Merry Mitra

Nuclease activity and anti-proliferative effect on human cancerous cells of a newly synthesized and characterized mononuclear copper(II) complex [CuII(L)(fu)2] [L = 2-(2-pyridyl)benzimidazole, fu = furoate]

A mononuclear copper(II) complex [CuII(L)(fu)2] (1) [L = 2-(2-pyridyl)benzimidazole, fu = furoate] has been synthesized and characterized by X-ray crystallography. Structural analysis reveals that 1 adopts a distorted square pyramidal geometry with CuN2O3 chromophore. Spectrophotometric and hydrodynamic investigations suggest that the complex binds with DNA in an intercalative mode with a binding constant of (3.19 ± 0.32) × 104 M−1. 1 induces oxidative cleavage of the supercoiled DNA to its nicked circular as well as linear forms. 1 is also proved to be an anti-cancer agent on human keratinocyte cells.

A mononuclear cobalt(III) complex and its catecholase activity

The structural analysis of a cobalt(III) complex [Co(HL)2](OAc)·H2O (1) [H2L = N-(2-hydroxyethyl)-3-methoxysalicylaldimine] reveals a tridentate chelation behaviour of the ligand H2L having a distorted octahedral coordination environment around the cobalt(III) center with a CoN2O4 chromophore. 1 behaves as an effective catalyst towards the oxidation of 3,5-di-tert-butylcatechol in different solvents, viz. dichloromethane (DCM), methanol (MeOH) and acetonitrile (MeCN) to its corresponding quinone derivative in aerial oxygen. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (Kcat), 1.46 × 103, 1.21 × 103 and 2.16 × 103 h−1 in DCM, MeOH and MeCN, respectively.

Synthesis, crystal structure and catecholase activity of a Ni(II) complex derived from a tetradentate Schiff base ligand

AbstractA new nickel(II) complex [Ni(L)] (1) [H2L = 1,1′-(1E,1′E)-(propane-1,3-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol] was synthesized and X-ray crystallographically characterized. 1 crystallizes in orthorhombic crystal system with Cmc21 space group. The unit cell dimensions of the crystal are a = 30.6345(4) Å, b = 8.45340(10) Å, c = 7.75180(10) Å. Structural analysis reveals a tetradentate chelation behaviour of the dianionic ligand H2L having a distorted square planar geometry around Ni(II) with NiN2O2 chromophore in 1. The title complex 1 behaves as an effective catalyst towards oxidation of 3,5-ditertiarybutyl catechol (3,5-DTBC) in acetonitrile to its corresponding quinone derivative in air. The reaction follows first-order reaction kinetics with rate constant 4.28 × 10−5 min −1. The reaction follows Michaelis-Menten enzymatic kinetics with a turnover number of (Kcat) 140.72 h−1 in acetonitrile. Graphical AbstractX-ray structural analysis of a newly synthesized nickel(II) complex [Ni(L)] (1) [H2L = 1,1′-(1E,1′E)-(propane-1,3-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol] reveals a tetradentate chelation behaviour of the dianionic ligand H2L having a distorted square planar geometry around Ni(II) with NiN2O2chromophore in 1. It (1) behaves as an effective catalyst towards oxidation of 3,5-ditertiarybutyl catechol (3,5-DTBC) in acetonitrile to its corresponding quinone derivative in air. The reaction follows first-order reaction kinetics with velocity 4.28 × 10−5 min−1. The Michaelis-Menten enzymatic kinetics is also followed by the reaction with turnover number (Kcat) 140.72 h−1 in acetonitrile.

Catecholase and phenoxazinone synthase activities of a ferromagnetically coupled tetranuclear Cu(II) complex

A crystallographically characterized tetranuclear Cu(II) complex [CuII4(L)4] (1) [H2L = N-(2-hydroxyethyl)-3-methoxysalicylaldimine] is found to show overall ferromagnetic exchange coupling. Complex (1) mimics the catalytic activity of the plant enzyme catechol oxidase by oxidising 3,5-di-tert-butylcatechol to its corresponding quinone in methanol and dichloromethane medium in the presence of aerial oxygen. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (Kcat) 6.99 × 103 and 1.85 × 103 h−1 in methanol and dichloromethane, respectively. 1 is also phenoxazinone synthase active in methanol medium with a turnover number of 1.21 × 105 h−1.

