira EM, Ferreira AMDC (2001) J 23. Tolulope MF, Olorunfemi O (2014) Der Pharma Chem 6:18–22 Chem Soc Dalton Trans 6:838–844 24. Gehad G, Abd El-Wahab MZ (2005) Spectrochim Acta 6. Reddy PS, Ananthalakshmi PV, Jayatyagaraju V (2011) Eur J 61:1059–1068 Chem 8:415–420 25. Wang P, Hong Z, Xie Z, Tong Sh, Wong O, Lee CS, Wong N, 7. Ran XG, Wang LY, Lin YC, Hao J, Cao DR (2010) Appl Orga- Hung L, Lee Sh (2003) Chem Commun 14:1664–1665 nomet Chem 24:741–747 26. Ledoux I, Zyss J (1996) Pure Appl Opt 5:603–612 8. Orio M, Jarjayes O, Kanso H, Philouze C, Neese F, Thomas F 27. Costes JP, Lamère JF, Lepetit Ch, Lacroix PG, Dahan F (2005) (2010) Angew Chem Int Ed 49:4989–4992 Inorg Chem 44:1973–1982 9. Fleck M, Layek M, Saha R, Bandyopadhyay D (2013) Transit 28. Aazam ES, Ng SW, Tiekink ERT (2011) Acta Cryst E Metal Chem 38:715–724 67:m314–m315 10. Raman N, Kulandaisamy A, Thangaraja C, Jeyasubramanian K 29. Wang ZCh, Chu J, Zhan ShZ (2013) Acta Cryst E 69:m419 (2003) Transit Metal Chem 28:29–36 30. Lin ChW, Chou PT, Liao YH, Lin YCh, Chen ChT, Chen YCh, 11. Viswanathamurthi P, Natarajan K (1999) Transit Metal Chem Lai ChH, Chen BS, Liu YH, Wang ChCh, Ho ML (2010) Chem 24:638–641 Eur J 16:3770–3782 12. Bendre RS, Tadavi SK, Patil MM (2018) Transit Metal Chem 43:83–89 1 3 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Transition Metal Chemistry Springer Journals

Synthesis, structures and antimicrobial activities of nickel(II) and zinc(II) diaminomaleonitrile-based complexes

Free
8 pages

Loading next page...
 
/lp/springer_journal/synthesis-structures-and-antimicrobial-activities-of-nickel-ii-and-ClG7Bq2NFW
Publisher
Springer Journals
Copyright
Copyright © 2018 by The Author(s)
Subject
Chemistry; Catalysis; Physical Chemistry; Inorganic Chemistry; Organometallic Chemistry
ISSN
0340-4285
eISSN
1572-901X
D.O.I.
10.1007/s11243-018-0241-5
Publisher site
See Article on Publisher Site

Abstract

Three Ni(II) and Zn(II) complexes [Ni(L1)], [Ni(L2)], and [Zn(L3)(DMSO)] (L1 = 2,3-bis(2-hydroxybenzylideneimino)- 2,3-butenedinitrile, L2 = 2,3-bis(2-hydroxy-3-methoxybenzylideneimino)-2,3-butenedinitrile, L3 = 2,3-bis(2-hydroxy- 1-naphthylideneimino)-2,3-butenedinitrile) were obtained in DMSO by one-pot syntheses. The complexes were characterized by physicochemical and spectroscopic methods. Also, their solid-state structures were determined by single-crystal X-ray diffraction. The geometries of the Ni(II) and Zn(II) complexes were square planar and square pyramidal, respectively. The complexes were screened in vitro against a fungal species and eight species of bacteria, revealing their antimicrobial activity. Introduction DAMN with different aromatic aldehydes can form 1:1 and/ or 1:2 Schiff base ligands [ 14]. In recent studies, we have The synthesis and characterization of Schiff bases and their reported the synthesis and characterization of complexes transition metal complexes has attracted considerable atten- incorporating tridentate NNO-Schiff base ligands based on tion in recent decades [1–3]. Schiff base ligands with a vari - diaminomaleonitrile [15, 16]. In this project, our efforts were ety