Ligand template synthesis of an undecametallic iron(III) complex: X-ray structure, magnetism and catecholase activity

Mal, Sunit Kumar; Mitra, Merry; Biswas, Bhaskar; Kaur, Gurpreet; Bag, Partha Pratim; Reddy, C. Malla; Choudhury, Angshuman Roy; Aliaga‐Alcalde, Núria; Ghosh, Rajarshi

doi:10.1016/j.ica.2014.09.027

Cited by 11 publications

(2 citation statements)

References 24 publications

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“…To investigate the efficiency of the catalytic activity we draw a comparison between our complex 1 and some recently reported iron complexes which show efficient catecholase activity (Table ) . This comparison also indicates that complex 1 acts as a better and effective catalyst towards catecholase activity than the reported ones …”

Section: Resultsmentioning

confidence: 92%

Catalytic promiscuity of an iron(II)–phenanthroline complex

De¹,

Garai²,

Yadav

et al. 2016

Applied Organom Chemis

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A mononuclear iron(II) complex, [Fe(phen) 3 ]Cl 2 (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 (k cat =3.55 × 10 3 h À1 ) 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 Fe 3+ À3,5-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 charge transfer bands (575 and 721 nm) are observed and the in situ generated catecholate intermediate reacts with dioxygen (k obs =9.89 × 10 À4 min À1 ) 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 substrate activation mechanism.

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Section: Resultsmentioning

confidence: 92%

Catalytic promiscuity of an iron(II)–phenanthroline complex

De¹,

Garai²,

Yadav

et al. 2016

Applied Organom Chemis

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“…They feature prominently as oxygen transporters in certain invertebrates (hemocyanin), and are ubiquitous in monophenol oxygenases (tyrosinase) or ortho ‐biphenol oxidases (catechol oxidase; Scheme a) . The enzymes activate dioxygen and initiate a polymerization cascade, finally giving the pigment melanin, which is vital in plant defense . During oxidative metabolism, dioxygen is reduced to water …”

Section: Introductionmentioning

confidence: 99%

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

Gülzow

Hörner

Strauch

et al. 2017

Chemistry A European J

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What is the most significant result of this study? Attempts to mimic metalloenzymes teach us about catalysis, and the lessons learnt find widespread application in an umber of chemical disciplines, including process engineering. Our catechol oxidase models show an unprecedented dependence of their reactivity on the method of oxygen administration:w hen going beyond the limits of homogeneously distributed reactants, by administering surplus dioxygen periodically during catalytic turnover, we observed reactivities increasing by factors of five to ten, in comparison with the well-established conditions of dioxygen saturation. This observation is not limited to our new system. Reference experiments with systems taken from the literature suggest that the effect, which is of interest in the context of reactive bubbly flows, is general, but has hitherto gone unnoticed. What was the inspiration for this cover design? When we were invited to submit ad esign, we took inspiration from the fact that the browning of cut fruit is effected by copper-and oxygen-dependent oxygenases, leading to melanine pigments, which are polymeric ortho-quinone derivatives. An abstract rendering of our dinuclear copper(II) complexes is shown in the foreground at left. In our cover art, as till life by Gabriele Endres, the browning of the half-eaten apple in the foreground denotes the enhanced reaction of our model substrate, ac atechol, under oxygen-enriched conditions, as provided by ab ubbly flow of oxygen. What other topics are you working on at the moment? We are interested in the activation of dioxygen and its exploitation as an environmentally benign, or green, oxidant, using bioinspired transition-metal complexes of tailor-made ligands. Our "workhorse" metal ions are iron and copper,i nt heir various oxidation states, and we are currently making our first forays into the coordination chemistry of manganese. Our ligands are polypodal, including tetra-and pentadentate ligands, as in the present work, or extended -tripodal hexadentate, as in recent spin-state dynamics studies. The former chelators shield am ajor part of the metal-coordination sphere, focusing the reactivity on one or two "labile" coordination sites. The coordinative strain of all these claw-like ligands can also be varied, enabling investigations, in which distortions of the coordination sphere and their influence on complex reactivity and spin multiplicity,c an be studied in isolation (and with reference to the concept of the entatic state). Invited for the cover of this issue is the group of Gerald Hçrner and Andreas Grohmann at the Technical University of Berlin. The image depicts that the browning of cut fruit is effected by copper-and oxygen-dependent oxygenases, leading to mela-nine pigments, which are polymeric ortho-quinone derivatives.R ead the full text of the article at

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An Oxido‐Bridged Diiron(II) Complex as Functional Model of Catechol Dioxygenase

Dey¹,

De²,

Yadav

et al. 2016

ChemistrySelect

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An oxido-bridged diiron(II)-phenanthroline complex, [Fe 2 O(phen) 2 Cl 2 ] (1) [phen = 1,10-phenanthroline] has been synthesized from an oxido-bridged diiron(III) precursor in presence of sodium azide and structurally characterized by different spectroscopic tools including single crystal X-ray diffraction study.-From X-ray crystal structure of 1, it is revealed that each of the Fe(II) centre is in distorted octahedral geometry with FeN 4 OCl core and the molecule crystallizes in Pnc2 space group. Bond valence sum (BVS) calculation confirms the existence of iron ions in + 2 oxidation state in 1. The diiron(II) complex has been evaluated as model system for the catechol dioxygenase enzyme by using 3,5-di-tert-butylcatechol (DTBC) as the substrate in acetonitrile medium, revealing that 1 efficiently mimics the catalytic cycle of catechol dioxygenase. Upon stoichiometric addition of DTBC pretreated with two equivalents of triethylamine (Et 3 N) to the diiron complex, two catecholate-to-iron(III) LMCT bands (515 nm and 734 nm) are observed. The in situgenerated catecholate adduct from 1in acetonitrile solution react with dioxygen to afford exclusively extradiol cleavage products along with a small amount of benzoquinone, which is also discerned from the appearance and decrease in intensity of the electronic spectral bands around (708 nm; 507 nm) nm. Nucleophilic attack by molecular oxygen on catecholate adduct in solution provides substantial evidence for the regioselective extradiol cleavage products.

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Ligand template synthesis of an undecametallic iron(III) complex: X-ray structure, magnetism and catecholase activity

Cited by 11 publications

References 24 publications

Catalytic promiscuity of an iron(II)–phenanthroline complex

Catalytic promiscuity of an iron(II)–phenanthroline complex

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

An Oxido‐Bridged Diiron(II) Complex as Functional Model of Catechol Dioxygenase

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