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Hindawi Heteroatom Chemistry Volume 2019, Article ID 9203435, 7 pages https://doi.org/10.1155/2019/9203435 Research Article SN-Donor Methylthioanilines and Copper(II) Complexes: Synthesis, Spectral Properties, and In Vitro Antimicrobial Activity 1,2 3 1 Temitope E. Olalekan , Adeniyi S. Ogunlaja, and Gareth M. Watkins Department of Chemistry, Rhodes University, P.O. Box 90, Grahamstown 6140, South Africa Department of Chemistry, University of Ibadan, Ibadan 200285, Nigeria Department of Chemistry, Nelson Mandela University, Port Elizabeth 6001, South Africa Correspondence should be addressed to Temitope E. Olalekan; topeolalekan11@yahoo.com Received 12 November 2018; Revised 24 January 2019; Accepted 5 February 2019; Published 3 March 2019 Academic Editor: Bartolo Gabriele Copyright © 2019 Temitope E. Olalekan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Methylthioanilines, a series of sulfur-nitrogen donor ligands substituted with OCH , CH , Cl, and Br, and their copper(II) 3 3 1 13 complexes have been synthesized and characterized by H and C NMR, elemental analysis, FTIR, UV-Vis and EPR spectra, molar conductance, and magnetic susceptibility measurements. eTh NMR spectra of the ligands revealed that the para/ortho protons and para carbon were sensitive to the electronic effect of substituents. eTh CHNS analysis presented CuLCl (L = OCH , CH ,Cl)and 2 3 3 CuL Cl (L = Br) stoichiometries for the copper complexes. FTIR spectra showed that the bidentate ligands were coordinated to the 2 2 copper ion through their nitrogen and sulfur atoms. The electronic spectra have suggested square planar and octahedral geometries 2 2 for these complexes. The EPR spectra demonstrated that the solid state copper(II) complexes possess d orbital ground state x –y and g > g > 2.0023 in a tetragonal environment. eTh compounds were evaluated for in vitro antimicrobial activity against S. ‖ ⊥ aureus, B. subtilis, E. coli, and C. albicans. eTh copper complexes showed higher activity than the parent ligands against S. aureus and B. subtilis; the electron-donating OCH and CH derivatives were more active than the withdrawing Br- and Cl-substituted 3 3 compounds. 1. Introduction of ortho- and para- substituted methylthiolated products resulted [5]. A two-pot synthetic route can also be used Thiomethylated anilines belong to a class of nitrogen- to generate substituted 2-(methylthio)anilines. By alkaline sulfur (SN) donor groups. eTh y n fi d application in prepa- hydrolysis of the appropriate 2-aminobenzothiazoles at a high ration of sulfoxides [1] which are desulfurized to generate temperature and subsequent methylation with methyl iodide, methylated anilines [2] and as starting materials [3] for the crude substituted 2-(methylthio)anilines were derived deriving aminobenzaldehydes which are also useful pre- [6]. The biological relevance of Cu(I)/Cu(II) in living systems cursors to many important heterocyclics. By coupling 2- includes their presence as cuproproteins to transport molec- (methylthioaniline) with another suitable aromatic polymer, ular oxygen and acts as good catalysts in related oxidation- a suitable chelating resin [4] has been derived for use reduction processes. Substituted 6-(methylthio)aniline lig- in preconcentration of metal ions such as Cd, Hg, Ni, ands are potential SN bidentate ligands of which bioactiv- Co, Cu, and Zn for analytical purposes. Substituted 2- ity has not been investigated. The synthesis, NMR, FTIR, (methylthio)anilines were synthesized from the reaction of UV/Vis, EPR, molar conductance, magnetic measurements, corresponding anilines with aliphatic disulfides in the pres- and in vitro antimicrobial studies of ortho-substituted-6- ence of Lewis acid catalysts, particularly aluminum chloride (methylthio)anilines and their copper(II) complexes are and copper iodide at high temperatures of>100 C; mixtures reported in this study. 