3–(2–Pyridyl)pyrazole Based Luminescent 1D-Coordination Polymers and Polymorphic Complexes of Various Lanthanide Chlorides Including Orange-Emitting Cerium(III)

A series of 18 lanthanide-containing 1D-coordination polymers 1∞[Ln2(2–PyPzH)4Cl6], Ln = La, Nd, Sm, dinuclear polymorphic complexes α–, β–[Ln2(2–PyPzH)4Cl6], Ln = Sm, Eu, Gd, α–[Tb2(2–PyPzH)4Cl6], and [Gd2(2–PyPzH)3(2–PyPz)Cl5], mononuclear complexes [Ce(2–PyPzH)3Cl3], [Ln(2–PyPzH)2Cl3], Ln = Tb, Dy, Ho, and Er, and salt-like complexes [Gd3(2–PyPzH)8Cl8]Cl and [PyH][Tb(2–PyPzH)2Cl4] were obtained from the reaction of the respective lanthanide chloride with the 3–(2–pyridyl)pyrazole (2–PyPzH) ligand at different temperatures. An antenna effect through ligand-to-metal energy transfer was observed for several products, leading to the highest luminescence efficiency displayed by a quantum yield of 92% in [Tb(2–PyPzH)2Cl3]. The Ce3+ ion in the complex [Ce(2–PyPzH)3Cl3] exhibits a bright and orange 5d-based broadband emission with a maximum at around 600 nm, marking an example of a strong reduction of the 5d-excited states of Ce(III). The absorption spectroscopy shows ion-specific 4f–4f transitions, which can be assigned to Nd3+, Sm3+, Eu3+, Dy3+, Ho3+, and Er3+ in a wide spectral range from UV–VIS to the NIR region.

Cerocene and Lanthanocene Chalcogenides: Synthesis, Structure, and Luminescence

A series of lanthanide chalcogenides {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln}₂(μ-η²:η²-Te₂) (Ln = Ce 1, La 2), {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(THF)}₂(μ-Se) (Ln = Ce 3, La 4), and {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(THF)}₂(μ-Te) (Ln = Ce 5, La 6) can be readily obtained by the reaction of the alkyl complexes [η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(CH₂C₆H₄-o-NMe₂) with elemental selenium or tellurium in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). The reaction of the alkyl complexes [η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln(CH₂C₆H₄-o-NMe₂) with 9-BBN in 1:2 molar ratio afforded the lanthanide (cyclooctane-1,5-diyl)dihydroborate complexes [η⁵-1,3-(Me₃C)₂C₅H₃]₂Ln[(μ-H)₂BC₈H₁₄] (Ln = Ce 7, La 8) concomitant with the (Me₂N-o-C₆H₄CH₂)BC₈H₁₄ release, indicating that [η⁵-1,3-(Me₃C)₂C₅H₃]₂LnH may be the reactive species for the synthesis of lanthanide chalcogenides. All the new compounds were characterized by various spectroscopic methods, and their solid-state structures were further confirmed by single-crystal X-ray diffraction analyses. Luminescence spectroscopy was also employed to characterize complexes 1-6. The Ce(III) complexes 3 and 5 display distinct luminescence properties at room temperature, as compared to the corresponding La(III) complexes 4 and 6. The complex {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Ce(THF)}₂(μ-Te) (5) exhibits unexpectedly red emission in solution which is found to depend strongly on the excitation wavelength.

Cerium(iii) complexes with azolyl-substituted thiophenolate ligands: synthesis, structure and red luminescence

In order to obtain molecular Ce(iii) complexes which emit red light by f–d transitions the azolyl-substituted thiophenolates were used as the ligands. The thiophenolate Ce(iii) complexes were synthesized by the reaction of Ce[N(SiMe₃)₂]₃ with respective thiophenols 2-(2′-mercaptophenyl)benzimidazole (H(NSN)), 2-(2′-mercaptophenyl)benzoxazole (H(OSN)) and 2-(2′-mercaptophenyl)benzothiazole (H(SSN)) in DME media. The structures of the benzimidazolate (Ce(NSN)₃(DME)) and benzothiazolate (Ce(SSN)₃(DME)) derivatives were determined by X-ray analysis which revealed that the cerium ion in the molecules is coordinated by one DME and three anionic thiophenolate ligands. The lanthanum complex La(OSN)₃(DME) has been synthesized similarly and structurally characterized. It was found that the solids of Ce(SSN)₃(DME) and Ce(OSN)₃(DME) exhibit a broad band photoluminescence peaking at 620 nm which disappears upon solvatation. With an example of OSN derivatives it was proposed that this behaviour is caused by the blue shift of the f–d transition of Ce³⁺ ions.

Novel Ce(iii) complexes with azolyl-substituted thiolate ligands have been synthesized. Some of them exhibit red PL.

Luminescent coordination polymers for the VIS and NIR range constituting LnCl3 and 1,2-bis(4-pyridyl)ethane

Variable luminescence of lanthanide coordination polymers with bis-pyridylethane and thiazole.