A two-component ligand system (1) containing 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A)as the hosting unit for the lanthanide cations and an appended asymmetrically functionalized 1,10-phenanthroline (phen) as the chromophore was synthesized. The 1:1 complexes with Eu3 +,Gd3+,Tb3+, and Yb3+ have been prepared and studied in aqueous solution. For Gd1, a relaxivity value of 2.4 mM-1 s-1 has been measured at 20 MHz and 25 °C, which indicates that there are no water molecules in the first coordination sphere of the metal ion. The analysis of high resolution 1H NMR spectra of Yb1 supports this view and suggests the direct involvement of the phen moiety in the coordination of the metal ion. For Eu1 and Tb1, the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centered (MC) lifetimes were obtained; coordination features were also determined by comparing luminescence properties in water and deuterated water. For Eu1 and Tb1, the overall emission sensitization (se) process in air-equilibrated water was found to be notably effective with ?se= 0.21 and 0.11, respectively. A detailed study of the steps originating from light absorption at the phen unit and leading to MC sensitized emission was performed.
Highly Luminescent Eu3+ and Tb3+ Macrocyclic Complexes Bearing an Appended Phenanthroline Chromophore
Quici S;Cavazzini M;Armaroli N;
2002
Abstract
A two-component ligand system (1) containing 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A)as the hosting unit for the lanthanide cations and an appended asymmetrically functionalized 1,10-phenanthroline (phen) as the chromophore was synthesized. The 1:1 complexes with Eu3 +,Gd3+,Tb3+, and Yb3+ have been prepared and studied in aqueous solution. For Gd1, a relaxivity value of 2.4 mM-1 s-1 has been measured at 20 MHz and 25 °C, which indicates that there are no water molecules in the first coordination sphere of the metal ion. The analysis of high resolution 1H NMR spectra of Yb1 supports this view and suggests the direct involvement of the phen moiety in the coordination of the metal ion. For Eu1 and Tb1, the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centered (MC) lifetimes were obtained; coordination features were also determined by comparing luminescence properties in water and deuterated water. For Eu1 and Tb1, the overall emission sensitization (se) process in air-equilibrated water was found to be notably effective with ?se= 0.21 and 0.11, respectively. A detailed study of the steps originating from light absorption at the phen unit and leading to MC sensitized emission was performed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
