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A mononuclear iron(II) complex, [Fe(phen)3]Cl2 ( 1) (phen =1,10-phenanthroline), has been synthesized in crystalline phase and characterized using various spectroscopic techniques including single crystal X-ray diffraction. Crystal structure analysis revealed that 1 crystallizes in a monoclinic system with C2/m space group. Complex 1 acts as a functional model for a biomimetic catalyst promoting the aerobic oxidation of 3,5-di- tert-butylcatechol (3,5-DTBC) through radical pathways with a significant turnover number ( kcat =3.55 × 103 h−1) and exhibits catechol dioxygenase activity towards the same 3,5-DTBC substrate at room temperature in oxygen-saturated ethanol medium. The existence of an isobestic point at 610 nm from spectrophotometric data indicates the presence of Fe3+ −3,5-DTBC adduct favouring an enzyme-substrate binding phenomenon. Upon stoichiometric addition of 3,5-DTBC pretreated with two equivalents of triethylamine to the iron complex, two catecholate-to-iron(III) ligand-to-metal bands (575 and 721 nm) are observed and the in situ generated catecholate reacts with dioxygen ( kobs =9.89 × 10−4 min−1) in ethanol medium to afford exclusively intradiol cleavage products along with a small amount of benzoquinone, and a small amount of extradiol cleavage products, which provide substantial evidence for a mechanism. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A dinuclear Cu(II) complex was synthesized and crystallographically characterized. The compound was found to have antiferromagnetic interaction in between the Cu(II) centres in the molecule. It had weak intermolecular ferromagnetic interaction. The compound was found to be tyrosinase and catecholase active. In case of tyrosinase activity, the diphenol formed was isolated using thin layer chromatography (TLC) and characterized through 1 H NMR as well as mass spectrometry. The o -quinone derivative formed in this reaction was characterized using GC–MS. The latter activity was monitored spectrophotometrically and the product o -quinone derivative was isolated (in MeOH and MeCN) column chromatographically and characterized using melting point determination. These were followed by Michealis–Menten kinetics with turnover numbers 4.95 × 10 3 and 1.58 × 10 3  h −1 in MeOH and MeCN, respectively. [ABSTRACT FROM AUTHOR]

A mononuclear copper(II) complex [Cu(phen)(OH 2 ) 2 (NO 3 )](NO 3 ) ( 1 ) [phen = 1,10-phenanthroline] has been synthesized and structurally characterized by different spectroscopic characterization methods including single crystal X-ray diffraction study. X-ray crystal structure analysis shows that 1 adopts square pyramidal geometry with CuN 2 O 3 chromophore and the molecule crystallises in P 2 1 / n space group. 1 has been evaluated as model system for the catechol oxidase enzyme by using 3,5 -di -tert-butylcatechol (DTBC) as the substrate in methanol medium, revealing that 1 exhibits greater catalytic activity with K cat value 3.91 × 10 3 h −1 compared to a few copper(II) complexes of the same class. Electrochemical analysis suggests that the mononuclar Cu(II) complex mimics the catechol oxidase enzyme in methanolic medium through radical pathway. The complex cleaves the double strand of pBR 322 plasmid DNA in a concentration-dependent manner so as for the DNA to change from super coiled form to both nicked circular and linear forms. The complex is cytotoxic to the human hepatocarcinoma cell HepG2, as revealed in MTT assay. AO/EB and Hoechst 33528 fluorescent staining techniques were used to find the mode of cell death. Interestingly, AO/EB and Hoechst stained cells observed at IC 50 concentration shows that 1 brings about conformational change on DNA to induce apoptosis which would be the basis underlying its cytotoxic property. [ABSTRACT FROM AUTHOR]

An undecairon(III) oxo-hydroxo-carboxylato bridged aggregate [Fe 11 (μ 3 -O) 6 (μ 3 -OH) 6 (μ-O 2 C-f) 15 ] ( 1 ) has been synthesized and characterized by single crystal X-ray diffraction study. The anionic ligand N -(2-hydroxyethyl)-3-methoxysalicylaldimine (L) has been used as template to synthesize such high nuclearity complex. Interestingly, the ligand neither enters into the coordination sphere nor crystallizes with the iron cluster. Bond distance data indicate that all the iron atoms in 1 are high-spin Fe(III) in O-donor environment. 1 behaves as an effective catalyst towards oxidation of 3,5-di- tert -butylcatechol in different solvents, viz. methanol, dichloromethane and acetonitrile, to its corresponding quinone derivative in aerial oxygen. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (K cat ) 3.21 × 10 3 , 1.23 × 10 3 and 1.11 × 10 3 h −1 in methanol, dichloromethane and acetonitrile, respectively. [ABSTRACT FROM AUTHOR]

A perfectly linear trinuclear zinc(II) complex [Zn3L2(µ-O2CCH3)2] (1) containing a (N,O)-donor Schiff base ligand, (H2L = N,N'-bis(salicyaldehydene)-1,3-diaminopropan-2-ol) has been synthesized and characterized by single crystal X-ray diffraction study. The X-ray crystal structure of 1 contains three zinc(II) centers which are inter-connected through µ2-phenolato and µ-acetato bridges. The terminal zinc centers are in square pyramid geometry and central zinc ion is in distorted octahedral coordination geometry. Both H2L and 1 exhibit good fluorescence properties in solution. 1 has been used as a precursor to fabricate zinc oxide nanoparticles (ZnONPs) by pyrolytic method. ZnONP has been characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), FT-IR spectroscopy and UV-Vis spectroscopy techniques. ZnONP has been employed as photocatalytic agent to degrade the organic dye, viz. Methylene blue under visible light and by exposing to visible light for 1 h, ZnONP degraded methylene blue dye nearly 80%. [ABSTRACT FROM AUTHOR]

Abstract: The syntheses of greenish-blue light emitting [Ir(ppy)2(dppel)] (2), [Ir(ppy)2(dppp)] (3) and [Ir(ppy)2(dppe)] (4) [ppy, 2-phenylpyridine; dppel, 1,2-bis(diphenylphosphino)ethylene; dppp, 1,3-bis(diphenylphosphino)propane; dppe, 1,2-bis(diphenylphosphino)ethane] complexes were carried out using [(ppy)2Ir(μ-Cl)2Ir(ppy)2] (1) as a starting material. These complexes were characterized by elemental analyses and NMR (1H, 13C and 31P) spectral studies. A single-crystal X-ray diffraction study confirmed a distorted octahedral geometry for 3. Complexes 2–4 were found to exhibit blue-shifted emission as compared to [Ir(ppy)2(acac)] (acacH=acetylacetone) and [Ir(ppy)2pic] (pic=2-picolinic acid) because of the presence of strongly π-accepting, Ph2P^PPh2 units. The solution quantum efficiency for 2–4 was measured and 2 showed the highest quantum efficiency. Ground state geometry optimizations for 2–4 were performed using density functional theory (DFT) with the B3LYP hybrid functional and excitation energies for low lying singlet and triplet excited states were obtained via time-dependent DFT (TDDFT) calculations. Further, complexes 1–4 were synthesized by a Microwave Irradiation technique (MW) in a reasonably shorter time. This facile and expeditive synthetic route has been extended and successfully verified for other heteroleptic complexes of Ir(III) with varying different bidentate [(N^N) (5), (O^O) (6), (N^O) (7)] and monodentate [PPh3 (8)] ancillary ligands. [Copyright &y& Elsevier]