Novel azacrown ether-containing spiro[indoline-2,3′-naphthoxazines]: design, synthesis and cation-dependent photochromism

Novel spironaphthoxazine compounds with an aza-15-crown-5 ether fragment at position 5′ or 9′ of the naphthalene ring were synthesised. Spectrokinetic measurements showed the occurrence of two competing formation processes for complexation with alkaline earth or rare earth metal cations. A comparative study of the prepared compounds demonstrated the role of molecular design and the metal cation nature in the cation-dependent photoinduced transformation of spiro[indoline-naphthoxazines].