of donor atoms including nitrogen, oxygen and sulfur directed to the synthesis and characterization of nickel(II) can be coordinated with transition metal atoms. Depending and zinc(II) complexes with tetradentate N O -Schiff base 2 2 on the type and oxidation state of the central metal atom ligands based on diaminomaleonitrile and various aldehydes and the ligand structure, they can be bidentate, tridentate, such as 2-hydroxybenzaldehyde, 3-methoxy-2-hydroxyben- tetradentate or polydentate, and depending on the nature zaldehyde and 2-hydroxy-1-naphthaldehyde. of the possible counter ion, transition metal Schiff’s base complexes show various coordination modes with varying degree of distortion [4, 5]. Among these, the tetradentate Experimental Schiff bases with N O coordination sites belong to ligands 2 2 investigated most often in coordination chemistry [6–8]. Materials and methods The transition metal complexes formed from tetradentate Schiff bases exhibit a wide range of biological properties All reagents for synthesis and analysis were purchased from [9–12]. 2,3-Diamino-cis-2-butenedinitrile (diaminomaleoni- Merck and used without further purification. Elemental anal - trile: DAMN) is an attractive precursors to nucleotides and yses were recorded on a Thermo Finnigan Flash Elemental is considered as an intermediate in the synthesis of a wide Analyzer 1112EA. Melting points were measured on an variety of heterocyclic compounds [13]. The condensation of Electrothermal-9100 apparatus. The IR measurements were taken on a FTIR Tensor 27 infrared spectrophotometer as −1 1 KBr disks in the range of 400–4000 cm . H NMR spectra * Iran Sheikhshoaie were measured on a Bruker AVANCE BRX 250 MHz spec- i_shoaie@yahoo.com; shoaie@uk.ac.ir trometer using d -DMSO as solvent for the complexes. The Department of Chemistry, Faculty of Science, Shahid chemical shift values (δ) are given in ppm. The electronic Bahonar University of Kerman, Kerman, Iran absorption spectra in DMSO solution were recorded by a Fakultät für Chemie und Mineralogie, Universität Leipzig, Cary 50 UV–Vis spectrophotometer. Bacteria were isolated 04103 Leipzig, Germany from clinical samples or purchased from Merck Company. Department of Biology, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran Vol.:(0123456789) 1 3 556 Transition Metal Chemistry (2018) 43:555–562 –CH=N), 7.20–6.45 (m, 6H, ArH), 3.74 (s, 6H, –OCH ). Preparation of [Ni(L1)] and [Ni(L2)] −1 −1 UV–Vis spectra [λ , nm (log ε, L mol  cm ); DMSO max solution]: 270 (4.29), 355 (4.16), 375 (4.13), 395 (4.14), A solution of 2-hydroxybenzaldehyde (2.0 mmol, 0.21 ml) 520 (3.97), 600 (4.13). Anal. Calcd. for C H N NiO : C, for H L1 and 3-methoxy-2-hydroxybenzaldehyde (0.304 g, 20 18 4 6 51.2; H, 3.8; N, 11.9%. Found: C, 51.0; H, 3.7; N, 11.7%. 