Synthesis, characterization, and luminescent properties of Eu³? dipyridophenazine functionalized complexes for potential bio-imaging applications

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Jeremy Beasley (Creator)
Western Carolina University (WCU )
Web Site:
Brian Dinkelmeyer

Abstract: Luminescent properties of lanthanide complexes possess unique characteristics that makethem good candidates for possible bioimaging agents and have inspired research initiatives tofurther explore these materials. However, the toxicity of these metals limits their applications asin-vivo bioimaging agents. One solution that eliminates the toxic effects is to encase theselanthanide complexes in silica. This project was designed to probe the variation in thefluorescence properties of a highly luminescent europium (III) complex, utilizing a fluorinated ß-diketonate ligand (thenoyltrifluoroacetone (tta)), upon the substitution of the solvent moleculesby various functionalized dipyrido[3,2-a:2’,3’-c]phenazine (DPPZ) ligands. A method forcovalently attaching, or occluding complexes in silica nanoparticles were also included in theproject design. The structure and properties of the functionalized DPPZ ligands and theirrespective complexes were determined by FT-IR, 1H-NMR, UV-Vis, and fluorescencespectroscopy techniques. UV excitation of the complexes resulted in red luminescence (~ 614nm) characteristic of trivalent europium ions. The differences in luminescence properties of thecomplexes are rationalized in terms of the electronic features of the different functionalizedDPPZ ligands. The higher overall quantum yield of the un-functionalized DPPZ complex,Eu(tta)3DPPZ (Q.Y.= 7.68 ± 0.06 %), and the low overall quantum yield observed forEu(tta)3DPPZ-COOEt (Q.Y.= 1.08 ± 0.05%), Eu(tta)3DPPZ-Si (Q.Y.= 0.65± 0.04%), Eu(tta)3DPPZ-COOH (Q.Y.= 0.61± 0.07 %), Eu(tta)3DPPZ-CH3 (Q.Y.= 0.59±0.02 %) arerationalized in terms of how electron donating or withdrawing groups affect their respectiveligand-to-metal energy transfer efficiencies. Eu(tta)3DPPZ was the only complex to showenhanced luminescent properties capable of potential applications in biomedical imaging.

Additional Information

Language: English
Date: 2014
Dipyridophenazine, Europium, Quantum Yield, Silica Nanoparticle, Thenoyltrifluoracetone
Rare earth metal compounds -- Synthesis
Rare earth metal compounds -- Optical properties

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