untitled European Journal of Chemistry 8 (4) (2017) 367‐370 European Journal of Chemistry ISSN 2153‐2249 (Print) / ISSN 2153‐2257 (Online)  2017 Atlanta Publishing House LLC ‐ All rights reserved ‐ Printed in the USA http://dx.doi.org/10.5155/eurjchem.8.4.367-370.1636 European Journal of Chemistry Journal webpage: www.eurjchem.com Synthesis, characterization and biological activity of some nickel(II) mixed ligands complexes of dithiocarbamate and 1,10‐phenanthroline Salih Hamza Abbas Department of Chemistry, College of Science, University of Basrah, Basrah, 61004, Iraq * Corresponding author at: Department of Chemistry, College of Science, University of Basrah, Basrah, 61004, Iraq. Tel.: +964.40.7707061351. Fax: +964.40.7707061351. E‐mail address: salihhabbas@yahoo.ca (S.H. Abbas). ARTICLE INFORMATION ABSTRACT DOI: 10.5155/eurjchem.8.4.367-370.1636 Received: 11 August 2017 Received in revised form: 23 September 2017 Accepted: 07 October 2017 Published online: 31 December 2017 Printed: 31 December 2017   Two ligands; pyrrolidine‐1‐carbodithioate sodium (L1) and piperidine‐1‐carbodithioate sodium salt(L2) and their nickel(II) mixed ligands complexes with 1,10‐phenanthroline (L3) have been synthesized and characterized by FT‐IR, UV‐visible,1H NMR spectra. The biological activities of these complexes were also evaluated. The spectral data indicated that the 1,10‐ phenanthrolineand dithiocarbamate ligands are considered as a bidentate nitrogen and sulfur ligands, respectively. The study suggested that the above ligands formed complexes of general formula [Ni(Lx)2(L3)1] and [Ni(Lx)1(L3)2]Cl (x=1 or 2) mononuclear (monomer) complexes. The complexes show moderate and selective activity against tested microorganisms. KEYWORDS Sulfur ligands Bidentate nitrogen ligands Heterocyclicdithiocarbamate Tetramethylenedithiocarbimate Pentamethylenedithiocarbimate Nickel(II) mixed ligand complexes Cite this: Eur. J. Chem. 2017, 8(4), 367‐370 1. Introduction Dithiocarbamates (DTCs) are the half amides of dithio‐ carbonic acids belong to a class of compounds known as the 1,1‐dithiolates [1,2], they are also include dithiophosphates, dithiophosphinates and other related compounds, which can function either as unidenate or bidentate chelating ligands [3‐ 5]. Dithiolates are formed when nucleophiles attack carbon disulphide [1]. There are some reports for synthesis of DTC derivatives in the literature [6‐9], also there is a substantial interest in developing efficient one‐pot‐three component reaction from a simple starting materials (amines, carbon disulfide and epoxides) in novel reaction media such as water and ionic liquid [10‐13]. These 1,1‐dithiolate systems are of current interest due to their potential biological activity and practical application in the field of rubber technology and agriculture in addition to general consideration of metal‐ sulfate bonding and electron delocalization in transition of metal complexes [14,15]. In this report, we synthesized two bidentate sulfur donor ligands, tetramethylene‐ or pentamethylene‐dithiocarbamate sodium salt (L1 and L2, respectively) and their nickel(II) mixed ligands complexes with 1,10‐phenanthroline (L3). The prepa‐ red compounds have been characterized by elemental analysis, FT‐IR, UV‐Visible, 1H NMR and anti‐bacterial activity. 2. Experimental 2.1. Materials All starting materials were purchased from Fluka Chemicals Comp. and they were used without farther purification. 