Schulte Robin, Schade Dustin, Paululat Thomas, Zähringer Till J B, Kerzig Christoph, Ihmels Heiko
Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cµ), University of Siegen, Adolf-Reichwein-Str. 2, 57068 Siegen, Germany.
Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Beilstein J Org Chem. 2024 Nov 21;20:3061-3068. doi: 10.3762/bjoc.20.254. eCollection 2024.
The photochromic norbornadiene/quadricyclane pair is a promising system for molecular solar thermal (MOST) energy storage, with which solar energy may be converted, stored, and released as heat in one integral molecular system. Herein, we present the synthesis of mono-, bis-, and tris-norbornadiene derivatives with alkynylbenzene and alkynylnaphthalene core units, along with studies of their photochemical properties. The target compounds were synthesized by Sonogashira-Hagihara coupling reactions of 2-bromonorbornadiene and the corresponding arylacetylenes. The norbornadienes showed absorption maxima in the range of 310-345 nm and long-wavelength zero onsets of up to 420 nm. The photoisomerization quantum yields were as high as 59% per photoisomerization event and the resulting quadricyclanes showed half-lives of up to 8 h at room temperature. Furthermore, the norbornadienes were transformed quantitatively into their quadricyclane photoproducts by irradiation with green light (520 nm) in the presence of a photosensitizer.
光致变色降冰片二烯/四环烷对是一种很有前景的分子太阳能热（MOST）储能体系，利用该体系太阳能可在一个完整的分子体系中转化、储存并以热的形式释放。在此，我们报道了具有炔基苯和炔基萘核心单元的单、双、三降冰片二烯衍生物的合成及其光化学性质研究。目标化合物通过2-溴降冰片二烯与相应芳基乙炔的Sonogashira-Hagihara偶联反应合成。降冰片二烯在310 - 345 nm范围内显示出最大吸收，长波长零起点可达420 nm。每次光异构化事件的光异构化量子产率高达59%，所得四环烷在室温下的半衰期长达8小时。此外，在光敏剂存在下，通过绿光（520 nm）照射，降冰片二烯可定量转化为其四环烷光产物。
