A. Kalilur Rahiman | The New College (Autonomous), Chennai-14, India. (original) (raw)
Papers by A. Kalilur Rahiman
Journal of Molecular Structure, 2015
Abstract A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL 1–4 (diimine... more Abstract A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL 1–4 (diimine)] ( 1 – 8 ), where L 1–4 = N 1 ,N 2 -bis(5-substituted-2-hydroxybenzylidene)-1,2-ethylene/phenylenediimine and diimine = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen), have been isolated and fully characterized by analytical and spectral techniques. Electronic spectra of complexes suggest Cu(II) cation has a d 9 electronic configuration, adopting distorted octahedral geometry with axial elongation, due to Jahn–Teller effect. Electrochemical studies of complexes evidenced one-electron irreversible reduction wave in the cathodic region. The observed rate constant ( k ) values for the hydrolysis of 4-nitrophenylphosphate (4-NPP) are in the range of 0.25–3.82 × 10 −2 min −1 . The obtained room temperature magnetic moment values (1.79–1.90 BM) lies within the range observed for octahedral copper(II) complexes. Antioxidant studies revealed that these complexes possess considerable radical scavenging potency against DPPH. The binding studies of complexes with calf thymus DNA (CT-DNA) revealed intercalation with minor-groove binding, and the complex 4 exhibits highest binding activity than the other complexes. The cleavage activity on supercoiled pBR322 DNA revealed the involvement of hydroxyl radical and singlet-oxygen as reactive oxygen species, and complexes encourage binding to minor-groove. Further, the cytotoxicity of complex 4 on human hepatocellular liver carcinoma HepG2 cell line implies the cell death through apoptosis.
Medicinal Chemistry Research, 2014
Journal of Photochemistry and Photobiology B: Biology, 2016
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Eight heteroleptic copper(II) complexes have been synthesized and characterized. All the complexe... more Eight heteroleptic copper(II) complexes have been synthesized and characterized. All the complexes were screened for their antioxidant activity. Binding studies with CT-DNA suggest the minor-groove/electrostatic mode of binding. The synthesized heteroleptic complexes cleave supercoiled plasmid DNA. The methyl substituted complexes show enhanced biological activity. g r a p h i c a l a b s t r a c t A series of heteroleptic copper(II) complexes have been synthesized and characterized. The structure of all the complexes has been assigned to be square-pyramidal. The antioxidant potency was evaluated against DPPH radical. The complex-DNA interaction was studied by electronic, viscometric, voltammetric and electrophoresis techniques. The methyl substituted complexes show higher biological activity than others due to its hydrophobic nature.
RSC Adv., 2014
A new class of chloro-bridged dinuclear nickel(II) and copper(II) phenolate complexes (1-8) were ... more A new class of chloro-bridged dinuclear nickel(II) and copper(II) phenolate complexes (1-8) were synthesized from 4-substituted-2-((2-(piperazin-1-yl)ethylimino)methyl)phenols (L 1À4 ) and characterized.
Journal of Coordination Chemistry, 2010
Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicy... more Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicylaldehyde/5-methylsalicylaldehyde and ethylenediamine or diaminomaleonitrile (DMN) were synthesized. The ligands and their complexes were characterized by elemental analysis, H NMR, FT IR, and mass spectroscopy. The electronic spectra of the complexes show d–d transitions in the region at 450–600 nm. Electrochemical studies of the complexes reveal that all
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
A series of dinuclear nickel(II) and copper(II) complexes (1-6) of hexaaza macrocycles of 2,6-dif... more A series of dinuclear nickel(II) and copper(II) complexes (1-6) of hexaaza macrocycles of 2,6-diformyl-4-methylphenol with three different benzoyl pendant-arms, 2,2'-benzoyliminodi(ethylamine) trihydrochloride (L), 2,2'-4-nitrobenzoyliminodi(ethylamine) trihydrochloride (L') and 2,2'-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride (L″) have been synthesized and characterized by spectral methods. The electrochemical studies of these complexes depict two irreversible one electron reduction processes around E(1)pc=-0.62 to -0.76 V and E(2)pc=-1.21 to -1.31, and nickel(II) complexes (1-3) exhibit two irreversible one electron oxidation processes around E(1)pa=1.08 to 1.14 V and E(2)pa=1.71 to 1.74 V. The room temperature magnetic moment values (μeff, 1.52-1.54 BM) indicate the presence of an antiferromagnetic interaction in the binuclear copper(II) complexes (4-6) which is also observed from the broad ESR spectra with a g value of 2.14-2.15. The synthesized complexes (1-6) were screened for their antibacterial activity. The results of DNA interaction studies indicate that the dinuclear complexes can bind to calf thymus DNA by intercalative mode and display efficient cleavage of plasmid DNA. Further, the cytotoxic activity of complexes 2, 5 and 6 on human liver adenocarcinoma (HepG2) cell line has been examined. Nuclear-chromatin cleavage has also been observed with PI staining and comet assays.
Journal of Molecular Structure, 2014
and sharing with colleagues.
Journal of Coordination Chemistry, 2014
Three dinuclear cobalt(II), nickel(II), and copper(II) complexes (1-3) of a phenol-based 'end-off... more Three dinuclear cobalt(II), nickel(II), and copper(II) complexes (1-3) of a phenol-based 'end-off' compartmental ligand, 2,6-bis[1-(N-ethyl)piperazineiminomethyl]-4-methylphenol (HL), have been synthesized and characterized by spectral analysis. The molecular structure of one of these complexes, 2,6-bis [1-(N-ethyl)
Journal of inclusion phenomena and macrocyclic chemistry
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
A new class of phenol based unsymmetrical side-off tetra and hexa coordinate homobinuclear Cu(II)... more A new class of phenol based unsymmetrical side-off tetra and hexa coordinate homobinuclear Cu(II) and heterobinuclear Cu(II)-Zn(II) complexes have been synthesized and characterized by elemental and spectral analysis. The electronic spectra of all the complexes show "Red shift" in LMCT band, for the ligand H(2)L(2) compared to that of the ligand H(2)L(1) due to the relatively higher electron donating nature of their substitutents. The homobinuclear Cu(II) complexes (1 and 2) illustrate an antiferromagnetic interaction (μ(eff): 1.58 and 1.60BM) at 298K with a broad EPR signal. Variable temperature magnetic moment study of the binuclear copper (II) complexes shows that the extent of antiferromagnetic coupling is greater in the case of H(2)L(2) complexes than H(2)L(1) complexes (-2J values: 192cm(-1) and 184cm(-1) respectively). The heterobinuclear Cu(II)-Zn(II) complexes (3 and 4) have a magnetic moment value close to the spin only value with four hyperfine EPR signals. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an "anodic shift" in the first reduction potential of the complexes, of the ligand H(2)L(1) when compared to that of the ligand H(2)L(2) due to the presence of relatively higher electron donating N-substituents in the later case than in the former case. The catecholase activity of the complexes reveals that the homobinuclear Cu(II) complexes show higher catalytic activity than the corresponding heterobinuclear Cu(II)-Zn(II) complexes. In the hydrolysis of 4-nitrophenylphosphate, the heterobinuclear Cu(II)-Zn(II) complexes show better catalytic activity than the corresponding homobinuclear Cu(II) complexes.
Polyhedron, 2011
New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,... more New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L1), 1,8-[N,N-bis(3-formyl-12-hydroxy-5-bromo)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L2), N,N-bis[1,8-dibenzoyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L3), N,N-bis[1,8-(2-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L4), and N,N-bis[1,8-(4-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L5) were synthesized. The ligands were characterized by elemental analysis, FT IR, 1H NMR and mass spectrometry studies. The crystal structure of L1 is also reported. The copper(II) and nickel(II) complexes of these ligands were prepared and characterized by elemental analysis, FT IR, UV–Vis and mass
Transition Metal Chemistry, 2009
... Shanmugam Sreedaran Æ Kuppannan Shanmuga Bharathi Æ Aziz Kalilur Rahiman Æ Raju Prabu Æ Raman... more ... Shanmugam Sreedaran Æ Kuppannan Shanmuga Bharathi Æ Aziz Kalilur Rahiman Æ Raju Prabu Æ Raman Jagadesh Æ Nanjian Raaman Æ Vengidusamy Narayanan ... One or two peaks in the range of 250320 nm are assigned to intra ligand transitions (pp*). ...
