The back cover picture shows a supramolecularly‐controlled topochemical reaction of conjugated dienes under irradiation in homogeneous system. Using this method, the cyclooctadiene‐cored derivatives are synthesized very efficiently. Moreover, the cyclooctadiene tetraimidazolium derivatives can be applied as fluorescent chemosensors for thymine in aqueous solution at physiological pH (7.4). More details are discussed in the article by Han et al. on page 1040—1044.