2 Heteroatom Chemistry 2. Materials and Methods .( .( 2 N b, c 2.1. Materials and Physical Measurements. All the reagents .( and solvents were of analytical grade and used as obtained S #( from commercial suppliers (Sigma Aldrich and Merck). a: KSCN, Bromine, Acetic acid CHNS analyses were determined on Elementar Analysensys- b: KOH, ( O teme varioMICRO V1.6.2. One- and two-dimensional NMR c: EtOH, MeI, KOtBu 1 13 spectra ( H, C, DEPT135, COSY, HMBC, and HSQC) R = -OC( , -C( , -Cl, Br 3 3 were obtained in CDCl on a Bruker Avance 400 MHz Scheme 1: Synthesis scheme for substituted 6-(methylthio)anilines. NMR spectrometer. Chemical shifts were recorded in ppm with reference to the residual solvent proton relative to tetramethylsilane. Infrared spectra of the compounds were –1 determined in the region 4000–400 cm on PerkinElmer in vacuo. eTh residue was dissolved in water, neutralized Spectrum 100 ATR-FTIR spectrometer. Far-infrared spectra to pH 7 with concentrated HCl and the product extracted –1 for the complexes in the region 700–30 cm were obtained with dichloromethane. Removal of the solvent under pres- as mulls held between polyethylene discs and recorded on sure yielded crude 2-methoxy-2-(methylthio)aniline. This Perkin Elmer Spectrum 400 FTIR/FIR spectrometer. eTh was purified by column chromatography on silica gel using UV/Vis electronic spectra (250–1100 nm) were determined hexane/ether (6:1 vol/vol) as eluent to ao ff rd the pure oil. in DMF on a PerkinElmer Lambda 25 UV/VIS Spectrometer. Yield: 55%, mp 68-70 C. Colour: Brown. Anal. Calc. for The molar conductance was measured in DMF at room C H NS (M 169.2):C,62.70;H,7.24;N,9.14;S,20.92.Found: H 8 11 r temperature on AZ 86555 p /mV/Cond./TDS/Temp at −1 C,61.97; H, 7.44;N,9.02;S, 20.64%.FTIR(cm ): 3383, 3293 –3 10 M. Magnetic susceptibility measurements were taken V (NH ), 1620𝛿(NH ), 1269 v(C–N). UV𝜆 (DMF, asy/sym 2 2 max on a Sherwood magnetic susceptibility balance Mark 1. –1 –1 sh nm (𝜀,M cm ): 284 , 308 (12240). A Galenkemp melting point apparatus was used to deter- Other 2-(methylthio)anilines were similarly prepared mine the melting points (uncorrected). The powder electron from their starting ortho-substituted anilines. paramagnetic resonance (EPR) spectra were recorded on a Bruker ESP 300E X-band EPR spectrometer with 100 kHz 2.2.2. 2-Methyl-6-(methylthio)aniline (L2). Yield 24%, brown field modulation. Other experimental parameters: 9.762 GHz, oil. Anal. Calc. for C H NS (M 153.3): C, 62.70; H, 7.24; N, 16.05 G modulation amplitude, 20 mW power, 1.25 ms time 8 11 r 9.14;S,20.92.Found:C,62.03;H,7.99;N,9.01;S,20.91%. FTIR constant, and 100 s sweep time. –1 (cm ): 3452, 3355 V (NH ), 1619𝛿(NH ), 1279 v(C–N). asy/sym 2 2 –1 –1 sh 2.2. Synthesis of Substituted 2-(Methylthio)anilines. Ortho- UV𝜆 (DMF, nm (𝜀,M cm ): 286 , 309 (11960). max substituted-2-(methylthio)anilines were prepared in a two- pot reaction involving the conversion of o-anisidine, o- 2.2.3. 