Cu(II) bipyridine and phenantroline complexes: Tailor-made catalysts for the selective oxidation of tetralin

Louis, Benoît; Detoni, Chaline; Carvalho, Nakédia M. F.; Duarte, Carolina D.; Antunes, O. A. C.

doi:10.1016/j.apcata.2009.03.022

Cited by 39 publications

(18 citation statements)

References 44 publications

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“…This deviation from ideal structure is probably due to the free rotation for C−C bond attached to the two pyridine rings in 2,2′‐bipyridine. Though B. Luis et al., previously reported the molecular structure of 1 without X‐ray structure but herein, we are able to isolate the single crystals of 1 with a presentation of X‐ray structure . Furthermore, we have attempted several ways to produce single crystals of mononuclear copper(II) complex containing phen ligand and dinuclear copper complex containing bpy ligand, but couldn't be able to produce the compounds in the form of single crystals.…”

Section: Resultsmentioning

confidence: 92%

Catalytic Fate of Two Copper Complexes towards Phenoxazinone Synthase and Catechol Dioxygenase Activity

Garai¹,

Dey²,

Yadav

et al. 2017

ChemistrySelect

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In this present work, we report the synthesis and structural characterization of two copper(II) complexes, [Cu(bpy)Cl2] (1) & [Cu(μ‐Cl)(phen)Cl]2 (2) [bpy=2,2′‐bipyridine; phen=1,10‐phenanthroline]. We have also studied their catalytic fate towards phenoxazinone synthase and catechol dioxygenase activity. X‐ray structural analyses revealed that 1 & 2 crystallize in triclinic & monoclinic system with P 1 and Cc space group respectively. The copper complexes catalyse the oxidative coupling of 2‐amino phenol (2‐AP) to aminophenoxazin‐3‐one with significant turn over number, kcat(h−1)=2.08×103 & 2.16×103 for 1 & 2 resectively. During investigation of catechol dioxygenase activity, stoichiometric addition of 1 & 2 to 3,5‐di‐tert‐butylcatechol (DTBC) in acetonitrile produce in situ catecholate‐to‐Cu(II) absorption bands at 812 and 821 nm respectively. The in situ Cu(II)‐catecholate species for both 1 & 2 react with molecular oxygen at the rate, kobs: 7.95×10−4 and 1.30×10−3 min−1 respectively and produce intradiol cleavage products in exclusive amount. Minor amount of benzoquinone is also found in solution. Intradiol products are found as major product in solution and accounts in favour of substrate activation mechanism.

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Section: Resultsmentioning

confidence: 92%

Catalytic Fate of Two Copper Complexes towards Phenoxazinone Synthase and Catechol Dioxygenase Activity

Garai¹,

Dey²,

Yadav

et al. 2017

ChemistrySelect

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“…Most recently, mononuclear cupric complexes with bipridine and phenanthroline ligands have also been shown to induce selective oxidation of tetralin with relatively high yield. 45 Note Added in Proof. Most recently, in a review, we further discussed the importance of physical confinement of enzymes and biomimetic complexes in the nanospaces of mesoporous materials to improve the stability and to enhance catalytic reactivity.…”

Section: Discussionmentioning

confidence: 97%

Hydroxo-Bridged Dinuclear Cupric Complexes Encapsulated in Various Mesoporous Silicas to Mimic the Catalytic Activity of Catechol Oxidases: Reactivity and Selectivity Study

et al. 2009

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We report the synthesis and characterization of two hydroxo-bridged dinuclear cupric complexes, HPC [((phen) 2 Cu-OH-Cu(phen) 2 ) 3+ , phen ) 1,10-phenanthroline] and HBC [((bpy) 2 Cu-OH-Cu(bpy) 2 ) 3+ , bpy ) 2,2′-bipyridine], encapsulated in porous materials for the oxidation of 3,5-di-tert-butylcatechol (DTBC) to the corresponding quinone, 3,5-di-tert-butylquinone (DTBQ), to mimic catechol oxidases (COs). The separations of the two Cu(II) centers are 2.9, 3.51, and 3.65 Å for CO, HPC, and HBC, respectively. The stability of dinuclear cupric complexes, turnover number (TON), and selectivity of DTBQ were examined in NaY zeolite (pore size 0.74 nm) and the solid mesoporous silicas (MPSs) MCM-41 (2.4 nm), MCM-48 (2.5 nm), and MAS-9 (9.0 nm). The studies showed that the MCM-41 and MCM-48 provided a better stability against the irreversible dissociation of dinuclear cupric complexes for their matching size, while NaY has too small and MAS-9 has too large pore size to stabilize these dinuclear copper complexes. The EPR studies showed that HBC immobilized in MPS solids yielded more mononuclear cupric complexes than HPC samples, which may come from the low stability of HBC undergoing the dissociation of OH bridge via the Lewis acid (aluminum sites in the solid support) catalytic activities under the ion-exchanging process. The catalytic pathways for the production of DTBQ and byproducts are proposed on the basis of spectroscopic characterizations and activity measurements. The main byproduct observed in NaY supports was formed from a DTBC-mononuclear copper intermediate and followed the pathway of electron transfer, oxygen insertion, ring-opening, and oxidation reaction. Furthermore, the rigid and bulky structure of HPC molecule (planar phen ligands) has more confinement effect in MCM-41 and MCM-48 solids than the flexible HBC molecule (nonplanar bpy), which can prevent an excessive separation of the dinuclear cupric centers in the deoxy state and yield a higher stability and selectivity. The smaller separation of the two Cu(II) ions in HPC may also be responsible for the observed higher oxidation selectivity. However, the bulky structure of four phen ligands in HPC molecules exhibits greater steric hindrance and decreases the contact of the substrate and yields a lower TON. The nanochannels of aluminum-substituted MPS provide the needed confined spaces and surface charge and maintain the separation of the dinuclear cupric centers after removing the hydroxo bridge in the catalytic cycle.

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“…Thus enantimeric pure (R)-α-tetralol has great economical value as it can be used as precursors for calcium antagonists [19]. Various strategies have been used in the synthesis of enatiopure (R)-α-tetralol using chemical [20][21][22][23][24], and enzymatic routes [25][26][27]. The industrial chemical synthesis procedure has their own limitation in term of operating conditions, generation of toxic by-products and disposal without harm to the environment.…”

Section: Introductionmentioning

confidence: 99%

Kinetic resolution of (R,S)-α-tetralol catalyzed by crosslinked Candida antarctica lipase B enzyme supported on mesocellular foam: A nanoscale enzyme reactor approach

Kamble

Shinde

Yadav

2016

Journal of Molecular Catalysis B: Enzymatic

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Cu(II) bipyridine and phenantroline complexes: Tailor-made catalysts for the selective oxidation of tetralin

Cited by 39 publications

References 44 publications

Catalytic Fate of Two Copper Complexes towards Phenoxazinone Synthase and Catechol Dioxygenase Activity

Catalytic Fate of Two Copper Complexes towards Phenoxazinone Synthase and Catechol Dioxygenase Activity

Hydroxo-Bridged Dinuclear Cupric Complexes Encapsulated in Various Mesoporous Silicas to Mimic the Catalytic Activity of Catechol Oxidases: Reactivity and Selectivity Study

Kinetic resolution of (R,S)-α-tetralol catalyzed by crosslinked Candida antarctica lipase B enzyme supported on mesocellular foam: A nanoscale enzyme reactor approach

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