Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 5 de 5
Filter
Add more filters










Database
Language
Publication year range
1.
Chem Commun (Camb) ; 53(25): 3579-3582, 2017 Mar 23.
Article in English | MEDLINE | ID: mdl-28289745

ABSTRACT

Artificial enzymes are required to catalyse non-natural reactions. Here, a hybrid catalyst was developed by embedding a novel Ru complex in the transport protein NikA. The protein scaffold activates the bound Ru complex to produce a catalyst with high regio- and stereo-selectivity. The hybrid efficiently and stably produced α-hydroxy-ß-chloro chlorohydrins from alkenes (up to 180 TON with a TOF of 1050 h-1).


Subject(s)
Alkenes/chemistry , Chlorohydrins/chemistry , Ruthenium/chemistry , Catalysis , Coordination Complexes/chemistry , Molecular Conformation , Spectroscopy, Fourier Transform Infrared , Stereoisomerism
2.
Inorg Chem ; 52(23): 13424-31, 2013 Dec 02.
Article in English | MEDLINE | ID: mdl-24224791

ABSTRACT

The structural and electronic properties as well as the catalytic activity toward sulfoxidation of two new vanadium complexes have been investigated. They both possess in their coordination sphere two alkyl thiolate ligands: a dioxido V(V) complex [VO2L(NS2)](HNEt3) (1) (L(NS2) = 2,2'-(pyridine-2,6-diyl)bis(1,1'-diphenylethanethiol)) and an oxido V(IV) complex [VOL(N2S2)] (2) (L(N2S2) = 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(1,1'-diphenylethanethiol)). The X-ray structure of 1 has revealed that the V(V) metal ion is at the center of a distorted trigonal bipyramid. The optimized structure of 2 obtained by DFT calculations displays a square-pyramidal geometry, consistent with its EPR spectrum characterized by an axial S = 1/2 signal (g⊥ = 1.988, g∥ = 1.966, Ax(V) = 45 × 10(-4) cm(-1), Ay(V) = 42 × 10(-4) cm(-1), Az(V) = 135 × 10(-4) cm(-1)). DFT calculations have shown that the HOMO (highest occupied molecular orbital) of 1 is notably localized on the two thiolate sulfur atoms (56% and 22%, respectively), consistent with the expected covalent character of the V(V)-S bond. On the other hand, the SOMO (singly occupied molecular orbital) of 2 is exclusively localized at the V(IV) ion (92%). Complexes 1 and 2 have shown an ability to catalytically oxidize sulfide into sulfoxide. The oxidation reactions have been carried out with thioanisole as substrate and hydrogen peroxide as oxidant. Yields of 80% and 75% have been obtained in 10 and 15 min for 1 and 2, respectively. However, in terms of conversion, 1 is more efficient than 2 (81% and 44%, respectively). More importantly, the reaction is completely selective with no trace of sulfone produced. While 1 displays a poor stability, catalyst 2 shows the same efficiency after five successive additions of oxidant and substrate. The difference in reactivity and stability between both complexes has been rationalized through a mechanism study performed by means of experimental data ((51)V NMR and EPR spectroscopy) combined with theoretical calculations. It has been shown that the structure of the cis-oxo peroxo V(V) intermediate species, which is related to its stability, can partly explain these discrepancies.


Subject(s)
Coordination Complexes/chemistry , Sulfhydryl Compounds/chemistry , Sulfoxides/chemistry , Vanadium/chemistry , Catalysis , Models, Molecular
4.
Chembiochem ; 10(3): 545-52, 2009 Feb 13.
Article in English | MEDLINE | ID: mdl-19137535

ABSTRACT

MAGIC Mn-salen mETALLOZYME: The design of an original, artificial, inorganic, complex-protein adduct, has led to a better understanding of the synergistic effects of both partners. The exclusive formation of sulfoxides by the hybrid biocatalyst, as opposed to sulfone in the case of the free inorganic complex, highlights the modulating role of the inorganic-complex-binding site in the protein. Artificial metalloenzymes based on the incorporation of Mn-salen complexes into human serum albumin display high efficiency and selectivity for sulfoxide production during sulfide oxidation. The reactions carried out by the artificial metallozymes are comparable to those carried out by natural biocatalysis. We have found that the polarity of the protein environment is crucial for selectivity and that a synergy between both partners of the hybrid results in the novel activity.


Subject(s)
Metalloproteins/chemistry , Oxidation-Reduction , Sulfides/chemistry , Antioxidants/chemistry , Circular Dichroism , Ethylenediamines/chemistry , Humans , Molecular Structure , Organometallic Compounds/chemistry , Protein Engineering , Serum Albumin/chemistry
5.
Chem Commun (Camb) ; (11): 1166-8, 2007 Mar 12.
Article in English | MEDLINE | ID: mdl-17347727

ABSTRACT

The dinuclear chiral complex Fe(2)O(bisPB)(4)(X)(2)(ClO(4))(4) (X = H(2)O or CH(3)CN) catalyzes with high efficiency (up to 850 TON) and moderate enantioselectivity (63%) the epoxidation of electron deficient alkenes at 0 degrees C by a peracid.


Subject(s)
Alkenes/chemistry , Epoxy Compounds/chemical synthesis , Ferric Compounds/chemistry , Organometallic Compounds/chemistry , Peracetic Acid/chemistry , Catalysis , Epoxy Compounds/chemistry , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Ultraviolet , Stereoisomerism
SELECTION OF CITATIONS
SEARCH DETAIL
...