2.2. Synthesis of Schiff-base ligands (HL1–HL2)
2,6-Diisopropilanilin (1.779 g, 10 mmol) was dissolved in ethanol (30 mL) and the corresponding aldehyde (2,3-dihydroxybenzaldehyde and 2,4-dihydroxybenzaldehyde) (0,138 g, 1 mmol) was added slowly. The yellow solution was refluxed for 6h and the solvent was removed on a rotary evaporator. The yellow solid was washed with water (2 mL) and hexane (4 mL). The products were dried in air. Single crystal of the ligand HL1 was obtained recrystallization from the CHCl3 solution (Scheme 1).
HL 1 - Yield: 92%, m.p. 134°C. Color: red-brown. Analysis Calc. for C19H23NO2 (MW: 297.38 g/mol): C, 76,73; H, 7,80; N, 4,71%. Found: C, 76,66; H, 7,87; N, 4,77%.IR (ATR, cm− 1): 3461, 3062, 2962, 2922, 2865, 1629, 1583, 1455, 1366, 1325, 1270, 1203,1177, 1101, 1029, 933, 868, 837, 800, 777, 762, 721, 556, 505.1HNMR: (CDCl3 as solvent, δin ppm): 1.22 (12H, d, –CH3), 3.02(2H, m,–CH2–), 6.90–7.23 (6H, d, aromatic protons), 8.32 (1H, s, –CH = N–).
HL 2 -Yield: 95%, m.p. 140°C. Color: orange. Analysis Calc. for (C19H23NO2) (MW: 297.38 g/mol) C, 76, 73; H, 7, 80; N, 4, 71 %. Found: C, 76,18; H, 7,84; N, 4,68 %.IR (ATR, cm− 1): 3162, 2960, 2865, 1626, 1584, 1519, 1463, 1322, 1256, 1214, 1169, 1120, 1057, 972, 931, 876, 842, 794, 751, 691, 664, 545, 479.NMR: (CDCl3 as solvent, δ in ppm): 1.22 (12H, d, –CH3), 3.05(2H, m,–CH2–), 6.48–7.22 (6H, d, aromatic protons), 8.15 (1H, s, –CH = N–).
2.3. Synthesis of the Metals complexes
Co(II), Mn(II), Fe(III), Ru(III), Cr(III) and VO(II) complexes were synthesized according to the general procedure: metal salts (CoCl2, MnCl2, FeCl3.6H2O, RuCl3.2H2O, CrCl3.6H2O, and VOSO4.H2O) (1 mmol) in methanol (30 mL) was added to Schiff base ligands (0.595 g, 2 mmol) in methanol. The resulting solutions were refluxed for 6 hours. The precipitations were collected and washed with methanol (Scheme 2). After the products were dried in a vacuum medium. The mass spectra are given in the supplementary file (Fig. S1-12). The analytic values of these products are shown below.
[HL1-Co]; Yield: 84% (based on Co(II)). Color: Brown. Elemental analysis data: Anal. (%) Calculated for [Co(L1)2] C38H44N2O4Co (MW: 669.73 g/mol): C, 68.15; H, 6.79; N, 4.09 Found (%): C, 68.33; H, 6.80; N, 4.20. IR (ATR, ν, cm− 1): 3458, 2961, 1620, 1583, 1456, 1365, 1324, 1269, 1202, 1176, 1100, 1058, 1028, 933, 867, 836, 800, 777, 761, 723, 504 cm− 1. Mass spec. (ESI) (m/z (rel. intensity), assignment): 635.16 (100%) {[Co (L1)2-OH]H}+, 651.16 (31.48%) {[Co (L1)2]H}+.
[HL1-Mn]; Yield: 81% (based on Mn(II)). Color: Orange. Elemental analysis data: Anal. (%) Calculated for [Mn (L1)2] C38H44N2O4Mn (MW: 647.27 g/mol): C, 70.47; H, 6.85; N, 4.33 Found (%): C, 70.61; H, 6.80; N, 4.31. IR (ATR, ν, cm− 1): 3458, 2962, 1621, 1584, 1455, 1365, 1324, 1269, 1201, 1177, 1100, 1058, 1028, 933, 868, 837, 800, 777, 761, 724, 506 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 648.13 (100%) {[Mn(L1)2]H}+, 630.29 (10.27%) {[Mn(L1)2-OH]H}+.
[HL1-Fe]; Yield: 83% (based on Fe(III)). Color: Black. Elemental analysis data: Anal. (%) Calculated for [Fe(L1)2ClH2O] C38H44N2O4FeCl.H2O (MW: 719.52 g/mol): C, 63.43; H, 6.16; N, 3.89 Found (%): C, 62.78; H, 6.03; N, 3.68. IR (ATR, ν, cm− 1): 2962, 1621, 1462, 1364, 1241, 1219, 1161, 1096, 1042, 983, 867, 799, 783, 764, 734, 615, 505 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 648.13 (100%) {[Fe(L1)2]H}+, 684.11 (13.54%) {[Fe(L1)2Cl]H}+.
[HL1-Cr]; Yield: 84% (based on Cr(III)). Color: Brown. Elemental analysis data: Anal. (%) Calculated for [Cr(L1)2ClH2O] C38H44N2O4CrCl.H2O (MW: 697.25 g/mol): C, 65.37; H, 6.64; N, 4.01 Found (%): C, 64.90; H, 6.34; N, 3.95. IR (ATR, ν, cm− 1): 2961, 1621, 1548, 1385, 1364, 1244, 1219, 1162, 1043, 867, 798, 764, 733, 644, 593, 504 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 644.09 (37.64%) {[Cr(L1)2]H}+, 680.13 (81.21%) {[Cr(L1)2Cl]H}+.
