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

Metal ions (Ag, Cd, Eu, Sm) 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 (HL(PF) and HL(CFSO)), a polymeric architecture [AgL](CFSO), two rack-like complexes ([EuHL(CFSO)](PF) and [SmHL(CFSO)](PF)) and a grid-like structure ([CdL](CFSO)).