Multi-controlled ternary emission of platinum(ii) switches as a visual optical sensor for enzyme and pH detection

Abstract

Near-infrared (NIR) optical sensors are widely applied in biomedical treatment, environmental monitoring, and food safety because of their advantages of avoiding the interference of self-absorption and self-emission. Herein, a pH-sensitive luminescent platinum(II) complex with dual-armed alkyl chains modified with an ammonium ionic head has been designed and explored as an NIR probe. The pH-responsive probe can switch between ternary emission, including green and dual NIR emission, from the monomer, excimer and aggregated ground states in aqueous medium, which can be further regulated by nucleoside polyphosphates via non-covalent interactions with remarkable spectroscopic changes. The time-dependent detection of the assembly/disassembly of an adenosine triphosphate (ATP) and phosphorescent platinum(II) complex can be achieved based on the continuous photophysical changes. Guanosine triphosphate (GTP) can be recognized by visualized dual apparent and emission colors among various nucleoside polyphosphates.