Reversible Red-green Photoluminescence Transformation Induced by Dynamic Coordination Bonds in a Phase-transition Hybrid Crystal

Abstract

Photoluminescence (PL) switchable materials have become an important class of intelligent materials for promising applications in sensors, anti-counterfeit and information storage. A longstanding challenge lies in the rational design of highcontrast, quick-response and reversible PL switch. Herein, we present a new organic-inorganic hybrid metal halide crystal, (C9H13N2O)2MnCl4 (1), which undergoes two-step P1 (1α)-P1 (1TS)-I42d (1β) phase transitions at 378 K and 423 K during heating process, accompanied by PL colour changes from red in 1α, to orange in 1TS and green in 1β, respectively. Moreover, 1β could controllably return to 1α under different humidity conditions. Detailed structural studies reveal that the reversible transition is driven by the breaking and reformation of Mn-O bonds between C9H13N2O + cations and Mn 2+ . In convenience of the good cyclability and high sensitivity of such phase-transition induced PL transformation, we designed different models to demonstrate the application in optical encryption. This work provides a new insight for designing stimulus-responsive luminescent materials through dynamic chemical bonding for advanced optical materials with tenable and recoverable properties.