A reversible luminescent lanthanide switch based on a dibenzo[24]-crown-8-dipicolinic acid conjugate.

A novel host molecule H(2)1 bearing a dibenzo[24]-crown-8 moiety and a dipicolinic acid group was synthesized, and its Tb(3+) complex displayed a satisfactory luminescent emission. The tris[2]pseudorotaxane formed from [Tb.1(3)](3-) and ferrocene derivative 2 reveals excellent reversible luminescent lanthanide behavior.

A proton-triggered ON-OFF-ON fluorescent chemosensor for Mg(II) via twisted intramolecular charge transfer.

A novel fluorescent chemosensor has been synthesized and shows interesting fluorescent ON-OFF-ON processes through mediating its twisted intramolecular charge transfer (TICT) state. An exclusively fluorescent enhancement is observed for Mg (2+).