Sensitization of europium(III) luminescence in bis(bipyridine) DTPA and DTTA-based ligands: effect of the deletion of amide groups

A dual-excitation fluorescent probe EuIII-dtpa-bis(HBT) for hydrazine detection in aqueous solutions and living cells

The Eu^III-dtpa-bis(HBT) dual-excitation fluorescence probe has good selectivity and strong anti-interference ability for the detection of N₂H₄.

Dual modal imaging agents based on chromophore-bearing DTPA analogues

Two new DTPA analogues, centrally (L1) and terminally (L2) functionalised with a 1,8-naphthalimide chromophore, have been successfully prepared and fully characterized.

Synthesis of a new DTTA- and 5-phenyl-2,2′-bipyridine-based ditopic ligand and its Eu3+ complex

A new ditopic ligand based on diethylenetriamine-N,N,N″,N″-tetraacetate (DTTA) and 5-phenyl-2,2′-bipyridine has been synthesized. The improved method for the synthesis of DTTA tert-butyl ester has been developed. The water-soluble Eu3+*DTTA complex of this ligand has been prepared, and its photophysical properties have been studied. Due to the presence of an extra chelating unit, 5-phenyl-2,2′-bipyridine, this Eu3+*DTTA complex demonstrated a strong fluorescence response to the Zn2+ cation (fluorescence enhancement) and the simultaneous fluorescent and phosphorescent response (fluorescence and phosphorescence quenching) to the Cu2+ or Ni2+ cations in aqueous solutions.

Evaluation of quinoline as a remote sensitiser for red and near-infrared emissive lanthanide(III) ions in solution and the solid state

In order to evaluate quinoline as a remote sensitiser, we have prepared a DTPA based ligand, H3L, bearing quinoline bisamide arms for the complexation of a range of lanthanide(III) ions to give the neutral complexes LnLwhere Ln(3+) = Y(3+), Eu(3+), Sm(3+), Tb(3+), Er(3+), Yb(3+), Nd(3+), Gd(3+). Detection of the phosphorescence signal exhibited by the GdLcomplex at 77 K confirmed that the triplet energy level of the sensitiser at 21,190 cm(-1) was suitable for the indirect population of a range of lanthanide luminescent states. A full photophysical analysis of the complexes reveals that SmL and EuL display red emission when excited through the ligand-based absorption band centred at 330 nm, extending the excitation to violet light around 370 nm. We demonstrate that quinoline sensitizes near-infrared emission in the YbL, ErL and NdL complexes, in powder form as well as in solution. Most importantly, the luminescence for YbL and NdL was sufficiently efficient to be detected in non-deuterated solvent.

The first observation of 4f-luminescence in new heteronuclear lanthanide-germanium complexes

New lanthanide-germanium complexes with diethylenetriaminepentaacetic acid (DTPA) have been synthesized and were characterized by means of elemental analysis, IR-, UV-absorption and luminescent spectroscopy. The 4f-luminescence of heteronuclear Ln(Ge-DTPA)2 (Ln=Sm, Eu, Tb, Dy) complexes in aqueous solutions was investigated for the first time.

Sensitized Emission of Luminescent Lanthanide Complexes Based on 4-Naphthalen-1-yl-Benzoic Acid Derivatives by a Charge-Transfer Process

The photophysical properties of 4-naphthalen-1-yl-benzoic acid ligands and their Eu(III)-cored complexes were systematically investigated to elucidate the effective energy-transfer pathway in luminescent lanthanide complexes. A series of 4-naphthalen-1-yl-benzoic acid ligands, such as 4-naphthalen-1-yl-benzoic acid (NA-1), 4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzoic acid (NA-2), and 4-{4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzyloxy}-benzoic acid (NA-3), were synthesized and utilized for the synthesis of their Eu(III)-cored complexes, corresponding to NAC-1, NAC-2, and NAC-3. The fluorescence spectra of NA-1 and NA-2 show large Stokes shifts with increasing solvent polarity. These large Stokes shifts might be dominantly due to the formation of an intramolecular charge transfer (ICT) complex in the excited state. Also, the intensive luminescence of the Eu(III) ions by the photoexcitation of the ligand in NAC-1 and NAC-2 in polar solvents supports that the energy transfer from the ligand to the Eu(III) ion takes place efficiently. In the case of NA-3, which has a -CH2OPh- group that acts as a blocking group, there is no dependence of the fluorescence spectrum on the solvent nature and no luminescence of the Eu(III) ions by the photoexcitation of the ligand, indicating no formation of the ICT state. This can be due to the fact that the formation of the ICT state in NA-3 was prevented because the -OCH2- group acts as a blocking group by interrupting the pi-conjugation between the benzoic acid and the naphthalene unit. From these photophysical studies, we suggest that the ICT state plays a very important role in the energy-transfer pathway from the ligand to the Eu(III) ion. To our best knowledge, this is the first demonstration of sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by the charge-transfer process.