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

Reactions of N,N-bis (salicylidene)-1,2-cyclohexanediamine (H2L) with mixed lanthanide counterions of LnCl(3)6H(2)O and Ln (NO3)(3)6H(2)O afford six H2L lanthanide coordination polymers, e.g. {[Pr(H2L)(2)(NO3)(2)Cl]2CH(2)Cl(2)}(n) (1); {[Ln(H2L)(1.5)(NO3)(3)](2)5CHCl(3)mCH(3)OH}(n) [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.