Single-Metallic Thermoresponsive Coordination Network as a Dual-Parametric Luminescent Thermometer

The single-metallic coordination networks (CNs), simultaneously exhibiting temperature-dependent lifetime (TDLT) and emission band shift (TDEBS), are desirable for application in luminescent thermometers with high accuracy and reliability in a large temperature range. Nonetheless, up to date, there are no reports on such kinds of materials due to the lack of in-depth understanding of the origin of TDLT and TDEBS at a molecule level, being critical for exploiting a universal approach to design a dual-parametric CN phosphorescent thermometer (CN-PT). Herein, we have constructed a thermoresponsive CN [Cu₂(L1)Br₂]_∞ (IAM21-1, L1 = N¹,N⁶-di(pyridin-3-yl)adipamide) via a flexible-ligand-implanted strategy. The TDLT and TDEBS properties of IAM21-1 enable it to be applied as a single-metallic dual-parametric CN-PT in 50-500 K, which is the widest temperature range reported so far. The combination of structure analysis and DFT calculations demonstrates that the redshift of the emission band upon the decreasing temperature originates from the reversible skeleton-shrinkage-triggered narrower band gap. This work has unveiled the origin of TDLT and TDEBS properties and proposed an efficient strategy for designing dual-parametric CN-PTs.