2-Chloro-6-(methylthio)aniline (L3). Yield 29%, brown toluidine, o-chloroaniline, and o-bromoaniline to the corre- oil. Anal. Calc. for C H ClNS (M 173.7): C, 48.41; H, 4.64; 7 8 r sponding aminobenzothiazoles [7, 8] which were hydrolyzed N, 8.07;S,18.46.Found:C,48.80;H,4.81; N, 8.02;S,18.39%. –1 and methylated to yield the crude products (Scheme 1) [6]. FTIR (cm ): 3459, 3358 V (NH ), 1615𝛿(NH ), 1292 asy/sym 2 2 –1 –1 sh v(C–N). UV𝜆 (DMF, nm (𝜀,M cm ): 285 , 317 (9975). max 2.2.1. 2-Methoxy-6-(methylthio)aniline (L1). o-Anisidine (1.00 g, 8.11 mmol) and potassium thiocyanate (3.16 g, 32.50 mmol) 2.2.4. 2-Bromo-6-(methylthio)aniline (L4). Yield 22%, light were rapidly stirred in glacial acetic acid (16 mL) and bromine yellow oil. Anal. Cald. for C H BrNS (M 218.1): C, 38.55; H, 7 8 r liquid (1.30 g, 8.11 mmol) was added dropwise. The mixture 3.70; N, 6.42;S,14.70.Found:C,39.54;H,3.71; N,6.36;S, was stirred for 10 h keeping the temperature below 35 C, –1 14.76%. FTIR (cm ): 3455, 3354 V (NH ), 1611𝛿(NH ), asy/sym 2 2 during which a precipitate was formed. This mixture was –1 –1 sh 1290 v(C–N).𝜆 (DMF, nm (𝜀,M cm ): 285 , 317 (9975). max filtered and the precipitate washed with water. The combined filtrate was neutralized to pH 7 with aqueous ammonia 2.2.5. Synthesis of [Cu(L1)Cl ]. 2-Methoxy-6-(methylthio)an- solution during which a shiny brown precipitate formed 2 iline, L1 (0.14 g, 0.80 mmol) in 3 mL ethanol was stirred andthemixturewas filteredand dried(2.00 g). ec Th rude at room temperature and ethanol solution of CuCl .2H O 6-methoxy-2-aminobenzothiazole (0.54 g, 3.00 mmol) was 2 2 (0.14 g, 0.80 mmol) was added dropwise. The mixture was slowly added to potassium hydroxide (1.54 g, 27.40 mmol) in stirred for 3 h. eTh deep brown precipitate was obtained 2mLwater.Themixture wasslowlyheatedto135 Callowing by filtration, washed with ethanol, and dried (0.08 g, 32%), the water to evaporate. eTh temperature was then increased mp>200 C. Anal. Calc. for C H Cl CuNOS (M 303.7): C, to 165 Candheldtherefor2h.Thereactionmixturewas 8 11 2 r 31.64; H, 3.65; N, 4.61; S, 10.56. Found: C, 31.72; H, 4.15; N, allowedtocooltoroomtemperatureandquenchedwith2mL −1 4.50; S, 10.33%. FTIR-ATR (cm ): 3251, 3171 V (NH ), of water. The mixture was filtered to remove the unreacted 2- asy/sym 2 1585𝛿(NH ), 1245 v(C–N), 414 v(Cu–N), 314 v(Cu–Cl), 280 aminobenzothiazole. eTh filtrate was collected and the water 2 –1 –1 sh v(Cu–S). UV-Vis𝜆 (DMF, nm (𝜀,M cm ): 275 ,315 removed under vacuum. Iodomethane (0.19 mL, 3.00 mmol) max –1 2 (5805), 335 (3664), 454 (3400).𝜇 (BM) = 1.8.Λ (Ω cm and 4 mL ethanol were each added to the residue and the eff –1 slurry was stirred for 16 h after which ethanol was removed mol ) = 33.4. Heteroatom Chemistry 3 1 13 Table 1: Hand C chemical shifts ( 𝛿) for substituted-6-(methylthio)aniline ligands in ppm. Ligands C1 C2 H, C3 H, C4 H, C5 H, C6 H, C7 H 8 H, C9 (L1) ---- ---- 6.84 d 6.83 t 6.64 d ---- 2.43 s 3.81 s 3.83 s 134.90 125.46 115.04 122.45 112.29 147.17 18.80 ---- 55.36 (L2) ---- ---- 7.11 d 7.09 t 6.61 d ---- 2.42 s 3.57 s 2.15 s 143.20 122.84 128.33 115.25 131.77 125.12 18.55 ---- 17.04 (L3) ---- ---- 7.26 d 6.68 t 7.07 d ---- 2.41 s 3.97 s ---- 141.32 119.41 129.06 116.16 130.05 126.58 18.42 ---- ---- (L4) ---- ---- 7.42 d 6.66 t 7.11 d ---- 2.40 s 4.02 s ---- 142.55 126.91 129.89 115.97 133.18 109.31 18.57 ---- ---- s singlet; d doublet; t triplet. [Cu(L2)Cl ], [Cu(L3)Cl ] and [Cu(L4)Cl ]weresimilarly was prepared by dissolving 0.85 g saline in double-distilled 2 2 2 prepared. water and making up to 100 mL. McFarland (0.5) solution was prepared by adding 0.5 mL of 1.175 % BaCl .2H O 2 2 2.2.6. Synthesis of [Cu(L2)Cl ]. [Cu(L2)Cl ]wasobtained to 99.5 mL of 1 % H SO [9]. Agar disc diffusion method 2 2 2 4 from 2-methyl-6-(methylthio)aniline, L2 (0.24 g, 0.80 mmol) [10, 11] was employed to determine the susceptibility of and CuCl .2H O (0.14 g, 0.80 mmol). Yield: 0.05 g (20%), mp 2 2 Staphylococcus aureus ATCC 6538, Bacillus subtilis (subsp. 