On the front cover: Fine tuning of the fluorescent colour of fluorophores can help improve their performance in photofunctional systems. Koji Araki and colleagues at the University of Tokyo describe the fluorescent properties of a series of terpyridine derivatives and demonstrate the effectiveness of N-substitution for the fluorescence tuning.

Perspective: Photochemical reactions can transform structurally simple molecules into compounds with complex skeletons. Daniel Morton and colleagues at the University of Leeds review the discovery, understanding and synthetic exploitation of the photochemical transformation of pyridinium salts.

Emerging Area: Antonio Echavarren and colleagues at the Institute of Chemical Research of Catalonia describe the mechanism of palladium catalysed arylation and show how the reaction can be applied to the synthesis of large polyarenes.