The work reported outlines the synthesis, film formation and application of NIR-absorbing metal dithiolene and metal diimine molecules suitable for film formation with varying ligands and central metals. Formation of an electroactive film on conducting glass or mesoporous TiO2 support can be achieved through electropolymerisation, electrodeposition, spin/drop coating or chemical attachment. In this context, we will outline the synthesis, characterisation and properties of a new family of NIR-absorbing aromatic metal diimine complexes. These complexes are shown to give rise to planar, delocalised structures with small HOMO-LUMO gaps, through the use of extended non-innocent ligands o-semibenzoquinonediimines. Herein we report the synthesis of a series of metal diimine complexes, modified to extend the electronic conjugation and shift the intense low-energy absorption from the visible to the NIR region. This study extends the range of available NIR absorping metal-complex chromophores and opens up new possibilities for wavelength tuning and application.
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