Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 33, 2019
Previous Article Next Article

Norbornadiene–dihydroazulene conjugates

Author affiliations

Abstract

The introduction of various photochromic units into the same molecule is an attractive approach for the development of novel molecular solar thermal (MOST) energy storage systems. Here, we present the synthesis and characterisation of a series of covalently linked norbornadiene/dihydroazulene (NBD/DHA) conjugates, using the Sonogashira coupling as the key synthetic step. Generation of the fully photoisomerized quadricyclane/vinylheptafulvene (QC/VHF) isomer was found to depend strongly on how the two units are connected – by linear conjugation (a para-phenylene bridge) or cross-conjugation (a meta-phenylene bridge) or by linking to the five- or seven-membered ring of DHA – as well as on the electronic character of another substituent group on the NBD unit. When the QC–VHF system could be reached, the QC-to-NBD back-reaction occurred faster than the VHF-to-DHA back-reaction, while the latter could be promoted simply by the addition of Cu(I) ions. The absence or presence of Cu(I) can thus be used to control whether heat releases should occur on different or identical time scales. The experimental findings were rationalized in a computational study by comparing natural transition orbitals (NTOs). Moreover, the calculations revealed an energy storage capacity of 106–110 kJ mol−1 of the QC–VHF isomers, which is higher than the sum of the capacities of the individual, separate units. The major contribution to the energy storage relates to the energetic QC form, while the major contribution to the absorption of visible light originates from the DHA photochrome; some of the NBD–DHA conjugates had absorption onsets at 450 nm or beyond.

Graphical abstract: Norbornadiene–dihydroazulene conjugates

Back to tab navigation

Supplementary files

Article information


Submitted
11 Jul 2019
Accepted
25 Jul 2019
First published
26 Jul 2019

Org. Biomol. Chem., 2019,17, 7735-7746
Article type
Paper

Norbornadiene–dihydroazulene conjugates

M. D. Kilde, M. Mansø, N. Ree, A. U. Petersen, K. Moth-Poulsen, K. V. Mikkelsen and M. B. Nielsen, Org. Biomol. Chem., 2019, 17, 7735
DOI: 10.1039/C9OB01545K

Social activity

Search articles by author

Spotlight

Advertisements