Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Synthesis, Characterization and Spectral Studies of Noble Heterobinuclear Complexes of Transition Metal Ions and their Biological Activity

Synthesis, Characterization and Spectral Studies of Noble Heterobinuclear Complexes of Transition... netrapal_chem@yahoo.com Received 17 July 2010; Accepted 5 September 2010 Abstract: Some noble heterobinuclear complexes of transition metal ions with bis(salicylaldehyde)malonyl-dihydrazone in the presence of 5-nitroindazole Cu(II) / Ni(II)- chloride of the type [ML1 M`L2Cl2] or [ML1FeL2Cl2]Cl, where M = Ni(II), Cu(II) and M’= Mn(II), Co(II), have been prepared. All the complexes have been characterized by IR, UV vis and EPR spectroscopy, elemental analysis, magnetic moment and molar conductance measurement. Spectral studies and magnetic moment measurement in DMF suggest the covalent nature of the complexes, except the [ML1FeL2Cl2]Cl complex which is 1:1 electrolyte. An octahedral geometry is proposed for M` and square planer for M for the heterobinuclear complexes. The low value of magnetic moment and overlapping EPR signals are due to spin crossover since both of the metals have unpaired electrons with same molecular symmetry. The lowering of the magnetic moment has been discussed. The biological activity (antifungal and antibacterial) of the represented compounds has been studied. Keywords: Heterobinuclear complexes, Malonyldihydrazone, 5-Nitroindazole, Biological activity. Introduction Many of the divalent metal ions are widely presented in vivo as trace elements and essential for the living organism to maintain and regulate biological activities1-2. There has been a great interest in the synthesis of heterobinuclear complexes for their interesting magnetic properties3-4 and active sites of biomolecules5. Heterobinuclear bridged complexes can be formed in stepwise fashion from a mononuclear compound which contains a dangling ligand. The first spin crossover complexes were reported by Tabassum et al.6. These complexes are also of interest of bioinorganic chemistry due to the importance of the structurally similar porphyrin complexes with unsymmetrical axial ligation7-9. The aim of this work is preparation NETRA PAL SINGH et al. and characterization of heterobinuclear complexes of Fe(III),Co(II), Mn(II), Cu(II) and Ni(II). Many other works have been done earlier by various chemists which show current importance and interest of coordination chemistry of transition metal ions10-13. Experimental All the chemicals used in this work were analytical grade. Hydrated Mn(II), Co(II), Ni(II), Cu(II) and Fe(III) chloride (BDH), 5-nitroindazole (Fluka), DMSO, DMF, acetonitrile, malonyl dihydrazone, salicylaldehyde and ethanol. Double distilled water was used throughout the experiment. The transition metal complexes of 5-nitroindazole and bis(salicylaldehyde)malonyl hydrazone were prepared as per the method reported earlier14-15. Preparation of [MnL1NiL2Cl2] A solution of MnL1 (0.393 g, 1 mmol) in DMF (15 mL) was added to the solution of NiL2Cl2 (0.455 g, 1 mmol) and refluxed for 10 h and then kept in refrigerator overnight. A light pink colour product was formed which was filtered and washed with ethanol, ether and dried in vacuo. Preparation of [MnL1CuL2Cl2] This compound was prepared by using same procedure as above. Preparation of [CoL1NiL2Cl2] A solution of CoL1 (0.397 g, 1 mmol) in dry DMF (15 mL) was refluxed with a methanolic solution (15 mL) of NiL2Cl2 (0.455 g, 1 mmol). The purple colour solution of CoL1 turned blue on addition of the solution of NiL2Cl2. A light yellow coloured product was precipitated on refluxing for 8 h. The compound was filtered, washed with ethanol, ether and dried in vacuo. Preparation of [CoL1CuL2Cl2] This compound was prepared by using same procedure as above. Preparation of [NiL1FeL2Cl2]Cl A solution of NiL1 (0.397g, 1 mmol) in methanol (15 mL) was treated with a solution of [FeL2Cl2]Cl (0.488 g, 1 mmol) in dry DMF (15 mL). The resultant solution was refluxed for 20 h. A brown product precipitated. The complex was filtered, washed with ethanol, ether and dried in vacuo. Preparation of [CuL1FeL2Cl2].Cl This complex was prepared by using same procedure as above. Results and Discussion The complexes were prepared according to the following chemical equationsMnL1 + NiL2Cl2 / CuL2Cl2 CoL1 + NiL2Cl2 / CuL2Cl2 Ni/Cu-L1 + [FeL2Cl2]Cl DMF -2HCl DMF -2HCl DMF -2HCl MnL1.NiLCl2 / CuL2Cl2 CoL1.NiL2Cl2 / CuL2Cl2 [Ni / Cu-L1.Fe(III) L2Cl2]Cl Where, L1 = bis(salicylaldehyde)malonyl hydrazone, L2 = 5-nitroindazole. Synthesis, Characterization and Spectral Studies Analytical data are given in Table 1. All the complexes are soluble in DMF and DMSO. Molar conductance values are measured in DMF solvent and show non- electrolyte nature of complexes, except [NiL1FeL2Cl2]Cl and [CuL1FeL2Cl2]Cl which are 1:1 electrolyte. (Figure1.) Table 1. Analytical data of heterobinuclear complexes Complexes [MnL1NiL2Cl2] [MnL1CuL2Cl2] [CoL1NiL2Cl2] [CoL1CuL2Cl2] [NiL1FeL2Cl2]Cl [CuL1FeL2Cl2]Cl Molecular Formula (Formula weight) C31H24Cl2MnN10O8Ni (849.15) C31H24Cl2MnN10O8Cu (853.97) C31 H24Cl2CoN10O8Ni (853.14) C31H24Cl2CoN10O8Cu (857.96) C31H24Cl3FeN10O8Ni (885.60) C31H24Cl3FeN10O8Cu (890.40) Colour Light pink Pink Light Yellow Dirty Yellow Brown Reddish Brown M.P., o C 326 330 338 320 340 348 Yield, % 32 38 40 41 29 35 Calcd. found% C H N 43.85 2.85 16.50 (43.88) (2.88) (16.54) 43.60 2.83 16.40 (43.65) (2.86) (16.45) 43.63 2.84 16.42 (43.68) (2.88) (16.44) 43.40 2.82 16.33 (43.44) (2.85) (16.38) 42.04 2.73 15.82 (42.08) (2.76) (15.86) 41.81 2.72 15.73 (41.84) (2.76) (15.76) Figure 1. Heterobinuclear complexes of the type [ML1.M`L2Cl2] IR spectra of the heterobinuclear complexes The relevant IR bands and their assignments are shown in Table 2. The IR spectra of the binuclear complexes under investigation show several bands belonging to ligands L1 and L2. They are considerably changed compared with the relevant bands of the ligands and monometallic complexes16. Results given in table are consistent with the some previous results17-22. Table 2. IR Spectral data, cm-1 of the heterobinuclear complexes Complexes [MnL1NiL2Cl2] [MnL1CuL2Cl2] [CoL1NiL2Cl2] [CoL1CuL2Cl2] [NiL1FeL2Cl2]Cl [CuL1FeL2Cl2]Cl ν ν Ring (C=O) (N-H) Stretching 1722 3320 1616 1714 3324 1618 1742 3332 1612 1745 3328 1624 1718 3322 1638 1738 3337 1630 ν (NO2) (Asym/Sym) 1532/1388 1526/1382 1532/1398 1538/1388 1570/1348 1564/1352 ν Ν Ν Ν (C=N) (M-N) (M-O) (M-Cl) 1618 485 478 322 1614 474 472 318 1632 472 472 324 1626 465 468 326 1572 468 472 320 1576 475 464 324 Electronic spectra and magnetic moments Electronic spectra and magnetic moment value of heterobinuclear complexes are given in Table 3. Magnetic moment values are measured in DMF solvent and show non-electrolyte nature of complexes, except [NiL1FeL2Cl2]Cl and [CuL1FeL2Cl2]Cl which are 1:1 electrolyte. NETRA PAL SINGH et al. The electronic