2.2. Instrumentation The FT‐IR spectra by KBr pellets were recorded by using a FT‐IR 8400S spectrophotometer model 2000 from Shimadzu Japan. The 1H NMR spectral data were recorded at room temperature by using a Bruker NMR spectrometer (300 MHz). The electronic spectra were recorded in the UV‐visible range 200‐800 nm by using a UV‐9200 Biotech Engineering Management Co. LTD. (UK.) UV spectrophotometer. 2.3. Synthesis of dithiocarbamate ligands A general method for the preparation of DTC ligands is the nucleophilic addition reaction of N‐nucleophiles with carbon disulphide (CS2) as in below. R2NH +CS2 +MOH → R2NCS2M + H2O (M: K or Na) (1) 368 Salih Hamza Abbas / European Journal of Chemistry 8 (4) (2017) 367‐370 [Ni(L1)2(L3)1] [Ni(L1)1(L3)2]Cl [Ni(L2)2(L3)1] [Ni(L2)1(L3)2]Cl Figure 1. Molecular structure of the prepared compounds. Dithiocarbamate ligands have been prepared according to literature [16‐18] by treating a solution of secondary amine (80 mmol) in 70 mL of ethanol with sodium hydroxide (80 mmol) in 10 mL of distilled water whilst cooling and stirring carbon disulphide (8 mmol) then added gradually with continuous cooling over 30 min and maintained the tempe‐ rature below 10 °C. The white product of dithiocarbamate was filtered, washed with methanol and dried in vacuum. Sodium tetramethylenedithiocarbamate (L1): Color: Yellowish‐white solid. Yield: 67%. M.p: 150‐152 °C. FT‐IR (KBr, , cm‐1): 1423 ν(C‐N), 999 ν(C‐S), 1326 ν(N‐C), 864 ν(C‐ S). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 3.62‐3.67 (s, 4H, CH2‐ N), 1.79‐1.83 (m, 4H, CH2). UV/Vis (CH3CHOH, λmax, nm): 241, 257, 308. Anal. calcd. for C5H8NNaS2: C, 35.48; H, 4.76; N, 8.28. Found: C, 34.3; H, 4.53; N, 8.2%. Sodium pentamethylenedithiocarbamate (L2): Color: White solid. Yield: 70%. M.p.: 160‐162 °C. FT‐IR (KBr, , cm‐1):1467 ν(C‐N), 1008 ν(C‐S), 1226 ν(N‐C), 889 ν(C‐S). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 4.23‐4.29 (s, 6H, CH2‐N), 1.51‐1.56 (m, 4H, CH2). UV/Vis (CH3CHOH, λmax, nm): 240, 270, 284. Anal. calcd. for C6H10NNaS2: C, 39.32; H, 5.50; N, 7.64. Found: C, 40.70; H, 5.31; N, 8.90%. 2.4. Synthesis of complexes L1 or L2 ligands (2 mmol, individually in H2O‐ethanol mixed solvent) were added dropwise with vigorous stirring to an aqueous solution of NiCl2·6H2O (1 mmol) and an aqueous solution of 1,10‐phenanthroline (L3) (1 mmol) with gentle heating for 1 h. The obtained green complexes were separated out, filtered, washed thoroughly with water, recrystallized from chloromethane and dried in vacuum over P2O5 (Figure 1) [19]. [Ni(L1)2(L3)1]: Color: Greenish Yellow. Yield: 75%. M.p.: 122‐124 °C. FT‐IR (KBr, , cm‐1): 1508 ν(C‐N), 946 ν(C‐S), 1336 ν(N‐C), 887 ν(C‐S), 453 ν(M‐S), 444 ν(M‐N). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 4.08‐4.10 (m, 8H, CH2‐N), 1.94‐1.97 (m, 8H, CH2). UV/Vis (CH3CHOH, λmax, nm): 234, 286, 384. Anal. calcd. for C22H24N4NiS4: C, 49.73; H, 4.55; N, 10.54. Found: C, 49.34; H, 4.80; N, 10.00%. [Ni(L1)1(L3)2]Cl: Color: Reddish Brown. Yield: 77%. M.p.: 115‐117 °C. FT‐IR (KBr, , cm‐1): 1458 ν(C‐N), 950 ν(C‐S), 1238 ν(N‐C), 846 ν(C‐S). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 4.09‐ 4.37 (m, 4H, CH2‐N), 1.39‐1.77 (m, 4H, CH2). UV/Vis (CH3CH OH, λmax, nm): 245, 266, 324. Anal. calcd. for C29H24ClN5NiS2: C, 57.97; H, 4.03; N, 11.66. Found: C, 58.10; H, 4.44; N, 12.13%. [Ni(L2)2(L3)1]: Color: Reddish Brown. Yield: 83%. M.p.: 132‐134 °C. FT‐IR (KBr, , cm‐1): 1509 ν(C‐N), 998 ν(C‐S), 1236 ν(N‐C), 883 ν(C‐S), 384 ν(M‐S), 470 ν(M‐N). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 3.07‐3.18 (m, 8H, CH2‐N), 1.03‐1.12 (m, 12H, CH2). UV/Vis (CH3CHOH, λmax, nm): 232, 270, 324. Anal. calcd. for C24H28N4NiS4: C, 51.53; H, 5.04; N, 10.01. Found: C, 51.30; H, 5.36; N, 9.88%. [Ni(L2)1(L3)2]Cl: Color: Yellow. Yield: 79%. M.p.: 128‐130 °C. FT‐IR (KBr, , cm‐1): 1440 ν(C‐N), 1111 ν(C‐S), 1238 ν(N‐C), 884 ν(C‐S). 