Self-Assembled Co(II) and Zn(II) Complexes with Soluble Bis(Hydrazone)Thiopyrimidine-Based Ligands: Electrochemical and Temperature-Dependent Properties

Herein, two bis(hydrazones) based on a pyridine-hydrazone-pyrimidine-hydrazone-pyridine (py-hyz-pym-hyz-py) template have been synthetized. These compounds have been self-assembled into grid-type [2 x 2] and corner-type complexes in the presence of Co(II) and Zn(II) metal ions. The identity of the corresponding structures has been confirmed by nuclear magnetic resonance (NMR) (1D and 2D) and MALDI-ToF mass spectrometry. In addition, the electrochemical properties of all compounds have been studied by cyclic voltammetry (CV) and osteryoung square wave voltammetry (OSWV). The results suggest that cobalt(II) complexes can be used as units that respond to electrochemical potentials in an electronic material. Furthermore, the behavior of the grid-type cobalt(II) complex has been studied using OSWV at different temperatures. A linear correlation between LUMO energies and temperature has been determined giving insight into the behavior of the grid-type complex at different temperatures, but more experiments are still needed to define whether spin-crossover occurs or if the Jahn-Teller effect plays a role.