Prospects of Improving Molecular Solar Energy Storage of the Norbornadiene/Quadricyclane System through Bridgehead Modifications

Abstract

We have investigated novel bicyclic diene molecular solar thermal energy storage systems that presently are the ones with the highest predicted energy density. Using a variety of different ab initio quantum chemical methods, we report storage energies, absorption spectra, and reaction barriers for the release of stored energy for a series of bicyclic dienes. The bicyclic dienes are all constructed by modifying the bridgehead of the well-known norbornadiene/quadricyclane (NBD/QC) system. In conclusion, we find it promising that it is possible to significantly amplify the storage energy of the NBD/QC system without seriously compromising other crucial properties by introducing simple modifications to the bridgehead.

Aza-bicyclooctadiene/tetracyclooctane couples as promising photoswitches for molecular solar thermal energy storage applications

“…1–12 An ideal photoswitching molecule forms a metastable isomer upon irradiation and converts back to the stable parent compound either thermally, electrochemically or with an aid of a catalyst. 13–16 The two photo-isomers of the molecular photochromic couple have different physical and chemical properties. 17,18 Therefore, light acts as an exceptional external stimulus that enables precise photochemical control of the properties of systems like drug and protein targets, peptide conformation, nucleotides, drug delivery systems, etc.…”

“…1,7,12,15,27,35,40,44,47–49 Numerous attempts have also been made by Mikkelsen and co-workers to tune the properties of different molecular photoswitches in the theoretical studies. 13–15,31–34,43,45,48,50–54…”

Reversible Photoisomerization of Norbornadiene‐Quadricyclane within a Confined Capsule†

“…Interestingly, keeping the potential usefulness of QC in solar energy applications, five decades after the initial report of QC production by triplet sensitization of NBD (10) a patent was issued for large-scale preparation QC via Michler's ketone sensitized synthesis from NBD in 2004 (27). After a gap of more than two decades, interest in this system has had a recent resurgence (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39). In addition to strain another unusual property of QC that has played an important role for energy storage and release is its low oxidation potential (0.91 V vs SCE) in comparison to NBD (1.54 V vs SCE) (40).…”

Ring strain release and pseudo anti-aromaticities control photochemical reactivities in photoclick reactions of solvated cyclopropenones

“…[7][8][9][10] CO delivery can be light-activated with a photoactive CO-releasing molecule (CORM). 11,12 Light enables spatiotemporal activation of different chemical processes, including energy storage in materials chemistry [13][14][15][16][17][18][19][20][21][22][23][24] and pro-drugs in drug delivery [25][26][27] . Strained cycloaddends (e.g., cyclooctynes and 1,3-dipoles) can be accessed using light through a class of biorthogonal reactions known as 'photoclick chemistry.'…”