Cross‐Linked Rhodium( III )‐Containing Polysiloxanes With Low‐Temperature Photoluminescence

ABSTRACT

Poly(2,2′‐bipyridine‐4,4′‐dicarboxamide‐ co ‐polydimethylsiloxanes) were cross‐linked by coordination with Rh ³⁺ to obtain flexible and stretchable polymer‐metal complexes (PMCs). The structure of the PMCs was confirmed by FTIR, UV–vis, CV, and by comparison with similar‐in‐structure low‐molecular weight Rh(III) bipyridine complexes. Upon UV–vis irradiation ( λ _ex  = 345–354 nm), the obtained Rh(III)‐containing PMCs exhibit yellow‐red phosphorescence at λ _em  = 672–767 nm and increased lifetime up to τ  = 2.44 ms under liquid nitrogen temperature (−196.2°C). The PMCs possess a wide range of elongation at break (up to 672%), tensile strength (up to 7.2 MPa) and self‐healing properties with efficiency up to 79% at room temperature and 90% at 100°C (especially for PMCs having M _n  = 25,000 of PDMS chain). Thus, the significant rise in phosphorescence intensity and lifetime by 420–430 times (from τ  = 5.4–5.8 μs to 2.3–2.4 ms) upon cooling from room temperature to −196.2°C enables these Rh(III)‐containing PMCs to act as luminescent thermometers, offering potential for cryogenic technologies in optoelectronics, aerospace applications, and biomedicine where non‐invasive temperature monitoring is crucial.