A Coordinating Small Organic Molecule with Tunable Lower Critical Solution Temperature for Efficient Management of Solar Radiation

Structurally well‐defined small molecules with lower critical solution temperature (LCST) behavior offer enormous prospects for fine‐tuning their phase transition properties to be “on‐demand” applied in the specific scene but are still underexplored. Herein, a novel amphiphilic small LCST molecule is rationally designed and synthesized. The molecule, namely TG , features a conjugation of multiple short ethylene glycol (EG) chains with the functional coordinating terpyridine (Tpy) moiety. The molecule TG demonstrates excellent LCST behavior down to 0.05 × 10 −3 m in a water solution. And a cloud point T cp = 30.9 °C with a very short thermal hysteresis Δ T = 0.2 °C and good reversibility can be achieved when c = 0.1 × 10 −3 m . The excellent LCST properties of TG have enabled its successful performance as the smart window for solar radiation management with the ∆ T lum , ∆ T IR , and ∆ T sol being 83.6%, 49.1%, and 67.2%, respectively. Moreover, the presence of Tpy moiety in TG enables its coordination with Ru 3+ and the resulting complex also exhibits modulated LCST behavior with different concentration‐dependent T cp . These studies would provide novel small‐molecule‐based scaffolds for constructing better solar radiation management systems as well as other thermal‐responsive smart materials.