2.0 mmol) for H L2 and 2,3-diamino-cis-2-butenedini- trile (0.108 g, 1.0 mmol) in DMSO (5 ml) was heated for Preparation of [Zn(L3)(DMSO)] 30 min. Afterward, triethylamine (0.200 g, 2.0 mmol) and NiCl ·6H O (0.238 g, 1.0 mmol) in DMSO (5 ml) were 2 2 This complex was synthesized similar to [Ni(L1)] and added dropwise and the resulting reaction mixture was [Ni(L2)] complexes. To a solution of 2-hydroxy-1-naph- refluxed for 4 h while stirring constantly. The clear green thaldehyde (0.344  g, 2.0  mmol) in DMSO (10  ml), solution was allowed to stand several days at room tem- 2,3-diamino-cis-2-butenedinitrile (0.108 g, 1.0 mmol) was perature, providing blue single crystals suitable for X-ray added and refluxed for 30 min. A deep brown solution was crystallography (Scheme 1). obtained. After adding triethylamine (0.200 g, 2.0 mmol) [Ni(L1)]: Yield: 0.242 g (65%); m.p. > 300 °C IR (KBr, −1 and Zn(CH CO ) ·2H O (0.219 g, 1.0 mmol) to the solution, cm ): 2218 (C≡N), 1611 (C=N), 1576 (C=C) , 3 2 2 2 aliphatic the color of the solution changed to black. Dark red single 1517 (C=C) , 1195 (C–O), 754 (Ni–N), 418 (Ni–O). aromatic crystals suitable for crystallography appeared after 2 weeks H NMR (250 MHz, d -DMSO, ppm): δ = 8.57 (s, 2H, standing (Scheme 2). Yield 0.407 g (73%); m.p. > 300 °C. –CH=N), 7.45–6.24 (m, 8H, ArH). UV–Vis spectra [λ , max −1 −1 −1 IR (KBr, cm ): 3007 (C–H), 2209 (C≡N), 1601 (C=N), nm (log ε, L mol  cm ); DMSO solution]: 265 (4.46), 1571 (C=C) , 1536 (C=C) , 1267 (C–O), 1183 305 (4.30), 380 (4.25), 440 (4.08), 530 (4.09), 595 (4.08). aliphatic aromatic (S=O), 747 (Zn–N), 412 (Zn–O). H NMR (250  MHz, Anal. Calcd. for C H N NiO : C, 57.9; H, 2.7; N, 15.0%. 18 10 4 2 d -DMSO, ppm): δ  =  9.25 (s, 2H, –CH=N), 8.06- 6.94 Found: C, 57.7; H, 2.6; N, 14.9%. (m, 12H, ArH), 3.30 (s, 6H, CH ). UV–Vis spectra [λ , [Ni(L2)]: Yield 0.259 g (60%); m.p. > 300 °C. IR (KBr, 3 max −1 −1 −1 nm (log ε, L mol cm ); DMSO solution]: 265 (4.65), cm ): 2225 (C≡N), 1612 (C=N), 1580 (C=C) , aliphatic 355 (4.31), 400 (4.40), 425 (4.38), 465 (4.23), 600 (4.71). 1538 (C=C) , 1253 (C–O), 735 (Ni–N), 414 (Ni–O). aromatic Anal. Calcd. for C H N O SZn: C, 60.2; H, 3.6; N, 10.0%. H NMR (250 MHz, d -DMSO, ppm): δ = 8.49 (s, 2H, 28 20 4 3 Found: C, 60.0; H, 3.3; N, 9.8%. NC CN C C H H H N NC CN Ni NiCl ·6H O 2 2 OH + CC O O H N NH 2 2 DMSO 1mmol 2mmol R= H[Ni(L1)] R= OCH3 [Ni(L2)] Scheme 1 A schematic representation of synthesis of [Ni(L1)] and [Ni(L2)] complexes NC CN C C H NC CN Zn(CH CO ) ·2H O 3 2 2 2 Zn OH + CC H N NH DMSO 2 2 2mmol1 mmol H C CH 3 3 Scheme 2 A schematic representation of synthesis of [Zn(L3)(DMSO)] complex 1 3 Transition Metal Chemistry (2018) 43:555–562 557 ATCC 27853, Staphylococcus aureus PTCC 1112, Escher- X‑ray structure determination ichia coli PTCC 1330, Bacillus cereus PTCC 1015 and Micrococcus luteus PTCC 1110) and three bacteria isolated Suitable crystals for single-crystal X-ray structure analysis were selected in mineral oil and mounted on glass fibers. from clinical samples (Klebsiella pneumoniae, Enterococcus faecalis and Listeria monocytogenes). Brain Heart Infusion Diffraction data for [Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)] were collected on an IPDS-1 diffractometer (Stoe&Cie medium (BHI-Merck) was used for L. monocytogenes and E. faecalis, whereas the other bacteria were cultured on Muel- GmbH, Darmstadt, Germany) using graphite-monochroma- tized Mo-Kα radiation, (λ = 0.71073 Å). The