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 2012
The catalytic activities of the iron(III) porphyrin encapsulated in mesoporous Al/Ti/V-MCM-41 cat... more The catalytic activities of the iron(III) porphyrin encapsulated in mesoporous Al/Ti/V-MCM-41 catalysts were tested in the epoxidation of styrene. The results obtained shows that the yield of epoxide formed depends not only on the nature of support materials but also on the combined effects of catalyst and the supports. The yield of epoxide formed were higher for iron(III) porphyrin encapsulated
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013
A series of new phenol based coordination asymmetric side-off homobinuclear Ni(II) and heterobinu... more A series of new phenol based coordination asymmetric side-off homobinuclear Ni(II) and heterobinuclear Ni(II)Zn(II) complexes have been synthesized and characterized by elemental analysis and spectral analysis. The electronic spectra of all the complexes show "Red shift" in LMCT band, for the ligand H(2)L(2) having electron donating C(2)H(5) groups as N-substituents in the free side arms compared to ligand H(2)L(1) having relatively lower electron donating CH(3) groups. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an "anodic shift" in the first reduction potential of the complexes of the ligand H(2)L(1) when compared to that of the complexes of the ligand H(2)L(2) due to the presence of higher electron donating C(2)H(5) N-substituents in the later case than the relatively lower electron donating N-substituents in the former case. Hydrolysis of p-nitrophenylphosphate using homobinuclear Ni(II) and heterobinuclear Ni(II)-Zn(II) complexes as catalysts showed that the homobinuclear complexes have higher rate constant values than that of the corresponding heterobinuclear complexes. A comparison of the spectral, electrochemical and catalytic behavior of the complexes of the ligands is discussed on the basis of the electron donating nature of the N-substituents at the free side arms.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of ... more The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclo-tetradecane (PC) with appropriate aliphatic diamines and nickel(II) perchlorate. All the five complexes were characterized by elemental and spectral analysis. The electronic spectra of the complexes show three d-d transition in the range of 550-1055 nm due to 3 A 2g → 3 T 2g (F), 3 A 2g → 3 T 1g (F) and 3 A 2g → 3 T 1g (P). These spin allowed electronic transitions are characteristic of an octahedral Ni 2+ center. Electrochemical studies of the complexes show two irreversible one electron reduction waves at cathodic region. The reduction potential of the complexes shifts towards anodically upon increasing the chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible one electron oxidation waves at anodic region. The oxidation potential of the complexes shift towards anodically upon increasing the chain length of the macrocyclic ring. The catalytic activities of the complexes were observed to be increase with increase the macrocyclic ring size. The observed rate constant values for the catalytic hydrolysis of 4-nitrophenyl phosphate are in the range of 5.85 × 10 −3 to 9.14 × 10 −3 min −1 . All the complexes were screened for antimicrobial activity.
Journal of Molecular Structure, 2015
Abstract A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL 1–4 (diimine... more Abstract A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL 1–4 (diimine)] ( 1 – 8 ), where L 1–4 = N 1 ,N 2 -bis(5-substituted-2-hydroxybenzylidene)-1,2-ethylene/phenylenediimine and diimine = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen), have been isolated and fully characterized by analytical and spectral techniques. Electronic spectra of complexes suggest Cu(II) cation has a d 9 electronic configuration, adopting distorted octahedral geometry with axial elongation, due to Jahn–Teller effect. Electrochemical studies of complexes evidenced one-electron irreversible reduction wave in the cathodic region. The observed rate constant ( k ) values for the hydrolysis of 4-nitrophenylphosphate (4-NPP) are in the range of 0.25–3.82 × 10 −2 min −1 . The obtained room temperature magnetic moment values (1.79–1.90 BM) lies within the range observed for octahedral copper(II) complexes. Antioxidant studies revealed that these complexes possess considerable radical scavenging potency against DPPH. The binding studies of complexes with calf thymus DNA (CT-DNA) revealed intercalation with minor-groove binding, and the complex 4 exhibits highest binding activity than the other complexes. The cleavage activity on supercoiled pBR322 DNA revealed the involvement of hydroxyl radical and singlet-oxygen as reactive oxygen species, and complexes encourage binding to minor-groove. Further, the cytotoxicity of complex 4 on human hepatocellular liver carcinoma HepG2 cell line implies the cell death through apoptosis.
Medicinal Chemistry Research, 2014
Journal of Photochemistry and Photobiology B: Biology, 2016
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Eight heteroleptic copper(II) complexes have been synthesized and characterized. All the complexe... more Eight heteroleptic copper(II) complexes have been synthesized and characterized. All the complexes were screened for their antioxidant activity. Binding studies with CT-DNA suggest the minor-groove/electrostatic mode of binding. The synthesized heteroleptic complexes cleave supercoiled plasmid DNA. The methyl substituted complexes show enhanced biological activity. g r a p h i c a l a b s t r a c t A series of heteroleptic copper(II) complexes have been synthesized and characterized. The structure of all the complexes has been assigned to be square-pyramidal. The antioxidant potency was evaluated against DPPH radical. The complex-DNA interaction was studied by electronic, viscometric, voltammetric and electrophoresis techniques. The methyl substituted complexes show higher biological activity than others due to its hydrophobic nature.
RSC Adv., 2014
A new class of chloro-bridged dinuclear nickel(II) and copper(II) phenolate complexes (1-8) were ... more A new class of chloro-bridged dinuclear nickel(II) and copper(II) phenolate complexes (1-8) were synthesized from 4-substituted-2-((2-(piperazin-1-yl)ethylimino)methyl)phenols (L 1À4 ) and characterized.
Journal of Coordination Chemistry, 2010
Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicy... more Ni(II) and Cu(II) metal complexes of simple unsymmetrical Schiff-base ligands derived from salicylaldehyde/5-methylsalicylaldehyde and ethylenediamine or diaminomaleonitrile (DMN) were synthesized. The ligands and their complexes were characterized by elemental analysis, H NMR, FT IR, and mass spectroscopy. The electronic spectra of the complexes show d–d transitions in the region at 450–600 nm. Electrochemical studies of the complexes reveal that all
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
A series of dinuclear nickel(II) and copper(II) complexes (1-6) of hexaaza macrocycles of 2,6-dif... more A series of dinuclear nickel(II) and copper(II) complexes (1-6) of hexaaza macrocycles of 2,6-diformyl-4-methylphenol with three different benzoyl pendant-arms, 2,2'-benzoyliminodi(ethylamine) trihydrochloride (L), 2,2'-4-nitrobenzoyliminodi(ethylamine) trihydrochloride (L') and 2,2'-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride (L″) have been synthesized and characterized by spectral methods. The electrochemical studies of these complexes depict two irreversible one electron reduction processes around E(1)pc=-0.62 to -0.76 V and E(2)pc=-1.21 to -1.31, and nickel(II) complexes (1-3) exhibit two irreversible one electron oxidation processes around E(1)pa=1.08 to 1.14 V and E(2)pa=1.71 to 1.74 V. The room temperature magnetic moment values (μeff, 1.52-1.54 BM) indicate the presence of an antiferromagnetic interaction in the binuclear copper(II) complexes (4-6) which is also observed from the broad ESR spectra with a g value of 2.14-2.15. The synthesized complexes (1-6) were screened for their antibacterial activity. The results of DNA interaction studies indicate that the dinuclear complexes can bind to calf thymus DNA by intercalative mode and display efficient cleavage of plasmid DNA. Further, the cytotoxic activity of complexes 2, 5 and 6 on human liver adenocarcinoma (HepG2) cell line has been examined. Nuclear-chromatin cleavage has also been observed with PI staining and comet assays.
Journal of Molecular Structure, 2014
and sharing with colleagues.
Journal of Coordination Chemistry, 2014
Three dinuclear cobalt(II), nickel(II), and copper(II) complexes (1-3) of a phenol-based 'end-off... more Three dinuclear cobalt(II), nickel(II), and copper(II) complexes (1-3) of a phenol-based 'end-off' compartmental ligand, 2,6-bis[1-(N-ethyl)piperazineiminomethyl]-4-methylphenol (HL), have been synthesized and characterized by spectral analysis. The molecular structure of one of these complexes, 2,6-bis [1-(N-ethyl)
Journal of inclusion phenomena and macrocyclic chemistry
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012
A new class of phenol based unsymmetrical side-off tetra and hexa coordinate homobinuclear Cu(II)... more A new class of phenol based unsymmetrical side-off tetra and hexa coordinate homobinuclear Cu(II) and heterobinuclear Cu(II)-Zn(II) complexes have been synthesized and characterized by elemental and spectral analysis. The electronic spectra of all the complexes show "Red shift" in LMCT band, for the ligand H(2)L(2) compared to that of the ligand H(2)L(1) due to the relatively higher electron donating nature of their substitutents. The homobinuclear Cu(II) complexes (1 and 2) illustrate an antiferromagnetic interaction (μ(eff): 1.58 and 1.60BM) at 298K with a broad EPR signal. Variable temperature magnetic moment study of the binuclear copper (II) complexes shows that the extent of antiferromagnetic coupling is greater in the case of H(2)L(2) complexes than H(2)L(1) complexes (-2J values: 192cm(-1) and 184cm(-1) respectively). The heterobinuclear Cu(II)-Zn(II) complexes (3 and 4) have a magnetic moment value close to the spin only value with four hyperfine EPR signals. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an "anodic shift" in the first reduction potential of the complexes, of the ligand H(2)L(1) when compared to that of the ligand H(2)L(2) due to the presence of relatively higher electron donating N-substituents in the later case than in the former case. The catecholase activity of the complexes reveals that the homobinuclear Cu(II) complexes show higher catalytic activity than the corresponding heterobinuclear Cu(II)-Zn(II) complexes. In the hydrolysis of 4-nitrophenylphosphate, the heterobinuclear Cu(II)-Zn(II) complexes show better catalytic activity than the corresponding homobinuclear Cu(II) complexes.
