DESIGN, SYNTHESIS, AND CHARACTERIZATION OF NOVEL LIGANDS CONTAINING SEVEN-MEMBERED RING FOR THE SENSITIZATION OF NEAR-INFRARED EMITTING LANTHANIDE CATIONS IN COMPLEXES AND NANOCRYSTALS
Near-infrared (NIR) emitting lanthanide cations have a great potential for practical applications such as fluoroimmunoassays, polymer-based optical signal amplifiers, active materials in lasers, and bioimaging. In the recent years, the quest for new lanthanide-based NIR compounds has been one of the most active research areas in lanthanide coordination chemistry and spectroscopy. The first part of this dissertation describes the discovery of tropolonate, a novel and efficient sensitizer for five different NIR emitting lanthanide cations (Yb3+, Nd3+, Er3+, Tm3+, and Ho3+). The detailed structural and photophysical properties of the lanthanide complexes formed with tropolonate were investigated. On the basis of this initial work, four different approaches have been initiated with the goal to explore the possibilities to gain more control and to improve the luminescence properties of NIR emitting lanthanide compounds. 1) By the attachment of four tropolonate units to a common backbone to form octadentate ligand in order to increase the thermodynamic stability and increase the protection for Ln3+. 2) By the substitution of the tropolonate ligand by six different functional groups to modify the electronic structure of tropolonate sensitizer to control the photophysical properties of the resulting complexes. 3) By the use of a ligand that incorporates azulene as a novel sensitizer, which is structurally similar to tropolonate; 4) By capping tropolonate ligands on the surface of inorganic nanocrystals doped with NIR emitting Ln3+. This approach allows the efficient sensitization of the NIR emitting lanthanides and eliminates the intrinsic non-radiative quenching from the ligand.
Advisor:David H. Waldeck; Tara Y. Meyer; Catalina Achim; Stéphane Petoud
School:University of Pittsburgh
School Location:USA - Pennsylvania
Source Type:Master's Thesis
Date of Publication:06/16/2008