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

Abstract

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).