Colorless metallodithiolene oligomers and polymers with intense near- and mid-infrared absorption

Abstract

Reported herein are the syntheses and properties of a series of multi-nuclear metallodithiolene complex oligomers (5, 6 and 7) and a homologous polymer (8). The Ni/Pd–dithiolene complexes 5, 6 and 7 are characterized by intense absorption in the spectral region of 1000–1800 nm with a high molar absorption coefficient (e.g., 10⁵ M⁻¹ cm⁻¹ at 1257 nm for 7). Complex polymer 8 is readily soluble in common organic solvents and shows remarkably broad and intense absorption in the entire near- and mid-infrared spectral region (800 nm–25 μm). The films of these metallodithiolene materials exhibit good visual transparency or extremely weak absorption in the visible region, making them potentially useful as excellent colourless infrared absorbers.