22802-86-4Relevant articles and documents
Catalytic promiscuity of an iron(II)–phenanthroline complex
De, Abhranil,Garai, Mamoni,Yadav, Hare Ram,Choudhury, Angshuman Roy,Biswas, Bhaskar
, (2017)
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 charge transfer bands (575 and 721?nm) are observed and the in situ generated catecholate intermediate 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 substrate activation mechanism. Copyright
Oxidative Ring Cleavage of o-Benzoquinone by Potassium Peroxomonosulphate
Ando, Wataru,Miyazaki, Hajime,Akasaka, Takeshi
, p. 518 - 519 (1983)
Oxidation of 3,5-di-t-butyl-1,2-benzoquinone by potassium peroxomonosulphate gave both extra- and intra-diol cleavage products.
Biomimetic intradiol-cleavage of catechols with incorporation of both atoms of O2: The role of the vacant coordination site on the iron center
Ogo, Seiji,Yamahara, Ryo,Funabiki, Takuzo,Masuda, Hideki,Watanabe, Yoshihito
, p. 1062 - 1063 (2001)
This is the first example of model system for the active site of protocatechuate 3,4-dioxygenase to display intradiol-cleavage of catechols with incorporation of two oxygen atoms of O2 promoted by iron complexes.
Iron(iii) complexes of tripodal tetradentate 4N ligands as functional models for catechol dioxygenases: The electronic vs. steric effect on extradiol cleavage
Balamurugan, Mani,Vadivelu, Prabha,Palaniandavar, Mallayan
, p. 14653 - 14668 (2015/02/19)
A few mononuclear iron(iii) complexes of the type [Fe(L)Cl2]Cl 1-6, where L is a tetradentate tripodal 4N ligand such as N,N-dimethyl-N′,N′-bis(pyrid-2-ylmethyl)ethane-1,2-diamine (L1), N,N-diethyl-N′,N′-bis(pyrid-2-ylmethyl)ethane-1,2-diamine (L2), N,N-dimethyl-N′,N′-bis-(6-methylpyrid-2-ylmethyl)ethane-1,2-diamine (L3), N,N-dimethyl-N′-(pyrid-2-ylmethyl)-N′-(1-methyl-1H-imidazol-2-ylmethyl)ethane-1,2-diamine (L4), N,N-dimethyl-N′,N′-bis(1-methyl-1H-imidazol-2-ylmethyl)ethane-1,2-diamine (L5) and N,N-dimethyl-N′,N′-bis(quinolin-2-ylmethyl)ethane-1,2-diamine (L6), have been isolated and characterized by CHN analysis, UV-Visible spectroscopy and electrochemical methods. The complex cation [Fe(HL1)Cl3]+1a possesses a distorted octahedral geometry in which iron is coordinated by the monoprotonated 4N ligand in a tridentate fashion and the remaining three sites of the octahedron are occupied by chloride ions. The DFT optimized octahedral geometries of 1, 5 and 6 contain iron(iii) with a high-spin (S = 5/2) ground state. The catecholate adducts [Fe(L)(DBC)]+, where H2DBC is 3,5-di-tert-butylcatechol, of all the complexes have been generated in situ in acetonitrile solution and their spectral and redox properties and dioxygenase activities have been studied. The DFT optimized geometries of the catecholate adducts [Fe(L1)(DBC)]+, [Fe(L5)(DBC)]+ and [Fe(L6)(DBC)]+ have also been generated to illustrate the ability of the complexes to cleave H2DBC in the presence of molecular oxygen to afford varying amounts of intra- (I) and extradiol (E) cleavage products. The extradiol to intradiol product selectivity (E/I, 0.1-2.0) depends upon the asymmetry in bidentate coordination of catecholate, as determined by the stereoelectronic properties of the ligand donor functionalities. While the higher E/I value obtained for [Fe(L6)(DBC)]+ is on account of the steric hindrance of the quinolyl moiety to coordination the lower value observed for [Fe(L4)(DBC)]+ and [Fe(L6)(DBC)]+ is on account of the electron-releasing effect of the N-methylimidazolyl moiety. Based on the data obtained it is proposed that the detachment of the -NMe2 group from the coordination sphere in the semiquinone intermediate is followed for dioxygen binding and activation to yield the extradiol cleavage product. This journal is
Biomimetic iron(iii) complexes of facially and meridionally coordinating tridentate 3N ligands: Tuning of regioselective extradiol dioxygenase activity in organized assemblies
Sankaralingam, Muniyandi,Saravanan, Natarajan,Anitha, Natarajan,Suresh, Eringathodi,Palaniandavar, Mallayan
, p. 6828 - 6841 (2014/05/06)
Four mononuclear iron(iii) complexes of the type [Fe(L)Cl3] 1-4, where L is a tridentate 3N ligand such as (2-pyridin-2-ylethyl)(pyridin-2- ylmethyl)amine (L1), (methyl)(2-pyridin-2-ylethyl)(pyridin-2-ylmethyl)amine (L2), bis(pyridin-2-ylethyl)amine (L3), and (1-methyl-1H-imidazol-2-ylmethyl) (pyridin-2-ylethyl)amine (L4), have been isolated and studied as functional models for catechol dioxygenase enzymes. In [Fe(L2)Cl3] 2, the ligand L2 is coordinated facially to iron(iii) whereas in [Fe(L1)Cl3] 1 and [Fe(L4)Cl3] 4 the ligands L1 and L4 are coordinated meridionally. In DCM, CH3CN and aqueous SDS, CTAB and TX-100 micellar media, the positions of both the low and high energy catecholate-to-iron(iii) LMCT bands (465-530, 690-860 nm) observed for the 3,4-di-tert-butylcatecholate (DBC 2-) adducts of the iron(iii) complexes vary in the order 2 > 1 > 3 > 4, which reflects the influence of the stereoelectronic factors, mode of coordination and the chelate ring size formed by the tridentate ligands. Spectral and electrochemical studies disclose the formation and location of the cationic adducts as solvated [Fe(L)(DBC)(H2O)]+ species mostly in the aqueous micellar pseudophases of SDS and TX-100 and in the aqueous phase of CTAB micellar solution. The [Fe(L)(DBC)Cl] adducts of 1, 3 and 4, generated in situ, afford major amounts of intradiol cleavage products (17.0-70.0%) and smaller amounts of extradiol (1.2-4.2%) products with varying extradiol to intradiol cleavage product selectivity (E/I: 1, 0.08:1; 3, 0.02:1; 4, 0.3:1). On the other hand, interestingly, the adduct [Fe(L2)(DBC)Cl] of 2 generated in DCM yields a major amount of extradiol (54.0%) and a lower amount (18.3%) of the intradiol cleavage products (E/I, 3:1). Remarkably, in aqueous SDS micellar media, it shows exclusive extradiol cleavage products (79.4%) while all the other complexes show very low selectivity (E/I: 1, 0.03:1; 2, 79.4:0, 3, 0.06:1, 4, 0.06:1), suggesting the suitability of SDS medium for 2 to elicit exclusive extradiol cleavage. The TX-100 micellar medium also provides a suitable hydrophobic environment for 2 to elicit extradiol cleavage. However, in CTAB micellar medium, 2 shows cleavage selectivity lower than others. Also, the rate of dioxygenation is higher in SDS micellar medium than in DCM, and is dependent upon the chelate ring size. This journal is the Partner Organisations 2014.