spectra of metal complexes were recorded in DMF solvent and contain mixed transitions due to two different metal ions. The binuclear complexes possess anti-ferromagnetic properties at room temperature by intra-molecular spin exchange interaction between M and M` metal ions. Results given in Table 3 are consistent with the heterobinuclear complexes23. Table 3. Electronic spectra, magnetic moment and EPR data of heterobinuclear complexes Complexes Transition, cm-1 (values, cm-1 M-1) 20,018(304) 18,182(264) 12,508(46) Assignments A2g 4 A2g 4 A2g µ eff (B.M.) EPR Value g|| g⊥ [MnL1NiL2Cl2] T1g(P) 4 T 1g 4 T 2g [MnL1CuL2Cl2] 38,322(58) 25,444(426) 20,410 16592(410) C.T. A1g(G) 4 T2g(G) 2 Eg(G) 4 T1g(G) A1g A1g 6 B1g 6 A1g [CoL1NiL2Cl2] 6,568(3.1) 14,418(5.4) 21,268(3.4) 16,376(2.1) 6,562(3.3) 14,416(5.2) 18,234(5.3) 15,510(6.3) 20,304(2.8) 40,466 29,116(28,414) 19,540(26,455) 15,512(24,270) 21,266(3.4) 18,784(2.4) 40,466 29,113(28,411) 15,510(24,241) 19,544(26,460) 15,508(6.04) 18,308(8.4) T2g(F) Ag(F) 2 A1g 1 A1g T1g(F) T1g(F) 1 B1g 1 B2g [CoL1CuL2Cl2] T2g(F) A2g(F) 4 T1g(P) 2 A1g 2 E1g T1g(F) T1g(F) 4 T1g(F) 1 B1g 2 B1g C.T. 6 E1g(G) A1g A1g A1g 1 B1g 1 A2g [NiL1FeL2Cl2]Cl T2g(G) T1(G) 1 A1g 1 A1g C.T. 6 A1g(G) A1g A1g A1g 2 A1g 2 Eg [CuL1FeL2Cl2]Cl T1g(G) T2(G) 1 B1g(G) 2 B1g Synthesis, Characterization and Spectral Studies EPR spectra EPR spectra value of all the metal complexes was given in Table 3. The EPR spectra of heterobinuclear complexes were recorded at room temperature. The spectra of [MnL1NiL2Cl2] show g|| = 1.91, g⊥= 1.86 which show square planer Mn(II) complexes. The signals for the two different metals are merged together and new signals are obtained. Antimicrobial activity In vitro antimicrobial activity of heterobinuclear metal complexes have been tested against the bacteria Bacillus subtilis and Escherichia coli and fungi Aspirgillus niger and Aspirgillus flavus and are summarized in Table 4. The values indicate that all complexes have higher antimicrobial activity than the free ligand. Such increased activity of the metal chelates can be explained on the basis of chelation theory. On chelation, the polarity of the metal ion will be reduced to a greater extent due to overlap of the ligand orbital and partial sharing of the positive charge of the metal ion with donor groups. Further, it increases the delocalization of π-electrons over the whole chelate ring and enhances the penetration of the complexes into lipid membranes and blocking of the metal binding sites in enzymes of microorganism. These complexes also disturb the respiration process of the cell and thus block the synthesis of proteins, which restricts further growth of microorganism24. Table 4. Antibacterial and antifungal activity of heterobinuclear metal complexes Compounds [MnL1.NiL2Cl2] [MnL1.CuL2Cl2] [CoL1.NiL2Cl2] [CoL1.CuL2Cl2] [NiL1.FeL2Cl2].Cl [CuL1.FeL2Cl2].Cl *Conc., µg moL -1 Bacterial Inhibition, % B. subtilis 42 46 44 55 50 58 44 62 44 50 47 56 E. coli 55 60 48 52 70 78 58 70 60 62 58 64 Antifungal Inhibition, % A. niger 66 72 74 86 73 82 65 74 71 78 61 83 A.flavus 59 72 68 81 76 85 72 81 73 76 76 82 Acknowledgment The authors are thankful to ACBR, Delhi for providing spectral data and SAIF, CDRI, Lucknow for providing elemental analysis data. Authors are also thankful to SARC, Meerut for providing antimicrobial activity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png E-Journal of Chemistry Hindawi Publishing Corporation

