Title

Spectroscopic Investigation of the Excited State Properties of Platinum(Ii) Charge Transfer Chromophores

Date of Award

2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Photochemical Sciences

First Advisor

Felix N. Castellano, PhD

Second Advisor

John R. Cable, PhD (Committee Member)

Third Advisor

Thomas H. Kinstle, PhD (Committee Member)

Fourth Advisor

Jill H. Zeilstra-Ryalls, PhD (Committee Member)

Abstract

Several platinum(II) diimine and triimine acetylides have been synthesized along with the relevant model compounds. The diversity of photophysical properties of the studied compounds makes them attractive for numerous applications such as photovoltaic devices, sensors and optical limiting materials. It has been shown that strong dependence of the absorption/emission characteristics of these complexes on the electronic nature of the ligands can be used to readily modulate photophysical properties of Pt(II) compounds.

Comprehensive photophysical measurements including investigation of the ground state absorption, steady-state and time-resolved photoluminescence, electrochemistry, reductive spectroelectrochemistry, and time-resolved excited state absorption measurements were employed to characterize the nature of the lowest excited state in these complexes. Moreover, it was demonstrated that the solvent polarity dependence could be used to precisely adjust the triplet charge transfer (CT) energy relative to the triplet intraligand (IL) levels in platinum(II) acetylides, accessing a variety of excited-state behaviors in single molecular systems. Transient absorption (TA) methods have been extremely useful in identifying intermediates and products generated in both intra- and intermolecular energy and electron transfer reactions utilizing platinum(II) complexes. In addition, a combination of time-resolved IR and TA spectroscopic techniques has been employed to study the photophysical properties of Pt(II) compounds possessing effective IR spectroscopic tags for charge transfer excited state characterization. The complementary TRIR and TA measurements were shown to be essential in exploring the complexities resulting from the strong orbital mixing in these structures.