Luminescence properties of lanthanide complexes-based molecular alloys

Abstract

Six lanthanides complexes with chemical formula [Ln(phen)2(NO3)3] (Ln = Sm(1), Tb (2), Nd (3), Eu (4), Ho (5) and Y (6), phen = 1,10-phenanthroline) were synthesized. 1 and 2 were obtained as single crystals by slow diffusion. Structural characterization was based on single crystal X-ray diffraction and IR and 89 Y-NMR spectroscopies. NMR spectroscopic measurements were performed on [Y(phen)2(NO3)3] (6) and [Y0.75Lu0.25(phen)2(NO3)3] (7). Compounds obtained as microcrystalline powders were characterized by powder X-ray diffraction. The complexes crystallize in the monoclinic system, space group P21/n. Each Ln(III) ion is surrounded by four N atoms from two bidentate phenanthroline ligands and six O atoms from three chelating nitrate groups. The phenanthroline ligand provides efficient sensitization of the complexes that exhibit sizeable luminescence under UV irradiation. Thermal properties have been studied. They confirm the absence of water molecules in the crystal structure. The complexes are thermally stable up to 290 °C. Microcrystalline powders of hetero-lanthanide complexes, with global chemical formula [Tb1-xEux(phen)2(NO3)3] (series 8) and [Tb1-xGdx(phen)2(NO3)3] (series 9) were synthesized. Their photo-physical properties have been investigated. They demonstrate that luminescent molecular alloys can be obtained from lanthanides complexes and not only from hetero-nuclear coordination polymers as previously reported.

Luminescent Complexes of Europium (III) with 2-(Phenylethynyl)-1,10-phenanthroline: The Role of the Counterions

“…The same band is also present in the excitation spectrum of Eu(PEP) 2 (NO 3 ) 3 , but it is not that significantly distinctive and its excitation can be performed in range of about 300 to 400 nm without leading to a noteworthy change in the emission. The Eu(PEP) 2 (NO 3 ) 3 complex exhibits very long lifetime of the excited state of about 1.3 ms in solid state ( Table 3 ), which is higher than the values for europium complexes with phenanthroline derivates reported by Maouche et al and Akerboom et al [ 29 , 30 ].…”

“…The phenanthroline and its derivatives are known for being ligands for different metal ions as well as effective photosensitizers of lanthanoids [ 27 ]. Therefore, a number of europium (III) complexes with phenanthroline-based antenna have been reported recently [ 29 , 30 , 31 ]. Since the antenna effect is extremely interesting from fundamental point of view, many theoretical and spectroscopic studies discussed the photophysical process of absorption of light, the excited state energy transfer from the ligand to the europium ion and the luminescent properties of these compounds [ 30 , 31 , 32 , 33 , 34 ].…”

“…For example, a number of articles are paying attention to the crystal structure of Eu (III) complexes with phenanthroline and different counter ions as nitrates, chlorides, thiocyanates, carboxylates anions [ 41 , 42 , 43 , 44 , 45 , 46 ]. However, as most of the complexes of lanthanoids with phenanthroline are with poor solubility in solvents usually used in spectroscopy, their photophysical properties are mostly studied in solid state [ 29 , 30 ] and there is limited information on the influence of different counter ions on the energy of the ligand-based triplet excited state, the photophysical properties and the stability of the complexes. The present work aims to give insights on these questions by design of two new structurally similar complexes of europium (III) with 2-(phenylethynyl)-1,10-phenanthroline (PEP) and nitrates or chlorides as inorganic ligands: [Eu(PEP) 2 Cl 3 ]·2CH 3 CN and [Eu(PEP) 2 (NO 3 ) 3 ]·2CH 3 CN ( Figure 1 and Figure 2 ).…”

Colloidal suspensions of highly luminescent lanthanide-based coordination polymer molecular alloys for ink-jet printing and tagging of technical liquids

“…14,41 Indeed, the chemical similarity of the lanthanide ions 42 will allow the complexes to co-crystallize during the drying process and each grain will contain the whole information. 43 On the contrary, if the target is to obtain a fingerprint in the liquid-state, such as for tagging technical liquids, the use of nanometric grains of molecular alloys, as we propose here, is mandatory.…”

A new praseodymium-based coordination polymers with 1,10-phenantroline and glutarate ligands: Synthesis, crystal structure and luminescent properties

“…The use of bulky ligands prevents solvent molecules coordination. Rigid organic ligands such as 1,10-phenantroline have proved their efficiency [19][20][21][22][23][24]. However, these bulky ligands often lead to 0D complexes.…”