Jump to main content
Jump to site search


Terphenyl Backbone-Based Donor-π-Acceptor Dyads: Geometric Isomer Effects on Intramolecular Charge Transfer

Abstract

The molecular geometry effects of ortho, meta, and para-terphenyl based donor-π-acceptor (D-π-A) dyads on intramolecular charge transfer (ICT) were studied to investigate structure-ICT relationships. Terphenyl based D-π-A dyads were prepared by two-step palladium catalyzed, Suzuki-Miyaura coupling reactions, in which triphenylamine (TPA) was used as the electron donor and 1,2-diphenyl-benzimidazole (IMI) as the electron acceptor. The photophysical and electrochemical properties of terphenyl backbone-based ortho (O), meta (M), and para (P) dyads were compared. In steady state absorption spectra, a gradual red-shift was observed in the order O < M < P, which was attributed to terphenyl isomer conjugation effects and agreed well with density functional theory (DFT) based calculations. In particular, the emission spectra of the three terphenyl D-π-A dyads produced showed similar emission maxima at ~475 nm and bathochromic shift property was observed in order to increasing the solvent polarity, indicating the ICT process. From Lippert–Mataga plots, excited-state dipole moment changes (Δμ) were estimated to be 31.5 Debye (D) for O, 62.9 D for M, and 51.5 D for P. Although M isomer was had a large Δμ and photo-induced electron transfer (PET) was expected in the excited state, no radical species were observed by femtosecond transient absorption (TA) measurements. Based on experimental results, we conclude that all three terphenyl based D-π-A dyads, including non-conjugated ortho- and meta-terphenyl dyads, exhibit partial charge transfer rather than unit-electron transfer.

Back to tab navigation

Article information


Submitted
29 Nov 2019
Accepted
10 Jan 2020
First published
10 Jan 2020

Phys. Chem. Chem. Phys., 2020, Accepted Manuscript
Article type
Paper

Terphenyl Backbone-Based Donor-π-Acceptor Dyads: Geometric Isomer Effects on Intramolecular Charge Transfer

M. Kim, M. Ahn, J. H. Shim and K. Wee, Phys. Chem. Chem. Phys., 2020, Accepted Manuscript , DOI: 10.1039/C9CP06466D

Social activity

Search articles by author

Spotlight

Advertisements