Synthesis, Characterization and Spectral Studies of Noble Heterobinuclear Complexes of Transition Metal Ions and their Biological Activity

E-Journal of Chemistry , Volume 8 (2) – Jan 1, 1900
Download PDF
6 pages

Loading next page...
 
/lp/hindawi-publishing-corporation/synthesis-characterization-and-spectral-studies-of-noble-trT6cB0XQp

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Hindawi Publishing Corporation
Copyright
Copyright © 2011 Hindawi Publishing Corporation.
ISSN
0973-4945
eISSN
2090-9810
Publisher site
See Article on Publisher Site

Abstract

netrapal_chem@yahoo.com Received 17 July 2010; Accepted 5 September 2010 Abstract: Some noble heterobinuclear complexes of transition metal ions with bis(salicylaldehyde)malonyl-dihydrazone in the presence of 5-nitroindazole Cu(II) / Ni(II)- chloride of the type [ML1 M`L2Cl2] or [ML1FeL2Cl2]Cl, where M = Ni(II), Cu(II) and M’= Mn(II), Co(II), have been prepared. All the complexes have been characterized by IR, UV vis and EPR spectroscopy, elemental analysis, magnetic moment and molar conductance measurement. Spectral studies and magnetic moment measurement in DMF suggest the covalent nature of the complexes, except the [ML1FeL2Cl2]Cl complex which is 1:1 electrolyte. An octahedral geometry is proposed for M` and square planer for M for the heterobinuclear complexes. The low value of magnetic moment and overlapping EPR signals are due to spin crossover since both of the metals have unpaired electrons with same molecular symmetry. The lowering of the magnetic moment has been discussed. The biological activity (antifungal and antibacterial) of the represented compounds has been studied. Keywords: Heterobinuclear complexes, Malonyldihydrazone, 5-Nitroindazole, Biological activity. Introduction Many of the divalent metal ions are widely presented in vivo as trace elements and essential for the living organism to maintain and regulate biological activities1-2. There has been a great interest in the synthesis of heterobinuclear complexes for their interesting magnetic properties3-4 and active sites of biomolecules5. Heterobinuclear bridged complexes can be formed in stepwise fashion from a mononuclear compound which contains a dangling ligand. The first spin crossover complexes were reported by Tabassum et al.6. These complexes are also of interest of bioinorganic chemistry due to the importance of the structurally similar porphyrin complexes with unsymmetrical axial ligation7-9. The aim of this work is preparation NETRA PAL SINGH et al. and characterization of heterobinuclear complexes of Fe(III),Co(II), Mn(II), Cu(II) and Ni(II). Many other works have been done earlier by various chemists which show current importance and interest of coordination chemistry of transition metal ions10-13. Experimental All the chemicals used in this work were analytical grade. Hydrated Mn(II), Co(II), Ni(II), Cu(II) and Fe(III) chloride (BDH), 5-nitroindazole (Fluka), DMSO, DMF, acetonitrile, malonyl dihydrazone, salicylaldehyde and ethanol. Double distilled water was used throughout the experiment. The transition metal complexes of 5-nitroindazole and bis(salicylaldehyde)malonyl hydrazone were prepared as per the method reported earlier14-15. Preparation of [MnL1NiL2Cl2] A solution of MnL1 (0.393 g, 1 mmol) in DMF (15 mL) was added to the solution of NiL2Cl2 (0.455 g, 1 mmol) and refluxed for 10 h and then kept in refrigerator overnight. A light pink colour product was formed which was filtered and washed with ethanol, ether and dried in vacuo. Preparation of [MnL1CuL2Cl2] This compound was prepared by using same procedure as above. Preparation of [CoL1NiL2Cl2] A solution of CoL1 (0.397 g, 1 mmol) in dry DMF (15 mL) was refluxed with a methanolic solution (15 mL) of NiL2Cl2 (0.455 g, 1 mmol). The purple colour solution of CoL1 turned blue on addition of the solution of NiL2Cl2. A light yellow coloured product was precipitated on refluxing for 8 h. The compound was filtered, washed with ethanol, ether and dried in vacuo. Preparation of [CoL1CuL2Cl2] This compound was prepared by using same procedure as above. Preparation of [NiL1FeL2Cl2]Cl A solution of NiL1 (0.397g, 1 mmol) in methanol (15 mL) was treated with a solution of [FeL2Cl2]Cl (0.488 g, 1 mmol) in dry DMF (15 mL). The resultant solution was refluxed for 20 h. A brown product precipitated. The complex was filtered, washed with ethanol, ether and dried in vacuo. Preparation of [CuL1FeL2Cl2].Cl This complex was prepared by using same procedure as above. Results and Discussion The complexes were prepared according to the following chemical equationsMnL1 + NiL2Cl2 / CuL2Cl2 CoL1 + NiL2Cl2 / CuL2Cl2 Ni/Cu-L1 + [FeL2Cl2]Cl DMF -2HCl DMF -2HCl DMF -2HCl MnL1.NiLCl2 / CuL2Cl2 CoL1.NiL2Cl2 / CuL2Cl2 [Ni / Cu-L1.Fe(III) L2Cl2]Cl Where, L1 = bis(salicylaldehyde)malonyl hydrazone, L2 = 5-nitroindazole. Synthesis, Characterization and Spectral Studies Analytical data are given in Table 1. All the complexes are soluble in DMF and DMSO. Molar conductance values are measured in DMF solvent and show non- electrolyte nature of complexes, except [NiL1FeL2Cl2]Cl and [CuL1FeL2Cl2]Cl which are 1:1 electrolyte. (Figure1.) Table 1. Analytical data of heterobinuclear complexes Complexes [MnL1NiL2Cl2] [MnL1CuL2Cl2] [CoL1NiL2Cl2] [CoL1CuL2Cl2] [NiL1FeL2Cl2]Cl [CuL1FeL2Cl2]Cl Molecular Formula (Formula weight) C31H24Cl2MnN10O8Ni (849.15) C31H24Cl2MnN10O8Cu (853.97) C31 H24Cl2CoN10O8Ni (853.14) C31H24Cl2CoN10O8Cu (857.96) C31H24Cl3FeN10O8Ni (885.60) C31H24Cl3FeN10O8Cu (890.40) Colour Light pink Pink Light Yellow Dirty Yellow Brown Reddish Brown M.P., o C 326 330 338 320 340 348 Yield, % 32 38 40 41 29 35 Calcd. found% C H N 43.85 2.85 16.50 (43.88) (2.88) (16.54) 43.60 2.83 16.40 (43.65) (2.86) (16.45) 43.63 2.84 16.42 (43.68) (2.88) (16.44) 43.40 2.82 16.33 (43.44) (2.85) (16.38) 42.04 2.73 15.82 (42.08) (2.76) (15.86) 41.81 2.72 15.73 (41.84) (2.76) (15.76) Figure 1. Heterobinuclear complexes of the type [ML1.M`L2Cl2] IR spectra of the heterobinuclear complexes The relevant IR bands and their assignments are shown in Table 2. The IR spectra of the binuclear complexes under investigation show several bands belonging to ligands L1 and L2. They are considerably changed compared with the relevant bands of the ligands and monometallic complexes16. Results given in table are consistent with the some previous results17-22. Table 2. IR Spectral data, cm-1 of the heterobinuclear complexes Complexes [MnL1NiL2Cl2] [MnL1CuL2Cl2] [CoL1NiL2Cl2] [CoL1CuL2Cl2] [NiL1FeL2Cl2]Cl [CuL1FeL2Cl2]Cl ν ν Ring (C=O) (N-H) Stretching 1722 3320 1616 1714 3324 1618 1742 3332 1612 1745 3328 1624 1718 3322 1638 1738 3337 1630 ν (NO2) (Asym/Sym) 1532/1388 1526/1382 1532/1398 1538/1388 1570/1348 1564/1352 ν Ν Ν Ν (C=N) (M-N) (M-O) (M-Cl) 1618 485 478 322 1614 474 472 318 1632 472 472 324 1626 465 468 326 1572 468 472 320 1576 475 464 324 Electronic spectra and magnetic moments Electronic spectra and magnetic moment value of heterobinuclear complexes are given in Table 3. Magnetic moment values are measured in DMF solvent and show non-electrolyte nature of complexes, except [NiL1FeL2Cl2]Cl and [CuL1FeL2Cl2]Cl which are 1:1 electrolyte. NETRA PAL SINGH et al. The electronic spectra of metal complexes were recorded in DMF solvent and contain mixed transitions due to two different metal ions. The binuclear complexes possess anti-ferromagnetic properties at room temperature by intra-molecular spin exchange interaction between M and M` metal ions. Results given in Table 3 are consistent with the heterobinuclear complexes23. Table 3. Electronic spectra, magnetic moment and EPR data of heterobinuclear complexes Complexes Transition, cm-1 (values, cm-1 M-1) 20,018(304) 18,182(264) 12,508(46) Assignments A2g 4 A2g 4 A2g µ eff (B.M.) EPR Value g|| g⊥ [MnL1NiL2Cl2] T1g(P) 4 T 1g 4 T 2g [MnL1CuL2Cl2] 38,322(58) 25,444(426) 20,410 16592(410) C.T. A1g(G) 4 T2g(G) 2 Eg(G) 4 T1g(G) A1g A1g 6 B1g 6 A1g [CoL1NiL2Cl2] 6,568(3.1) 14,418(5.4) 21,268(3.4) 16,376(2.1) 6,562(3.3) 14,416(5.2) 18,234(5.3) 15,510(6.3) 20,304(2.8) 40,466 29,116(28,414) 19,540(26,455) 15,512(24,270) 21,266(3.4) 18,784(2.4) 40,466 29,113(28,411) 15,510(24,241) 19,544(26,460) 15,508(6.04) 18,308(8.4) T2g(F) Ag(F) 2 A1g 1 A1g T1g(F) T1g(F) 1 B1g 1 B2g [CoL1CuL2Cl2] T2g(F) A2g(F) 4 T1g(P) 2 A1g 2 E1g T1g(F) T1g(F) 4 T1g(F) 1 B1g 2 B1g C.T. 6 E1g(G) A1g A1g A1g 1 B1g 1 A2g [NiL1FeL2Cl2]Cl T2g(G) T1(G) 1 A1g 1 A1g C.T. 6 A1g(G) A1g A1g A1g 2 A1g 2 Eg [CuL1FeL2Cl2]Cl T1g(G) T2(G) 1 B1g(G) 2 B1g Synthesis, Characterization and Spectral Studies EPR spectra EPR spectra value of all the metal complexes was given in Table 3. The EPR spectra of heterobinuclear complexes were recorded at room temperature. The spectra of [MnL1NiL2Cl2] show g|| = 1.91, g⊥= 1.86 which show square planer Mn(II) complexes. The signals for the two different metals are merged together and new signals are obtained. Antimicrobial activity In vitro antimicrobial activity of heterobinuclear metal complexes have been tested against the bacteria Bacillus subtilis and Escherichia coli and fungi Aspirgillus niger and Aspirgillus flavus and are summarized in Table 4. The values indicate that all complexes have higher antimicrobial activity than the free ligand. Such increased activity of the metal chelates can be explained on the basis of chelation theory. On chelation, the polarity of the metal ion will be reduced to a greater extent due to overlap of the ligand orbital and partial sharing of the positive charge of the metal ion with donor groups. Further, it increases the delocalization of π-electrons over the whole chelate ring and enhances the penetration of the complexes into lipid membranes and blocking of the metal binding sites in enzymes of microorganism. These complexes also disturb the respiration process of the cell and thus block the synthesis of proteins, which restricts further growth of microorganism24. Table 4. Antibacterial and antifungal activity of heterobinuclear metal complexes Compounds [MnL1.NiL2Cl2] [MnL1.CuL2Cl2] [CoL1.NiL2Cl2] [CoL1.CuL2Cl2] [NiL1.FeL2Cl2].Cl [CuL1.FeL2Cl2].Cl *Conc., µg moL -1 Bacterial Inhibition, % B. subtilis 42 46 44 55 50 58 44 62 44 50 47 56 E. coli 55 60 48 52 70 78 58 70 60 62 58 64 Antifungal Inhibition, % A. niger 66 72 74 86 73 82 65 74 71 78 61 83 A.flavus 59 72 68 81 76 85 72 81 73 76 76 82 Acknowledgment The authors are thankful to ACBR, Delhi for providing spectral data and SAIF, CDRI, Lucknow for providing elemental analysis data. Authors are also thankful to SARC, Meerut for providing antimicrobial activity.

Journal

E-Journal of Chemistry – Hindawi Publishing Corporation

Published: Jan 1, 1900

There are no references for this article.