140-141 C. Colour: Black. Anal. Calc. for C H Cl CuNOS spizizenii) ATCC 6633,Escherichia coli ATCC 8739, and 8 11 2 (M 287.7): C, 35.40; H, 3.85; N, 4.87; S, 11.15. Found: C, r for antifungal activity against Candida albicans ATCC –1 36.24; H, 3.76; N, 4.89; S, 10.24%. FTIR-ATR (cm ): 3313, 2091 to the synthesized compounds. Ampicillin (AMP) 3199 V (NH ), 1576𝛿(NH ), 1250 v(C–N), 406 v(Cu–N), and ketoconazole (KTZ) were used as positive controls asy/sym 2 2 –1 290 v(Cu–Cl), 279 v(Cu–S). UV-Vis𝜆 (DMF, nm (𝜀,M for the antibacterial and antifungal tests, respectively. eTh max –1 sh preparation of the growth media, reference drugs, agar cm ): 273 , 300 (5080), 336 (3360), 428 (2070).𝜇 (BM) = eff –1 2 –1 plates, the culture of microbial strains, and inoculation 1.9.Λ (Ω cm mol )=32.4. of agar plates followed standard procedures [12, 13]. Each microbial inoculum was standardized with reference to 0.5 2.2.7. Synthesis of [Cu(L3)Cl ]. [Cu(L3)Cl ]wasobtained 2 2 from 2-chloro-6-(methylthio)aniline, L3 (0.14 g, 0.80 mmol) McFarland solution [14]. 250 𝜇gofeachtestcompounds dissolved in DMF was delivered on to sterile assay discs. and CuCl .2H O (0.14 g, 0.80 mmol). Yield: 0.06 g 2 2 Ampicillin andketoconazole(125𝜇g) were measured onto (24%), mp 150-152 C. Colour: Deep brown. Anal. Calc. for separate discs and allowed to dry under the laminar flow. Six C H Cl CuNS (M 308.1):C,29.83;H,3.13; N,4.35;S,9.95. 7 8 3 r discs were placed on each inoculated agar plate containing Found: C, 29.54; H, 2.87; N, 4.32; S, 9.73%. FTIR-ATR 3340, 3199 V (NH ), 1576𝛿(NH ), 1271 v(C–N), 406 v(Cu–N), the appropriate growth medium and incubated for 24 h asy/sym 2 2 –1 (bacteria) and 60 h (fungus) at 35 C. The diameter of zone of 301 v(Cu–Cl), 278 v(Cu–S). UV-Vis𝜆 (DMF, nm (𝜀,M max inhibition of the microbial growth by each compound was –1 sh cm ): 275 , 304 (5690), 333 (3280), 364 (5424), 413 (3335). –1 2 –1 measured. eTh tests were carried out in triplicate and the 𝜇 (BM) = 1.8.Λ (Ω cm mol )=29.2. eff mean values were recorded in Table 3. 2.2.8. Synthesis of [Cu(L4) Cl ]. [Cu(L4) Cl ]wasobtained 2 2 2 2 from 2-bromo-6-(methylthio)aniline, L4 (0.18 g, 0.80 3. Results and Discussion mmol) and CuCl .2H O (0.14 g, 0.80 mmol). Yield: 0.11 2 2 3.1. Synthesis and Properties. The ligands are soluble in g (22%), mp 110-111 C. Colour: Black Anal. Cald. for common organic solvents and their copper(II) complexes are C H Br Cl CuN OS (M 588.7): C, 28.56; H, 3.08; N, 14 18 2 2 2 2 r soluble in DMSO and DMF. The compounds were obtained in 4.76;S,10.89.Found:C,28.95;H,2.90;N,4.78;S,10.61%. –1 low to moderate yields and are stable in air. eTh experimental FTIR-ATR (cm ): 3276, 3183 V (NH ), 1583 𝛿(NH ), asy/sym 2 2 CHNS analyses corresponded with the calculated values; 1273 v(C–N), 409 v(Cu–N), 303 v(Cu–Cl), 275 v(Cu–S). –1 –1 the complexes showed CuLCl stoichiometry except the Br- UV-Vis𝜆 (DMF, nm (𝜀,M cm ): 281 (3210), 314 (3622), max –1 2 –1 substituted Cu(L4) Cl . eTh molar conductance measure- 2 2 332 (2430), 436 (370).𝜇 (BM) = 1.9.