1H NMR (400 MHz, DMSO‐d6, δ, ppm): 4.28‐4.35 (m, 4H, CH2‐N), 1.06‐1.51 (m, 6H, CH2). UV/Vis (CH3CHOH, λmax, nm): 246, 326, 390. Anal. calcd. for C30H26ClN5NiS2: C, 58.61; H, 4.26; N, 11.39. Found: C, 58.12; H, 4.70; N, 12.10%. 2.5. Antibacterial activity The antibacterial activity of the ligands and their nickel complexes were assessed against some bacterial species: Staphylococcus aureus and Escherichia coli. Overnight cultures were used after 24 h of incubation; bacterial suspension (inoculums) was diluted with sterile physiological solution for the diffusion test, to 1×108 CFU/mL; (CFU = Colony forming unit). (Turbidity = McFarland barium sulfate standard 0.5). The bacterial inoculums was uniformly spread using sterile cotton swab on a sterile Petri dish Mueller Hinton agar. 50 μL of each concentration of the ligands and complexes were added to each well (7 mm diameter holes cut in the agar gel, 20 mm apart from one another). The plates were incubated for 24 h at 36±1 °C, under aerobic condition. After incubation, confluent bacterial growth was observed. Inhibition of the bacterial growth was measured in mm [20,21]. 3. Result and discussion 3.1. Synthesis The elemental analysis gives satisfactory agreement between observed and calculated values for carbon, hydrogen and nitrogen. The prepared ligands are generally soluble in water, ethanol, methanol, DMF, DMSO and THF. 3.2. Infrared spectroscopy The structure of dithiocarbamates can be illustrated in the terms of four resonance structures (Scheme 1), where the ligands can coordinate to a metal center via sulfur atom in a monodentate (structures a and b) or in a bidentate (structures c and d) [22]. The contribution of structure was shown to be very important in the overall electronic structure, which was achieved by the assignment of the polar bond at 1450‐1550 cm‐1 [17]. The ligands and complexes show a sharp bands between 1423 and 1509 cm‐1 which attributed to the (C N) stretching vibration [22]. The high vibrational frequency of this band in mixed ligand complexes indicate a partial double bond character, of C N group arising from mesomeric drift of electrons from the dithiocarbamate moiety toward the nickel(II) ion center [23]. Salih Hamza Abbas / European Journal of Chemistry 8 (4) (2017) 367‐370 369 Table 1. Antibacterial activity at concentration 100mg/mLof ligands and complexes. No Compound Inhibition diameters (mm) Escherichia coli Staphylococcus aureus I L1 4 4 II Ni(L1)2(L3)1 No activity No activity III [Ni(L1)1(L3)2]Cl 3 3 IV L2 4.1 4.3 V Ni(L2)2(L3)1 No activity No activity VI [Ni(L2)1(L3)2]Cl 1.5 2 Scheme1 Scheme 2 All complexes show (C N) bands in the range 1440‐ 1509 cm‐1 which is lie between (C=N) and (C‐N) in the 1640‐ 1690 cm‐1 and 1250‐1350 cm‐1 ranges, respectively [24]. In metal dithiocarbamato complexes the region 950‐1050 cm‐1 is considered characteristic of the nature of binding of the dithiocarbamato moiety. The presence of a solitary band in the above region is due to symmetrical bidentate coordination of the dithiocarbamato group while the splitting of this band within a narrow range of 20 cm‐1 is due to the unsymmetrical monodentate nature of the dithiocarba‐mato group as shown in Scheme 2 [25]. In the present study, a single sharp band of high intensity has been observed in the two complexes in 946‐1111 cm‐1 range, indicating symmetrical bidentate binding of the dithiocarbamato moiety. However, the ring frequencies associated with 1,10‐phenanthroline have been observed in the range 1650 and 