Modulation of the structural information in shape-defined heterocyclic strands: the case of a (pyridine-hydrazone) 2 pyrazine ligand.

Metal ions (Ag + , Cd 2+ , Eu 3+ , Sm 3+ ) and protons can, through coordination and protonation, modulate in three specific ways the structural information contained in the pyrazine-based heterocyclic strand L (obtained from 2,5-bis(methylhydrazino)pyrazine and 2 equivalents of 2-pyridinecarboxaldehyde), thus generating two linear rod-like conformations and a bent one. This conformational diversity is associated with a structural one that consists of two diprotonated forms (H 2 L(PF 6 ) 2 and H 2 L(CF 3 SO 3 ) 2 ), a polymeric architecture [AgL] n (CF 3 SO 3 ) n , two rack-like complexes ([Eu 2 H 2 L 3 (CF 3 SO 3 ) 6 ](PF 6 ) 2 and [Sm 2 H 2 L 3 (CF 3 SO 3 ) 6 ](PF 6 ) 2 ) and a grid-like structure ([Cd 4 L 4 ](CF 3 SO 3 ) 8 ).