Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes. In accordance with certain aspects of the present invention, a thermochromic system is disclosed comprising a transition metal ion and a ligand wherein the ligand comprises a nitrogen-containing five or six membered heterocyclic compound that coordinates through the nitrogen atom to the transition metal ion in a H?MLC formed between the transition metal ion and the ligand.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes. In accordance with one aspect of the present invention, a thermochromic system is disclosed comprising a first metal ion and a second metal ion and at least one ligand that complexes with the first metal ion to form a L?MLC and complexes with the second metal ion to form a H?MLC wherein an increase in temperature of the system results in a reversible net increase in its ability to absorb light energy in the 400 nm to 1400 nm range due to the ligand transferring from the first metal ion to the second metal ion.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes. In accordance with one aspect of the present invention, a thermochromic device is disclosed comprising at least two thermochromic layers when each thermochromic layer includes a polymer, at least one transition metal ion, at least one H?L ligand capable of forming a H?MLC with the transition metal ion and at least one L?L ligand capable of forming an L?MLC with the transition metal ion.

Abstract: Ligand exchange of thermochromic, LETC, systems exhibiting a reversible change in absorbance of electromagnetic radiation as the temperature of the system is reversibly changed are described. The described LETC systems include one or more than one transition metal ion, which experiences thermally induced changes in the nature of the complexation or coordination around the transition metal ion(s) and, thereby, the system changes its ability to absorb electromagnetic radiation as the temperature changes.

Abstract: An energy efficient, thermochromic device that may be used to allow sunlight or solar radiation into a building or structure when sunlight is absent or at high sun angles and substantially blocks solar radiation when sunlight is directly on the window.