Factors affecting the quantum efficiencies of fluorescent terbium(III) chelates in the solid state

Abstract

Andrews KY16 9ST, Scot I a n d Investigations of tris-and tetrakis-hexafluoroacetylacetonato-and trifluoroacetylacetonato-terbium(iii) complexes have established that the temperature-dependence of the lifetime is caused by thermal depopulation of the ion level to a ligand triplet state. Ligand triplet to ground state deactivation rates, A, have been determined and range from 1 O4 to l O7 s-l. Neither variation in thermal depopulation rates norA i s sufficient to explain the observed differences in quantum efficiencies and it is suggested that significant losses may occur before the triplet state in the energy transfer process.LANTHANIDE ions form two general types of complex with p-diketoenolate anions (a) neutral tris complexes, LnL,, which may be solvated, and (b) anionic tetrakis complexes, [LnL,]-, which are associated with a cationic species.l Many of these complexes, especially those of Eu3+, Tb3+, and Sm3+, emit narrow line fluorescence owing to radiative transitions within the 4f electron shell of the lanthanide ion when they are irradiated in the first excited singlet absorption band of the ligand. The energy-transfer mechanism leading to this emission involves intersystem crossing from the ligand singlet, S,,

Terbium β‐Diketonate Based Highly Luminescent Soft Materials

“…The Tb ( 5 D 4 ) lifetime of 2 is about 0.06 ms (λ ex,em = 363, 542 nm), obviously shorter than that of 1, but still not unusal for compounds which contain [Tb(hfacac) 4 ] -anions. [13] The shorter lifetime for 2 most probably is caused by the motion of the pyrrolidinium cation which leads to an enhanced radiationless decay. Once the compounds are frozen in liquid nitrogen, the ff transitions for Tb III are also obviously enhanced.…”

Structures and luminescent properties of Sm(III) and Dy(III) coordination polymers with 2,4,6-pyridinetricarboxylic acid

“…Fortunately the two emission bands are clearly shown in emission spectra of 1 and 2. The two complexes have relatively strong emission intensity in the visible region probably due to [30][31][32][33][34][35] the pta 3À ligands absorbing excitation energy by pyridyl rings and transferring energy to Sm(III) or Dy(III) and the double-layered 2-D structure is a rigid structure and less energy was lost with the vibrations of the crystal lattice.…”

Terbium/zinc luminescent hybrid siloxane-oxide materials bridged by novel ureasils linkages

“…The intramolecular energy transfer efficiency depends mainly on the two energy transfer processes [27]. One is from the lowest triplet state energy of organic to the resonant energy level by DexterÕs resonant exchange interaction theory [28]:…”