structures were ler–Hinton medium (Merck). Also, YGC medium (Merck) was used as the test medium for the yeast strain. solved by direct methods using SHELXS and refined using SHELXL [17]. All non-hydrogen atoms with the exception Determination of antimicrobial activity of the disordered S atom of the DMSO ligand in [Zn(L3) (DMSO)] were refined anisotropically. Hydrogen atoms The antimicrobial activities of [Ni(L1)], [Ni(L2)] were included in idealized positions. The molecular graph- ics were drawn with DIAMOND [18]. Crystallographic data and [Zn(L3)(DMSO)] complexes, NiCl ·6H O and 2 2 Zn(CH CO ) ·2H O against some Gram positive bacteria and details of the data collection and structure refinement 3 2 2 2 are listed in Table 1, selected bond lengths and angles are strains (L. monocytogenes, E. faecalis, S. aureus PTCC 1112, M. luteus PTCC 1110 and B. cereus PTCC 1015), presented in Table 2, and Scheme 3 shows packing views of the three complexes. some Gram negative bacterial strains (E. coli PTCC 1330, K. pneumoniae, P. aeruginosa ATCC 27853) and Microorganism strains and culture a fungal species (C. albicans PTCC 5027) were investi- gated using agar well diffusion plate methods [19]. The In this research, we used one yeast (Candida albicans PTCC agar media were inoculated with 100 µl of the inoculums which were prepared using an overnight culture of each 5027), five standard bacteria ( Pseudomonas aeruginosa Table 1 Crystallographic Complex [Ni(L1)] [Ni(L2)] [Zn(L3)(DMSO)] data collection parameters for [Ni(L1)], [Ni(L2)] and [Zn(L3) Formula C H N NiO C H N NiO C H N O SZn 18 10 4 2 20 18 4 6 28 20 4 3 (DMSO)] −1 Formula weight, g mol 373.01 469.09 557.91 Crystal size, mm 0.30 × 0.10 × 0.05 0.10 × 0.10 × 0.08 0.20 × 0.20 × 0.10 Crystal color Blue Blue Red Temperature, K 213 213 213 Crystal system Orthorhombic Monoclinic Triclinic Space group Pbcn I2/a P 1 Unit cell dimensions (Å, °)  a 17.133 (2) 13.291 (1) 10.4479 (5)  b 6.9752 (4) 13.0637 (6) 11.1601 (5)  c 26.088 (2) 22.605 (2) 11.8326 (6)  α 90 90.00 102.406 (6)  β 90 102.322 (7) 100.556 (6)  γ 90 90.00 111.140 (5)  Volume, Å 3117.6 (4) 3834.5 (5) 1204.22 (11)  Z 8 8 2 −3 Calculated density, g cm 1.589 1.625 1.539 −1 Absorption coefficient, mm 1.264 1.061 1.146 θ range for data collection, ° 2.0–25.0 2.2– 25.0 2.1–25.9 Reflections collected 18,304 12,828 11,951 Independent reflections (R ) 2681 (0.146) 3335 (0.165) 4372 (0.0273) int Observed reflections [I  ≥ 2σ(I)] 1003 1617 3683 Parameters 226 280 344 R1 (observed reflections) 0.0445 0.0786 0.031 wR2 (all data) 0.1028 0.1825 0.078 −3 Largest diff. peak/hole, eÅ 0.47/− 0.84 0.74/− 0.72 0.49/− 0.30 1 3 558 Transition Metal Chemistry (2018) 43:555–562 Table 2 Selected bond lengths [Ni(L1)] (Å) and angles (°) of [Ni(L1)],  Ni1–N1 1.854 (6) N1–C5 1.320 (9) Ni1–O2 1.834 (5) [Ni(L2)] and [Zn(L3)(DMSO)]  Ni1–N2 1.862 (6) N2–C2 1.406 (8) N1–C1 1.387 (7)  Ni1–O1 1.836 (5) C5–C6 1.400 (11) C1–C2 1.349 (7)  N1–Ni1–N2 86.2 (3) O2–Ni1–N2 94.19 (16) O1–Ni1–O2 85.0 (2)  N1–Ni1–O1 94.71 (15) Ni1–N1–C1 112.0 (5) O1–Ni1–N2 177.9 (2)  N1–Ni1–O2 178.4 (2) Ni1–N1–C5 127.5 (5) N1–C5–C6 124.2 (7) [Ni(L2)]  