1000 cm‐1. In the present study, the complexes (II and V) show small band at 1624 and 1631 cm‐1, respectively. Other bands are masked by those of dithio‐ carbamate ligand [26]. A new band appears in spectra of compounds (II and V) at 444 and 470cm‐1, respectively, due to (M‐N) stretching mode, which matches well with the literature values [27]. A new band of weak to medium intensity was observed in the region 453‐384 cm‐1, which may be assigned to (M‐S) [28]. Thus the FT‐IR spectral results provide strong evidences for the complexation of dithiocarbamate ligands with metal ions in a bidentate mode. 3.3. 1H NMR Spectra 1H NMR spectroscopy provides more information beside the identification of functional groups present in the structure of dithiocarbamate ligands and their complexes. The 1H NMR spectral data for the dithiocarbamate ligands and the nickel(II) complexes were recorded at room temperature. The expected protons ratio are agree well with pervious work [23,29]. The 1H NMR spectra displayed the chemical shift of methylene (‐CH2) protons as multiplets at δ 1.79‐1.83 ppm and δ 1.51‐1.56 ppm for the ligands (L1 and L2 ligands), respectively, and (‐HC‐N) are observed in the deshielded region at about δ 3.62‐3.67 and 4.23‐4.29 ppm for these ligands, respectively. This deshielding was caused by the high electron density around the sulphur or metal atom via the thioureide π‐system [30]. This deshielding confirmed the coordination of the dithiocarbamate to the metal atom and was attributed to the mesomeric drift of electrons from heterocyclic ring towards the metal atom. On complexation there was an only slight chemical shift. The 1H NMR spectra of the complexes showed that resonance of aromatic rings in the region δ 7.77‐9.11 ppm, which was agreed with literature [31]. 3.4. Electronic spectra The electronic spectra for the dithiocarbamate ligands and the nickel(II) complexes were recorded in the UV‐Visible range 200‐800 nm. Dithiocarbamate ligands generally show three bands in the UV region, which are related to an intra‐ molecular charge transfer. Band I corresponding to π‐π* transitions of the N‐C=S system [24]. Band II is attributed to π‐ π* transitions of S‐C=S group [25]. Band III with low intensity is assigned to an n‐π* transitions, i.e. transition of an electron of the lone pair on the sulphur atom to an antibonding π‐ orbital [32]. When metal complexes absorb radiation, the transition obtained is attributed to excitation of the metal ion, excitation of the ligand or charge transfer transition. Therefore, two types of transitions are expected. While the transition on the ligand can be π‐π* and n‐π * transitions, but π‐π* transitions are stronger than n‐π* transitions. Transitions due to the excitation of the metal ions are known as d‐d transitions and these are normally weak [33]. Charge transfer transition is very intense and is as a result of the excitation of an electron from the metal ion to the ligand and vice versa. 3.5. Antibacterial activity The general screening of the pathogenic bacteria was obtained for the prepared compounds. In the screening, it was clear that most of these compounds possess a selective antibacterial activity against Gram negative bacteria; Escherichia coli and Gram positive; Staphylococcus aureus except the complexes (II and V) as shown in Table 1. 