Λ (Ω cm mol )= eff –1 2 –1 ments (DMF) were in the range 28.3–33.4Ω cm mol ; 28.3. thus the complexes behave as nonelectrolytes with the chlo- rine species covalently bound to the Cu(II) ions. 2.3. Antimicrobial Studies. eTh microorganism strains, growth media, and sterile assay disks (diameter 6 mm) were purchased from Microbiologics, Merck, Becton Dickinson 3.2. NMR Spectra of the Ligands. The atom labeling for H and Company in South Africa. Ampicillin powder was and C NMR shifts of the ligands have been recorded in obtained from Roche Diagnostics, Germany. Double- Figure 1. The NMR resonances (Table 1) were assigned with distilled water was collected from the Pharmaceutics Unit the aid of DEPT135, COSY, HMBC, and HSQC spectra. of Faculty of Pharmacy, Rhodes University. Sterile saline The thiomethyl protons (-SCH )appearassinglet peaks 3 4 Heteroatom Chemistry Table 2: EPR parameters for copper(II) complexes. 6 Compound g g ⊥ ‖ .( [Cu(L1)Cl] 2.108 2.293 [Cu(L2)Cl] 2.129 2.256 [Cu(L3)Cl] 2.052 2.142 2 2 3 [Cu(L4) Cl] 2.066 2.215 2 2 #( R = MeO, Me, Cl, Br bands. The more intense bands at 308–317 nm were assigned 1 13 Figure 1: Atom labeling for Hand C NMR chemical shifts. to n→∗𝜋 of the nitrogen lone pairs to the aromatic ring. In the spectra of the copper(II) complexes,𝜋→𝜋∗ transitions were bathochromically shifted to 273–281 nm. Two intense absorbing between 2.40 and 2.43 ppm. eTh broad singlet bands around 300–364 nm were assigned to n → ∗𝜋 peaks in the range 3.57–4.02 ppm were assigned to amine (- transitions in the complexes. In the spectra of [Cu(L1)Cl ], NH ) protons. eTh aromatic protons appear as doublets and [Cu(L2)Cl ] and [Cu(L3)Cl ], moderately intense bands at 2 2 triplets in the downfield region 6.61–7.42 ppm. Additional 413, 428, and 454 nm, respectively, were assigned to B → 1g single peaks at 3.83 and 2.15 ppm were observed in L1 and A in a square planar geometry around the copper ion. The L2 due to –OCH and –CH proton resonances respectively. 1g 3 3 band at 436 nm in the spectrum of [Cu(L4) Cl ] was assigned The methyl carbon ( C7) resonated in the range 18.42–18.80 2 2 2 2 ppm and the aromatic carbon atoms have higher absorptions to E → T transition in an octahedral geometry. g 2g between 112.29 and 147.17 ppm. The methyl and methoxy The magnetic moments in the range 1.8–1.9 BM indicate carbon atoms of L1 and L2 resonated at 17.04 and 55.36 ppm, the availability of an unpaired electron in the copper(II) respectively. eTh electronic effect of substituents on the NMR complexes which are magnetically dilute. shiso ft famineprotonsaswellasthe ortho (H3)and para (H5) protons was observed. es Th e protons were more deshielded 3.5. EPR Studies. The powdered EPR spectra of a series of 6- in the derivatives with electron-withdrawing substituents (L3 (methylthio)aniline copper(II) complexes, substituted with - and L4), resonating at higher frequencies compared to those OCH [Cu(L1)Cl ], -CH [Cu(L2)Cl ], -Cl [Cu(L3)Cl ], and 3 2 3 2 2 of substituents L1 and L2. A similar shift was observed at the –Br [Cu(L4) Cl ], are presented in Figure 2. eTh spectra 2 2 para carbon atom (C3)(Table1). consist of two g values (g and g )intherange2.052–2.293 ‖ ⊥ (Table 2). es Th e values are typical of copper(II) coordination 3.3. IR Spectra. In the vibrational spectra of the ligands, the to electron-donating group (such as nitrogen) [19]. eTh strong asymmetric and symmetric stretches due to vN–H of relation g > g > g (g = 2.0023) observed in the the primary amine group were observed