[HL1-Ru]; Yield: 96% (based on Ru(III)). Color: Black. Elemental analysis data: Anal. (%) Calculated for [Ru(L1)2ClH2O] C38H44N2O4RuCl.H2O (MW: 837.27 g/mol): C, 54.50; H, 6.74; N, 3.35 Found (%): C, 54.48; H, 6.47; N, 3.26. IR (ATR, ν, cm− 1): 2962, 1621, 1581, 1462, 1386, 1219, 1162, 1043, 866, 764, 733, 617, 506 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 729.05 (48.80%) {[Ru(L1)2 Cl]H}+, 692.18 (9.66%) {[Ru(L1)2]H}+.
[HL1-VO]; Yield: 94% (based on VO(II)). Color: Black. Elemental analysis data: Anal. (%) Calculated for [VO(L1)2] C38H44N2O4VO (MW: 767.33 g/mol): C, 59.44; H, 7.35; N, 3.65 Found (%): C, 59.22; H, 7.25; N, 3.57. IR (ATR, ν, cm− 1): 2961, 1622, 1568, 1456, 1386, 1364, 1219, 1171, 1044, 849, 736, 618, 497 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 616.05 (38.60%) {[VO(L1)2 ]H}+.
[HL2-Co]; Yield: 96% (based on Co(II)). Color: Light Green. Elemental analysis data: Anal.(%) Calculated for [Co(L2)2] C38H44N2O4Co (MW: 687.28 g/mol): C, 66.32; H, 7.04; N, 4.07 Found (%): C, 66.32; H, 7.08; N, 4.10. IR (ATR, ν, cm− 1): 3478, 2961, 1619, 1594, 1518, 1455, 1362, 1324, 1255, 1214, 1169, 1121, 1058, 977, 931, 876, 851, 795, 752, 645, 477 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 652.12 (100%) {[Co(L2)2]H}+, 635.19 (12.32%) {[Co(L2)2-OH]H}+.
[HL2-Mn]; Yield: 97% (based on Mn(II)). Color: Beige. Elemental analysis data: Anal. (%) Calculated for [Mn(L2)2] C38H44N2O4Mn (MW: 647.27 g/mol): C, 63.41; H, 7.28; N, 3.89 Found (%): C, 63.38; H, 7.20; N, 3.81. IR (ATR, ν, cm− 1): 3197, 2961, 1618, 1584, 1495, 1323, 1255, 1214, 1169, 1121, 1058, 977, 876, 839, 794, 752, 645, 478, 461 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 646.29 (11.32%) {[Mn(L1)2]H}+, 632.19 (10.68%) {[Mn(L1)2-OH]H}+.
[HL2-Fe]; Yield: 72% (based on Fe(III)). Color: Black. Elemental analysis data: Anal. (%) Calculated for [Fe(L2)2ClH2O] C38H44N2O4FeCl.H2O (MW: 774.15 g/mol): C, 58.96; H, 7.03; N, 3.62 Found (%): C, 58.85; H, 7.11; N, 3.69. IR (ATR, ν, cm− 1): 2962, 1603, 1537, 1463, 1317, 1225, 1169, 1123, 977, 851, 795, 751, 544, 484 cm-1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 684.02 (11,15%) {[Fe(L2)2Cl]H}+, 649.10 (17.94%) {[Fe(L2)2]H}+
[HL2-Cr]; Yield: 84% (based on Cr(III)). Color: Olive. Elemental analysis data: Anal. (%) Calculated for [Cr(L2)2ClH2O] C38H44N2O4CrCl.H2O (MW: 715.26 g/mol): C, 63.72; H, 6.76; N, 3.91 Found (%): C, 63.74; H, 6.72; N, 3.96. IR (ATR, ν, cm− 1): 2962, 1580, 1531, 1482, 1385, 1347, 1227, 1173, 1122, 978, 851, 795, 752, 639, 544, 484, 465 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 644.33 (9.13%) {[Cr(L1)2]H}+, 680.03 (16.28%) {[Cr(L1)2Cl]H}+.
[HL2-Ru]; Yield: 63% (based on Ru(III)). Color: Brown. Elemental analysis data: Anal. (%) Calculated for [Ru(L2)2ClH2O] C38H44N2O4RuCl.H2O (MW: 765.33g/mol): C, 59.64; H, 6.32; N, 3.66 Found (%): C, 59.73; H, 6.30; N, 3.61. IR (ATR, ν, cm− 1): 2962, 1608, 1581, 1463, 1317, 1224, 1171, 1123, 975, 850, 795, 751, 631, 485 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 727.04 (13.01%) {[Ru(L1)2 Cl]H}+, 697.14 (9.83%) {[Ru(L1)2]H}+.
[HL2-VO]; Yield: 82% (based on VO(II)). Colour: Black. Elemental analysis data: Anal. (%) Calculated for [VO(L2)2] C38H44N2O4VO (MW: 731.78 g/mol): C, 62.37; H, 7.16; N, 3.83 Found (%): C, 62.52; H, 7.14; N, 3.81. IR (ATR, ν, cm− 1): 2962, 1620, 1568, 1463, 1320, 1227, 1169, 1021, 974, 852, 794, 750, 603, 545 cm− 1. Mass spect. (ESI) (m/z (rel. intensity), assignment): 615.12 (16.70%) {[VO(L1)2 ]H}+.