Structural systematics of some metal complexes with 4,5-diazafluoren-9-one

AbstractSynthesis and X-ray structural characterization of three complexes of type cis-[M(dafone)2(NCS)2] (M = Co(II), 1; Ni(II), 2; Zn(II), 3; dafone = 4,5-diazafluoren-9-one) and a polymer cis-[Cd(dafone)(NCS)2]n (4) have been reported. Each of the four complexes is crystallized in orthorhombic crystal system. Structural study reveals that each metal(II) centre in the four complexes adopts distorted octahedral geometry with MN6 chromophore in 1-3 and MN4S2 chromophore in 4. The room temperature steady-state fluorescent intensity of dafone in dimethyl formamide at 402 nm is found to be quenched in these reported dafone complexes (1-4). Graphical AbstractSynthesis and X-ray structural characterization of three complexes of type cis-[M(dafone)2(NCS)2] (M = Co(II), 1; Ni(II), 2; Zn(II), 3; dafone = 4,5-diazafluoren-9-one) and a polymer cis-[Cd(dafone)(NCS)2]n (4) have been reported. The fluorescent intensity of dafone in DMF is found to be quenched in these reported dafone complexes (1-4).

DNA binding and cleavage activity of a structurally characterized Ni(II) Schiff base complex

AbstractSynthesis and characterization of a mononuclear Ni(II) compound [Ni(L)(H2O)2](NO3)2 [L = N,N’-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol] (1) is reported. 1 crystallizes in triclinic P-1 space group with a = 8.1911(2) Å, b = 11.6624(3) Å, c = 16.5356(4) Å and α = 108.8120(10)°, β = 91.2010(10)°, γ = 91.1500(10)°. The binding property of the complex with DNA has been investigated using absorption and emission studies, and viscosity experiment. The binding constant (Kb) and the linear Stern-Volmer quenching constant (Ksv) of the complex have been determined as 9.23 × 104 M−1 and 2.0 × 104 M−1, respectively. Spectroscopic and hydrodynamic investigations revealed groove or electrostatic nature of binding of 1 with DNA. 1 is also found to induce oxidative cleavage of the supercoiled pUC 18 DNA to its nicked circular form in a concentration dependent manner. Graphical AbstractSynthesis and characterization of a mononuclear Ni(II) complex [Ni(L)2(H2O)2](NO3)2 [L = N,N′-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol] (1) is reported. 1 crystallizes in P-1 space group. Spectroscopic and hydrodynamic investigations on the binding property of the complex with DNA have been revealed groove or electrostatic nature of binding of 1 with DNA. 1 is also found to induce oxidative cleavage of the supercoiled pUC 18 DNA to its nicked circular form in a concentration dependent manner.

A ferromagnetic tetranuclear CuII complex: catecholase and phenoxazinone synthase activities

Merry Mitra1, Tanay Kundu2, Gurpreet Kaur3, Gyaneswar Sharma4, Angshuman Roy Choudhury3, Yogesh Singh4, Rajarshi Ghosh5 1Indian Institute Of Science Education And Research, Kolkata, Kolkata, India, 2Physical/Materials Chemistry Division, National Chemical Laboratory, Pune 411 008, India, Pune, India, 3Department of Chemical Sciences, Indian Institute of Science Education & Research, Mohali, Sector 81, S.A.S. Nagar, Knowledge City, Manauli PO, Mohali 140 306, India, Mohali, India, 4Department of Physical Sciences, Indian Institute of Science Education & Research, Mohali, Sector 81, S.A.S. Nagar, Knowledge City, Manauli PO, Mohali 140 306, India, Mohali, India, 5Department of Chemistry, The University of Burdwan, Burdwan 713 104, India, Burdwan, India E-mail: merry.mitra@gmail.com