Organic−Inorganic Manganese Bromide Hybrids with Water‐Triggered Luminescence for Rewritable Paper

Abstract Stimuli‐responsive luminescent material‐based rewritable paper has received great attention for its potential application in a wide range of areas from anti‐counterfeiting to information encryption. Herein, a photoluminescence (PL) rewritable paper based on an organic metal halide, trans ‐2,5‐dimethylpiperazine manganese(II) bromide (C 6 N 2 H 16 MnBr 4 ) (1), is reported. This 0D organic metal halide hybrid exhibits green emission centered at 548 nm originating from 4 T 1 – 6 A 1 transition of tetrahedrally coordinated Mn 2+ ions with a PL quantum efficiency of 82%. Interestingly, complex 1 can be transformed into the non‐emissive hydrated phase C 6 N 2 H 16 MnBr 4 (H 2 O) 2 (2) by uptake of coordinating water molecules, wherein Mn 2+ adopts a quasi‐octahedral coordination sphere. The reversible single‐crystal structure transformation between the hydrated and dehydrated phases can switch the PL on and off. Rewritable PL paper has been fabricated by coating complex 1 on filter paper, which exhibits high resolution and excellent “write‐erase‐write” cycle capability. This work presents a new avenue for low‐dimensional lead‐free organic metal halide hybrids toward multilevel information security applications.