4,4′-Bis(trifluoromethyl)-2,2′-bipyridine – a multipurpose ligand scaffold for lanthanoid-based luminescence/19F NMR probes

Abstract

The tetradentate ligand 4,4'-bis(trifluoromethyl)-2,2'-bipyridine-6,6'-dicarboxylic acid (H(2)1) and three corresponding anionic rare earth complexes [RE(1)2](-) (RE = Y, Tb, Dy) were synthesized. The terbium and dysprosium complexes show lanthanoid-centered luminescence in aqueous solution, as well as paramagnetically enhanced longitudinal magnetic relaxation of the (19)F nuclei.

19F MRI Probes for Multimodal Imaging**

“…The 19 F NMR spectra exhibited a single signal of rather short longitudinal relaxation time (15 ms for Tb, 10 ms for Dy); T 2 , which was presumably very low, was not reported. As no further investigations have been performed, this system remains a model with only potential practical applications [34] …”

“…As no further investigations have been performed, this system remains a model with only potential practical applications. [34] One interesting attempt to achieve high F content employed a multifunctional scaffold. The probe was based on a per-hydroxylated icosahedral [closo-B 12 (OH) 12 ] 2À anion with a single fluorophore moiety and 11 3,5-bis(trifluoromethyl) benzoic acid-derived units covalently attached to the core with tetraethyleneglycol linkers (Figure 6).…”

Discovery of quinolone derivatives as antimycobacterial agents

“…The target compounds 7a1-7a2, 7b1-7b2, 7c1 and 8a1-8a5 were obtained by the route described in Scheme 3. [23][24][25] The butanedione derivatives were cyclized and reduced to amines under H 2 , which then condensed with carboxylic acid at room temperature to afford target compounds 7a1-7a2, 7b1-7b2, 7c1 and 8a1-8a5.…”

Reaktionen auf die Vollsperrung der Schiersteiner Brücke auf der A643

“…Metallionen des f‐Blocks haben eine lange Geschichte als MRT‐Kontrastmittel. Seitz (Bochum) und Mitarbeiter stellten im letzten Jahr ein neues Diagnosekonzept vor, indem sie Terbium und Dysprosium an fluorsubstituierte Bipyridinliganden koordinierten (Abbildung 4) 2_15. Eine solche Kombination eröffnet die Möglichkeit, die Verbindung diagnostisch gleich zweifach einzusetzen: Zum einen ließe sich das 19F‐NMR‐Signal, das durch die Wechselwirkung mit Tb und Dy noch verschoben wird, in der MRT nutzen; außerdem beobachteten die Autoren die für Lanthanoidkomplexe typischen intensiven Lumineszenzen im sichtbaren Bereich, welche eine optische Detektion möglich machen.…”