Impact of 1,10-Phenanthroline-Induced Intermediate Valence on the Luminesence of Divalent Europium Halides

Abstract

Starting from EuX 2 (X = Cl, Br, I), we systematically investigated a variety of divalent europium complexes containing bidentate 1,10-phenanthroline (Phen) ligands. Depending on the Eu/Phen ratio, mono-, di-, and polynuclear complexes are formed, with the latter yielding one-dimensional ∞ 1 [EuBr 2 (phen)] chains. Seven new divalent europium complexes, [Eu(phen) 4 (H 2 O)]Br 2 •2MeCN, [Eu(phen) 4 ]I 2 •1.7Tol, [EuBr-(phen) 3 ] 2 Br 2 •4MeCN, [EuCl 2 (phen) 2 ] 2 •2MeCN, [EuBr 2 (phen) 2 ] 2 , [Eu-I 2 (phen) 2 ] 2 , and [EuBr 2 (phen)] x , are presented in this work. All species show remarkable optical properties based on a partial electron transfer from the Eu II center to the Phen ligand. The photophysical characterization is further supported by electrochemistry studies in order to describe the intermediate valence of the Eu center.

Divalent ansa-Octaphenyllanthanocenes: Synthesis, Structures, and EuII Luminescence

“…Molecular divalent europium complexes have recently gained renewed interest for their luminescence properties, especially as the emission can vary in energy (from blue to red), demonstrated with a range of organic or inorganic ligands or host lattices . This has led to applications in light-emitting devices, sensing, and catalysis .…”

“…As a result, the emission wavelengths, lifetimes, and quantum yields of divalent europium can vary in energy depending on the ligands, lattice, and nature of any counterions. Whereas emission for complexes based on Cp and COT ligands is generally found in the orange-red spectral range, ,,− inorganic halide or pseudo halide complexes often emit in the blue, including the recent NHC complex [EuI 2 (IMes)­(thf) 3 ] and the strongly emissive aza–cryptand complexes. − The bulky CNT sandwich complex [Eu­(C 9 H 9 ) 2 ] showed luminescence in the green region and the air-stable trispyrazolylborate-based complexes [Eu­(Tp) 2 ] showed emission from yellow to orange-red depending on the substitution. , The bulky amido ligands afforded near-linear complexes [Eu­(NR 2 ) 2 ] (R = Si­( i Pr) 3 ) or trigonal planar complexes [K­(2.2.2-cryptand)]­[Ln­(NR′ 2 ) 3 ] (R′ = Si­( t BuMe 2 )) exhibiting strong and long-lived emission in the green and yellow regions. , Solvents and counterions can significantly alter emission properties, and very recently, the temperature influence was shown, for example, in the [Cp*Eu­(BH 4 )­(thf) 2 ] 2 complex, making this the first organometallic Eu II -based optical thermometer…”

Trendbericht Festkörperchemie und Materialforschung 2024

“…Diese lässt sich durch die starke Wechselwirkung mit dem Phenan thro lin-Li gan den erklären. 63) Häufig lassen sich mit einfachen Konzepten aus anderen Gebieten der Chemie komplexe (elektronische) Sachverhalte veranschaulichen. Wie Dehnen und Mitarbeitende zeigen, haben regelmäßige {Bi 6 }-Prismen ein nicht lokalisierbares Molekülorbital mit f-Symmetrie und erzeugen einen starken Ringstrom, der zu einem als φ-Aromatizität bezeichneten Verhalten führt.…”

The Divalent Lanthanoid Triflates Ln(CF3SO3)2(CH3CN) (Ln=Sm, Eu): Structure, Luminescence, and Magnetism

“…The best-studied class of solid-state divalent lanthanoid compounds are certainly halides, although molecular compounds have been studied extensively in the last decades. [14][15][16][17][18][19][20][21] The dihalides LnX 2 are known for Ln = Sm, Eu, Tm, Yb with X = Cl, Br, I and for Sm and Eu also for X = F. Moreover, several ternary Ln 2 + halides have been reported. [22] The luminescence properties of various halides have been investigated, including measurements on "diluted" samples using the Sr 2 + and Ca 2 + halides as host lattices.…”

“…Thus, the spectroscopic properties of divalent lanthanoids can vary significantly in different host lattices. The best‐studied class of solid‐state divalent lanthanoid compounds are certainly halides, although molecular compounds have been studied extensively in the last decades [14–21] . The dihalides LnX 2 are known for Ln=Sm, Eu, Tm, Yb with X=Cl, Br, I and for Sm and Eu also for X=F.…”