Neodymium, Gadolinium, and Terbium Complexes Containing Hexafluoroacetylacetonate and 2,2‘-Bipyrimidine:  Structural and Spectroscopic Characterization

Abstract

Lanthanide complexes of the form Ln(hfa)3bpm (where Ln=Nd(III), Gd(III), or Tb(III); hfa=1,1,1,5,5,5-hexafluoroacetylacetone and bpm=2,2'-bipyrimidine) have been structurally characterized. The Nd and Gd complexes form one-dimensional arrays when X-ray-quality crystals are grown by the slow evaporation of concentrated solutions of the complexes. Each metal is 10-coordinate with repeating Ln-bpm units. The Tb complex does not form a one-dimensional array under these conditions. Its structure is 9-coordinate with the ninth position occupied by a covalently bonded water molecule that is hydrogen-bonded to the bpm group from another complex in solution. Luminescent studies show that the Nd complex undergoes nonradiative relaxation through solvent vibrational deactivation, while the lowest excited state of the Gd complex, 6P7/2, is higher in energy than the T1 state of the hfa ligand, making luminescence improbable for both of these complexes. In contrast, the Tb complex emits in the visible region of the spectrum when solutions of the complex are excited at 304 nm associated with the pi-pi* transition of the hfa ligand. Emission lines corresponding to transitions from the 5D4 state to the 7FJ manifold of the Tb(III) are observed. The intensity of these emissions decreases as temperature is increased. Lifetime measurements of the Tb monometallic complex fit to a monoexponential with the lifetime decreasing as the temperature is increased.

2,2′‐Bipyrimidine as Efficient Sensitizer of the Solid‐State Luminescence of Lanthanide and Uranyl Ions from Visible to Near‐Infrared

“…However, reactions of the nitrate salts of the heavier lanthanide ions with BPM in THF or methanol afforded crystals of only the bis adducts [Ln(NO 3 ) 3 (bpm) 2 ]⋅THF (Ln=Nd, Sm, Eu, Tb, Er, Yb) or [Ln(NO 3 ) 3 (bpm) 2 ] (Ln=Eu, Gd, Dy, Tm), respectively. These compounds are rare examples of lanthanide complexes with BPM as a terminal ligand and, with the recently reported [Tb(hfac) 3 (bpm)(H 2 O)] compound (hfac=hexafluoroacetylacetonate anion),45 they are the only mononuclear lanthanide compounds comprising BPM to have been characterized crystallographically. The synthesis of [Ln(NO 3 ) 3 (bpm) 2 ]⋅THF (Ln=Eu, Tb) contrasts with that of the corresponding dinuclear complexes [{Ln(NO 3 ) 3 (bpm)} 2 (μ‐bpm)], which were reported to be the only isolable products from the Ln(NO 3 ) 3 ⋅6H 2 O/BPM reaction system, whatever the reagent ratio, the solvent, and the crystallization method used 46.…”

Optical emission studies of new europium and terbium dinuclear complexes with trifluoroacetylacetone and bridging bipyrimidine. Fast radiation and high emission quantum yield

“…3 phen] (18%) [38] [dbm-carb = 1-{[6-(9H-carbazol-9-yl)hexoxy]phenyl}-3-{[6 (9H-carbazol-9-yl)-hexoxy]phenyl}-propane-1,3-dione)]. Similarly the intrinsic quantum yield of the 3 ]bpm (4.6%) [39].…”

Luminescent Hybrid Materials Based on Laponite Clay

“…The organic ligands can absorb light strongly and transfer it to the lanthanide ions efficiently, as well as protecting the coordinated metal ions from solvent molecules. [8] Luminescent hybrid materials based on Ln 3 + complexes in matrices have long been in the focus of intensive study not only because they are of fundamental interest, but also because they show great potential for different applications. [9][10][11][12][13][14][15] The hybrid materials typically show enhanced stability and improved luminescence with respect to the pristine materials [16][17][18] Sol-gel-derived materials are highly promising matrices for designing new luminescent materials due to attractive characteristics such as highly controlled purity, versatile shaping and patterning, mechanical, thermal, and chemical stability, and biocompatibility.…”