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.

单金属配位网络（coordination networks，CNs）同时展现出温度依赖寿命（temperature-dependent lifetime，TDLT）与发射带温移（temperature-dependent emission band shift，TDEBS）特性，在宽温区高精度、高可靠的发光测温领域具备极佳应用前景。然而截至目前，由于尚未在分子层面深入阐明TDLT与TDEBS的起源，此类材料的相关研究仍为空白，而明确该起源对于开发通用的双参数CN基磷光测温仪（CN-PT）的设计方案至关重要。本文通过柔性配体植入策略，构筑了热响应型CN[Cu₂(L¹)Br₂]∞（IAM21-1，L¹ = N¹,N⁶-二(吡啶-3-基)己二酰胺）。IAM21-1所具备的TDLT与TDEBS特性，使其可作为单金属双参数CN-PT应用于50~500 K的温区，这是目前已报道的最宽测温温区。结构分析与密度泛函理论（Density Functional Theory，DFT）计算结果表明，随温度降低而发生的发射带红移，源于可逆骨架收缩引发的带隙收窄。本研究阐明了TDLT与TDEBS特性的起源，并为双参数CN-PT的设计提供了高效可行的策略。