Modulation of the structural information in shape-defined heterocyclic strands: the case of a (pyridine-hydrazone)₂pyrazine 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 ($H_{2}L(P{F}_6{)}_2$ and $H_{2}L(C{F}_{3}S{O}_3{)}_2$), a polymeric architecture $[AgL{]}_n(C{F}_{3}S{O}_3{)}_n$, two rack-like complexes $([E{u}_2{H}_2{L}_3(C{F}_{3}S{O}_3{)}_6](P{F}_6{)}_2$ and $[S{m}_2{H}_2{L}_3(C{F}_{3}S{O}_3{)}_6](P{F}_6{)}_2)$ and a grid-like structure ($[C{d}_4{L}_4](C{F}_{3}S{O}_3{)}_8$).