Dynamic Ultralong Phosphorescence and Optical Waveguiding Switches in Silver‐Organic Complex via Reversible Single‐Crystal‐to‐Single‐Crystal Conversion

Dynamic ultralong room-temperature phosphorescent (RTP) materials with stimuli-responsive properties have attracted considerable interest for applications in sensors, light-emitting devices, and information security. Here, we introduce a novel class of silver (Ag)-organic complexes exhibiting rare, direct ultralong RTP, achieved through the heavy-atom effect of Ag⁺ ions and highly ordered assembly of coordination polymers. The Ag-based complex displays reversible solvent-responsive RTP, shifting from green to yellow emission in response to humidity and solvent variations. This transformation is driven by a solvent-mediated single-crystal-to-single-crystal (SCSC) conversion, enabling color-tunable active optical waveguides and one-dimensional (1D) polarization switching. Therefore, this study provides a new strategy for creating dynamically controllable ultralong all-phosphorescent metal-organic complexes and advances the design of stimuli-responsive 1D photonic systems for promising information encryption and anti-counterfeiting applications.