Structures and luminescent sensors of mixed-counterions based salen-type lanthanide coordination polymers.

Reactions of N,N'-bis (salicylidene)-1,2-cyclohexanediamine (H L) with mixed lanthanide counterions of LnCl ·6H O and Ln (NO ) ·6H O afford six H L lanthanide coordination polymers, e.g. {[Pr(H L) (NO ) Cl]·2CH Cl } (1); {[Ln(H L) (NO ) ] ·5CHCl ·mCH OH} [Ln = Sm (2), Eu (3), Gd (4), Tb (5) and Yb (6); m = 1 (2-5); m = 0 (6)]. X-ray crystallographic analysis reveals that complex 1 exhibits three-dimensional diamondoid topologic structure and complexes 2-6 are of two-dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near-infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2-5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.