Ni1–N1 1.838 (6) N1–C5 1.327 (9) Ni1–O2 1.849 (5)  Ni1–N2 1.860 (6) C5–C6 1.382 (9) N1–C1 1.366 (9)  Ni1–O1 1.846 (4) C1–C2 1.341 (10)  N1–Ni1–N2 86.0 (3) O2–Ni1–N2 94.1 (2) O1–Ni1–O2 85.9 (2)  N1–Ni1–O1 94.0 (2) Ni1–N1–C1 112.5 (5) O1–Ni1–N2 178.8 (3)  N1–Ni1–O2 179.9 (3) Ni1–N1–C5 127.5 (5) N1–C5–C6 124.1 (8) [Zn(L3)(DMSO)]  Zn1–N1 2.0813 (14) Zn1–O3 2.0430 (16) N3–C3 1.135 (3)  Zn1–N2 2.0992 (17) N1–C1 1.378 (3) C1–C2 1.371 (3)  Zn1–O1 1.9530 (16) N1–C5 1.319 (2) C1–C3 1.450 (3)  Zn1–O2 1.9742 (13) N2–C2 1.386 (2) C5–C6 1.404 (3)  N1–Zn1–O1 87.43 (6) O1–Zn1–O3 100.55 (8) C1–N1–C5 121.68 (16)  N1–Zn1–O2 146.31 (7) O1–Zn1–N2 159.77 (7) Zn1–N1–C1 111.94 (12)  N1–Zn1–O3 108.81 (7) O2–Zn1–O3 102.96 (6) Zn1–N1–C5 126.06 (13)  N1–Zn1–N2 79.12 (6) O2–Zn1–N2 85.71 (6) N1–C5–C6 126.17 (17)  O1–Zn1–O2 97.67 (6) O3–Zn1–N2 98.08 (8) Scheme 3 The packing view of [Ni(L1)] (a), [Ni(L2)] (b) and [Zn(L3)(DMSO)] (c) microorganism (18–24 h) adjusted to a turbidity equivalent was used as a negative control. The minimum inhibitory to a 0.5-McFarland standard. Wells were cut and 50 µl of concentration (MIC) and minimal bactericidal concen- the compounds (10 mg/ml; DMSO was used as solvent) tration (MBC) were determined by microdilution assay were added. Each compound was tested in triplicate along (NCCLS, 2008). The cultures were prepared in 24 and with standard ciprofloxacin for bacteria and fluconazole 72 h broth cultures of microorganisms, respectively. The for yeast. The plates were incubated at 37 °C for 24 h. MIC was defined as the lowest concentration of compound The antimicrobial activity was assayed by measuring the to inhibit the growth of microorganisms, and the MBC was diameter of the inhibition zone formed around the well. defined as the lowest concentration of compound to kill the The diameter of the zone of inhibition was measured by microorganisms. Serial dilutions ranging from 10 mg/ml measuring scale in millimeters (mm). DMSO as solvent to 39 µg/ml were prepared in medium. 1 3 Transition Metal Chemistry (2018) 43:555–562 559 Results and discussion Structure description of [Ni(L1)] and [Ni(L2)] Syntheses and spectroscopic characterization The molecular structure of [Ni(L1)] in solid state is shown in Fig. 1. This complex crystallizes in the orthorhombic space In general, metal complexes [Ni(L1)], [Ni(L2)] and group Pbcn. The Schiff base ligand coordinates to one nickel atom in a tetradentate manner via phenolate O and imine [Zn(L3)(DMSO)] were obtained from the condensation of DAMN with various aldehydes in the presence of metal N atoms. The geometry around the nickel atom is square planar, and the angle sum in the nickel plane is 360.1°. atoms. The IR spectra of the complexes exhibit absorption −1 bands at 1612, 1611 and 1601 cm respectively, which The bond distances between Ni(1) and O are 1.836(5) and 1.834(5) Å, and the Ni(1)–N bond lengths are 1.854(6) and are assigned to the (C=N) stretching vibration [20]. The absence of an OH stretching vibration suggests that the 1.862(6) Å [27]. The molecular structure of [Ni(L2)] in solid state is shown O phenolic atoms of the ligands are deprotonated and participate in coordination to the nickel and zinc atoms in Fig. 2. [Ni(L2)] crystallizes in the monoclinic space group I2/a. The nickel atom is also four-coordinated with a square [21]. The symmetric diimine nature of the complexes is proven by the single band observed in the range of planar geometry. The coordination environment of the nickel −1 atom is very similar to that of the [Ni(L1)]. 