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

Metal ions (Ag+, Cd2+, Eu3+, Sm3+) 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 (H2L(PF6)(2) and H2L(CF3SO3)(2)), a polymeric architecture [AgL](n)(CF3SO3)(n), two rack-like complexes ([Eu2H2L3(CF3SO3)(6)](PF6)(2) and [Sm2H2L3(CF3SO3)(6)](PF6)(2)) and a grid-like structure ([Cd4L4](CF3SO3)(8)).