within the ranges ‖ ⊥ o o –1 EPR spectra of the copper(II) complexes is consistent with 3459–3383 and 3358–3293 cm ,respectively[7,14,15].The an elongated octahedral, square pyramidal or square planar frequencies of both bands were lowered in the complexes –1 2 2 to 3340–3251 and 3199–3171 cm ,respectively. eTh reduced geometry with d orbital ground state [20, 21]. eTh spectra x –y frequency of these stretches upon chelation has been inter- of the complexes display an axial signal with g ≈ 2.2 and preted to be the result of the electron density of the nitrogen g ≈ 2.0, which has been associated with copper(II) square being directed to the metal ion, leaving the amino protons planar geometry [21–23]. eTh g < 2. 3 suggests the covalent less tightly bound to the nitrogen [16]. N–H scissor and vC–N character of the copper coordination to the ligand [24]. which appeared as medium bands in the ligands in the ranges Asquareplanargeometryisthusimpliedfor[Cu(L1)Cl ], –1 1620–1611 and 1292–1269 cm in the spectra of the ligands [Cu(L2)Cl ] and [Cu(L3)Cl ], and a distorted octahedral 2 2 –1 were shieft d to 1585–1576 and 1273–1245 cm ,respectively, geometry is proposed for Cu(L4) Cl ] (Figure 3). 2 2 in the Cu(II) complexes. A shift to lower frequency of vC–N couldbeduetothedecreaseinthe C–Ndoublebond 3.6. Antimicrobial Susceptibility Testing. The agar disc diffu- character. These reductions in frequencies upon chelation sion technique was used to assess the antimicrobial activity suggested the coordination of the ligands to the copper ion of the synthesized compounds using the sterile assay discs of through the nitrogen lone pair [16]. eTh bands due to vC–S–C –1 –1 diameter 6 mm. The results have been recorded in Table 3. (∼1100 cm )and vC–S (∼780–650 cm ) of the thioether The gram-positive S. aureus and B. subtilis were susceptible group were not observed as they were too weak [17]. In the far to the compounds and were inhibited by the measured IR region, new medium bands in the spectra of the complexes –1 diameters of 8–20 mm while the gram-negative Ecoli and were observed andassignedas vCu–N (414–406 cm ), –1 –1 the fungus C. albicans were resistant. The copper complexes vCu–Cl (314–290 cm ), and vCu–S (280-275 cm )[18]. with methoxy and methyl substituents demonstrated better activity than the compounds with the electron-withdrawing 3.4. Electronic Spectra and Magnetic Moments. The electronic substituents, with the diameters of inhibition in the range spectra of the ligands include the intraligand𝜋→𝜋∗ tran- sitionsinthe range284–286nmwhichappearasshoulder 19–20 mm. Heteroatom Chemistry 5 –1 Table 3: Diameter of inhibition zones (mm) at 250 𝜇gdisc of samples. Compounds S. B. E. C. aureus subtilis coli albicans L1 9 11 6 6 [Cu(L1)Cl] 20 19 6 6 L2 7 11 6 6 [Cu(L2)Cl] 19 20 6 6 L3 7 15 6 6 [Cu(L3)Cl] 910 6 7 L4 8 13 7 7 [Cu(L4)Cl] 914 6 7 DMF 6 6 6 6 AMP 40 38 23 -- KTZ -- -- -- 23 –1 125𝜇 gdisc . 2500 4500 4500 3000 3500 4000 3000 3500 4000 Gauss (G) Gauss (G) [Cu(L1)CF ] [Cu(L2)CF ] 2 2 2500 4500 3000 3500 4000 2500 3000 3500 4000 4500 Gauss (G) Gauss (G) [Cu(L3)CF ]. [Cu(L4) CF ] 2 2 2 Figure 2: Powder EPR spectra of copper(II) complexes. 