2209–2225 cm assigned to the (C≡N) stretching vibra- tion, contrary to two bands observed in monoimine Structure description of [Zn(L3)(DMSO)] compounds [22]. The absorption bands in the range of −1 −1 735–754 cm and 412–418 cm in the metal complexes The molecular structure of [Zn(L3)(DMSO)] in the solid are assigned to stretching modes of the M–N and M–O bonds, respectively [23]. In the H NMR spectra of the state is shown in Fig. 3. This complex crystallizes in the triclinic space group P1 . The zinc atom is surrounded by complexes, the signal at 9.25, 8.57 and 8.49 ppm respec- tively is attributed to azomethine protons [15]. The elec- two nitrogen atoms and two oxygen atoms from the Schiff base ligand and one oxygen atom from a DMSO ligand. tronic spectra of the complexes were recorded in DMSO. The bands at 265 and 270 nm are attributed to the elec- The zinc atom is five-coordinated with a square pyramidal coordination geometry. The tetradentate ligand occupies tronic transitions π→π* of the aromatic rings. The bands between 305 and 400 nm are due to n→π* transitions. The the equatorial plane, and one O-coordinating DMSO ligand (sulfur atom disordered on two positions with 87.8(2) and bands above 400 nm are attributed to the intense charge transfer and intraligand transitions, indicating efficient 12.2(2)%) occupies the apical position. The coordinating N and O atoms form a plane with a maximum deviation of conjugation in the metal complexes [24–26]. 0.1254(9) Å. Zn(1) is positioned 0.4381(9) Å below this plane (Fig. 3), the angle sum in the zinc plane amounts to Fig. 1 ORTEP view of [Ni (L1)]; thermal ellipsoids are drawn at the 50% probability 1 3 560 Transition Metal Chemistry (2018) 43:555–562 Fig. 2 ORTEP view of [Ni(L2)] (50% ellipsoids) Fig. 3 ORTEP view of [Zn(L3) (DMSO)] (50% ellipsoids) 349.9°. The average bond length of Zn–N is 2.0902 Å. The in vitro antimicrobial activities (Table 3). Results showed Zn(1)–O(3) bond distance [2.0430(16) Å] to the DMSO that all three complexes have potential as antimicrobial ligand is slightly longer than those of Zn(1)–O(1) and agents. The complex [Ni(L1)] has activity against three Zn(1)–O(2) to the tetradentate ligand (av, 1.9636 Å) [28–30]. Gram positive bacteria. The rest of the compounds show no selectivity between Gram positive and Gram negative Antimicrobial activities bacterial strains. NiCl ·6H O and complex [Ni(L2)] have an 2 2 antifungal effect against Candida albicans PTCC 5027. As [Ni(L1)], [Ni(L2)] and [Zn(L3)(DMSO)] as well as shown in Table 3, while E. faecalis and L. monocytogenes NiCl ·6H O and Zn(CH CO ) ·2H O were tested for their isolated from clinical samples are resistant to the antibiotics 2 2 3 2 2 2 1 3 