Reversibly thermochromic bismuth-organic materials with tunable optical gaps†
Five reversibly thermochromic bismuth-based inorganic–organic hybrid materials were synthesized via facile one-step condensation reactions between triphenylbismuth and four arenedithiols and a diselenol. The materials were characterized by UV-vis and FT-IR spectroscopy, powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), elemental analysis (EA), and thermogravimetric analysis (TGA). The bismuth-organic materials (Bi-OMs) are colored materials with optical HOMO–LUMO gaps that were readily tuned by systematic modification of the steric and electronic character of the π-conjugated organic linkers. All five Bi-OMs exhibit completely reversible thermochromism in the solid-state, and possess excellent thermal stability in air up to nearly 300 °C. This combination of physical properties, coupled with the ease of synthesis and the inexpensive, non-toxic nature of bismuth, make this class of inorganic–organic hybrid materials potentially promising for reversible smart window applications, camouflage coatings, temperature sensing, photocatalysis, color filters and displays.