4. Conclusion New mixed ligands and their ternary nickel(II) complexes of dithiocarbamate with 1,10‐phenanthroline have been synthesized and characterized. Based on analytical, FT‐IR and electronic spectral data, they adopt octahedral geometry 370 Salih Hamza Abbas / European Journal of Chemistry 8 (4) (2017) 367‐370 around nickel(II). The two ligands moieties display a bidentate coordination mode in the complexes. Most of the prepared compounds possess a selective antibacterial activity against Gram negative bacteria; Escherichia coli and Gram positive; Staphylococcus aureus except the complexes (II and V). Acknowledgments I am grateful to Prof. Hayat Hamza Abbas and two final year project’s students; Radhwan Salman Abdulhussien and Zaynab Ali Mhayer for their help. References [1]. Menezes, D. C.; Viera, F. T.; DeLima, G. M. A.; Porto, A. O.; Cortes, M. E.; Ardisson, J.; Albrecht‐Schmitt, T. E. Eur. J. Med. Chem. 2005, 40, 1277‐ 1282. [2]. Halls, D. J. Microchim. Acta 1969, 57(1), 62‐77. [3]. Djordjevic, C.; Lee, M.; Sinn, E. Synth. Inorg. Chem. 1989, 28(4), 719‐ 723. [4]. Kana, A. T.; Hibbert, T. G.; Mahon, M. F.; Molloy, K. C.; Parkin, I. P.; Price, L. S. Polyhedron 2001, 20(24), 2989‐2995. [5]. Law, N. A.; Dietzsch, W.; Duffy, N. V. Polyhedron 2003, 22(27), 3423‐ 3432. [6]. Chaturvedi, D.; Ray, S. Monatsh. Chem. / Chem. Mon. 2006, 137(3), 311‐317. [7]. Devdutt, C.; Nisha, M.; Virendra, M. Synthesis (Stuttg). 2008, 3, 355‐ 357. [8]. Chaturvedi, D. J. Sulfur Chem. 2005, 26(4‐5), 365‐371. [9]. Rudorf, W. D. J. Sulfur Chem. 2007, 28(3), 295‐339. [10]. Alizadeh, A.; Rostamnia, S.; Zohreh, N.; Hosseinpour, R. Tetrahedron Lett. 2009, 50, 1533‐1535. [11]. Cui, J. L.; Ge, Z. M.; Cheng, T. M.; Li, R. Synth. Commun. 2003, 33(12), 1969‐1976. [12]. Azizi, N.; Pourhasan, B.; Aryanasab, F.; Saidi, M. R. Synlett. 2007, 8, 1239‐1242. [13]. Azizi, N.; Aryanasab, F.; Torkiyan, L.; Ziyaei, A.; Saidi, M. R. J. Org. Chem. 2006, 71(9), 3634‐3635. [14]. Siddiqi, K. S.; Nami, S. A. A.; Lutfulla; Chebude, Y. Synth. React. Inorg. Met. Nano‐Metal Chem. 2005, 35(6), 445‐451. [15]. Cervantes, G.; Moreno, V.; Molins, E.; Miravitlles, C. Met. Based. Drugs 1997, 4(6), 317‐325. [16]. Mohammad, A.; Varshney, C.; Nami, S. A. A. Spectrochim. Acta A 2009, 73(1), 20‐24. [17]. Kaul, B. B.; Pandeya, K. B. Transit. Met. Chem. 1979, 4(2), 112‐114. [18]. Manav, N.; Mishra, A. K.; Kaushik, N. K. Spectrochim. Acta A 2006, 65(1), 32‐35. [19]. Azizi, N.; Ebrahimi, F.; Aakbari, E.; Aryanasab, F.; Saidi, M. R. Synlett. 2007, 18, 2797‐2800. [20]. Uddin, M. N.; Chowdhury, D. A; Islam, M. T.; Hoque, F. Orbital 2012, 4(4), 273‐287. [21]. Smania Jr, A.; Monache, F. D.; Smania, E. D. F. A.; Cuneo, R. S. Int. J. Med. 1999, 1(4), 325‐330. [22]. Odola, A. J.; Woods, J. A. O. Arch. Appl. Sci. Res. 2011, 3(4), 463‐470. [23]. Prakasam, B. A.; Ramalingam, K.; Baskaran, R.; Bocelli, G.; Cantoni, A. Polyhedron 2007, 26(5), 1133‐1138. [24]. Fahdawi, A. S.; Al‐Kafajy, H. A. Iraqi Natl. J. Chem. 2013, 52, 414‐429. [25]. Al‐Jeboori, M. J.; Al‐Jebouri, F. A.; Al‐Azzawi, M. A. R. Inorg. Chim. Acta 2011, 379(1), 163‐170. [26]. Ekennia, A. C.; Onwudiwe, D. C.; Ume, C.; Ebenso, E. E. Bioinorg. Chem. Appl. 2015, 2015(2), 1‐10. [27]. Li, M. Y.; Hu, P. Z.; Zhu, J. C.; Liu, Y.; Xu, K. X. Chinese J. Chem. 2004, 22(2), 162‐166. [28]. Hasan, A. H.; Yousif, E. I.; Al‐Jeboori, M. J. Glob. J. Inorg. Chem. 2012, 1(2), 132‐138. [29]. Srinivasan, N.; Thirumaran, S.; Ciattini, S. J. Mol. Struct. 2009, 921(1‐ 3), 63‐67. [30]. Hassan, A. F. J. Chem. Mater. Res. 2015, 7(4), 9‐16. [31]. Yilmaz, T. K.; Yazicilar, H.; Cesur, R.; Ozkanca; Maros, F. Z. Synth. React. Inorg. Met‐Org. Chem. 2003, 33(4), 589‐600. [32]. Ronconi, L.; Giovagnini, L.; Marzano, C.; Bettio, F.; Graziani, R.; Pilloni, G.; Fregona, D. Inorg. Chem. 2005, 44(6), 1867‐1881. [33]. Christian, G. D. Analytical Chemistry, 6th Ed.; John Wiley and Sons Inc., Washington, 2004.