Tandem Restriction Between Spatial Confinement and Dipole Interaction for Suppressing Thermal Quenching of Phosphorescence from Cycloolefin Polymers

Abstract

Construction of a rigid environment is a well-developed strategy for suppressing non-radiative deactivation of organic chromophores and generating long-lived room-temperature phosphorescence (RTP). However, it is challenging for the formed rigid networks to maintain their stability at elevated temperature. In this work, a series of ester-rich cycloolefin polymers (COPs) are synthesized via controlled copolymerization procedure. The dipole interactions originated from ester groups show efficient suppressing effects on the non-radiative deactivation of multi-cyclic chromophores, achieving irradiation-dependent and multi-colored RTP. These COPs can also emit decent high-temperature phosphorescence (HTP). The investigation about the phosphorescence thermal quenching reveals that the spatial confinement of the cyclic skeleton in COPs can suppress the dissociation of dipole interactions of ester. By further incorporating bulky adamantyl groups, a breakthrough in red, yellow, and green HTP from common multi-cyclic chromophores is successfully achieved, even under hygrothermal exposure. Benefiting from the irradiation-dependent RTP and HTP performance, the obtained COPs are successfully applied in imaging under hygrothermal exposure, temperature monitoring of chemical reactions, and hydrogen peroxide detection.