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.