52093-25-1, Catalysts are substances that increase the reaction rate of a chemical reaction without being consumed in the process. 52093-25-1, Name is Europium(III) trifluoromethanesulfonate, molecular formula is C3EuF9O9S3. In a Article, authors is Nwe, Kido£¬once mentioned of 52093-25-1
Tethered dinuclear europium(III) macrocyclic catalysts for the cleavage of RNA
Dinuclear europium(III) complexes of the macrocycles 1,3-bis[1-(4,7,10- tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-m-xylene (1), 1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane] -p-xylene (2), and mononuclear europium(III) complexes of macrocycles 1-methyl-,4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (3), 1-[3?-(N,N-diethylaminomethyl)benzyl]-4,7,10-tris(carbamoylmethyl)-1,4,7, 10-tetraazacyclododecane (4), and 1,4,7-tris(carbamoylmethyl)-1,4,7,10- tetraazacyclododecane (5) were prepared. Studies using direct excitation ( 7F0 ? 5D0) europium(III) luminescence spectroscopy show that each Eu(III) center in the mononuclear and dinuclear complexes has two water ligands at pH 7.0, I = 0.10 M (NaNO 3) and that there are no water ligand ionizations over the pH range of 7-9. All complexes promote cleavage of the RNA analogue 2-hydroxypropyl-4- nitrophenyl phosphate (HpPNP) at 25C (I = 0.10 M (NaNO3), 20 mM buffer). Second-order rate constants for the cleavage of HpPNP by the catalysts increase linearly with pH in the pH range of 7-9. The second-order rate constant for HpPNP cleavage by the dinuclear Eu(III) complex (Eu2(1)) at pH 7 is 200 and 23-fold higher than that of Eu(5) and Eu(3), respectively, but only 7-fold higher than the mononuclear complex with an aryl pendent group, Eu(4). This shows that the macrocycle substituent modulates the efficiency of the Eu(III) catalysts. Eu2(1) promotes cleavage of a dinucleoside, uridylyl-3?,5?-uridine (UpU) with a second-order rate constant at pH 7.6 (0.021 M-1 s-1) that is 46-fold higher than that of the mononuclear Eu(5) complex. Methyl phosphate binding to the Eu(III) complexes is energetically most favorable for the best catalysts, and this supports an important role for the catalyst in stabilization of the developing negative charge on the phosphorane transition state. Despite the formation of a bridging phosphate ester between the two Eu(III) centers in Eu2(1) as shown by luminescence spectroscopy, the two metal ion centers are only weakly cooperative in cleavage of RNA and RNA analogues.
Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data. 52093-25-1, If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 52093-25-1, in my other articles.
Reference£º
Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI