Luminescent Thermochromic Silver Iodides as Wavelength-Dependent Thermometers

Abstract

Luminescent thermochromic materials with a dramatic shift of emission band under different temperatures are highly desirable in temperature sensing fields. However, the design of the synthesis of such compounds remains a great challenge. In this work, two new luminescent thermochromic silver iodides, (emIm)Ag₃I₄ (<b>1</b>) and (emIm)Ag₂I₃ (<b>2</b>) (emIm = 1-ethyl-3-methyl imidazole), have been synthesized under solvothermal conditions. Compound <b>1</b> features a [Ag₃I₄]^- anionic layer, while compound <b>2</b> possesses an infinite [Ag₂I₃]^- chain structure, both of which are charge balanced by emIm⁺ cations. Particularly, they display luminescent thermochromism with a significant wavelength shift of emission maximum with temperature change. They represent rare examples of infinite layered or chain silver iodides that show luminescent thermochromism. Furthermore, the results indicate that compounds <b>1</b> and <b>2</b> are promising wavelength-dependent luminescent thermometers.