Transition Metal Chemistry (2018) 43:555–562 561 Table 3 In vitro antimicrobial activity of the compounds, 10 mg/ml (IZ) Microorganism Inhibition zone (mm) [Ni(L1)] [Ni(L2)] [Zn(L3) NiCl ·6H O Zn(CH CO ) ·2H O Ciprofloxacin Fluconazole 2 2 3 2 2 2 (DMSO)] P. aeruginosa 0 10 11 9 9 22 0 K. pneumonia 0 0 0 11 11 0 0 E. faecalis 8 11 0 9 8 0 0 S. aureus 9 9 0 8 9 25 0 E. coli 0 16 0 9 10 27 0 B. cereus 0 10 0 10 18 24 0 M. luteus 10 8 7 10 16 31 0 C. albicans 0 9 0 11 0 0 35 L. monocytogenes 0 9 8 8 10 0 0 Bacteria isolated from clinical samples ciprofloxacin and fluconazole, E. faecalis is sensitive to to the metal atoms through both the azomethine N atoms [Ni(L1)], [Ni(L2)], NiCl ·6H O and Zn(CH CO ) ·2H O and phenolic O atoms. The nickel(II) complexes had four- 2 2 3 2 2 2 and L. monocytogenes is sensitive to [Ni(L2)], [Zn(L3) coordinate square planar geometries, while the zinc(II) (DMSO)], NiCl ·6H O and Zn(CH CO ) ·2H O. The results complex was five-coordinated with square pyramidal coor - 2 2 3 2 2 2 of minimum inhibitory concentration (MIC) and mini- dination geometry. In the zinc(II) complex, the tetradentate mum lethal concentration (MBC) experiments are shown ligand occupied the equatorial plane and one O-coordinating in Table 4. As can be seen, the MIC and MBC values for DMSO ligand occupied the apical position. The antimicro- [Ni(L1)] and [Ni(L2)] are considerably lower than that for bial activities of the three complexes and NiCl ·6H O and 2 2 NiCl ·6H O and also, for [Zn(L3)(DMSO)] is lower than Zn (CH CO ) ·2H O were also studied against different 2 2 3 2 2 2 that for Zn(CH CO ) ·2H O. It means that low concentra- microorganisms. The results showed that all three complexes 3 2 2 2 tions of the complexes not only inhibit the growth of micro- have some potential as antimicrobial agents. Also, accord- organisms, but also kill them. So, they have both bacterio- ing to the results of MIC and MBC, these complexes have static and bactericidal effects. both bacteriostatic and bactericidal effects. Further studies on the antimicrobial activities of diaminomaleonitrile-based complexes are planned for the future. Conclusion Acknowledgements The authors gratefully acknowledge the financial support provided for this work by the Shahid Bahonar University of In conclusion, three metal Schiff base complexes have been Kerman and also by the Universität of Leipzig, Germany, 04103 Leip- synthesized and structurally characterized. The results indi- zig, Germany. cated that the ligands were N O -tetradentate coordinated 2 2 Table 4 In vitro antimicrobial Microorganisms [Ni(L1)] [Ni(L2)] [Zn(L3) NiCl ·6H O Zn(CH CO ) · 2 2 3 2 2 activity of the compounds, (DMSO)] 2H O (MIC and MBC, mg/ml) MIC MBC MIC MBC MIC MBC MIC MBC MIC MBC P. aeruginosa – – 2.5 5 1.25 – 2.5 5 0.156 2.5 K. pneumonia – – – – – – 1.25 2.5 2.5 10 E. faecalis 2.5 5 1.25 5 – – 5 10 0.625 5 S. aureus 0.625 2.5 2.5 5 – – 5 10 2.5 5 E. coli – – 0.625 2.5 – – 2.5 5 0.625 2.5 B. cereus – 5 2.5 5 – – 5 10 0.039 1.25 M. luteus 0.16 2.5 1.25 2.5 0.13 1.25 1.25 5 0.156 2.5 C. albicans – – 1.25 2.5 – – 2.5 5 – – L. monocytogenes – – 2.5 5 