Photophysics, Exciton and Charge Transport in Conjugated Organometallic Oligomers and Aggregates

University Of Florida, Gainesville FL

Investigators

Abstract

This award by the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Kirk S. Schanze of the University of Florida to pursue studies on the "Photophysics, Exciton and Charge Transport in Conjugated Organometallic Oligomers and Aggregates." Excited-state properties along with charge and exciton transport in metal-containing pi-conjugated oligomers and supramolecular assemblies will be examined. The overall objectives are to develop a clear understanding of excited state delocalization, energy, and charge transport within isolated single chains of organometallic pi-conjugated systems (molecular wires) and within supramolecular aggregates produced by self-assembly of pi-conjugated monomers. Several molecular systems will be studied. 1) A family of metal-acetylide oligomers that contain repeat units consisting of trans-(Ar-C=C-)2M(P-P)2 moieties (M = Ru and Os, and P-P is a diphosphine) will be investigated in order to determine the factors that control excited state delocalization in organometallic pi-conjugated systems. 2) The nature of the triplet excited state will be probed in a series of platinum(II)-capped polyynes of the type, trans,trans-Ar(P)2Pt-(C=C)n-Pt(P)2Ar in order to define the relationship between excited state properties and carbon chain length. 3) A series of long-chain, monodisperse Pt-acetylide oligomers will be studied to determine the rates of triplet exciton and negative polaron transport through single organometallic conjugated chains. 4) Photophysical and exciton transport studies will be extended to well-defined supramolecular aggregates formed by self-assembly of a) pi-conjugated rigid-rod Pt-acetylide oligomers capped with one or more long alkyl chains, or b) hexabenzocoronenes functionalized with metal complex chromophores. The objective of this work will be to determine the effect of aggregation on the properties of the triplet state and to study triplet exciton migration in well defined supramolecular aggregates. This investigation is directly relevant to emerging technologies that have a significant potential to benefit society, the economy, and improve the nation's defense capabilities. Specifically, the materials that are the focuses of this work have applications in opto-electronic devices such as visible and near infrared light emitting diodes (novel light sources), photovoltaic cells (light to electrical energy conversion), non-linear optics (laser protection and color shifting) and sensors (chemical- and bio-agent detection). This program also serves as the primary research training conduit for undergraduate and graduate students. The broader impacts of this project are augmented by the Light and Matter Outreach program at the University of Florida, through which PI, graduate students and undergraduate students will bring photochemistry related scientific demonstrations to middle schools in the North Florida region.