Characterization and photophysical properties of lanthanide macrocyclic complexes derived from (2,1)
摘要:
The isolation and characterization of Ln(NO3)(3) complexes (Ln=La, Pr, Nd, Eu, Tb, Lu) with 2,3-benzo-1,4,7,13-tetraoxa-10-azacyclopenta-decane (L-1) and two of its N-substituted derivatives (L-2, L-3) are reported. Structural information in the solid state is derived from spectroscopic data (vibrational, absorption, reflectance and luminescence spectra). Both ligand- and metal-centered luminescence of solutions of the complexes in oxygen-free and anhydrous acetonitrile are investigated. Substitution of the N-proton of the crown ether enhances metal emission. Ligand L-2 displays a good antenna effect for Eu-III luminescence, while L-3 is especially effective in transferring energy from its triplet state onto the excited states of Tb-III. The Eu-III site in Eu(NO3)(3)L-2. 0.5C(2)H(5)OH . 1.5H(2)O possesses a low local symmetry and a relatively long D-5(0) lifetime (1.01 ms). (C) 1999 Elsevier Science Ltd. All rights reserved.
Carboxylic Groups as Cofactors in the Lanthanide-Catalyzed Hydrolysis of Phosphate Esters. Stabilities of Europium(III) Complexes with Aza-benzo-15-crown-5 Ether Derivatives and Their Catalytic Activity vs Bis(p-nitrophenyl)phosphate and DNA
摘要:
[GRAPHICS]The stability of europium(III) complexes with benzocrown ether derivatives 2-4 containing carboxylic functions with methylene spacers of different length was found to vary surprisingly little. In sharp contrast, the hydrolytic activity of these catalysts against bis(p-nitrophenyl)-phosphate (BNPP) varied by a factor of 30. The results show for the first time the efficiency of the carboxylic group as cofactor in phosphate ester hydrolysis, which until now was established only in some enzymes, Other than with BNPP, the hydrolysis with plasmid DNA (nicking experiments) showed no rate enhancement.