Issue 38, 2009
From the journal:

Physical Chemistry Chemical Physics

Solvent-induced configuration mixing and triplet excited-state inversion: insights from transient absorption and transient dc photoconductivity measurements

Chunxing She,a   Aaron A. Rachford,b   Xianghuai Wang,b   Sébastien Goeb,b   Ala'a O. El-Ballouli,b   Felix N. Castellano*b  and  Joseph T. Hupp*a  

* Corresponding authors

a Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, USA
E-mail: j-hupp@northwestern.edu
Fax: +1 847-467-1425
Tel: +1 847-491-3504

b Department of Chemistry & Center for Photochemical Sciences, Bowling Green State University, Bowling Green, USA
E-mail: castell@bgsu.edu
Fax: +1 419-372-9809
Tel: +1 419-372-7513

Abstract

Solvent-induced excited-state configuration mixing in a Pt(II) diimine chromophore with phenylene ethynylene containing acetylide ligands, [Pt(tBu2bpy)(PE3)2] (1), was characterized by nanosecond transient absorption spectroscopy and transient dc photoconductivity (TDCP). The mixing is a result of closely spaced triplet charge transfer (3CT) and intraligand-localized (3IL) triplet energy levels that are finely tuned with solvent polarity as ascertained by their parent model chromophores [Pt(tBu2bpy)(PE1)2] (2) and [Pt(P2)(PE3)2] (3), respectively. The absorption difference spectrum of the mixed triplet state is dramatically different from those of the 3CT and 3IL state model chromophores. The 3CT, 3IL and configuration-mixed triplet states led to distinct TDCP signals. The TDCP response is of negative polarity for 3CT excited states but of positive polarity for 3IL excited states. TDCP transients for 1 in mixed solvents are a combination of signals from the 3IL and 3CT states, with the signal magnitude depending on the polarity of solvent composition. The fraction of 3CT state character in the configurationally mixed excited state was quantified by TDCP to be ∼0.24 in pure benzene, while it decreased to ∼0.05 in 20 : 80 (v : v) benzene–CH2Cl2. The charge transfer fraction appears to increase slightly to ∼0.11 in the lower polarity 20 : 80 n-hexane–CH2Cl2 medium. TDCP is shown to be a useful tool for the identification of the lowest excited state in electrically neutral metal–organic chromophores.

Graphical abstract: Solvent-induced configuration mixing and triplet excited-state inversion: insights from transient absorption and transient dc photoconductivity measurements

About
Cited by
Related
Download options Please wait...

Article information

DOI
https://doi.org/10.1039/B908977B
Article type
Paper
Submitted
06 May 2009
Accepted
11 Jun 2009
First published
13 Jul 2009

Phys. Chem. Chem. Phys., 2009,11, 8586-8591

Permissions

Request permissions

Solvent-induced configuration mixing and triplet excited-state inversion: insights from transient absorption and transient dc photoconductivity measurements

C. She, A. A. Rachford, X. Wang, S. Goeb, A. O. El-Ballouli, F. N. Castellano and J. T. Hupp, Phys. Chem. Chem. Phys., 2009, 11, 8586 DOI: 10.1039/B908977B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements