Coordination-Induced Syntheses of Two Hybrid Framework Iodides: A Thermochromic Luminescent Thermometer

Two
new 3D hybrid framework iodides, Hmta­[(Hmta)­Ag4I4] (1; Hmta = hexamethylenetetramine) and [(Hmta)2Ag8I6]­I2 (2),
have been synthesized under solvothermal conditions. Compound 1 consists of a neutral 3D framework built up from alternation
of the tetrahedral Ag4I4 unit and Hmta with
dia-b topology. Compound 2 features a 3D cationic framework
with flu topology, constructed by cationic [Ag8I6]2+ units linked with Hmta. Tetrahedral Hmta plays crucial
structure-directing roles in the formation of these 3D frameworks
with high symmetry. The temperature-dependent photoluminescent measurement
reveals luminescent thermochromism of the compounds, the emission
maximum of which shows a gradual blue shift with increasing temperature.
The results indicate that 1 is a promising wavelength-
and intensity-dependent luminescent thermometer applicable in two
different temperature ranges.