Photosensitized isomerization of norbornadiene for solar energy storage and supression of side reaction.

Abstract

Photosensitized isomerization of norbornadiene to quadricyclene was investigated by using several photosensitizers such as toluene, acetone, acetophenone, benzophenone and a-naphthoquinone. The effect of wavelength on the quantum yield of quadricyclene and on the energy conversion efficiency was measured by using spectroirradiator. The formation of byproduct polymer in the presence of photosensitizers was also studied. The formation of polymers during irradiation, which prevents the repeated use of energy storage material, was effectively suppressed by the addition of several phenolic substances into norbornadiene.

Molecular Solar Thermal Batteries through Combination of Magnetic Nanoparticle Catalysts and Tailored Norbornadiene Photoswitches

“…These benefits are to some extent hampered by the fact that the parent NBD does not absorb light above 267 nm [10] . Therefore, a triplet photosensitizer is necessary to facilitate the light‐induced isomerization of unsubstituted NBD to the energy‐rich QC [8a, 25] . During this work, we opted to utilize acetophenone as a photosensitizer.…”

Photoswitchable Norbornadiene–Quadricyclane Interconversion Mediated by Covalently Linked C60

“…According to the literature, acetophenone is ideal for this purpose. [5] Irradiation of am ixture of malonate 2 and 5mol %a cetophenone in diethyl ether resulted in the formation of the desired QC malonate. To our surprise the successive Bingel-Hirsch reaction with this malonate did not give the expected product.…”

“…[4] Hence, at riplet photosensitizer with E T (sensitizer) > E T (NBD),s uch as acetophenone or benzophenone, is neededt oe nable the isomerization of neat NBD to QC. [5] Alternatively,i th as been shown that, by functionalization of the NBD scaffold, it is possible to redshift the absorption and simultaneously increase the quantum yield. [6] However,f unctionalization of the NBD scaffoldnaturally is alwaysa ccompanied with an increased molecular weight and, therefore, al ower energy storage density.N ext to the photoisomerization, also the corresponding back reactionf rom QC to NBD mustb ec onsidered and optimized.…”

Storing energy with molecular photoisomers

“…In addition to direct chemical modification, different photophysical methods have also been explored, including the use of sensitizers [48][49][50][51] and more recently, the use of photon upconversion systems. The latter systems convert low-energy photons that otherwise cannot be absorbed by the molecules into higher-energy photons.…”