Selective Formation of Twisted Intramolecular Charge Transfer and Excimer Emissions on 2,7-bis(4-Diethylaminophenyl)-fluorenone by Choice of Solvent

Masayuki Shigeta,Gen-Ichi Konishi,Mifumi Morita

doi:10.3390/molecules17044452

Abstract

We designed and synthesized a donor-acceptor-donor dye consisting of a 2,7-disubstituted fluorenone with diethylaminophenyl moieties present as strong electron donating groups. Switching between twisted intramolecular charge transfer (TICT) emission and excimer emission was achieved, with no ground state changes, by simply changing the solvent used. In a nonpolar solvent, excimer emission was observed; with increasing polarity, the emission gradually disappeared, and the TICT emission appeared.

Highlights

Twisted intramolecular charge transfer (TICT) with donor-acceptor dyes is a basic phenomenon utilized in various applications, and investigations have been carried out in order to analyze this phenomenon in detail [1,2]
The dye is based on fluorenone, with two diethylaniline moieties attached at the 2,7-positions
The dye was synthesized via a Suzuki-Miyaura coupling [36] using 2,7-dibromofluorenone and

Summary

Introduction

Twisted intramolecular charge transfer (TICT) with donor-acceptor dyes is a basic phenomenon utilized in various applications, and investigations have been carried out in order to analyze this phenomenon in detail [1,2]. In the case when a donor-acceptor dye forms an excimer, the ratio of TICT emission decreases, and excimer emission appears (Scheme 1) [18,19] This had raised the possibility that switching between. The direct attachment of this donor group to the fluorenone molecule changes the spectra in the ground state [34], and the addition of a rigid -spacer, such as a phenylene or ethynylene group, inhibits the ground state interaction [22]. These spacer-containing compounds were shown to display TICT emission behavior [35]; they have not been sufficiently investigated

Results and Discussion

Instruments

Materials

Conclusions