Materials and method
Solvents were distilled before used. The compounds 4 and 5 were carried out under N2 atmosphere. All other chemicals were purchased from commercial sources and used directly without further purification. [FcPS2]2 (Fc: Fe(η5-C5H5)(η5-C5H4) and [Cu(PPh3)2]NO3 were prepared as described in the literature [32, 42], respectively. Elemental analyses were determined with a GmbH varioMICRO CHNS apparatus. Melting points were determined by using Electrotermal apparatus. NMR spectra were recorded on a Bruker AVANCE DRX 400 NMR spectrometer and Jeol GSX 270 in CDCl3 and d6-DMSO. IR spectra was measured on a Perkin-Elmer 2000 FTIR spectrophotometer (4000 – 400 cm−1). Mass spectra were recorded with an AGILENT 1100 MSD and Waters machines. Optical rotation values were determined with an automatic digital ADP 440+ polarimeter.
Electrospinning
The co-polymer polyacrylonitrile (PAN) and solvent dimethylacetamide (DMAc) were obtained from “AKSA acrylic chemistry company”. 15% polymer was dissolved in 85% solvent (w/w-weight by weight basis) at 80–100°C and stirred at least 4 hours. Polymer solution was prepared for electrospinning process by feeding into a pipette. Matsusada AU-40-0.75 high voltage supply were used to create electric field. Tip to collector distance was adjusted for 12 cm and voltage was adjusted 30 kV between the electrodes (Figure 4).
Antibacterial activity
Two different antimicrobial test methods were used. Firstly the antimicrobial activity of synthesized compounds was determined by using well diffusion assay [43]. After filter sterilization of relevant compounds, approximately 100 μl was filled to the wells which had been prepared previously by overlaying LB soft agar including the indicator strains Micrococcus luteus NCBI8166 and Escherichia coliATCC25922 on to the Müller-Hilton agar plates, then 5 mm wells were created with cork borer respectively. DSMO was used for controlling. To test antimicrobial efficiency of relevant compounds on fibers, the dynamic assessment of antimicrobial activity was carried out according to the standard test method released from American Society for Testing and Materials (ASTM) for immobilized antimicrobial agents under dynamic contact (E2149-01). Test bacteria (Escherichia coli ATCC25922) were cultured in LB broth (Fluka) overnight inoculations at 37°C. Subsequently, bacterial culture was diluted in 0.3 mM KH2PO4 buffer until the solution has an absorbance of 0.28 ± 0.02 at 475 nm as measured spectrophotometrically to reach bacterial suspension (1.5-3.0×105 CFU ml−1). Rounds of fibers having total 4 in.2 treated surface area were inoculated with 50 ± 0.5 ml of bacterial suspension and incubated at 37°C 1 h ±5 min. Standard plate counts were performed after decimal dilution of the samples in 9 ml of 0.1% peptone water. The percent inhibition rate (%) was calculated as formula of (N1-N2/N1) × 100, where N1 and N2 represent the number of colonies on the plates before and after inhibition, respectively. Untreated fibers were used as a negative control.
Synthesis of t-Butyl ammonium salt of (1S,2S,5S)- (−)- O-myrtanyl ferrocenyl dithiophosphonate (1)
2,4-Bis(ferrocenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide [FcPS(μ-S)]2 (1.80 g, 3.21 mmol) was reacted with 1S,2S,5S)-(−)-myrtanol (1.05 g, 6.42 mmol) in toluene (20 mL). The mixture was refluxed until all solids had dissolved. The dark brown solution was cooled to rt, filtered and treated with excess tert-butyl amine. The product was precipitated in freezer from toluene as a yellow solid, which was isolated by filtration, washed with toluene and n-hexane and then dried in air. Yield: 2.10 g 65%, m.p.: >187(dec.)°C. [α]58925 = −3.61 (c = 0.55 in THF). IR(KBr, cm−1) νmax: 648 (s,PS2, asym) and 582 (m, PS2, sym). 1H NMR (DMSO-d6, ppm) δ: 4.42 (br, 2H, C5H4), 4.23 (s, 5H, C5H5), 4.21 (br, 2H, C5H5), 4.18 (br, 2H, OCH2), 1.80-1.25 (m, 9H in myrtanyl group), 1.18 (s, 9H, tBu), 1.02 (s, 3H, CH3), 1.01(s, 3H, CH3). 13C NMR (DMSO-d6, ppm) δ: 90.94 (d, C1; ipso-C in C5H4, 1JP,C = 124.7 Hz), 84.23(d, 2JP,C = 7.9 Hz), 71.30 (d, C2 and C2′, 2JP,C = 13.9 Hz), 70.06 (s, C5H5), 69.71(d, 4JP,C = 2.7 Hz), 68.91 (d, C3 and C3′, 3JP,C = 4.9 Hz), 49.81 (s, tBut), 49.12 (d, 3JP,C = 5.2 Hz), 48.37, 41.50, 29.95 (s, tBu), 29.71, 26.78, 26.41, 22.23, 20.8 ppm. 31P NMR (DMSO-d6 ppm) δ: 105.46. MS (ESI): m/z 433.1 [M–(H3N+C(CH3)3]. Anal. Calcd. for C24H38FeNOPS2: C, 56.80; H, 7.55; N, 2.76; S, 12.64%. Found: C, 57.08; H, 7.38; N, 2.72; S, 12.18%.
Synthesis of (S) –(−)-1-(4-fluorophenylethyl)–amidoferrocenyldithiophoshonate (2)
[FcP(S)(μ-S)]2 1.50 g (2.67 mmol) was treated with (S) – (−)-1-(4-fluorophenylethyl) amine (0.745 g, 5.35 mmol) in a 1:2 ratio in toluene (25 mL) to give the corresponding amidoferrocenyldithiophosphonate. The reaction was carefully heated until all the solids dissolved and a brown solution was obtained and then a solid product was formed, which was isolated by filtration. The product was washed with petroleum ether (40–60°C). The yellow crystalline product was dried under vacuum. Yield: 1.57 g, 70%, m.p.: 169°C. [α]58925 = 75 (c = 0.08 in THF). IR(KBr, cm−1) νmax: 645 (s, PS2, asym) and 526 (m, PS2, sym). 1H NMR (DMSO-d6 ppm) δ: 7.63 (br, 2H, arom.), 7.25 (br, 2H, arom.), 4.56 (br, 2H, C5H4), 4.43 (br, 2H, C5H4), 4.37 (s, 5H, C5H5), 2.50 (s, 3H, CH3), 1.59 (s, 1H, CH). 31P NMR (DMSO-d6 ppm) δ: 61.80 (d, JPNH = 41.7 Hz) ppm. MS (ESI): m/z = 401.95 [M-F]+. Anal. Calcd. for C18H19NFPS2Fe: C, 51.56; H, 4.57; N, 3.34; S, 15.29%. Found: C, 51.71; H, 5.07; N, 3.54; S, 14.20%.
Synthesis of (1S,2S)-(+)-benzyloxycyclopentyl–amidoferrocenyldithiophoshonate (3)
Compound 3 was prepared in the same manner as compound 2, from [FcP(S)(μ-S)]2 (1.00 g, 1.78 mmol) and 1S,2S-(+)-benzyloxycyclopentyl amine 0.68 g (3.56 mmol) in toluene (25 mL). Yield: 1.19 g (76%), m.p.: 174–176°C. [α]58925 = 53.33 (c = 0.15 in THF). IR(KBr, cm−1) νmax: 645 (s, PS2, asym) and 525 (m, PS2, sym). 1H NMR (DMSO-d6 ppm) δ: 8.29(br, 1H, NH), 7.37(br, 5H, arom.), 4.54 (br, s, 2H, C5H4), 4.21 (br, s, 5H, C5H5), 4.18 (br, s, 2H, C5H4), 3.99 (br, 2H, OCH2), 3.80 – 1.69(br, m, 8H, C5H8 group). 31P NMR (DMSO-d6 ppm) δ: 62.09 ppm (JPN-H = 38.2 Hz) ppm. MS (ESI): m/z = 296.86 [M-C5H8OCH2C6H5]+. Anal. Calcd. for C22H27NOPS2Fe: C, 56.06; H, 5.59; N, 2.97%. Found: C, 60.07; H, 6.34; N, 3.30%.
Synthesis of [Cu{Fe(η5-C5H5)(η5-C5H4P(OR)S2)(PPh3)2}] (R = myrtanyl) (4)
A solution of [Cu(PPh3)2NO3] (0.13 g, 0.20 mmol) in THF(10 mL) was added dropwise to a solution of (1S, 2S, 5S)–O-myrtanyl-ferrocenyldithiophoshonate 1 (0.10 g, 0.20 mmol) in THF (10 mL) and stirred at r.t. for 2 h. A yellow-orange solution was observed. The reaction mixture was filtered and the solvent was removed under reduced pressure. A yellow-orange crystalline product was isolated. Yield: 0.12 g, 60%, m.p.: 179–180°C. [α]58925 = 120 (c = 0.05 in THF). IR (KBr, cm−1) νmax: 642 (s, PS2, asym) and 515 (m, PS2, sym). 1H NMR (CDCl3, ppm) δ: 7.43 – 7.25 (m, 30H, arom.), 4.36 (br, 2H, C5H4), 4.25 (s, 2H, C5H5), 4.21 (s, 2H, C5H4), 3.80 (m, 2H, OCH2), 2.40–1.10 (m, 9H, in myrtanyl group), 1.24 (s, 3H,CH3), 0.87 (s, 3H, −CH3). 31P NMR (CDCl3, ppm) δ: 97.85 (PS2) and −2.87 (PPh3) ppm. Anal. Calcd. for C56H56OP3S2FeCu (1021.51 g.mol−1): C, 65.84; H, 5.52; S, 6.27%. Found: C, 65.49; H, 5.54; S, 5.93%.
Synthesis of [Ag{Fe(η5-C5H5)(η5-C5H4P(OR)S2)(PPh3)2}]2 (R = CH3) (5)
A mixture of AgNO3 (0.12 g, 0.70 mmol) and PPh3 (0.18 g, 0.70 mmol) in MeOH (20 mL) was added dropwise to a solution of the compound (R) - (+) – 1 - Phenylethyl amidoferrocenyldithiophosphonate [35] (0.28 g, 0.70 mmol) in toluene (25 mL) and stirred for 2 h. A yellow precipitate product was immediately formed. The product was filtered, washed with petroleum ether(40–60°C) and dried in air. Yield: 0.38 g (79%). M.p.:>160°C(dec.). IR(KBr, cm−1) νmax: 649 (νasym PS2) and 560 (νsym PS2). 1H NMR (CDCl3, ppm) δ: 7.36 – 7.02 (m, 30H, arom.), 4.55 (br, 4H, 2× C5H4), 4.36 (br, 4H, 2xC5H4), 4.16 (s, br, 10H, 2xC5H5), 1.39 (d, br, 6H, 2xOCH3, 3JP,H = 5.4 Hz). 31P NMR (CDCl, ppm) δ: 97.82 (PS2) and 6.03 (PPh3). MS (ESI) (m/z): 279.1 [FcPS2]+. Anal. Calc. for C58H54O2P4S4Fe2Ag2: C, 51.12; H, 3.99; S, 9.41. Found: C, 50.76; H, 3.96; S, 9.87%.