Photochemical synthesis of dibenzo-18-crown-6 ligands containing two 1-hydroxy-2-R-9,10-anthraquinone-9-imino side arms

4,4’- and 4,5’-Bis(1-hydroxy-2-R-9,10-anthraquinone-9-imino)dibenzo-18-crown-6 ethers (novel alkaline-earth cation chemosensors) were synthesised by the photochemical condensation of 1-aryloxy-2-R-9,10-anthraquinones with aromatic diamines containing a 18-crown-6 ether bridge in benzene at room temperature.