A Robust Porous Quinoline Cage by Transformation of a [4+6]-Salicylimine Cage via Povarov-Cyclization.

Porous shape-persistent organic cages have become the object of interest in recent years, because they are soluble and thus processable from solution. A variety of cages can be achieved by applying dynamic covalent chemistry (DCC), which are less chemical stable. Here we describe the transformation of a salicylimine cages to a quinoline cage by a twelvefold Povarov reaction as key-step. Besides the chemical stability of the cage in a broad pH regime, it shows a unique absorption and emission depending on acid concentration. Furthermore, thin films for the vapor detection of acids were investigated, showing color switches from pale yellow to red and characteristic emission profiles.