4. Conclusion NMR shifts of some protons in the ligands. The infrared spectral bands were consistent with primary amine groups, 6-(Methylthio)aniline derivatives and their Cu(II) complexes of which frequencies reduced in the copper complexes upon were prepared.Thecompounds werecharacterizedbyele- chelation. The substituted 6-(methylthioanilines) behaved mental analysis and spectroscopic means. eTh CHNS analysis as bidentate ligands binding with SN-donor atoms to the showed the metal complexes stoichiometry as CuLCl and copper(II) ions. Molar conductance values were indicative of nonelectrolytic complexes. eTh electronic and powder EPR CuL Cl . eTh electronic nature of substituents aeff cted the 2 2 6 Heteroatom Chemistry Br Br ( Cl N Cl 2 Cu Cu Cl Cl #( 3 #( 3 #( R = -OC( , -C( , Cl 3 3 Figure 3: Proposed structures of copper(II) complexes. spectra suggested a square planar geometry for [Cu(L1)Cl ], [4] Y.Guo,B.Din,Y. Liu,X. Chang,S.Meng,andM. Tian, “Preconcentration of trace metals with 2-(methylthio)aniline- [Cu(L2)Cl ], and [Cu(L3)Cl ]and adistorted octahedral 2 2 functionalized XAD-2 and their determination by flame atomic geometry for [Cu(L4) Cl ] (Figure 3). eTh evaluation of the 2 2 absorption spectrometry,” Analytica Chimica Acta,vol.504,no. synthesized compounds for in vitro antimicrobial activity 2,pp.319–324,2004. against S. aureus, B. subtilis, E. coli,and C. albicans demon- [5] P. F. Ranken and B. G. McKinnie, “Alkylthio aromatic amines,” strated that the copper complexes showed higher activity The Journal of Organic Chemistry , vol. 54, no. 12, pp. 2985–2988, than the parent ligands against S. aureus and B. subtilis.The electron-donating OCH and CH derivatives were more 3 3 [6] B. A. Dreikorn, G. P. Jourdan, H. R. Hall, J. B. Deeter, and active than the electron-withdrawing Br- and Cl-substituted N. Jones, “Synthesis, separation, and fungicidal activity compounds. of the rotationally hindered isomers (atropisomers) of N-(methoxyacetyl)-N-[2-methyl-6-(methylthio)phenyl]- D,L-alanine methyl ester,” Journal of Agricultural and Food Data Availability Chemistry,vol.38, no.2,pp. 549–552, 1990. eTh data supplied in the manuscript are available and will be [7] M. Matsui, Y. Marui, M. Kushida et al., “Second-order optical supplied when required. nonlinearity of 6-(peruo fl roalkyl)benzothiazolylazo dyes,” Dyes and Pigments, vol. 38, no. 1-3, pp. 57–64, 1998. [8] G. Trapani, M. Franco, A. Latrofa, A. Reho, and G. Liso, Conflicts of Interest “Synthesis, in vitro and in vivo cytotoxicity, and prediction of the intestinal absorption of substituted 2-ethoxycarbonyl- eTh authors declare that there are no conflicts of interest imidazo[2,1-b]benzothiazoles,” European Journal of Pharmaceu- regarding the publication of this paper. tical Sciences, vol. 14, no. 3, pp. 209–216, 2001. [9] J. Mcfarland, “The nephelometer: an instrument for estimating the number of bacteria in suspensions used for calculating Acknowledgments the opsonic index and for vaccines,” Journal of the American Medical Association,vol.49, no.14,pp.1176–1178,1907. One of the authors (Temitope E. Olalekan) thanks the Organization of Women in Science for the Developing World [10] A. W. Bauer, W. M. Kirby, J. C. Sherris, and M. Turck, “Antibiotic susceptibility testing by a standardized single disk method,” (OWSDW) for providing a Research Fellowship and Rhodes American Journal of Clinical Pathology,vol.45,no.4,pp. 493– University for academic bursary. 496, 1966. [11] J. H. Jorgensen and J. D. Turnidge, “Susceptibility test methods: References dilution and disk diffusion methods,” in Manual of Clinical Microbiology, P. R. Murray, E. J. Baron, J. H. Jorgensen, M. L. [1] H. L. Holland, F. M. Brown, A. Kerridge, and C. D. Turner, Landry, and M. A. Pfaller, Eds., vol. 1, pp. 1152–1172, American “Biotransformation of organic sulfides Part. 10. Formation of Society for Microbiology, Washington, DC, USA, 9th edition, chiral ortho-and meta-substituted benzyl methyl sulfoxides by biotransformation using Helminthosporium species NRRL [12] S. M. Finegold and E. J. Baron, Bailey and Scott’s Diagnostic 4671,” Journal of Molecular Catalysis B: Enzymatic,vol.6,no. Microbiology,C.V.MosbyCo., St.Louis,Missouri, MO,7th 5, pp. 463–471, 1999. edition, 1986. [2] J. P. Chupp, T. M. Balthazor, M. J. Miller, and M. J. Pozzo, [13] Clinical Laboratory Standards Institute, Performance Standards “Behavior of benzyl sulfoxides toward acid chlorides. useful for Antimicrobial Disk Susceptibility Tests, Clinical Laboratory departures from the pummerer reaction,” The Journal of Organic StandardsInstitute,Wayne,PA,9thedition,Approvedstandard, Chemistry, vol. 49, no. 24, pp. 4711–4716, 1984. CLSI document M2-A9 26:1, 2006. [3] P. G. Gassman and H. R. Drewes, “Selective ortho formylation [14] M. Tsuboi, “ N isotope effects on the vibrational frequencies of aromatic amines,” Journal of the American Chemical Society, of aniline and assignments of the frequencies of its nh group,” vol. 96, no. 9, pp. 3002-3003, 1974. Spectrochim Acta,vol.16,no.4,pp. 505–512, 1960. Heteroatom Chemistry 7 [15] L. F. Lindoy and S. E. Livingstone, “Reactions of nickel chelates derived from 2-aminobenzenethiol,” Inorganic Chemistry,vol. 7, no. 6, pp. 1149–1154, 1968. [16] R. J. H. Clark, “Metal-halogen stretching frequencies in inor- ganic complexes,” Spectrochim Acta,vol.21, no.5,pp. 955–963, [17] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, John Wiley and Sons, New York, NY, USA, 3rd edition, 1978. [18] M. Ikram and D. B. Powell, “Low frequency infrared spectra of complexes of 2-methylthioanilene with palladium II, platinum II, nickel II and copper II,” Spectrochimica Acta Part A: Molecu- lar and Biomolecular Spectroscopy,vol.27, no.9,pp.1845–1848, [19] G. M. Larin, A. N. Gusev, Y. V. Trush et al., “EPR spectra and structures of dinuclear copper(II) complexes with acyldihydra- zones of benzenedicarboxylic acids,” Russian Chemical Bulletin, vol. 56, no. 10, pp. 1964–1971, 2007. [20] E. Garribba and G. Micera, “eTh determination of the geometry of Cu(II) complexes. An EPR spectroscopy experiment,” Journal of Chemical Education, vol. 83, no. 8, pp. 1229–1232, 2006. [21] M. Lavanya, M. Jagadeesh, J. Haribabu et al., “Synthesis, crystal structure, DNA binding and antitumor studies of𝛽-diketonate complexes of divalent copper, zinc and palladium,” Inorganica Chimica Acta,vol.469,pp. 76–86, 2018. [22] S. Das, S. A. Maloor, S. Pal, and S. Pal, “Solvated square-planar ternary copper(II) complexes: Solvent-dependent zipper and columnar structures,” Crystal Growth and Design,vol.6,no.9, pp.2103–2108,2006. [23] A. Reiss and M. Mureseanu, “Transition metal complexes with ligand containing thioamide moiety: Synthesis, characteriza- tion and antibacterial activities,”JournaloftheChileanChemical Society,vol.57,no.9,pp.1409–1414, 2012. [24] K. Singh, Y. Kumar, P.Puri,C.Sharma, andK.R.Aneja, “er Th mal, spectral, uo fl rescence, and antimicrobial studies of cobalt, nickel, copper, and zinc complexes derived from 4-[(5-Bromo-thiophen-2-ylmethylene)-amino]-3-mercapto-6- methyl-5-oxo-[1,2,4]triazine,” International Journal of Inorganic Chemistry, vol. 2012, Article ID 873232, 9 pages, 2012. 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Published: Mar 3, 2019
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