Synthesis and characterisation of a new six-coordinated thermochromic Ni complex

•A new six-coordinated Ni complex was synthesised and characterised.•The complex showed thermochromism in the solid state.•The complex showed structural change depends on the temperature.•The thermochromism was assessed by absorption spectrum and TD-DFT calculation.•Structural change at various temperatures would cause the thermochromism.

The Ni(II) complex [Ni(diethylenetriamine)(2,6-bis(hydroxymethyl)pyridine)]·PF6·CF3COO·H2O is described here. A single crystal X-ray crystallographic study revealed that the Ni(II) in the complex has a six-coordinated octahedral structure. The complex shows thermochromic behaviour in the solid state. X-ray crystallographic studies at various temperatures suggested that the thermochromism is caused by anisotropic structural change. The relationship between the structural change and the colour change was confirmed by absorption spectrum and TD-DFT calculation.

Graphical abstractThermochromism in a six-coordinated Ni complex was assessed by comparing structural changes and colour changes at various temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slide