Developing luminescent ratiometric thermometers based on copolymers containing Platinum(II) isocyanide complex

Luminescent platinum(II) small molecules have aroused much attention due to their unique Pt(II)-Pt(II) interaction and intriguing luminescence properties; while incorporation of Pt(II) centers into polymers is still in its infancy. In this work, a class of random copolymers ((M-1)(x)-co-(M-pt)(y); x = 200, y = 1, 2, 4) was synthesized by copolymerization of a newly designed norbornene-functionalized platinum(II) complex M-pt and oligoethylene glycol modified monomer M-1 using ROMP method. Compared to monomer M-pt, the resulting polymers exhibit enhanced Pt(II)-Pt(II) interaction and intense low-energy emissions because of the confinement effect. Moreover, the photophysical properties of M-pt and polymers ((M-1)(x)-co-(Mp(t))(y); x = 200, y = 1, 2, 4) were found to be highly dependent on the solvents and platinum(II) content in the polymers. Through switching on and off of the Pt(II)-Pt(II) interaction, (M-1)(200)-co-(M-pt)(4) has been successfully demonstrated to be a self-referenced luminescent thermometer, which showed 2.11% KD-1 (in TCE, 278K) relative temperature sensitivity, excellent reversibility and repeatability.

Automated summary

Luminescent platinum(II) small molecules have unique properties due to Pt(II)-Pt(II) interaction, while the incorporation of Pt(II) into polymers is still in early stages. In this study, random copolymers were synthesized using ROMP method, showing enhanced Pt(II)-Pt(II) interaction and intense low-energy emissions. The photophysical properties of the polymers were highly dependent on solvents and Pt(II) content, with one polymer successfully demonstrated as a self-referenced luminescent thermometer.