Seminar: Novel π-Conjugated Materials – Planar and Twisted

26/11/2018 - 12:00 - 13:00

S E M I N A R

Monday  26/11/18, 12:00 pm

Building 211, seminar room

 

SPEAKER:

Dr. Ori Gidron

Institute of Chemistry, The Hebrew University of Jerusalem, Israel.

 

TOPIC:

Novel π-Conjugated Materials – Planar and Twisted 

 

For organic electronic materials which composed of π-conjugated backbones, planarity is a crucial factor determining their electronic and optical properties. In this talk, I will discuss two examples of planar and non-planar systems: planar oligofurans and twisted acenes.

In the first part, we demonstrate the transformation of planar oligofurans through sequential Diels–Alder cycloaddition reactions to provide oligoarenes in two chemical steps, regardless of the oligomer length. By this method, oligonaphthalenes containing up to six units were obtained in high yield through the formation of up to 12 new C−C bonds. The versatility of this method was demonstrated for various polyaromatic hydrocarbons.[1]

In the second part, I will introduce a series of twisted acenes having an anthracene backbone diagonally tethered by an n-alkyl bridge, which induces a twist of various angles. This allows us to systematically monitor the effect of twisting on electronic and optical properties. We find that absorption is bathochromically shifted with increasing twist, while fluorescence quantum efficiency drops dramatically. The tethered twistacenes were isolated to their enantiomerically pure form, displaying strong chiroptical properties and anisotropy factor (g- value). No racemization was observed even upon prolonged heating, rendering these tethered twistacenes suitable as enantiopure helical building units for π-conjugated backbones. [2]

 

Reference

 

  1. S. Phatangare, L. J. W. Shimon and O. Gidron Angew. Chem. Int. Ed. 2017, 56, 13601–13605.
  2. A. Bedi, L. J. W. Shimon, and O. Gidron J. Am. Chem. Soc. 2018, 140, 8086.

Abstract