Polyhedron, 2011
New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,... more New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L1), 1,8-[N,N-bis(3-formyl-12-hydroxy-5-bromo)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L2), N,N-bis[1,8-dibenzoyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L3), N,N-bis[1,8-(2-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L4), and N,N-bis[1,8-(4-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L5) were synthesized. The ligands were characterized by elemental analysis, FT IR, 1H NMR and mass spectrometry studies. The crystal structure of L1 is also reported. The copper(II) and nickel(II) complexes of these ligands were prepared and characterized by elemental analysis, FT IR, UV–Vis and mass
Transition Metal Chemistry, 2009
... Shanmugam Sreedaran Æ Kuppannan Shanmuga Bharathi Æ Aziz Kalilur Rahiman Æ Raju Prabu Æ Raman... more ... Shanmugam Sreedaran Æ Kuppannan Shanmuga Bharathi Æ Aziz Kalilur Rahiman Æ Raju Prabu Æ Raman Jagadesh Æ Nanjian Raaman Æ Vengidusamy Narayanan ... One or two peaks in the range of 250320 nm are assigned to intra ligand transitions (pp*). ...
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 2012
The catalytic activities of the iron(III) porphyrin encapsulated in mesoporous Al/Ti/V-MCM-41 cat... more The catalytic activities of the iron(III) porphyrin encapsulated in mesoporous Al/Ti/V-MCM-41 catalysts were tested in the epoxidation of styrene. The results obtained shows that the yield of epoxide formed depends not only on the nature of support materials but also on the combined effects of catalyst and the supports. The yield of epoxide formed were higher for iron(III) porphyrin encapsulated
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013
A series of new phenol based coordination asymmetric side-off homobinuclear Ni(II) and heterobinu... more A series of new phenol based coordination asymmetric side-off homobinuclear Ni(II) and heterobinuclear Ni(II)Zn(II) complexes have been synthesized and characterized by elemental analysis and spectral analysis. The electronic spectra of all the complexes show "Red shift" in LMCT band, for the ligand H(2)L(2) having electron donating C(2)H(5) groups as N-substituents in the free side arms compared to ligand H(2)L(1) having relatively lower electron donating CH(3) groups. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an "anodic shift" in the first reduction potential of the complexes of the ligand H(2)L(1) when compared to that of the complexes of the ligand H(2)L(2) due to the presence of higher electron donating C(2)H(5) N-substituents in the later case than the relatively lower electron donating N-substituents in the former case. Hydrolysis of p-nitrophenylphosphate using homobinuclear Ni(II) and heterobinuclear Ni(II)-Zn(II) complexes as catalysts showed that the homobinuclear complexes have higher rate constant values than that of the corresponding heterobinuclear complexes. A comparison of the spectral, electrochemical and catalytic behavior of the complexes of the ligands is discussed on the basis of the electron donating nature of the N-substituents at the free side arms.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of ... more The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclo-tetradecane (PC) with appropriate aliphatic diamines and nickel(II) perchlorate. All the five complexes were characterized by elemental and spectral analysis. The electronic spectra of the complexes show three d-d transition in the range of 550-1055 nm due to 3 A 2g → 3 T 2g (F), 3 A 2g → 3 T 1g (F) and 3 A 2g → 3 T 1g (P). These spin allowed electronic transitions are characteristic of an octahedral Ni 2+ center. Electrochemical studies of the complexes show two irreversible one electron reduction waves at cathodic region. The reduction potential of the complexes shifts towards anodically upon increasing the chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible one electron oxidation waves at anodic region. The oxidation potential of the complexes shift towards anodically upon increasing the chain length of the macrocyclic ring. The catalytic activities of the complexes were observed to be increase with increase the macrocyclic ring size. The observed rate constant values for the catalytic hydrolysis of 4-nitrophenyl phosphate are in the range of 5.85 × 10 −3 to 9.14 × 10 −3 min −1 . All the complexes were screened for antimicrobial activity.