Zhonghua Guo

Date of Award

8-2009

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor

Howard Patterson

Second Committee Member

Alice Bruce

Third Committee Member

Jayendran Rasaiah

Abstract

The focus of this thesis is on d8 and d10 metal-metal interactions, e.g. weak bonding in homometallic and heterometallic systems in liquid solutions, the tunability of luminescent energy due to the variation of metal-metal interaction strength in different solvents and different concentrations, as well as energy transfer from the luminescent energy tunable d8 and d10 metal ions clusters as donor ions to the lanthanide ions as acceptor ions at room temperature. First, energy transfer has been studied between dicyanoaurate(I) luminescent nanocluster donor ions and Eu3+ and Tb3+ acceptor ions in aqueous solutions. The emission of Tb" ions can be enhanced by varying the dicyanoaurate(I) donor ion's concentration due to the different nanoclusters of donor ions. However, Eu3+ acceptor ions quench the donor's emission thorough a non-radiative charge transfer pathway. Second, luminescent energy tunability has been observed with d10 [M(CN)2]-(M = Cu, Ag, Au) ions in water, methanol, acetonitrile and dioxane solutions due to the formation of different excimer and exciplex nanoclusters in different solvents at different concentrations and different excitation energies. The energy transfer processes from [M(CN)2]-(M= Au, Ag, Cu) cluster ions to lanthanide Eu3+ and Tb3+ acceptor ions in selected solutions follow the Förster mechanism.

Further, we report for the first time the presence of closed shell d8-d10 heterometallic metal-metal interactions with Pt(II)-M(I) nanoclusters in aqueous solution containing both d8[Pt(CN)4]2- and d10[M(CN)2]-(M = Cu, Ag, Au) ions at room temperature with luminescence, UV-visible and FTIR spectroscopic evidence.

Finally, we report energy transfer studies between Ce3+ lanthanide ions and d10[Cu(CN)2], d8[Pt(CN)4]2 in aqueous and acetonitrile solutions. The strong luminescence of Ce3+ lanthanide ions in aqueous solution is quenched in the presence of d10[Cu(CN)2], d8[Pt(CN)4]2- and CN- ions through a charge-transfer process. In acetonitrile solution, the weak emission of Ce3+ ions is enhanced in the presence of [Pt(CN)4]2- ions. The new emission and excitation bands are due to the formation of the CN bridging between the [Pt(CN)4]2- cluster ions and the Ce3+ ions, through which the energy is transferred from the [Pt(CN)4]2- donor ions to the Ce3- lanthanide ions.

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