0.25 2.5 5 10 0.625 2.5 1 3 562 Transition Metal Chemistry (2018) 43:555–562 Open Access This article is distributed under the terms of the Crea- 13. Al-Azmi A, Elassar AZA, Booth BL (2003) Tetrahedron tive Commons Attribution 4.0 International License (http://creat iveco 59:2749–2763 mmons.or g/licenses/b y/4.0/), which permits unrestricted use, distribu- 14. MacLachlan MJ, Park MK, Thompson LK (1996) Inorg Chem tion, and reproduction in any medium, provided you give appropriate 35:5492–5499 credit to the original author(s) and the source, provide a link to the 15. Sheikhshoaie I, Ebrahimipour SY, Lotfi N, Mague JT, Khaleghi Creative Commons license, and indicate if changes were made. M (2016) Inorg Chim Acta 442:151–157 16. Lotfi N, Sheikhshoaei I, Ebrahimipour SY, Krautscheid H (2017) J Mol Struct 1149:432–438 17. Sheldrick GM (2008) Acta Crystallogr Sect A Found Crystallogr References 64:112–122 18. Brandenburg K (2010) DIAMOND Version 3.2f Crystal Impact 1. Ray MS, Chattopadhyay Sh, Drew MGB, Figuerola A, Ribas J, GbR Bonn, Germany Diaz C, Ghosh A (2005) Eur J Inorg Chem 2005:4562–4571 19. Irshad S, Mahmood M, Perveen F (2012) Res J Biol 2:1–8 2. Costes JP, Dahan F, Laurent JP (1986) Inorg Chem 25:413–416 20. Kumar V, Mishra RK, Shukla S, Mishra R, Singh M, Tiwari I, 3. Bian HD, Xu JY, Gu W, Yan SP, Cheng P, Liao DZ, Jiang ZH Thapliyal K, Upadhyay KK (2013) J Mol Struct 1047:66–72 (2003) Polyhedron 22:2927–2932 21. Ebrahimipour SY, Ranjabr ZR, Kermani ET, Amiri BP, Rudbari 4. Losada J, Del Peso I, Beyer L (2001) Inorg Chim Acta HA, Saccá A, Hoseinzade F (2015) Transit Metal Chem 40:39–45 321:107–115 22. Lacroix PG, Di Bella S, Ledoux I (1996) Chem Mater 8:541–545 5. Santos MLP, Bagatin IA, Pereira EM, Ferreira AMDC (2001) J 23. Tolulope MF, Olorunfemi O (2014) Der Pharma Chem 6:18–22 Chem Soc Dalton Trans 6:838–844 24. Gehad G, Abd El-Wahab MZ (2005) Spectrochim Acta 6. Reddy PS, Ananthalakshmi PV, Jayatyagaraju V (2011) Eur J 61:1059–1068 Chem 8:415–420 25. Wang P, Hong Z, Xie Z, Tong Sh, Wong O, Lee CS, Wong N, 7. Ran XG, Wang LY, Lin YC, Hao J, Cao DR (2010) Appl Orga- Hung L, Lee Sh (2003) Chem Commun 14:1664–1665 nomet Chem 24:741–747 26. Ledoux I, Zyss J (1996) Pure Appl Opt 5:603–612 8. Orio M, Jarjayes O, Kanso H, Philouze C, Neese F, Thomas F 27. Costes JP, Lamère JF, Lepetit Ch, Lacroix PG, Dahan F (2005) (2010) Angew Chem Int Ed 49:4989–4992 Inorg Chem 44:1973–1982 9. Fleck M, Layek M, Saha R, Bandyopadhyay D (2013) Transit 28. Aazam ES, Ng SW, Tiekink ERT (2011) Acta Cryst E Metal Chem 38:715–724 67:m314–m315 10. Raman N, Kulandaisamy A, Thangaraja C, Jeyasubramanian K 29. Wang ZCh, Chu J, Zhan ShZ (2013) Acta Cryst E 69:m419 (2003) Transit Metal Chem 28:29–36 30. Lin ChW, Chou PT, Liao YH, Lin YCh, Chen ChT, Chen YCh, 11. Viswanathamurthi P, Natarajan K (1999) Transit Metal Chem Lai ChH, Chen BS, Liu YH, Wang ChCh, Ho ML (2010) Chem 24:638–641 Eur J 16:3770–3782 12. Bendre RS, Tadavi SK, Patil MM (2018) Transit Metal Chem 43:83–89 1 3

Journal

Transition Metal ChemistrySpringer Journals

Published: May 28, 2018

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off