Tuning Molecular Solar Thermal Properties by Modification of a Promising Norbornadiene Photoswitch

Martyn Jevric, Zhihang Wang, Anne U. Petersen, Mads Mansø, Christopher J. Sumby, Mogens Brøndsted Nielsen, Kasper Moth-Poulsen

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Carefully targeted modifications to the norbornadiene-quadricyclane couple should give molecules with great potential for solar energy storage. Here we report the synthesis of derivatives of a well-studied compound, 2-cyano-3-anisyl norbornadiene (NBD5). The conjugation was extended by conversion of the nitrile into acrylonitrile and acrylate derivatives over two steps. Despite red-shifting the absorbance properties, the metastable quadricyclanes exhibited extremely short lifetimes. Meanwhile, treatment of NBD5 with acetyl halides in the presence of aluminum trihalides led to the formation of 7-acetyl norbornenes through a Wagner–Meerwein rearrangement. Subsequent transformations made it possible to synthesise norbornadienes with varying degrees of steric bulk at the 7-position of the molecular scaffold. It was found that the bulkier this group was, the more stable the quadricyclane form. This reaction sequence allows for the synthesis of norbornadiene derivatives which are more suited to molecular solar thermal applications in domestic heating despite providing a slightly lower energy density.

Original languageEnglish
Pages (from-to)2354-2361
Number of pages8
JournalEuropean Journal of Organic Chemistry
Volume2019
Issue number13
DOIs
Publication statusPublished - 9 Apr 2019
Externally publishedYes

Keywords

  • Photochromism
  • Conjugation
  • Wagner-Meerwein rearrangement
  • Strained molecules
  • Energy density
  • Wagner–Meerwein rearrangement

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