Next Article in Journal
Top-Down Polyelectrolytes for Membrane-Based Post-Combustion CO2 Capture
Previous Article in Journal
Heavy Metals as a Factor Increasing the Functional Genetic Potential of Bacterial Community for Polycyclic Aromatic Hydrocarbon Biodegradation
Previous Article in Special Issue
Recent Advances in Conjugated Graft Copolymers: Approaches and Applications
Open AccessArticle

Donor-Acceptor Substituted Benzo-, Naphtho- and Phenanthro-Fused Norbornadienes

1
Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
2
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 10, 41296 Gothenburg, Sweden
*
Author to whom correspondence should be addressed.
Molecules 2020, 25(2), 322; https://doi.org/10.3390/molecules25020322 (registering DOI)
Received: 17 December 2019 / Revised: 8 January 2020 / Accepted: 9 January 2020 / Published: 13 January 2020
(This article belongs to the Special Issue New Studies of Conjugated Compounds)
The photochromic norbornadiene/quadricyclane (NBD/QC) couple has found interest as a molecular solar thermal energy (MOST) system for storage of solar energy. To increase the energy difference between the two isomers, we present here the synthesis of a selection of benzo-fused NBD derivatives that contain an aromatic unit, benzene, naphthalene or phenanthrene, fused to one of the NBD double bonds, while the carbon atoms of the other double bond are functionalized with donor and acceptor groups. The synthesis protocols involve functionalization of benzo-fused NBDs with bromo/chloro substituents followed by a subjection of these intermediates to a cyanation reaction (introducing a cyano acceptor group) followed by a Sonogashira coupling (introducing an arylethynyl donor group, -C≡CC6H4NMe2 or -C≡CC6H4OMe). While the derivatives have good absorption properties in the visible region (redshifted relative to parent system) in the context of MOST applications, they lack the ability to undergo NBD-to-QC photoisomerization, even in the presence of a photosensitizer. It seems that loss of aromaticity of the fused aromatics is too significant to allow photoisomerization to occur. The concept of destroying aromaticity of a neighboring moiety as a way to enhance the energy density of the NBD/QC couple thus needs further structural modifications, in the quest for optimum MOST systems. View Full-Text
Keywords: aromaticity; chromophore; cycloaddition; norbornadiene; photoswitch; polycyclic aromatic hydrocarbon; ring strain; solar energy storage; Sonogashira coupling; quadricyclane aromaticity; chromophore; cycloaddition; norbornadiene; photoswitch; polycyclic aromatic hydrocarbon; ring strain; solar energy storage; Sonogashira coupling; quadricyclane
Show Figures

Figure 1

MDPI and ACS Style

Mansø, M.; Fernandez, L.; Wang, Z.; Moth-Poulsen, K.; Nielsen, M.B. Donor-Acceptor Substituted Benzo-, Naphtho- and Phenanthro-Fused Norbornadienes. Molecules 2020, 25, 322.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop