INVESTIGATION OF ULTRAFAST ELECTRON AND PROTON TRANSFER PROCESSES IN COPPER-ANTHRAQUINONE DONOR-ACCEPTOR MOLECULES

Haddock, Tyler N

Permalink

https://hdl.handle.net/2142/122702 Copy

Description

Title

INVESTIGATION OF ULTRAFAST ELECTRON AND PROTON TRANSFER PROCESSES IN COPPER-ANTHRAQUINONE DONOR-ACCEPTOR MOLECULES

Author(s)

Haddock, Tyler N

Contributor(s)

• Chen, Lin X
• Mulfort, Karen
• Henke, Wade C

Issue Date

2023-06-23

Keyword(s)

Photodissociation and photochemistry

Abstract

We have investigated the photochemistry of molecular dyads composed of a light absorbing Cu(I) diimine species co-valently linked to an anthraquinone moiety (CuAnQ). These donor-acceptor molecules serve as Earth-abundant prototypes for studying charge accumulation mechanisms in donor-acceptor-donor triads. We have utilized ultrafast optical and NIR spectroscopy to study the kinetics of the electron transfer, taking advantage of the optical and NIR signatures of the AnQ− radical anion. After excitation into a ¹MLCT band, we observe electron transfer from Cu to AnQ in 10’s of picoseconds, forming a charge-separated state (CSS). The assignment of the CSS to Cu²⁺AnQ− was confirmed by spectroelectrochemical study of the Cu⁺AnQ− species. The CSS relaxes back to the ground state in 3 nanoseconds. In the presence of a protic solvent, the charge-separated state further transforms into a new species. The spectral changes suggest this product results from protonation of the AnQ− into the semiquinone radical (HAnQ•). Accompanying this protonation is an extension of the charge-separated state lifetime from 3 ns to 15 ns. These results provide promise for future studies on the CuAnQCu triad, which can potentially form the double reduced Cu²⁺AnQ²−Cu²⁺ and Cu²⁺HAnQCu²⁺ CSSs. Preliminary experiments which indicate CO₂ binding to the Cu²⁺AnQ− and Cu²⁺HAnQ• CSSs are still underway.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122702

DOI

https://doi.org/10.15278/isms.2023.7260

Owning Collections